17 files changed, 1638 insertions, 2278 deletions

diff --git a/applypatch/Android.mk b/applypatch/Android.mk
index 2f96f0ab7..9cbe3e2a9 100644
--- a/applypatch/Android.mk
+++ b/applypatch/Android.mk
@@ -31,6 +31,7 @@ $(foreach board_define,$(BOARD_RECOVERY_DEFINES), \
   )
 
 LOCAL_C_INCLUDES += \
+    $(LOCAL_PATH)/include \
     external/bzip2 \
     external/zlib \
     $(commands_recovery_local_path)
@@ -42,27 +43,99 @@ LOCAL_MODULE_TAGS := eng
 LOCAL_C_INCLUDES += $(RECOVERY_PATH)
 LOCAL_STATIC_LIBRARIES += libbase libotafault libmtdutils libcrypto_static libbz libz
 
+# libapplypatch (static library)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    applypatch.cpp \
+    bspatch.cpp \
+    freecache.cpp \
+    imgpatch.cpp
+LOCAL_MODULE := libapplypatch
+LOCAL_MODULE_TAGS := eng
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include \
+    $(commands_recovery_local_path)
+LOCAL_STATIC_LIBRARIES := \
+    libotafault \
+    libbase \
+    libcrypto \
+    libbspatch \
+    libbz \
+    libz
+LOCAL_WHOLE_STATIC_LIBRARIES += libmtdutils
+LOCAL_CFLAGS := \
+    -DZLIB_CONST \
+    -Werror
 include $(BUILD_STATIC_LIBRARY)
 
+# libimgpatch (static library)
+# ===============================
 include $(CLEAR_VARS)
 
-ifeq ($(HOST_OS),linux)
-include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    bspatch.cpp \
+    imgpatch.cpp
+LOCAL_MODULE := libimgpatch
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include \
+    $(commands_recovery_local_path)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_STATIC_LIBRARIES := \
+    libcrypto \
+    libbspatch \
+    libbase \
+    libbz \
+    libz
+LOCAL_CFLAGS := \
+    -DZLIB_CONST \
+    -Werror
+include $(BUILD_STATIC_LIBRARY)
 
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := bspatch.cpp imgpatch.cpp utils.cpp
+# libimgpatch (host static library)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    bspatch.cpp \
+    imgpatch.cpp
 LOCAL_MODULE := libimgpatch
 LOCAL_C_INCLUDES += $(RECOVERY_PATH)
+LOCAL_MODULE_HOST_OS := linux
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include \
+    $(commands_recovery_local_path)
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES += libcrypto_static libbz libz
-
+LOCAL_STATIC_LIBRARIES := \
+    libcrypto \
+    libbspatch \
+    libbase \
+    libbz \
+    libz
+LOCAL_CFLAGS := \
+    -DZLIB_CONST \
+    -Werror
 include $(BUILD_HOST_STATIC_LIBRARY)
-endif  # HOST_OS == linux
 
+# libapplypatch_modes (static library)
+# ===============================
 include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    applypatch_modes.cpp
+LOCAL_MODULE := libapplypatch_modes
+LOCAL_C_INCLUDES := $(commands_recovery_local_path)
+LOCAL_STATIC_LIBRARIES := \
+    libapplypatch \
+    libbase \
+    libedify \
+    libcrypto
+LOCAL_CFLAGS := -Werror
+include $(BUILD_STATIC_LIBRARY)
 
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := main.cpp
+# applypatch (target executable)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := applypatch_main.cpp
 LOCAL_MODULE := applypatch
 LOCAL_C_INCLUDES += $(RECOVERY_PATH)
 LOCAL_STATIC_LIBRARIES += libapplypatch libbase libotafault libmtdutils libcrypto_static libbz \
@@ -70,15 +143,78 @@ LOCAL_STATIC_LIBRARIES += libapplypatch libbase libotafault libmtdutils libcrypt
 
 LOCAL_SHARED_LIBRARIES += libz libcutils libc
 
+LOCAL_C_INCLUDES := $(commands_recovery_local_path)
+LOCAL_STATIC_LIBRARIES := \
+    libapplypatch_modes \
+    libapplypatch \
+    libbase \
+    libedify \
+    libotafault \
+    libcrypto \
+    libbspatch \
+    libbz
+LOCAL_SHARED_LIBRARIES := \
+    libbase \
+    libz \
+    libcutils
+LOCAL_CFLAGS := -Werror
 include $(BUILD_EXECUTABLE)
 
+libimgdiff_src_files := imgdiff.cpp
+
+# libbsdiff is compiled with -D_FILE_OFFSET_BITS=64.
+libimgdiff_cflags := \
+    -Werror \
+    -D_FILE_OFFSET_BITS=64
+
+libimgdiff_static_libraries := \
+    libbsdiff \
+    libdivsufsort \
+    libdivsufsort64 \
+    libziparchive \
+    libutils \
+    liblog \
+    libbase \
+    libz
+
+# libimgdiff (static library)
+# ===============================
 include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    $(libimgdiff_src_files)
+LOCAL_MODULE := libimgdiff
+LOCAL_CFLAGS := \
+    $(libimgdiff_cflags)
+LOCAL_STATIC_LIBRARIES := \
+    $(libimgdiff_static_libraries)
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+include $(BUILD_STATIC_LIBRARY)
 
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := imgdiff.cpp utils.cpp bsdiff.cpp
-LOCAL_MODULE := imgdiff
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_C_INCLUDES += external/zlib external/bzip2
-LOCAL_STATIC_LIBRARIES += libz libbz
+# libimgdiff (host static library)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    $(libimgdiff_src_files)
+LOCAL_MODULE := libimgdiff
+LOCAL_CFLAGS := \
+    $(libimgdiff_cflags)
+LOCAL_STATIC_LIBRARIES := \
+    $(libimgdiff_static_libraries)
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+include $(BUILD_HOST_STATIC_LIBRARY)
 
+# imgdiff (host static executable)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := imgdiff_main.cpp
+LOCAL_MODULE := imgdiff
+LOCAL_CFLAGS := -Werror
+LOCAL_STATIC_LIBRARIES := \
+    libimgdiff \
+    $(libimgdiff_static_libraries) \
+    libbz
 include $(BUILD_HOST_EXECUTABLE)
diff --git a/applypatch/Makefile b/applypatch/Makefile
new file mode 100644
index 000000000..fb4984303
--- /dev/null
+++ b/applypatch/Makefile
@@ -0,0 +1,33 @@
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is for building imgdiff in Chrome OS.
+
+CPPFLAGS += -iquote.. -Iinclude
+CXXFLAGS += -std=c++11 -O3 -Wall -Werror
+LDLIBS += -lbz2 -lz
+
+.PHONY: all clean
+
+all: imgdiff libimgpatch.a
+
+clean:
+	rm -f *.o imgdiff libimgpatch.a
+
+imgdiff: imgdiff.o bsdiff.o utils.o
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(LDLIBS) -o $@ $^
+
+libimgpatch.a utils.o: CXXFLAGS += -fPIC
+libimgpatch.a: imgpatch.o bspatch.o utils.o
+	${AR} rcs $@ $^
diff --git a/applypatch/applypatch.cpp b/applypatch/applypatch.cpp
index c2fe11b3b..54c37eb34 100644
--- a/applypatch/applypatch.cpp
+++ b/applypatch/applypatch.cpp
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "applypatch/applypatch.h"
+
 #include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
@@ -27,72 +29,65 @@
 
 #include <memory>
 #include <string>
+#include <utility>
+#include <vector>
 
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
 #include <android-base/strings.h>
+#include <openssl/sha.h>
 
-#include "openssl/sha.h"
-#include "applypatch.h"
 #include "bmlutils/bmlutils.h"
 #include "mtdutils/mtdutils.h"
+
 #include "edify/expr.h"
 #include "ota_io.h"
 #include "print_sha1.h"
 
-static int LoadPartitionContents(const char* filename, FileContents* file);
+static int LoadPartitionContents(const std::string& filename, FileContents* file);
 static ssize_t FileSink(const unsigned char* data, ssize_t len, void* token);
-static int GenerateTarget(FileContents* source_file,
-                          const Value* source_patch_value,
-                          FileContents* copy_file,
-                          const Value* copy_patch_value,
-                          const char* source_filename,
-                          const char* target_filename,
-                          const uint8_t target_sha1[SHA_DIGEST_LENGTH],
-                          size_t target_size,
-                          const Value* bonus_data);
+static int GenerateTarget(const FileContents& source_file, const std::unique_ptr<Value>& patch,
+                          const std::string& target_filename,
+                          const uint8_t target_sha1[SHA_DIGEST_LENGTH], const Value* bonus_data);
 
 static bool mtd_partitions_scanned = false;
 
-// Read a file into memory; store the file contents and associated
-// metadata in *file.
-//
+// Read a file into memory; store the file contents and associated metadata in *file.
 // Return 0 on success.
 int LoadFileContents(const char* filename, FileContents* file) {
-    // A special 'filename' beginning with "MTD:" or "EMMC:" means to
-    // load the contents of a partition.
-    if (strncmp(filename, "MTD:", 4) == 0 ||
-        strncmp(filename, "EMMC:", 5) == 0 ||
-        strncmp(filename, "BML:", 4) == 0) {
-        return LoadPartitionContents(filename, file);
-    }
-
-    if (stat(filename, &file->st) != 0) {
-        printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
-        return -1;
-    }
+  // A special 'filename' beginning with "MTD:" or "EMMC:" means to
+  // load the contents of a partition.
+  if (strncmp(filename, "MTD:", 4) == 0 ||
+    strncmp(filename, "EMMC:", 5) == 0 ||
+    strncmp(filename, "BML:", 4) == 0) {
+    return LoadPartitionContents(filename, file);
+  }
+
+  if (stat(filename, &file->st) == -1) {
+    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+    return -1;
+  }
 
-    std::vector<unsigned char> data(file->st.st_size);
-    FILE* f = ota_fopen(filename, "rb");
-    if (f == NULL) {
-        printf("failed to open \"%s\": %s\n", filename, strerror(errno));
-        return -1;
-    }
+  std::vector<unsigned char> data(file->st.st_size);
+  unique_file f(ota_fopen(filename, "rb"));
+  if (!f) {
+    printf("failed to open \"%s\": %s\n", filename, strerror(errno));
+    return -1;
+  }
 
-    size_t bytes_read = ota_fread(data.data(), 1, data.size(), f);
-    if (bytes_read != data.size()) {
-        printf("short read of \"%s\" (%zu bytes of %zd)\n", filename, bytes_read, data.size());
-        ota_fclose(f);
-        return -1;
-    }
-    ota_fclose(f);
-    file->data = std::move(data);
-    SHA1(file->data.data(), file->data.size(), file->sha1);
-    return 0;
+  size_t bytes_read = ota_fread(data.data(), 1, data.size(), f.get());
+  if (bytes_read != data.size()) {
+    printf("short read of \"%s\" (%zu bytes of %zu)\n", filename, bytes_read, data.size());
+    return -1;
+  }
+  file->data = std::move(data);
+  SHA1(file->data.data(), file->data.size(), file->sha1);
+  return 0;
 }
 
-// Load the contents of an MTD or EMMC partition into the provided
+// Load the contents of an EMMC partition into the provided
 // FileContents.  filename should be a string of the form
-// "MTD:<partition_name>:<size_1>:<sha1_1>:<size_2>:<sha1_2>:..."  (or
-// "EMMC:<partition_device>:...").  The smallest size_n bytes for
+// "EMMC:<partition_device>:...".  The smallest size_n bytes for
 // which that prefix of the partition contents has the corresponding
 // sha1 hash will be loaded.  It is acceptable for a size value to be
 // repeated with different sha1s.  Will return 0 on success.
@@ -106,223 +101,166 @@ int LoadFileContents(const char* filename, FileContents* file) {
 // to find one of those hashes.
 enum PartitionType { MTD, EMMC };
 
-static int LoadPartitionContents(const char* filename, FileContents* file) {
-    std::string copy(filename);
-    std::vector<std::string> pieces = android::base::Split(copy, ":");
-    if (pieces.size() < 4 || pieces.size() % 2 != 0) {
-        printf("LoadPartitionContents called with bad filename (%s)\n", filename);
-        return -1;
-    }
-
-    enum PartitionType type;
-    if (pieces[0] == "MTD") {
-        type = MTD;
-    } else if (pieces[0] == "EMMC") {
-        type = EMMC;
-    } else if (pieces[0] == "BML") {
-        type = EMMC;
-    } else {
-        printf("LoadPartitionContents called with bad filename (%s)\n", filename);
+static int LoadPartitionContents(const std::string& filename, FileContents* file) {
+  std::vector<std::string> pieces = android::base::Split(filename, ":");
+  if (pieces.size() < 4 || pieces.size() % 2 != 0) {
+    printf("LoadPartitionContents called with bad filename \"%s\"\n", filename.c_str());
+    return -1;
+  }
+
+  enum PartitionType type;
+  if (pieces[0] == "MTD") {
+    type = MTD;
+  } else if (pieces[0] == "EMMC") {
+    type = EMMC;
+  } else if (pieces[0] == "BML") {
+    type = EMMC;
+  } else {
+    printf("LoadPartitionContents called with bad filename (%s)\n", filename.c_str());
+    return -1;
+  }
+
+  size_t pair_count = (pieces.size() - 2) / 2;  // # of (size, sha1) pairs in filename
+  std::vector<std::pair<size_t, std::string>> pairs;
+  for (size_t i = 0; i < pair_count; ++i) {
+    size_t size;
+    if (!android::base::ParseUint(pieces[i * 2 + 2], &size) || size == 0) {
+      printf("LoadPartitionContents called with bad size \"%s\"\n", pieces[i * 2 + 2].c_str());
+      return -1;
+    }
+    pairs.push_back({ size, pieces[i * 2 + 3] });
+  }
+
+  // Sort the pairs array so that they are in order of increasing size.
+  std::sort(pairs.begin(), pairs.end());
+
+  const char* partition = pieces[1].c_str();
+  unique_file dev(ota_fopen(partition, "rb"));
+  if (!dev) {
+    printf("failed to open emmc partition \"%s\": %s\n", partition, strerror(errno));
+    return -1;
+  }
+
+  SHA_CTX sha_ctx;
+  SHA1_Init(&sha_ctx);
+
+  // Allocate enough memory to hold the largest size.
+  std::vector<unsigned char> buffer(pairs[pair_count - 1].first);
+  unsigned char* buffer_ptr = buffer.data();
+  size_t buffer_size = 0;  // # bytes read so far
+  bool found = false;
+
+  for (const auto& pair : pairs) {
+    size_t current_size = pair.first;
+    const std::string& current_sha1 = pair.second;
+
+    // Read enough additional bytes to get us up to the next size. (Again,
+    // we're trying the possibilities in order of increasing size).
+    size_t next = current_size - buffer_size;
+    if (next > 0) {
+      size_t read = ota_fread(buffer_ptr, 1, next, dev.get());
+      if (next != read) {
+        printf("short read (%zu bytes of %zu) for partition \"%s\"\n", read, next, partition);
         return -1;
+      }
+      SHA1_Update(&sha_ctx, buffer_ptr, read);
+      buffer_size += read;
+      buffer_ptr += read;
     }
-    const char* partition = pieces[1].c_str();
 
     if (pieces[0] == "BML") {
-        if (strcmp(partition, "boot") == 0) {
-            partition = BOARD_BML_BOOT;
-        } else if (strcmp(partition, "recovery") == 0) {
-            partition = BOARD_BML_RECOVERY;
-        }
+      if (strcmp(partition, "boot") == 0) {
+        partition = BOARD_BML_BOOT;
+      } else if (strcmp(partition, "recovery") == 0) {
+        partition = BOARD_BML_RECOVERY;
+      }
     }
 
-    size_t pairs = (pieces.size() - 2) / 2;    // # of (size, sha1) pairs in filename
-    std::vector<size_t> index(pairs);
-    std::vector<size_t> size(pairs);
-    std::vector<std::string> sha1sum(pairs);
-
-    for (size_t i = 0; i < pairs; ++i) {
-        size[i] = strtol(pieces[i*2+2].c_str(), NULL, 10);
-        if (size[i] == 0) {
-            printf("LoadPartitionContents called with bad size (%s)\n", filename);
-            return -1;
-        }
-        sha1sum[i] = pieces[i*2+3].c_str();
-        index[i] = i;
-    }
-
-    // Sort the index[] array so it indexes the pairs in order of increasing size.
-    sort(index.begin(), index.end(),
-        [&](const size_t& i, const size_t& j) {
-            return (size[i] < size[j]);
-        }
-    );
-
-    MtdReadContext* ctx = NULL;
-    FILE* dev = NULL;
-
-    switch (type) {
-        case MTD: {
-            if (!mtd_partitions_scanned) {
-                mtd_scan_partitions();
-                mtd_partitions_scanned = true;
-            }
-
-            const MtdPartition* mtd = mtd_find_partition_by_name(partition);
-            if (mtd == NULL) {
-                printf("mtd partition \"%s\" not found (loading %s)\n", partition, filename);
-                return -1;
-            }
+    // Duplicate the SHA context and finalize the duplicate so we can
+    // check it against this pair's expected hash.
+    SHA_CTX temp_ctx;
+    memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
+    uint8_t sha_so_far[SHA_DIGEST_LENGTH];
+    SHA1_Final(sha_so_far, &temp_ctx);
 
-            ctx = mtd_read_partition(mtd);
-            if (ctx == NULL) {
-                printf("failed to initialize read of mtd partition \"%s\"\n", partition);
-                return -1;
-            }
-            break;
-        }
-
-        case EMMC:
-            dev = ota_fopen(partition, "rb");
-            if (dev == NULL) {
-                printf("failed to open emmc partition \"%s\": %s\n", partition, strerror(errno));
-                return -1;
-            }
-    }
-
-    SHA_CTX sha_ctx;
-    SHA1_Init(&sha_ctx);
     uint8_t parsed_sha[SHA_DIGEST_LENGTH];
-
-    // Allocate enough memory to hold the largest size.
-    std::vector<unsigned char> data(size[index[pairs-1]]);
-    char* p = reinterpret_cast<char*>(data.data());
-    size_t data_size = 0;                // # bytes read so far
-    bool found = false;
-
-    for (size_t i = 0; i < pairs; ++i) {
-        // Read enough additional bytes to get us up to the next size. (Again,
-        // we're trying the possibilities in order of increasing size).
-        size_t next = size[index[i]] - data_size;
-        if (next > 0) {
-            size_t read = 0;
-            switch (type) {
-                case MTD:
-                    read = mtd_read_data(ctx, p, next);
-                    break;
-
-                case EMMC:
-                    read = ota_fread(p, 1, next, dev);
-                    break;
-            }
-            if (next != read) {
-                printf("short read (%zu bytes of %zu) for partition \"%s\"\n",
-                       read, next, partition);
-                return -1;
-            }
-            SHA1_Update(&sha_ctx, p, read);
-            data_size += read;
-            p += read;
-        }
-
-        // Duplicate the SHA context and finalize the duplicate so we can
-        // check it against this pair's expected hash.
-        SHA_CTX temp_ctx;
-        memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
-        uint8_t sha_so_far[SHA_DIGEST_LENGTH];
-        SHA1_Final(sha_so_far, &temp_ctx);
-
-        if (ParseSha1(sha1sum[index[i]].c_str(), parsed_sha) != 0) {
-            printf("failed to parse sha1 %s in %s\n", sha1sum[index[i]].c_str(), filename);
-            return -1;
-        }
-
-        if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_LENGTH) == 0) {
-            // we have a match.  stop reading the partition; we'll return
-            // the data we've read so far.
-            printf("partition read matched size %zu sha %s\n",
-                   size[index[i]], sha1sum[index[i]].c_str());
-            found = true;
-            break;
-        }
+    if (ParseSha1(current_sha1.c_str(), parsed_sha) != 0) {
+      printf("failed to parse SHA-1 %s in %s\n", current_sha1.c_str(), filename.c_str());
+      return -1;
     }
 
-    switch (type) {
-        case MTD:
-            mtd_read_close(ctx);
-            break;
-
-        case EMMC:
-            ota_fclose(dev);
-            break;
+    if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_LENGTH) == 0) {
+      // We have a match. Stop reading the partition; we'll return the data we've read so far.
+      printf("partition read matched size %zu SHA-1 %s\n", current_size, current_sha1.c_str());
+      found = true;
+      break;
     }
+  }
 
+  if (!found) {
+    // Ran off the end of the list of (size, sha1) pairs without finding a match.
+    printf("contents of partition \"%s\" didn't match %s\n", partition, filename.c_str());
+    return -1;
+  }
 
-    if (!found) {
-        // Ran off the end of the list of (size,sha1) pairs without finding a match.
-        printf("contents of partition \"%s\" didn't match %s\n", partition, filename);
-        return -1;
-    }
-
-    SHA1_Final(file->sha1, &sha_ctx);
+  SHA1_Final(file->sha1, &sha_ctx);
 
-    data.resize(data_size);
-    file->data = std::move(data);
-    // Fake some stat() info.
-    file->st.st_mode = 0644;
-    file->st.st_uid = 0;
-    file->st.st_gid = 0;
+  buffer.resize(buffer_size);
+  file->data = std::move(buffer);
+  // Fake some stat() info.
+  file->st.st_mode = 0644;
+  file->st.st_uid = 0;
+  file->st.st_gid = 0;
 
-    return 0;
+  return 0;
 }
 
-
 // Save the contents of the given FileContents object under the given
 // filename.  Return 0 on success.
 int SaveFileContents(const char* filename, const FileContents* file) {
-    int fd = ota_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC, S_IRUSR | S_IWUSR);
-    if (fd < 0) {
-        printf("failed to open \"%s\" for write: %s\n", filename, strerror(errno));
-        return -1;
-    }
+  unique_fd fd(ota_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC, S_IRUSR | S_IWUSR));
+  if (fd == -1) {
+    printf("failed to open \"%s\" for write: %s\n", filename, strerror(errno));
+    return -1;
+  }
 
-    ssize_t bytes_written = FileSink(file->data.data(), file->data.size(), &fd);
-    if (bytes_written != static_cast<ssize_t>(file->data.size())) {
-        printf("short write of \"%s\" (%zd bytes of %zu) (%s)\n",
-               filename, bytes_written, file->data.size(), strerror(errno));
-        ota_close(fd);
-        return -1;
-    }
-    if (ota_fsync(fd) != 0) {
-        printf("fsync of \"%s\" failed: %s\n", filename, strerror(errno));
-        return -1;
-    }
-    if (ota_close(fd) != 0) {
-        printf("close of \"%s\" failed: %s\n", filename, strerror(errno));
-        return -1;
-    }
+  ssize_t bytes_written = FileSink(file->data.data(), file->data.size(), &fd);
+  if (bytes_written != static_cast<ssize_t>(file->data.size())) {
+    printf("short write of \"%s\" (%zd bytes of %zu): %s\n", filename, bytes_written,
+           file->data.size(), strerror(errno));
+    return -1;
+  }
+  if (ota_fsync(fd) != 0) {
+    printf("fsync of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
+  if (ota_close(fd) != 0) {
+    printf("close of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
 
-    if (chmod(filename, file->st.st_mode) != 0) {
-        printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
-        return -1;
-    }
-    if (chown(filename, file->st.st_uid, file->st.st_gid) != 0) {
-        printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
-        return -1;
-    }
+  if (chmod(filename, file->st.st_mode) != 0) {
+    printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
+  if (chown(filename, file->st.st_uid, file->st.st_gid) != 0) {
+    printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
+    return -1;
+  }
 
-    return 0;
+  return 0;
 }
 
 // Write a memory buffer to 'target' partition, a string of the form
-// "MTD:<partition>[:...]" or "EMMC:<partition_device>[:...]". The target name
+// "EMMC:<partition_device>[:...]". The target name
 // might contain multiple colons, but WriteToPartition() only uses the first
 // two and ignores the rest. Return 0 on success.
-int WriteToPartition(const unsigned char* data, size_t len, const char* target) {
+int WriteToPartition(const unsigned char* data, size_t len, const std::string& target) {
     std::string copy(target);
     std::vector<std::string> pieces = android::base::Split(copy, ":");
 
     if (pieces.size() < 2) {
-        printf("WriteToPartition called with bad target (%s)\n", target);
+        printf("WriteToPartition called with bad target (%s)\n", target.c_str());
         return -1;
     }
 
@@ -334,7 +272,7 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
     } else if (pieces[0] == "BML") {
         type = EMMC;
     } else {
-        printf("WriteToPartition called with bad target (%s)\n", target);
+        printf("WriteToPartition called with bad target (%s)\n", target.c_str());
         return -1;
     }
 
@@ -358,7 +296,7 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
     }
 
     if (partition == NULL) {
-        printf("bad partition target name \"%s\"\n", target);
+        printf("bad partition target name \"%s\"\n", target.c_str());
         return -1;
     }
 
@@ -404,7 +342,7 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
         case EMMC: {
             size_t start = 0;
             bool success = false;
-            int fd = ota_open(partition, O_RDWR | O_SYNC);
+            unique_fd fd(ota_open(partition, O_RDWR | O_SYNC));
             if (fd < 0) {
                 printf("failed to open %s: %s\n", partition, strerror(errno));
                 return -1;
@@ -434,7 +372,7 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
                    printf("failed to close %s (%s)\n", partition, strerror(errno));
                    return -1;
                 }
-                fd = ota_open(partition, O_RDONLY);
+                unique_fd fd(ota_open(partition, O_RDONLY));
                 if (fd < 0) {
                    printf("failed to reopen %s for verify (%s)\n", partition, strerror(errno));
                    return -1;
@@ -443,7 +381,7 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
                 // Drop caches so our subsequent verification read
                 // won't just be reading the cache.
                 sync();
-                int dc = ota_open("/proc/sys/vm/drop_caches", O_WRONLY);
+                unique_fd dc(ota_open("/proc/sys/vm/drop_caches", O_WRONLY));
                 if (TEMP_FAILURE_RETRY(ota_write(dc, "3\n", 2)) == -1) {
                     printf("write to /proc/sys/vm/drop_caches failed: %s\n", strerror(errno));
                 } else {
@@ -513,7 +451,6 @@ int WriteToPartition(const unsigned char* data, size_t len, const char* target)
     return 0;
 }
 
-
 // Take a string 'str' of 40 hex digits and parse it into the 20
 // byte array 'digest'.  'str' may contain only the digest or be of
 // the form "<digest>:<anything>".  Return 0 on success, -1 on any
@@ -546,52 +483,47 @@ int ParseSha1(const char* str, uint8_t* digest) {
 // Search an array of sha1 strings for one matching the given sha1.
 // Return the index of the match on success, or -1 if no match is
 // found.
-int FindMatchingPatch(uint8_t* sha1, char* const * const patch_sha1_str,
-                      int num_patches) {
+static int FindMatchingPatch(uint8_t* sha1, const std::vector<std::string>& patch_sha1_str) {
+  for (size_t i = 0; i < patch_sha1_str.size(); ++i) {
     uint8_t patch_sha1[SHA_DIGEST_LENGTH];
-    for (int i = 0; i < num_patches; ++i) {
-        if (ParseSha1(patch_sha1_str[i], patch_sha1) == 0 &&
-            memcmp(patch_sha1, sha1, SHA_DIGEST_LENGTH) == 0) {
-            return i;
-        }
+    if (ParseSha1(patch_sha1_str[i].c_str(), patch_sha1) == 0 &&
+        memcmp(patch_sha1, sha1, SHA_DIGEST_LENGTH) == 0) {
+      return i;
     }
-    return -1;
+  }
+  return -1;
 }
 
 // Returns 0 if the contents of the file (argv[2]) or the cached file
 // match any of the sha1's on the command line (argv[3:]).  Returns
 // nonzero otherwise.
-int applypatch_check(const char* filename, int num_patches,
-                     char** const patch_sha1_str) {
-    FileContents file;
-
-    // It's okay to specify no sha1s; the check will pass if the
-    // LoadFileContents is successful.  (Useful for reading
-    // partitions, where the filename encodes the sha1s; no need to
-    // check them twice.)
-    if (LoadFileContents(filename, &file) != 0 ||
-        (num_patches > 0 &&
-         FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0)) {
-        printf("file \"%s\" doesn't have any of expected "
-               "sha1 sums; checking cache\n", filename);
-
-        // If the source file is missing or corrupted, it might be because
-        // we were killed in the middle of patching it.  A copy of it
-        // should have been made in CACHE_TEMP_SOURCE.  If that file
-        // exists and matches the sha1 we're looking for, the check still
-        // passes.
-
-        if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
-            printf("failed to load cache file\n");
-            return 1;
-        }
-
-        if (FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0) {
-            printf("cache bits don't match any sha1 for \"%s\"\n", filename);
-            return 1;
-        }
-    }
-    return 0;
+int applypatch_check(const char* filename, const std::vector<std::string>& patch_sha1_str) {
+  FileContents file;
+
+  // It's okay to specify no sha1s; the check will pass if the
+  // LoadFileContents is successful.  (Useful for reading
+  // partitions, where the filename encodes the sha1s; no need to
+  // check them twice.)
+  if (LoadFileContents(filename, &file) != 0 ||
+      (!patch_sha1_str.empty() && FindMatchingPatch(file.sha1, patch_sha1_str) < 0)) {
+    printf("file \"%s\" doesn't have any of expected sha1 sums; checking cache\n", filename);
+
+    // If the source file is missing or corrupted, it might be because
+    // we were killed in the middle of patching it.  A copy of it
+    // should have been made in CACHE_TEMP_SOURCE.  If that file
+    // exists and matches the sha1 we're looking for, the check still
+    // passes.
+    if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
+      printf("failed to load cache file\n");
+      return 1;
+    }
+
+    if (FindMatchingPatch(file.sha1, patch_sha1_str) < 0) {
+      printf("cache bits don't match any sha1 for \"%s\"\n", filename);
+      return 1;
+    }
+  }
+  return 0;
 }
 
 int ShowLicenses() {
@@ -633,116 +565,97 @@ size_t FreeSpaceForFile(const char* filename) {
 
 int CacheSizeCheck(size_t bytes) {
     if (MakeFreeSpaceOnCache(bytes) < 0) {
-        printf("unable to make %ld bytes available on /cache\n", (long)bytes);
+        printf("unable to make %zu bytes available on /cache\n", bytes);
         return 1;
     } else {
         return 0;
     }
 }
 
-// This function applies binary patches to files in a way that is safe
-// (the original file is not touched until we have the desired
-// replacement for it) and idempotent (it's okay to run this program
-// multiple times).
+// This function applies binary patches to EMMC target files in a way that is safe (the original
+// file is not touched until we have the desired replacement for it) and idempotent (it's okay to
+// run this program multiple times).
 //
-// - if the sha1 hash of <target_filename> is <target_sha1_string>,
-//   does nothing and exits successfully.
+// - If the SHA-1 hash of <target_filename> is <target_sha1_string>, does nothing and exits
+//   successfully.
 //
-// - otherwise, if the sha1 hash of <source_filename> is one of the
-//   entries in <patch_sha1_str>, the corresponding patch from
-//   <patch_data> (which must be a VAL_BLOB) is applied to produce a
-//   new file (the type of patch is automatically detected from the
-//   blob data).  If that new file has sha1 hash <target_sha1_str>,
-//   moves it to replace <target_filename>, and exits successfully.
-//   Note that if <source_filename> and <target_filename> are not the
-//   same, <source_filename> is NOT deleted on success.
-//   <target_filename> may be the string "-" to mean "the same as
-//   source_filename".
+// - Otherwise, if the SHA-1 hash of <source_filename> is one of the entries in <patch_sha1_str>,
+//   the corresponding patch from <patch_data> (which must be a VAL_BLOB) is applied to produce a
+//   new file (the type of patch is automatically detected from the blob data). If that new file
+//   has SHA-1 hash <target_sha1_str>, moves it to replace <target_filename>, and exits
+//   successfully. Note that if <source_filename> and <target_filename> are not the same,
+//   <source_filename> is NOT deleted on success. <target_filename> may be the string "-" to mean
+//   "the same as <source_filename>".
 //
-// - otherwise, or if any error is encountered, exits with non-zero
-//   status.
+// - Otherwise, or if any error is encountered, exits with non-zero status.
 //
-// <source_filename> may refer to a partition to read the source data.
-// See the comments for the LoadPartitionContents() function above
-// for the format of such a filename.
-
-int applypatch(const char* source_filename,
-               const char* target_filename,
-               const char* target_sha1_str,
-               size_t target_size,
-               int num_patches,
-               char** const patch_sha1_str,
-               Value** patch_data,
-               Value* bonus_data) {
-    printf("patch %s: ", source_filename);
-
-    if (target_filename[0] == '-' && target_filename[1] == '\0') {
-        target_filename = source_filename;
-    }
-
-    uint8_t target_sha1[SHA_DIGEST_LENGTH];
-    if (ParseSha1(target_sha1_str, target_sha1) != 0) {
-        printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
-        return 1;
-    }
-
-    FileContents copy_file;
-    FileContents source_file;
-    const Value* source_patch_value = NULL;
-    const Value* copy_patch_value = NULL;
-
-    // We try to load the target file into the source_file object.
-    if (LoadFileContents(target_filename, &source_file) == 0) {
-        if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) == 0) {
-            // The early-exit case:  the patch was already applied, this file
-            // has the desired hash, nothing for us to do.
-            printf("already %s\n", short_sha1(target_sha1).c_str());
-            return 0;
-        }
-    }
-
-    if (source_file.data.empty() ||
-        (target_filename != source_filename &&
-         strcmp(target_filename, source_filename) != 0)) {
-        // Need to load the source file:  either we failed to load the
-        // target file, or we did but it's different from the source file.
-        source_file.data.clear();
-        LoadFileContents(source_filename, &source_file);
-    }
-
-    if (!source_file.data.empty()) {
-        int to_use = FindMatchingPatch(source_file.sha1, patch_sha1_str, num_patches);
-        if (to_use >= 0) {
-            source_patch_value = patch_data[to_use];
-        }
-    }
-
-    if (source_patch_value == NULL) {
-        source_file.data.clear();
-        printf("source file is bad; trying copy\n");
-
-        if (LoadFileContents(CACHE_TEMP_SOURCE, &copy_file) < 0) {
-            // fail.
-            printf("failed to read copy file\n");
-            return 1;
-        }
-
-        int to_use = FindMatchingPatch(copy_file.sha1, patch_sha1_str, num_patches);
-        if (to_use >= 0) {
-            copy_patch_value = patch_data[to_use];
-        }
-
-        if (copy_patch_value == NULL) {
-            // fail.
-            printf("copy file doesn't match source SHA-1s either\n");
-            return 1;
-        }
-    }
-
-    return GenerateTarget(&source_file, source_patch_value,
-                          &copy_file, copy_patch_value,
-                          source_filename, target_filename,
-                          target_sha1, target_size, bonus_data);
+// <source_filename> must refer to an EMMC partition to read the source data. See the comments for
+// the LoadPartitionContents() function above for the format of such a filename. <target_size> has
+// become obsolete since we have dropped the support for patching non-EMMC targets (EMMC targets
+// have the size embedded in the filename).
+int applypatch(const char* source_filename, const char* target_filename,
+               const char* target_sha1_str, size_t target_size __unused,
+               const std::vector<std::string>& patch_sha1_str,
+               const std::vector<std::unique_ptr<Value>>& patch_data, const Value* bonus_data) {
+  printf("patch %s: ", source_filename);
+
+  if (target_filename[0] == '-' && target_filename[1] == '\0') {
+    target_filename = source_filename;
+  }
+
+  if (strncmp(target_filename, "EMMC:", 5) != 0) {
+    printf("Supporting patching EMMC targets only.\n");
+    return 1;
+  }
+
+  uint8_t target_sha1[SHA_DIGEST_LENGTH];
+  if (ParseSha1(target_sha1_str, target_sha1) != 0) {
+    printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
+    return 1;
+  }
+
+  // We try to load the target file into the source_file object.
+  FileContents source_file;
+  if (LoadFileContents(target_filename, &source_file) == 0) {
+    if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) == 0) {
+      // The early-exit case: the patch was already applied, this file has the desired hash, nothing
+      // for us to do.
+      printf("already %s\n", short_sha1(target_sha1).c_str());
+      return 0;
+    }
+  }
+
+  if (source_file.data.empty() ||
+      (target_filename != source_filename && strcmp(target_filename, source_filename) != 0)) {
+    // Need to load the source file: either we failed to load the target file, or we did but it's
+    // different from the expected.
+    source_file.data.clear();
+    LoadFileContents(source_filename, &source_file);
+  }
+
+  if (!source_file.data.empty()) {
+    int to_use = FindMatchingPatch(source_file.sha1, patch_sha1_str);
+    if (to_use != -1) {
+      return GenerateTarget(source_file, patch_data[to_use], target_filename, target_sha1,
+                            bonus_data);
+    }
+  }
+
+  printf("source file is bad; trying copy\n");
+
+  FileContents copy_file;
+  if (LoadFileContents(CACHE_TEMP_SOURCE, &copy_file) < 0) {
+    printf("failed to read copy file\n");
+    return 1;
+  }
+
+  int to_use = FindMatchingPatch(copy_file.sha1, patch_sha1_str);
+  if (to_use == -1) {
+    printf("copy file doesn't match source SHA-1s either\n");
+    return 1;
+  }
+
+  return GenerateTarget(copy_file, patch_data[to_use], target_filename, target_sha1, bonus_data);
 }
 
 /*
@@ -754,281 +667,124 @@ int applypatch(const char* source_filename,
  */
 int applypatch_flash(const char* source_filename, const char* target_filename,
                      const char* target_sha1_str, size_t target_size) {
-    printf("flash %s: ", target_filename);
-
-    uint8_t target_sha1[SHA_DIGEST_LENGTH];
-    if (ParseSha1(target_sha1_str, target_sha1) != 0) {
-        printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
-        return 1;
-    }
-
-    FileContents source_file;
-    std::string target_str(target_filename);
-
-    std::vector<std::string> pieces = android::base::Split(target_str, ":");
-    if (pieces.size() != 2 || (pieces[0] != "MTD" && pieces[0] != "EMMC")) {
-        printf("invalid target name \"%s\"", target_filename);
-        return 1;
-    }
-
-    // Load the target into the source_file object to see if already applied.
-    pieces.push_back(std::to_string(target_size));
-    pieces.push_back(target_sha1_str);
-    std::string fullname = android::base::Join(pieces, ':');
-    if (LoadPartitionContents(fullname.c_str(), &source_file) == 0 &&
-        memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) == 0) {
-        // The early-exit case: the image was already applied, this partition
-        // has the desired hash, nothing for us to do.
-        printf("already %s\n", short_sha1(target_sha1).c_str());
-        return 0;
-    }
-
-    if (LoadFileContents(source_filename, &source_file) == 0) {
-        if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) != 0) {
-            // The source doesn't have desired checksum.
-            printf("source \"%s\" doesn't have expected sha1 sum\n", source_filename);
-            printf("expected: %s, found: %s\n", short_sha1(target_sha1).c_str(),
-                    short_sha1(source_file.sha1).c_str());
-            return 1;
-        }
-    }
-
-    if (WriteToPartition(source_file.data.data(), target_size, target_filename) != 0) {
-        printf("write of copied data to %s failed\n", target_filename);
-        return 1;
-    }
+  printf("flash %s: ", target_filename);
+
+  uint8_t target_sha1[SHA_DIGEST_LENGTH];
+  if (ParseSha1(target_sha1_str, target_sha1) != 0) {
+    printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
+    return 1;
+  }
+
+  std::string target_str(target_filename);
+  std::vector<std::string> pieces = android::base::Split(target_str, ":");
+  if (pieces.size() != 2 || pieces[0] != "EMMC") {
+    printf("invalid target name \"%s\"", target_filename);
+    return 1;
+  }
+
+  // Load the target into the source_file object to see if already applied.
+  pieces.push_back(std::to_string(target_size));
+  pieces.push_back(target_sha1_str);
+  std::string fullname = android::base::Join(pieces, ':');
+  FileContents source_file;
+  if (LoadPartitionContents(fullname, &source_file) == 0 &&
+      memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) == 0) {
+    // The early-exit case: the image was already applied, this partition
+    // has the desired hash, nothing for us to do.
+    printf("already %s\n", short_sha1(target_sha1).c_str());
     return 0;
+  }
+
+  if (LoadFileContents(source_filename, &source_file) == 0) {
+    if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_LENGTH) != 0) {
+      // The source doesn't have desired checksum.
+      printf("source \"%s\" doesn't have expected sha1 sum\n", source_filename);
+      printf("expected: %s, found: %s\n", short_sha1(target_sha1).c_str(),
+             short_sha1(source_file.sha1).c_str());
+      return 1;
+    }
+  }
+
+  if (WriteToPartition(source_file.data.data(), target_size, target_filename) != 0) {
+    printf("write of copied data to %s failed\n", target_filename);
+    return 1;
+  }
+  return 0;
 }
 
-static int GenerateTarget(FileContents* source_file,
-                          const Value* source_patch_value,
-                          FileContents* copy_file,
-                          const Value* copy_patch_value,
-                          const char* source_filename,
-                          const char* target_filename,
-                          const uint8_t target_sha1[SHA_DIGEST_LENGTH],
-                          size_t target_size,
-                          const Value* bonus_data) {
-    int retry = 1;
-    SHA_CTX ctx;
-    std::string memory_sink_str;
-    FileContents* source_to_use;
-    int made_copy = 0;
-
-    bool target_is_partition = (strncmp(target_filename, "MTD:", 4) == 0 ||
-                                strncmp(target_filename, "EMMC:", 5) == 0 ||
-                                strncmp(target_filename, "BML:", 4) == 0);
-    const std::string tmp_target_filename = std::string(target_filename) + ".patch";
-
-    // assume that target_filename (eg "/system/app/Foo.apk") is located
-    // on the same filesystem as its top-level directory ("/system").
-    // We need something that exists for calling statfs().
-    std::string target_fs = target_filename;
-    auto slash_pos = target_fs.find('/', 1);
-    if (slash_pos != std::string::npos) {
-        target_fs.resize(slash_pos);
-    }
-
-    const Value* patch;
-    if (source_patch_value != NULL) {
-        source_to_use = source_file;
-        patch = source_patch_value;
-    } else {
-        source_to_use = copy_file;
-        patch = copy_patch_value;
-    }
-    if (patch->type != VAL_BLOB) {
-        printf("patch is not a blob\n");
-        return 1;
-    }
-    char* header = patch->data;
-    ssize_t header_bytes_read = patch->size;
-    bool use_bsdiff = false;
-    if (header_bytes_read >= 8 && memcmp(header, "BSDIFF40", 8) == 0) {
-        use_bsdiff = true;
-    } else if (header_bytes_read >= 8 && memcmp(header, "IMGDIFF2", 8) == 0) {
-        use_bsdiff = false;
-    } else {
-        printf("Unknown patch file format\n");
-        return 1;
-    }
-
-    do {
-        // Is there enough room in the target filesystem to hold the patched
-        // file?
-
-        if (target_is_partition) {
-            // If the target is a partition, we're actually going to
-            // write the output to /tmp and then copy it to the
-            // partition.  statfs() always returns 0 blocks free for
-            // /tmp, so instead we'll just assume that /tmp has enough
-            // space to hold the file.
-
-            // We still write the original source to cache, in case
-            // the partition write is interrupted.
-            if (MakeFreeSpaceOnCache(source_file->data.size()) < 0) {
-                printf("not enough free space on /cache\n");
-                return 1;
-            }
-            if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
-                printf("failed to back up source file\n");
-                return 1;
-            }
-            made_copy = 1;
-            retry = 0;
-        } else {
-            int enough_space = 0;
-            if (retry > 0) {
-                size_t free_space = FreeSpaceForFile(target_fs.c_str());
-                enough_space =
-                    (free_space > (256 << 10)) &&          // 256k (two-block) minimum
-                    (free_space > (target_size * 3 / 2));  // 50% margin of error
-                if (!enough_space) {
-                    printf("target %zu bytes; free space %zu bytes; retry %d; enough %d\n",
-                           target_size, free_space, retry, enough_space);
-                }
-            }
-
-            if (!enough_space) {
-                retry = 0;
-            }
-
-            if (!enough_space && source_patch_value != NULL) {
-                // Using the original source, but not enough free space.  First
-                // copy the source file to cache, then delete it from the original
-                // location.
-
-                if (strncmp(source_filename, "MTD:", 4) == 0 ||
-                    strncmp(source_filename, "EMMC:", 5) == 0 ||
-                    strncmp(source_filename, "BML:", 4) == 0) {
-                    // It's impossible to free space on the target filesystem by
-                    // deleting the source if the source is a partition.  If
-                    // we're ever in a state where we need to do this, fail.
-                    printf("not enough free space for target but source is partition\n");
-                    return 1;
-                }
-
-                if (MakeFreeSpaceOnCache(source_file->data.size()) < 0) {
-                    printf("not enough free space on /cache\n");
-                    return 1;
-                }
-
-                if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
-                    printf("failed to back up source file\n");
-                    return 1;
-                }
-                made_copy = 1;
-                unlink(source_filename);
-
-                size_t free_space = FreeSpaceForFile(target_fs.c_str());
-                printf("(now %zu bytes free for target) ", free_space);
-            }
-        }
-
-
-        SinkFn sink = NULL;
-        void* token = NULL;
-
-        int output_fd = -1;
-        if (target_is_partition) {
-            // We store the decoded output in memory.
-            sink = MemorySink;
-            token = &memory_sink_str;
-        } else {
-            // We write the decoded output to "<tgt-file>.patch".
-            output_fd = ota_open(tmp_target_filename.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_SYNC,
-                          S_IRUSR | S_IWUSR);
-            if (output_fd < 0) {
-                printf("failed to open output file %s: %s\n", tmp_target_filename.c_str(),
-                       strerror(errno));
-                return 1;
-            }
-            sink = FileSink;
-            token = &output_fd;
-        }
-
-
-        SHA1_Init(&ctx);
-
-        int result;
-        if (use_bsdiff) {
-            result = ApplyBSDiffPatch(source_to_use->data.data(), source_to_use->data.size(),
-                                      patch, 0, sink, token, &ctx);
-        } else {
-            result = ApplyImagePatch(source_to_use->data.data(), source_to_use->data.size(),
-                                     patch, sink, token, &ctx, bonus_data);
-        }
-
-        if (!target_is_partition) {
-            if (ota_fsync(output_fd) != 0) {
-                printf("failed to fsync file \"%s\" (%s)\n", tmp_target_filename.c_str(),
-                       strerror(errno));
-                result = 1;
-            }
-            if (ota_close(output_fd) != 0) {
-                printf("failed to close file \"%s\" (%s)\n", tmp_target_filename.c_str(),
-                       strerror(errno));
-                result = 1;
-            }
-        }
-
-        if (result != 0) {
-            if (retry == 0) {
-                printf("applying patch failed\n");
-                return result != 0;
-            } else {
-                printf("applying patch failed; retrying\n");
-            }
-            if (!target_is_partition) {
-                unlink(tmp_target_filename.c_str());
-            }
-        } else {
-            // succeeded; no need to retry
-            break;
-        }
-    } while (retry-- > 0);
-
-    uint8_t current_target_sha1[SHA_DIGEST_LENGTH];
-    SHA1_Final(current_target_sha1, &ctx);
-    if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_LENGTH) != 0) {
-        printf("patch did not produce expected sha1\n");
-        return 1;
-    } else {
-        printf("now %s\n", short_sha1(target_sha1).c_str());
-    }
-
-    if (target_is_partition) {
-        // Copy the temp file to the partition.
-        if (WriteToPartition(reinterpret_cast<const unsigned char*>(memory_sink_str.c_str()),
-                             memory_sink_str.size(), target_filename) != 0) {
-            printf("write of patched data to %s failed\n", target_filename);
-            return 1;
-        }
-    } else {
-        // Give the .patch file the same owner, group, and mode of the
-        // original source file.
-        if (chmod(tmp_target_filename.c_str(), source_to_use->st.st_mode) != 0) {
-            printf("chmod of \"%s\" failed: %s\n", tmp_target_filename.c_str(), strerror(errno));
-            return 1;
-        }
-        if (chown(tmp_target_filename.c_str(), source_to_use->st.st_uid, source_to_use->st.st_gid) != 0) {
-            printf("chown of \"%s\" failed: %s\n", tmp_target_filename.c_str(), strerror(errno));
-            return 1;
-        }
-
-        // Finally, rename the .patch file to replace the target file.
-        if (rename(tmp_target_filename.c_str(), target_filename) != 0) {
-            printf("rename of .patch to \"%s\" failed: %s\n", target_filename, strerror(errno));
-            return 1;
-        }
-    }
-
-    // If this run of applypatch created the copy, and we're here, we
-    // can delete it.
-    if (made_copy) {
-        unlink(CACHE_TEMP_SOURCE);
-    }
-
-    // Success!
-    return 0;
+static int GenerateTarget(const FileContents& source_file, const std::unique_ptr<Value>& patch,
+                          const std::string& target_filename,
+                          const uint8_t target_sha1[SHA_DIGEST_LENGTH], const Value* bonus_data) {
+  if (patch->type != VAL_BLOB) {
+    printf("patch is not a blob\n");
+    return 1;
+  }
+
+  const char* header = &patch->data[0];
+  size_t header_bytes_read = patch->data.size();
+  bool use_bsdiff = false;
+  if (header_bytes_read >= 8 && memcmp(header, "BSDIFF40", 8) == 0) {
+    use_bsdiff = true;
+  } else if (header_bytes_read >= 8 && memcmp(header, "IMGDIFF2", 8) == 0) {
+    use_bsdiff = false;
+  } else {
+    printf("Unknown patch file format\n");
+    return 1;
+  }
+
+  CHECK(android::base::StartsWith(target_filename, "EMMC:"));
+
+  // We still write the original source to cache, in case the partition write is interrupted.
+  if (MakeFreeSpaceOnCache(source_file.data.size()) < 0) {
+    printf("not enough free space on /cache\n");
+    return 1;
+  }
+  if (SaveFileContents(CACHE_TEMP_SOURCE, &source_file) < 0) {
+    printf("failed to back up source file\n");
+    return 1;
+  }
+
+  // We store the decoded output in memory.
+  SinkFn sink = MemorySink;
+  std::string memory_sink_str;  // Don't need to reserve space.
+  void* token = &memory_sink_str;
+
+  SHA_CTX ctx;
+  SHA1_Init(&ctx);
+
+  int result;
+  if (use_bsdiff) {
+    result = ApplyBSDiffPatch(source_file.data.data(), source_file.data.size(), patch.get(), 0,
+                              sink, token, &ctx);
+  } else {
+    result = ApplyImagePatch(source_file.data.data(), source_file.data.size(), patch.get(), sink,
+                             token, &ctx, bonus_data);
+  }
+
+  if (result != 0) {
+    printf("applying patch failed\n");
+    return 1;
+  }
+
+  uint8_t current_target_sha1[SHA_DIGEST_LENGTH];
+  SHA1_Final(current_target_sha1, &ctx);
+  if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_LENGTH) != 0) {
+    printf("patch did not produce expected sha1\n");
+    return 1;
+  } else {
+    printf("now %s\n", short_sha1(target_sha1).c_str());
+  }
+
+  // Write back the temp file to the partition.
+  if (WriteToPartition(reinterpret_cast<const unsigned char*>(memory_sink_str.c_str()),
+                       memory_sink_str.size(), target_filename) != 0) {
+    printf("write of patched data to %s failed\n", target_filename.c_str());
+    return 1;
+  }
+
+  // Delete the backup copy of the source.
+  unlink(CACHE_TEMP_SOURCE);
+
+  // Success!
+  return 0;
 }
diff --git a/applypatch/applypatch_main.cpp b/applypatch/applypatch_main.cpp
new file mode 100644
index 000000000..197077c93
--- /dev/null
+++ b/applypatch/applypatch_main.cpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "applypatch_modes.h"
+
+// This program (applypatch) applies binary patches to files in a way that
+// is safe (the original file is not touched until we have the desired
+// replacement for it) and idempotent (it's okay to run this program
+// multiple times).
+//
+// See the comments to applypatch_modes() function.
+
+int main(int argc, char** argv) {
+    return applypatch_modes(argc, const_cast<const char**>(argv));
+}
diff --git a/applypatch/main.cpp b/applypatch/applypatch_modes.cpp
index 9013760c4..7b191a801 100644
--- a/applypatch/main.cpp
+++ b/applypatch/applypatch_modes.cpp
@@ -14,61 +14,72 @@
  * limitations under the License.
  */
 
+#include "applypatch_modes.h"
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include <memory>
+#include <string>
 #include <vector>
 
-#include "applypatch.h"
+#include <android-base/parseint.h>
+#include <android-base/strings.h>
+#include <openssl/sha.h>
+
+#include "applypatch/applypatch.h"
 #include "edify/expr.h"
-#include "openssl/sha.h"
 
-static int CheckMode(int argc, char** argv) {
+static int CheckMode(int argc, const char** argv) {
     if (argc < 3) {
         return 2;
     }
-    return applypatch_check(argv[2], argc-3, argv+3);
+    std::vector<std::string> sha1;
+    for (int i = 3; i < argc; i++) {
+        sha1.push_back(argv[i]);
+    }
+
+    return applypatch_check(argv[2], sha1);
 }
 
-static int SpaceMode(int argc, char** argv) {
+static int SpaceMode(int argc, const char** argv) {
     if (argc != 3) {
         return 2;
     }
-    char* endptr;
-    size_t bytes = strtol(argv[2], &endptr, 10);
-    if (bytes == 0 && endptr == argv[2]) {
+
+    size_t bytes;
+    if (!android::base::ParseUint(argv[2], &bytes) || bytes == 0) {
         printf("can't parse \"%s\" as byte count\n\n", argv[2]);
         return 1;
     }
     return CacheSizeCheck(bytes);
 }
 
-// Parse arguments (which should be of the form "<sha1>:<filename>"
-// into the new parallel arrays *sha1s and *files.Returns true on
-// success.
-static bool ParsePatchArgs(int argc, char** argv, std::vector<char*>* sha1s,
+// Parse arguments (which should be of the form "<sha1>:<filename>" into the
+// new parallel arrays *sha1s and *files. Returns true on success.
+static bool ParsePatchArgs(int argc, const char** argv, std::vector<std::string>* sha1s,
                            std::vector<FileContents>* files) {
-    uint8_t digest[SHA_DIGEST_LENGTH];
-
+    if (sha1s == nullptr) {
+        return false;
+    }
     for (int i = 0; i < argc; ++i) {
-        char* colon = strchr(argv[i], ':');
-        if (colon == nullptr) {
-            printf("no ':' in patch argument \"%s\"\n", argv[i]);
+        std::vector<std::string> pieces = android::base::Split(argv[i], ":");
+        if (pieces.size() != 2) {
+            printf("failed to parse patch argument \"%s\"\n", argv[i]);
             return false;
         }
-        *colon = '\0';
-        ++colon;
-        if (ParseSha1(argv[i], digest) != 0) {
+
+        uint8_t digest[SHA_DIGEST_LENGTH];
+        if (ParseSha1(pieces[0].c_str(), digest) != 0) {
             printf("failed to parse sha1 \"%s\"\n", argv[i]);
             return false;
         }
 
-        sha1s->push_back(argv[i]);
+        sha1s->push_back(pieces[0]);
         FileContents fc;
-        if (LoadFileContents(colon, &fc) != 0) {
+        if (LoadFileContents(pieces[1].c_str(), &fc) != 0) {
             return false;
         }
         files->push_back(std::move(fc));
@@ -81,20 +92,17 @@ static int FlashMode(const char* src_filename, const char* tgt_filename,
     return applypatch_flash(src_filename, tgt_filename, tgt_sha1, tgt_size);
 }
 
-static int PatchMode(int argc, char** argv) {
+static int PatchMode(int argc, const char** argv) {
     FileContents bonusFc;
-    Value bonusValue;
-    Value* bonus = nullptr;
+    Value bonus(VAL_INVALID, "");
 
     if (argc >= 3 && strcmp(argv[1], "-b") == 0) {
         if (LoadFileContents(argv[2], &bonusFc) != 0) {
             printf("failed to load bonus file %s\n", argv[2]);
             return 1;
         }
-        bonus = &bonusValue;
-        bonus->type = VAL_BLOB;
-        bonus->size = bonusFc.data.size();
-        bonus->data = reinterpret_cast<char*>(bonusFc.data.data());
+        bonus.type = VAL_BLOB;
+        bonus.data = std::string(bonusFc.data.cbegin(), bonusFc.data.cend());
         argc -= 2;
         argv += 2;
     }
@@ -103,42 +111,38 @@ static int PatchMode(int argc, char** argv) {
         return 2;
     }
 
-    char* endptr;
-    size_t target_size = strtol(argv[4], &endptr, 10);
-    if (target_size == 0 && endptr == argv[4]) {
+    size_t target_size;
+    if (!android::base::ParseUint(argv[4], &target_size) || target_size == 0) {
         printf("can't parse \"%s\" as byte count\n\n", argv[4]);
         return 1;
     }
 
     // If no <src-sha1>:<patch> is provided, it is in flash mode.
     if (argc == 5) {
-        if (bonus != nullptr) {
+        if (bonus.type != VAL_INVALID) {
             printf("bonus file not supported in flash mode\n");
             return 1;
         }
         return FlashMode(argv[1], argv[2], argv[3], target_size);
     }
-    std::vector<char*> sha1s;
+
+    std::vector<std::string> sha1s;
     std::vector<FileContents> files;
     if (!ParsePatchArgs(argc-5, argv+5, &sha1s, &files)) {
         printf("failed to parse patch args\n");
         return 1;
     }
-    std::vector<Value> patches(files.size());
-    std::vector<Value*> patch_ptrs(files.size());
+
+    std::vector<std::unique_ptr<Value>> patches;
     for (size_t i = 0; i < files.size(); ++i) {
-        patches[i].type = VAL_BLOB;
-        patches[i].size = files[i].data.size();
-        patches[i].data = reinterpret_cast<char*>(files[i].data.data());
-        patch_ptrs[i] = &patches[i];
+        patches.push_back(std::make_unique<Value>(
+                VAL_BLOB, std::string(files[i].data.cbegin(), files[i].data.cend())));
     }
-    return applypatch(argv[1], argv[2], argv[3], target_size,
-                      patch_ptrs.size(), sha1s.data(),
-                      patch_ptrs.data(), bonus);
+    return applypatch(argv[1], argv[2], argv[3], target_size, sha1s, patches, &bonus);
 }
 
-// This program applies binary patches to files in a way that is safe
-// (the original file is not touched until we have the desired
+// This program (applypatch) applies binary patches to files in a way that
+// is safe (the original file is not touched until we have the desired
 // replacement for it) and idempotent (it's okay to run this program
 // multiple times).
 //
@@ -160,11 +164,11 @@ static int PatchMode(int argc, char** argv) {
 // - otherwise, or if any error is encountered, exits with non-zero
 //   status.
 //
-// <src-file> (or <file> in check mode) may refer to an MTD partition
+// <src-file> (or <file> in check mode) may refer to an EMMC partition
 // to read the source data.  See the comments for the
-// LoadMTDContents() function above for the format of such a filename.
+// LoadPartitionContents() function for the format of such a filename.
 
-int main(int argc, char** argv) {
+int applypatch_modes(int argc, const char** argv) {
     if (argc < 2) {
       usage:
         printf(
@@ -175,8 +179,8 @@ int main(int argc, char** argv) {
             "   or  %s -l\n"
             "\n"
             "Filenames may be of the form\n"
-            "  MTD:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
-            "to specify reading from or writing to an MTD partition.\n\n",
+            "  EMMC:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
+            "to specify reading from or writing to an EMMC partition.\n\n",
             argv[0], argv[0], argv[0], argv[0]);
         return 2;
     }
diff --git a/applypatch/utils.h b/applypatch/applypatch_modes.h
index bc97f1720..3d9d08df5 100644
--- a/applypatch/utils.h
+++ b/applypatch/applypatch_modes.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009 The Android Open Source Project
+ * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,17 +14,9 @@
  * limitations under the License.
  */
 
-#ifndef _BUILD_TOOLS_APPLYPATCH_UTILS_H
-#define _BUILD_TOOLS_APPLYPATCH_UTILS_H
+#ifndef _APPLYPATCH_MODES_H
+#define _APPLYPATCH_MODES_H
 
-#include <stdio.h>
+int applypatch_modes(int argc, const char** argv);
 
-// Read and write little-endian values of various sizes.
-
-void Write4(int value, FILE* f);
-void Write8(long long value, FILE* f);
-int Read2(void* p);
-int Read4(void* p);
-long long Read8(void* p);
-
-#endif //  _BUILD_TOOLS_APPLYPATCH_UTILS_H
+#endif // _APPLYPATCH_MODES_H
diff --git a/applypatch/bsdiff.cpp b/applypatch/bsdiff.cpp
deleted file mode 100644
index 55dbe5cf1..000000000
--- a/applypatch/bsdiff.cpp
+++ /dev/null
@@ -1,410 +0,0 @@
-/*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/*
- * Most of this code comes from bsdiff.c from the bsdiff-4.3
- * distribution, which is:
- */
-
-/*-
- * Copyright 2003-2005 Colin Percival
- * All rights reserved
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted providing that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sys/types.h>
-
-#include <bzlib.h>
-#include <err.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-#define MIN(x,y) (((x)<(y)) ? (x) : (y))
-
-static void split(off_t *I,off_t *V,off_t start,off_t len,off_t h)
-{
-	off_t i,j,k,x,tmp,jj,kk;
-
-	if(len<16) {
-		for(k=start;k<start+len;k+=j) {
-			j=1;x=V[I[k]+h];
-			for(i=1;k+i<start+len;i++) {
-				if(V[I[k+i]+h]<x) {
-					x=V[I[k+i]+h];
-					j=0;
-				};
-				if(V[I[k+i]+h]==x) {
-					tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
-					j++;
-				};
-			};
-			for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
-			if(j==1) I[k]=-1;
-		};
-		return;
-	};
-
-	x=V[I[start+len/2]+h];
-	jj=0;kk=0;
-	for(i=start;i<start+len;i++) {
-		if(V[I[i]+h]<x) jj++;
-		if(V[I[i]+h]==x) kk++;
-	};
-	jj+=start;kk+=jj;
-
-	i=start;j=0;k=0;
-	while(i<jj) {
-		if(V[I[i]+h]<x) {
-			i++;
-		} else if(V[I[i]+h]==x) {
-			tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
-			j++;
-		} else {
-			tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
-			k++;
-		};
-	};
-
-	while(jj+j<kk) {
-		if(V[I[jj+j]+h]==x) {
-			j++;
-		} else {
-			tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
-			k++;
-		};
-	};
-
-	if(jj>start) split(I,V,start,jj-start,h);
-
-	for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
-	if(jj==kk-1) I[jj]=-1;
-
-	if(start+len>kk) split(I,V,kk,start+len-kk,h);
-}
-
-static void qsufsort(off_t *I,off_t *V,u_char *old,off_t oldsize)
-{
-	off_t buckets[256];
-	off_t i,h,len;
-
-	for(i=0;i<256;i++) buckets[i]=0;
-	for(i=0;i<oldsize;i++) buckets[old[i]]++;
-	for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
-	for(i=255;i>0;i--) buckets[i]=buckets[i-1];
-	buckets[0]=0;
-
-	for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
-	I[0]=oldsize;
-	for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
-	V[oldsize]=0;
-	for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
-	I[0]=-1;
-
-	for(h=1;I[0]!=-(oldsize+1);h+=h) {
-		len=0;
-		for(i=0;i<oldsize+1;) {
-			if(I[i]<0) {
-				len-=I[i];
-				i-=I[i];
-			} else {
-				if(len) I[i-len]=-len;
-				len=V[I[i]]+1-i;
-				split(I,V,i,len,h);
-				i+=len;
-				len=0;
-			};
-		};
-		if(len) I[i-len]=-len;
-	};
-
-	for(i=0;i<oldsize+1;i++) I[V[i]]=i;
-}
-
-static off_t matchlen(u_char *olddata,off_t oldsize,u_char *newdata,off_t newsize)
-{
-	off_t i;
-
-	for(i=0;(i<oldsize)&&(i<newsize);i++)
-		if(olddata[i]!=newdata[i]) break;
-
-	return i;
-}
-
-static off_t search(off_t *I,u_char *old,off_t oldsize,
-		u_char *newdata,off_t newsize,off_t st,off_t en,off_t *pos)
-{
-	off_t x,y;
-
-	if(en-st<2) {
-		x=matchlen(old+I[st],oldsize-I[st],newdata,newsize);
-		y=matchlen(old+I[en],oldsize-I[en],newdata,newsize);
-
-		if(x>y) {
-			*pos=I[st];
-			return x;
-		} else {
-			*pos=I[en];
-			return y;
-		}
-	};
-
-	x=st+(en-st)/2;
-	if(memcmp(old+I[x],newdata,MIN(oldsize-I[x],newsize))<0) {
-		return search(I,old,oldsize,newdata,newsize,x,en,pos);
-	} else {
-		return search(I,old,oldsize,newdata,newsize,st,x,pos);
-	};
-}
-
-static void offtout(off_t x,u_char *buf)
-{
-	off_t y;
-
-	if(x<0) y=-x; else y=x;
-
-		buf[0]=y%256;y-=buf[0];
-	y=y/256;buf[1]=y%256;y-=buf[1];
-	y=y/256;buf[2]=y%256;y-=buf[2];
-	y=y/256;buf[3]=y%256;y-=buf[3];
-	y=y/256;buf[4]=y%256;y-=buf[4];
-	y=y/256;buf[5]=y%256;y-=buf[5];
-	y=y/256;buf[6]=y%256;y-=buf[6];
-	y=y/256;buf[7]=y%256;
-
-	if(x<0) buf[7]|=0x80;
-}
-
-// This is main() from bsdiff.c, with the following changes:
-//
-//    - old, oldsize, newdata, newsize are arguments; we don't load this
-//      data from files.  old and newdata are owned by the caller; we
-//      don't free them at the end.
-//
-//    - the "I" block of memory is owned by the caller, who passes a
-//      pointer to *I, which can be NULL.  This way if we call
-//      bsdiff() multiple times with the same 'old' data, we only do
-//      the qsufsort() step the first time.
-//
-int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* newdata, off_t newsize,
-           const char* patch_filename)
-{
-	int fd;
-	off_t *I;
-	off_t scan,pos,len;
-	off_t lastscan,lastpos,lastoffset;
-	off_t oldscore,scsc;
-	off_t s,Sf,lenf,Sb,lenb;
-	off_t overlap,Ss,lens;
-	off_t i;
-	off_t dblen,eblen;
-	u_char *db,*eb;
-	u_char buf[8];
-	u_char header[32];
-	FILE * pf;
-	BZFILE * pfbz2;
-	int bz2err;
-
-        if (*IP == NULL) {
-            off_t* V;
-            *IP = reinterpret_cast<off_t*>(malloc((oldsize+1) * sizeof(off_t)));
-            V = reinterpret_cast<off_t*>(malloc((oldsize+1) * sizeof(off_t)));
-            qsufsort(*IP, V, old, oldsize);
-            free(V);
-        }
-        I = *IP;
-
-	if(((db=reinterpret_cast<u_char*>(malloc(newsize+1)))==NULL) ||
-		((eb=reinterpret_cast<u_char*>(malloc(newsize+1)))==NULL)) err(1,NULL);
-	dblen=0;
-	eblen=0;
-
-	/* Create the patch file */
-	if ((pf = fopen(patch_filename, "w")) == NULL)
-              err(1, "%s", patch_filename);
-
-	/* Header is
-		0	8	 "BSDIFF40"
-		8	8	length of bzip2ed ctrl block
-		16	8	length of bzip2ed diff block
-		24	8	length of new file */
-	/* File is
-		0	32	Header
-		32	??	Bzip2ed ctrl block
-		??	??	Bzip2ed diff block
-		??	??	Bzip2ed extra block */
-	memcpy(header,"BSDIFF40",8);
-	offtout(0, header + 8);
-	offtout(0, header + 16);
-	offtout(newsize, header + 24);
-	if (fwrite(header, 32, 1, pf) != 1)
-		err(1, "fwrite(%s)", patch_filename);
-
-	/* Compute the differences, writing ctrl as we go */
-	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
-		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
-	scan=0;len=0;
-	lastscan=0;lastpos=0;lastoffset=0;
-	while(scan<newsize) {
-		oldscore=0;
-
-		for(scsc=scan+=len;scan<newsize;scan++) {
-			len=search(I,old,oldsize,newdata+scan,newsize-scan,
-					0,oldsize,&pos);
-
-			for(;scsc<scan+len;scsc++)
-			if((scsc+lastoffset<oldsize) &&
-				(old[scsc+lastoffset] == newdata[scsc]))
-				oldscore++;
-
-			if(((len==oldscore) && (len!=0)) ||
-				(len>oldscore+8)) break;
-
-			if((scan+lastoffset<oldsize) &&
-				(old[scan+lastoffset] == newdata[scan]))
-				oldscore--;
-		};
-
-		if((len!=oldscore) || (scan==newsize)) {
-			s=0;Sf=0;lenf=0;
-			for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
-				if(old[lastpos+i]==newdata[lastscan+i]) s++;
-				i++;
-				if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
-			};
-
-			lenb=0;
-			if(scan<newsize) {
-				s=0;Sb=0;
-				for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
-					if(old[pos-i]==newdata[scan-i]) s++;
-					if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
-				};
-			};
-
-			if(lastscan+lenf>scan-lenb) {
-				overlap=(lastscan+lenf)-(scan-lenb);
-				s=0;Ss=0;lens=0;
-				for(i=0;i<overlap;i++) {
-					if(newdata[lastscan+lenf-overlap+i]==
-					   old[lastpos+lenf-overlap+i]) s++;
-					if(newdata[scan-lenb+i]==
-					   old[pos-lenb+i]) s--;
-					if(s>Ss) { Ss=s; lens=i+1; };
-				};
-
-				lenf+=lens-overlap;
-				lenb-=lens;
-			};
-
-			for(i=0;i<lenf;i++)
-				db[dblen+i]=newdata[lastscan+i]-old[lastpos+i];
-			for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
-				eb[eblen+i]=newdata[lastscan+lenf+i];
-
-			dblen+=lenf;
-			eblen+=(scan-lenb)-(lastscan+lenf);
-
-			offtout(lenf,buf);
-			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
-			if (bz2err != BZ_OK)
-				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
-
-			offtout((scan-lenb)-(lastscan+lenf),buf);
-			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
-			if (bz2err != BZ_OK)
-				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
-
-			offtout((pos-lenb)-(lastpos+lenf),buf);
-			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
-			if (bz2err != BZ_OK)
-				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
-
-			lastscan=scan-lenb;
-			lastpos=pos-lenb;
-			lastoffset=pos-scan;
-		};
-	};
-	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
-	if (bz2err != BZ_OK)
-		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
-
-	/* Compute size of compressed ctrl data */
-	if ((len = ftello(pf)) == -1)
-		err(1, "ftello");
-	offtout(len-32, header + 8);
-
-	/* Write compressed diff data */
-	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
-		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
-	BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
-	if (bz2err != BZ_OK)
-		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
-	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
-	if (bz2err != BZ_OK)
-		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
-
-	/* Compute size of compressed diff data */
-	if ((newsize = ftello(pf)) == -1)
-		err(1, "ftello");
-	offtout(newsize - len, header + 16);
-
-	/* Write compressed extra data */
-	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
-		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
-	BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
-	if (bz2err != BZ_OK)
-		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
-	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
-	if (bz2err != BZ_OK)
-		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
-
-	/* Seek to the beginning, write the header, and close the file */
-	if (fseeko(pf, 0, SEEK_SET))
-		err(1, "fseeko");
-	if (fwrite(header, 32, 1, pf) != 1)
-		err(1, "fwrite(%s)", patch_filename);
-	if (fclose(pf))
-		err(1, "fclose");
-
-	/* Free the memory we used */
-	free(db);
-	free(eb);
-
-	return 0;
-}
diff --git a/applypatch/bspatch.cpp b/applypatch/bspatch.cpp
index ebb55f1d1..9920c2be1 100644
--- a/applypatch/bspatch.cpp
+++ b/applypatch/bspatch.cpp
@@ -21,16 +21,12 @@
 // notice.
 
 #include <stdio.h>
-#include <sys/stat.h>
 #include <sys/types.h>
-#include <errno.h>
-#include <unistd.h>
-#include <string.h>
 
-#include <bzlib.h>
+#include <bspatch.h>
 
+#include "applypatch/applypatch.h"
 #include "openssl/sha.h"
-#include "applypatch.h"
 
 void ShowBSDiffLicense() {
     puts("The bsdiff library used herein is:\n"
@@ -64,184 +60,25 @@ void ShowBSDiffLicense() {
         );
 }
 
-static off_t offtin(u_char *buf)
-{
-    off_t y;
-
-    y=buf[7]&0x7F;
-    y=y*256;y+=buf[6];
-    y=y*256;y+=buf[5];
-    y=y*256;y+=buf[4];
-    y=y*256;y+=buf[3];
-    y=y*256;y+=buf[2];
-    y=y*256;y+=buf[1];
-    y=y*256;y+=buf[0];
-
-    if(buf[7]&0x80) y=-y;
-
-    return y;
-}
-
-int FillBuffer(unsigned char* buffer, int size, bz_stream* stream) {
-    stream->next_out = (char*)buffer;
-    stream->avail_out = size;
-    while (stream->avail_out > 0) {
-        int bzerr = BZ2_bzDecompress(stream);
-        if (bzerr != BZ_OK && bzerr != BZ_STREAM_END) {
-            printf("bz error %d decompressing\n", bzerr);
-            return -1;
-        }
-        if (stream->avail_out > 0) {
-            printf("need %d more bytes\n", stream->avail_out);
-        }
-    }
-    return 0;
-}
-
-int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
-                     const Value* patch, ssize_t patch_offset,
-                     SinkFn sink, void* token, SHA_CTX* ctx) {
-
-    std::vector<unsigned char> new_data;
-    if (ApplyBSDiffPatchMem(old_data, old_size, patch, patch_offset, &new_data) != 0) {
-        return -1;
-    }
-
-    if (sink(new_data.data(), new_data.size(), token) < static_cast<ssize_t>(new_data.size())) {
-        printf("short write of output: %d (%s)\n", errno, strerror(errno));
-        return 1;
-    }
-    if (ctx) SHA1_Update(ctx, new_data.data(), new_data.size());
-    return 0;
+int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size, const Value* patch,
+                     ssize_t patch_offset, SinkFn sink, void* token, SHA_CTX* ctx) {
+  auto sha_sink = [&](const uint8_t* data, size_t len) {
+    len = sink(data, len, token);
+    if (ctx) SHA1_Update(ctx, data, len);
+    return len;
+  };
+  return bsdiff::bspatch(old_data, old_size,
+                         reinterpret_cast<const uint8_t*>(&patch->data[patch_offset]),
+                         patch->data.size(), sha_sink);
 }
 
-int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
-                        const Value* patch, ssize_t patch_offset,
-                        std::vector<unsigned char>* new_data) {
-    // Patch data format:
-    //   0       8       "BSDIFF40"
-    //   8       8       X
-    //   16      8       Y
-    //   24      8       sizeof(newfile)
-    //   32      X       bzip2(control block)
-    //   32+X    Y       bzip2(diff block)
-    //   32+X+Y  ???     bzip2(extra block)
-    // with control block a set of triples (x,y,z) meaning "add x bytes
-    // from oldfile to x bytes from the diff block; copy y bytes from the
-    // extra block; seek forwards in oldfile by z bytes".
-
-    unsigned char* header = (unsigned char*) patch->data + patch_offset;
-    if (memcmp(header, "BSDIFF40", 8) != 0) {
-        printf("corrupt bsdiff patch file header (magic number)\n");
-        return 1;
-    }
-
-    ssize_t ctrl_len, data_len, new_size;
-    ctrl_len = offtin(header+8);
-    data_len = offtin(header+16);
-    new_size = offtin(header+24);
-
-    if (ctrl_len < 0 || data_len < 0 || new_size < 0) {
-        printf("corrupt patch file header (data lengths)\n");
-        return 1;
-    }
-
-    int bzerr;
-
-    bz_stream cstream;
-    cstream.next_in = patch->data + patch_offset + 32;
-    cstream.avail_in = ctrl_len;
-    cstream.bzalloc = NULL;
-    cstream.bzfree = NULL;
-    cstream.opaque = NULL;
-    if ((bzerr = BZ2_bzDecompressInit(&cstream, 0, 0)) != BZ_OK) {
-        printf("failed to bzinit control stream (%d)\n", bzerr);
-    }
-
-    bz_stream dstream;
-    dstream.next_in = patch->data + patch_offset + 32 + ctrl_len;
-    dstream.avail_in = data_len;
-    dstream.bzalloc = NULL;
-    dstream.bzfree = NULL;
-    dstream.opaque = NULL;
-    if ((bzerr = BZ2_bzDecompressInit(&dstream, 0, 0)) != BZ_OK) {
-        printf("failed to bzinit diff stream (%d)\n", bzerr);
-    }
-
-    bz_stream estream;
-    estream.next_in = patch->data + patch_offset + 32 + ctrl_len + data_len;
-    estream.avail_in = patch->size - (patch_offset + 32 + ctrl_len + data_len);
-    estream.bzalloc = NULL;
-    estream.bzfree = NULL;
-    estream.opaque = NULL;
-    if ((bzerr = BZ2_bzDecompressInit(&estream, 0, 0)) != BZ_OK) {
-        printf("failed to bzinit extra stream (%d)\n", bzerr);
-    }
-
-    new_data->resize(new_size);
-
-    off_t oldpos = 0, newpos = 0;
-    off_t ctrl[3];
-    off_t len_read;
-    int i;
-    unsigned char buf[24];
-    while (newpos < new_size) {
-        // Read control data
-        if (FillBuffer(buf, 24, &cstream) != 0) {
-            printf("error while reading control stream\n");
-            return 1;
-        }
-        ctrl[0] = offtin(buf);
-        ctrl[1] = offtin(buf+8);
-        ctrl[2] = offtin(buf+16);
-
-        if (ctrl[0] < 0 || ctrl[1] < 0) {
-            printf("corrupt patch (negative byte counts)\n");
-            return 1;
-        }
-
-        // Sanity check
-        if (newpos + ctrl[0] > new_size) {
-            printf("corrupt patch (new file overrun)\n");
-            return 1;
-        }
-
-        // Read diff string
-        if (FillBuffer(new_data->data() + newpos, ctrl[0], &dstream) != 0) {
-            printf("error while reading diff stream\n");
-            return 1;
-        }
-
-        // Add old data to diff string
-        for (i = 0; i < ctrl[0]; ++i) {
-            if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
-                (*new_data)[newpos+i] += old_data[oldpos+i];
-            }
-        }
-
-        // Adjust pointers
-        newpos += ctrl[0];
-        oldpos += ctrl[0];
-
-        // Sanity check
-        if (newpos + ctrl[1] > new_size) {
-            printf("corrupt patch (new file overrun)\n");
-            return 1;
-        }
-
-        // Read extra string
-        if (FillBuffer(new_data->data() + newpos, ctrl[1], &estream) != 0) {
-            printf("error while reading extra stream\n");
-            return 1;
-        }
-
-        // Adjust pointers
-        newpos += ctrl[1];
-        oldpos += ctrl[2];
-    }
-
-    BZ2_bzDecompressEnd(&cstream);
-    BZ2_bzDecompressEnd(&dstream);
-    BZ2_bzDecompressEnd(&estream);
-    return 0;
+int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size, const Value* patch,
+                        ssize_t patch_offset, std::vector<unsigned char>* new_data) {
+  auto vector_sink = [new_data](const uint8_t* data, size_t len) {
+    new_data->insert(new_data->end(), data, data + len);
+    return len;
+  };
+  return bsdiff::bspatch(old_data, old_size,
+                         reinterpret_cast<const uint8_t*>(&patch->data[patch_offset]),
+                         patch->data.size(), vector_sink);
 }
diff --git a/applypatch/freecache.cpp b/applypatch/freecache.cpp
index c84f42797..331cae265 100644
--- a/applypatch/freecache.cpp
+++ b/applypatch/freecache.cpp
@@ -32,7 +32,7 @@
 #include <android-base/parseint.h>
 #include <android-base/stringprintf.h>
 
-#include "applypatch.h"
+#include "applypatch/applypatch.h"
 
 static int EliminateOpenFiles(std::set<std::string>* files) {
   std::unique_ptr<DIR, decltype(&closedir)> d(opendir("/proc"), closedir);
diff --git a/applypatch/imgdiff.cpp b/applypatch/imgdiff.cpp
index f22502e38..41d73ab98 100644
--- a/applypatch/imgdiff.cpp
+++ b/applypatch/imgdiff.cpp
@@ -121,618 +121,687 @@
  * information that is stored on the system partition.
  */
 
+#include "applypatch/imgdiff.h"
+
 #include <errno.h>
-#include <inttypes.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
-#include <unistd.h>
 #include <sys/types.h>
+#include <unistd.h>
 
-#include "zlib.h"
-#include "imgdiff.h"
-#include "utils.h"
+#include <algorithm>
+#include <string>
+#include <vector>
 
-typedef struct {
-  int type;             // CHUNK_NORMAL, CHUNK_DEFLATE
-  size_t start;         // offset of chunk in original image file
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/memory.h>
+#include <android-base/unique_fd.h>
+#include <ziparchive/zip_archive.h>
 
-  size_t len;
-  unsigned char* data;  // data to be patched (uncompressed, for deflate chunks)
+#include <bsdiff.h>
+#include <zlib.h>
 
-  size_t source_start;
-  size_t source_len;
+using android::base::get_unaligned;
 
-  off_t* I;             // used by bsdiff
+static constexpr auto BUFFER_SIZE = 0x8000;
 
-  // --- for CHUNK_DEFLATE chunks only: ---
+// If we use this function to write the offset and length (type size_t), their values should not
+// exceed 2^63; because the signed bit will be casted away.
+static inline bool Write8(int fd, int64_t value) {
+  return android::base::WriteFully(fd, &value, sizeof(int64_t));
+}
+
+// Similarly, the value should not exceed 2^31 if we are casting from size_t (e.g. target chunk
+// size).
+static inline bool Write4(int fd, int32_t value) {
+  return android::base::WriteFully(fd, &value, sizeof(int32_t));
+}
+
+class ImageChunk {
+ public:
+  static constexpr auto WINDOWBITS = -15;  // 32kb window; negative to indicate a raw stream.
+  static constexpr auto MEMLEVEL = 8;      // the default value.
+  static constexpr auto METHOD = Z_DEFLATED;
+  static constexpr auto STRATEGY = Z_DEFAULT_STRATEGY;
+
+  ImageChunk(int type, size_t start, const std::vector<uint8_t>* file_content, size_t raw_data_len)
+      : type_(type),
+        start_(start),
+        input_file_ptr_(file_content),
+        raw_data_len_(raw_data_len),
+        compress_level_(6),
+        source_start_(0),
+        source_len_(0),
+        source_uncompressed_len_(0) {
+    CHECK(file_content != nullptr) << "input file container can't be nullptr";
+  }
+
+  int GetType() const {
+    return type_;
+  }
+  size_t GetRawDataLength() const {
+    return raw_data_len_;
+  }
+  const std::string& GetEntryName() const {
+    return entry_name_;
+  }
+
+  // CHUNK_DEFLATE will return the uncompressed data for diff, while other types will simply return
+  // the raw data.
+  const uint8_t * DataForPatch() const;
+  size_t DataLengthForPatch() const;
+
+  void Dump() const {
+    printf("type %d start %zu len %zu\n", type_, start_, DataLengthForPatch());
+  }
 
-  // original (compressed) deflate data
-  size_t deflate_len;
-  unsigned char* deflate_data;
+  void SetSourceInfo(const ImageChunk& other);
+  void SetEntryName(std::string entryname);
+  void SetUncompressedData(std::vector<uint8_t> data);
+  bool SetBonusData(const std::vector<uint8_t>& bonus_data);
 
-  char* filename;       // used for zip entries
+  bool operator==(const ImageChunk& other) const;
+  bool operator!=(const ImageChunk& other) const {
+    return !(*this == other);
+  }
+
+  size_t GetHeaderSize(size_t patch_size) const;
+  // Return the offset of the next patch into the patch data.
+  size_t WriteHeaderToFd(int fd, const std::vector<uint8_t>& patch, size_t offset);
+
+  /*
+   * Cause a gzip chunk to be treated as a normal chunk (ie, as a blob
+   * of uninterpreted data).  The resulting patch will likely be about
+   * as big as the target file, but it lets us handle the case of images
+   * where some gzip chunks are reconstructible but others aren't (by
+   * treating the ones that aren't as normal chunks).
+   */
+  void ChangeDeflateChunkToNormal();
+  bool ChangeChunkToRaw(size_t patch_size);
+
+  /*
+   * Verify that we can reproduce exactly the same compressed data that
+   * we started with.  Sets the level, method, windowBits, memLevel, and
+   * strategy fields in the chunk to the encoding parameters needed to
+   * produce the right output.
+   */
+  bool ReconstructDeflateChunk();
+  bool IsAdjacentNormal(const ImageChunk& other) const;
+  void MergeAdjacentNormal(const ImageChunk& other);
+
+ private:
+  int type_;                                    // CHUNK_NORMAL, CHUNK_DEFLATE, CHUNK_RAW
+  size_t start_;                                // offset of chunk in the original input file
+  const std::vector<uint8_t>* input_file_ptr_;  // ptr to the full content of original input file
+  size_t raw_data_len_;
+
+  // --- for CHUNK_DEFLATE chunks only: ---
+  std::vector<uint8_t> uncompressed_data_;
+  std::string entry_name_;  // used for zip entries
 
   // deflate encoder parameters
-  int level, method, windowBits, memLevel, strategy;
-
-  size_t source_uncompressed_len;
-} ImageChunk;
-
-typedef struct {
-  int data_offset;
-  int deflate_len;
-  int uncomp_len;
-  char* filename;
-} ZipFileEntry;
-
-static int fileentry_compare(const void* a, const void* b) {
-  int ao = ((ZipFileEntry*)a)->data_offset;
-  int bo = ((ZipFileEntry*)b)->data_offset;
-  if (ao < bo) {
-    return -1;
-  } else if (ao > bo) {
-    return 1;
-  } else {
-    return 0;
+  int compress_level_;
+
+  size_t source_start_;
+  size_t source_len_;
+  size_t source_uncompressed_len_;
+
+  const uint8_t* GetRawData() const;
+  bool TryReconstruction(int level);
+};
+
+const uint8_t* ImageChunk::GetRawData() const {
+  CHECK_LE(start_ + raw_data_len_, input_file_ptr_->size());
+  return input_file_ptr_->data() + start_;
+}
+
+const uint8_t * ImageChunk::DataForPatch() const {
+  if (type_ == CHUNK_DEFLATE) {
+    return uncompressed_data_.data();
   }
+  return GetRawData();
 }
 
-// from bsdiff.c
-int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* newdata, off_t newsize,
-           const char* patch_filename);
+size_t ImageChunk::DataLengthForPatch() const {
+  if (type_ == CHUNK_DEFLATE) {
+    return uncompressed_data_.size();
+  }
+  return raw_data_len_;
+}
 
-unsigned char* ReadZip(const char* filename,
-                       int* num_chunks, ImageChunk** chunks,
-                       int include_pseudo_chunk) {
-  struct stat st;
-  if (stat(filename, &st) != 0) {
-    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
-    return NULL;
+bool ImageChunk::operator==(const ImageChunk& other) const {
+  if (type_ != other.type_) {
+    return false;
   }
+  return (raw_data_len_ == other.raw_data_len_ &&
+          memcmp(GetRawData(), other.GetRawData(), raw_data_len_) == 0);
+}
 
-  size_t sz = static_cast<size_t>(st.st_size);
-  unsigned char* img = reinterpret_cast<unsigned char*>(malloc(sz));
-  FILE* f = fopen(filename, "rb");
-  if (fread(img, 1, sz, f) != sz) {
-    printf("failed to read \"%s\" %s\n", filename, strerror(errno));
-    fclose(f);
-    return NULL;
+void ImageChunk::SetSourceInfo(const ImageChunk& src) {
+  source_start_ = src.start_;
+  if (type_ == CHUNK_NORMAL) {
+    source_len_ = src.raw_data_len_;
+  } else if (type_ == CHUNK_DEFLATE) {
+    source_len_ = src.raw_data_len_;
+    source_uncompressed_len_ = src.uncompressed_data_.size();
   }
-  fclose(f);
+}
+
+void ImageChunk::SetEntryName(std::string entryname) {
+  entry_name_ = std::move(entryname);
+}
 
-  // look for the end-of-central-directory record.
+void ImageChunk::SetUncompressedData(std::vector<uint8_t> data) {
+  uncompressed_data_ = std::move(data);
+}
 
-  int i;
-  for (i = st.st_size-20; i >= 0 && i > st.st_size - 65600; --i) {
-    if (img[i] == 0x50 && img[i+1] == 0x4b &&
-        img[i+2] == 0x05 && img[i+3] == 0x06) {
-      break;
-    }
-  }
-  // double-check: this archive consists of a single "disk"
-  if (!(img[i+4] == 0 && img[i+5] == 0 && img[i+6] == 0 && img[i+7] == 0)) {
-    printf("can't process multi-disk archive\n");
-    return NULL;
+bool ImageChunk::SetBonusData(const std::vector<uint8_t>& bonus_data) {
+  if (type_ != CHUNK_DEFLATE) {
+    return false;
   }
+  uncompressed_data_.insert(uncompressed_data_.end(), bonus_data.begin(), bonus_data.end());
+  return true;
+}
 
-  int cdcount = Read2(img+i+8);
-  int cdoffset = Read4(img+i+16);
+// Convert CHUNK_NORMAL & CHUNK_DEFLATE to CHUNK_RAW if the target size is
+// smaller. Also take the header size into account during size comparison.
+bool ImageChunk::ChangeChunkToRaw(size_t patch_size) {
+  if (type_ == CHUNK_RAW) {
+    return true;
+  } else if (type_ == CHUNK_NORMAL && (raw_data_len_ <= 160 || raw_data_len_ < patch_size)) {
+    type_ = CHUNK_RAW;
+    return true;
+  }
+  return false;
+}
 
-  ZipFileEntry* temp_entries = reinterpret_cast<ZipFileEntry*>(malloc(
-      cdcount * sizeof(ZipFileEntry)));
-  int entrycount = 0;
+void ImageChunk::ChangeDeflateChunkToNormal() {
+  if (type_ != CHUNK_DEFLATE) return;
+  type_ = CHUNK_NORMAL;
+  entry_name_.clear();
+  uncompressed_data_.clear();
+}
 
-  unsigned char* cd = img+cdoffset;
-  for (i = 0; i < cdcount; ++i) {
-    if (!(cd[0] == 0x50 && cd[1] == 0x4b && cd[2] == 0x01 && cd[3] == 0x02)) {
-      printf("bad central directory entry %d\n", i);
-      return NULL;
-    }
+// Header size:
+// header_type    4 bytes
+// CHUNK_NORMAL   8*3 = 24 bytes
+// CHUNK_DEFLATE  8*5 + 4*5 = 60 bytes
+// CHUNK_RAW      4 bytes + patch_size
+size_t ImageChunk::GetHeaderSize(size_t patch_size) const {
+  switch (type_) {
+    case CHUNK_NORMAL:
+      return 4 + 8 * 3;
+    case CHUNK_DEFLATE:
+      return 4 + 8 * 5 + 4 * 5;
+    case CHUNK_RAW:
+      return 4 + 4 + patch_size;
+    default:
+      CHECK(false) << "unexpected chunk type: " << type_;  // Should not reach here.
+      return 0;
+  }
+}
 
-    int clen = Read4(cd+20);   // compressed len
-    int ulen = Read4(cd+24);   // uncompressed len
-    int nlen = Read2(cd+28);   // filename len
-    int xlen = Read2(cd+30);   // extra field len
-    int mlen = Read2(cd+32);   // file comment len
-    int hoffset = Read4(cd+42);   // local header offset
+size_t ImageChunk::WriteHeaderToFd(int fd, const std::vector<uint8_t>& patch, size_t offset) {
+  Write4(fd, type_);
+  switch (type_) {
+    case CHUNK_NORMAL:
+      printf("normal   (%10zu, %10zu)  %10zu\n", start_, raw_data_len_, patch.size());
+      Write8(fd, static_cast<int64_t>(source_start_));
+      Write8(fd, static_cast<int64_t>(source_len_));
+      Write8(fd, static_cast<int64_t>(offset));
+      return offset + patch.size();
+    case CHUNK_DEFLATE:
+      printf("deflate  (%10zu, %10zu)  %10zu  %s\n", start_, raw_data_len_, patch.size(),
+             entry_name_.c_str());
+      Write8(fd, static_cast<int64_t>(source_start_));
+      Write8(fd, static_cast<int64_t>(source_len_));
+      Write8(fd, static_cast<int64_t>(offset));
+      Write8(fd, static_cast<int64_t>(source_uncompressed_len_));
+      Write8(fd, static_cast<int64_t>(uncompressed_data_.size()));
+      Write4(fd, compress_level_);
+      Write4(fd, METHOD);
+      Write4(fd, WINDOWBITS);
+      Write4(fd, MEMLEVEL);
+      Write4(fd, STRATEGY);
+      return offset + patch.size();
+    case CHUNK_RAW:
+      printf("raw      (%10zu, %10zu)\n", start_, raw_data_len_);
+      Write4(fd, static_cast<int32_t>(patch.size()));
+      if (!android::base::WriteFully(fd, patch.data(), patch.size())) {
+        CHECK(false) << "failed to write " << patch.size() <<" bytes patch";
+      }
+      return offset;
+    default:
+      CHECK(false) << "unexpected chunk type: " << type_;
+      return offset;
+  }
+}
 
-    char* filename = reinterpret_cast<char*>(malloc(nlen+1));
-    memcpy(filename, cd+46, nlen);
-    filename[nlen] = '\0';
+bool ImageChunk::IsAdjacentNormal(const ImageChunk& other) const {
+  if (type_ != CHUNK_NORMAL || other.type_ != CHUNK_NORMAL) {
+    return false;
+  }
+  return (other.start_ == start_ + raw_data_len_);
+}
 
-    int method = Read2(cd+10);
+void ImageChunk::MergeAdjacentNormal(const ImageChunk& other) {
+  CHECK(IsAdjacentNormal(other));
+  raw_data_len_ = raw_data_len_ + other.raw_data_len_;
+}
 
-    cd += 46 + nlen + xlen + mlen;
+bool ImageChunk::ReconstructDeflateChunk() {
+  if (type_ != CHUNK_DEFLATE) {
+    printf("attempt to reconstruct non-deflate chunk\n");
+    return false;
+  }
 
-    if (method != 8) {  // 8 == deflate
-      free(filename);
-      continue;
+  // We only check two combinations of encoder parameters:  level 6
+  // (the default) and level 9 (the maximum).
+  for (int level = 6; level <= 9; level += 3) {
+    if (TryReconstruction(level)) {
+      compress_level_ = level;
+      return true;
     }
+  }
+
+  return false;
+}
 
-    unsigned char* lh = img + hoffset;
+/*
+ * Takes the uncompressed data stored in the chunk, compresses it
+ * using the zlib parameters stored in the chunk, and checks that it
+ * matches exactly the compressed data we started with (also stored in
+ * the chunk).
+ */
+bool ImageChunk::TryReconstruction(int level) {
+  z_stream strm;
+  strm.zalloc = Z_NULL;
+  strm.zfree = Z_NULL;
+  strm.opaque = Z_NULL;
+  strm.avail_in = uncompressed_data_.size();
+  strm.next_in = uncompressed_data_.data();
+  int ret = deflateInit2(&strm, level, METHOD, WINDOWBITS, MEMLEVEL, STRATEGY);
+  if (ret < 0) {
+    printf("failed to initialize deflate: %d\n", ret);
+    return false;
+  }
 
-    if (!(lh[0] == 0x50 && lh[1] == 0x4b && lh[2] == 0x03 && lh[3] == 0x04)) {
-      printf("bad local file header entry %d\n", i);
-      return NULL;
+  std::vector<uint8_t> buffer(BUFFER_SIZE);
+  size_t offset = 0;
+  do {
+    strm.avail_out = buffer.size();
+    strm.next_out = buffer.data();
+    ret = deflate(&strm, Z_FINISH);
+    if (ret < 0) {
+      printf("failed to deflate: %d\n", ret);
+      return false;
     }
 
-    if (Read2(lh+26) != nlen || memcmp(lh+30, filename, nlen) != 0) {
-      printf("central dir filename doesn't match local header\n");
-      return NULL;
+    size_t compressed_size = buffer.size() - strm.avail_out;
+    if (memcmp(buffer.data(), input_file_ptr_->data() + start_ + offset, compressed_size) != 0) {
+      // mismatch; data isn't the same.
+      deflateEnd(&strm);
+      return false;
     }
+    offset += compressed_size;
+  } while (ret != Z_STREAM_END);
+  deflateEnd(&strm);
 
-    xlen = Read2(lh+28);   // extra field len; might be different from CD entry?
+  if (offset != raw_data_len_) {
+    // mismatch; ran out of data before we should have.
+    return false;
+  }
+  return true;
+}
 
-    temp_entries[entrycount].data_offset = hoffset+30+nlen+xlen;
-    temp_entries[entrycount].deflate_len = clen;
-    temp_entries[entrycount].uncomp_len = ulen;
-    temp_entries[entrycount].filename = filename;
-    ++entrycount;
+// EOCD record
+// offset 0: signature 0x06054b50, 4 bytes
+// offset 4: number of this disk, 2 bytes
+// ...
+// offset 20: comment length, 2 bytes
+// offset 22: comment, n bytes
+static bool GetZipFileSize(const std::vector<uint8_t>& zip_file, size_t* input_file_size) {
+  if (zip_file.size() < 22) {
+    printf("file is too small to be a zip file\n");
+    return false;
   }
 
-  qsort(temp_entries, entrycount, sizeof(ZipFileEntry), fileentry_compare);
-
-#if 0
-  printf("found %d deflated entries\n", entrycount);
-  for (i = 0; i < entrycount; ++i) {
-    printf("off %10d  len %10d unlen %10d   %p %s\n",
-           temp_entries[i].data_offset,
-           temp_entries[i].deflate_len,
-           temp_entries[i].uncomp_len,
-           temp_entries[i].filename,
-           temp_entries[i].filename);
+  // Look for End of central directory record of the zip file, and calculate the actual
+  // zip_file size.
+  for (int i = zip_file.size() - 22; i >= 0; i--) {
+    if (zip_file[i] == 0x50) {
+      if (get_unaligned<uint32_t>(&zip_file[i]) == 0x06054b50) {
+        // double-check: this archive consists of a single "disk".
+        CHECK_EQ(get_unaligned<uint16_t>(&zip_file[i + 4]), 0);
+
+        uint16_t comment_length = get_unaligned<uint16_t>(&zip_file[i + 20]);
+        size_t file_size = i + 22 + comment_length;
+        CHECK_LE(file_size, zip_file.size());
+        *input_file_size = file_size;
+        return true;
+      }
+    }
   }
-#endif
 
-  *num_chunks = 0;
-  *chunks = reinterpret_cast<ImageChunk*>(malloc((entrycount*2+2) * sizeof(ImageChunk)));
-  ImageChunk* curr = *chunks;
+  // EOCD not found, this file is likely not a valid zip file.
+  return false;
+}
+
+static bool ReadZip(const char* filename, std::vector<ImageChunk>* chunks,
+                    std::vector<uint8_t>* zip_file, bool include_pseudo_chunk) {
+  CHECK(chunks != nullptr && zip_file != nullptr);
 
-  if (include_pseudo_chunk) {
-    curr->type = CHUNK_NORMAL;
-    curr->start = 0;
-    curr->len = st.st_size;
-    curr->data = img;
-    curr->filename = NULL;
-    curr->I = NULL;
-    ++curr;
-    ++*num_chunks;
+  android::base::unique_fd fd(open(filename, O_RDONLY));
+  if (fd == -1) {
+    printf("failed to open \"%s\" %s\n", filename, strerror(errno));
+    return false;
+  }
+  struct stat st;
+  if (fstat(fd, &st) != 0) {
+    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+    return false;
   }
 
-  int pos = 0;
-  int nextentry = 0;
+  size_t sz = static_cast<size_t>(st.st_size);
+  zip_file->resize(sz);
+  if (!android::base::ReadFully(fd, zip_file->data(), sz)) {
+    printf("failed to read \"%s\" %s\n", filename, strerror(errno));
+    return false;
+  }
+  fd.reset();
 
-  while (pos < st.st_size) {
-    if (nextentry < entrycount && pos == temp_entries[nextentry].data_offset) {
-      curr->type = CHUNK_DEFLATE;
-      curr->start = pos;
-      curr->deflate_len = temp_entries[nextentry].deflate_len;
-      curr->deflate_data = img + pos;
-      curr->filename = temp_entries[nextentry].filename;
-      curr->I = NULL;
+  // Trim the trailing zeros before we pass the file to ziparchive handler.
+  size_t zipfile_size;
+  if (!GetZipFileSize(*zip_file, &zipfile_size)) {
+    printf("failed to parse the actual size of %s\n", filename);
+    return false;
+  }
+  ZipArchiveHandle handle;
+  int err = OpenArchiveFromMemory(zip_file->data(), zipfile_size, filename, &handle);
+  if (err != 0) {
+    printf("failed to open zip file %s: %s\n", filename, ErrorCodeString(err));
+    CloseArchive(handle);
+    return false;
+  }
 
-      curr->len = temp_entries[nextentry].uncomp_len;
-      curr->data = reinterpret_cast<unsigned char*>(malloc(curr->len));
+  // Create a list of deflated zip entries, sorted by offset.
+  std::vector<std::pair<std::string, ZipEntry>> temp_entries;
+  void* cookie;
+  int ret = StartIteration(handle, &cookie, nullptr, nullptr);
+  if (ret != 0) {
+    printf("failed to iterate over entries in %s: %s\n", filename, ErrorCodeString(ret));
+    CloseArchive(handle);
+    return false;
+  }
 
-      z_stream strm;
-      strm.zalloc = Z_NULL;
-      strm.zfree = Z_NULL;
-      strm.opaque = Z_NULL;
-      strm.avail_in = curr->deflate_len;
-      strm.next_in = curr->deflate_data;
+  ZipString name;
+  ZipEntry entry;
+  while ((ret = Next(cookie, &entry, &name)) == 0) {
+    if (entry.method == kCompressDeflated) {
+      std::string entryname(name.name, name.name + name.name_length);
+      temp_entries.push_back(std::make_pair(entryname, entry));
+    }
+  }
 
-      // -15 means we are decoding a 'raw' deflate stream; zlib will
-      // not expect zlib headers.
-      int ret = inflateInit2(&strm, -15);
+  if (ret != -1) {
+    printf("Error while iterating over zip entries: %s\n", ErrorCodeString(ret));
+    CloseArchive(handle);
+    return false;
+  }
+  std::sort(temp_entries.begin(), temp_entries.end(),
+            [](auto& entry1, auto& entry2) {
+              return entry1.second.offset < entry2.second.offset;
+            });
 
-      strm.avail_out = curr->len;
-      strm.next_out = curr->data;
-      ret = inflate(&strm, Z_NO_FLUSH);
-      if (ret != Z_STREAM_END) {
-        printf("failed to inflate \"%s\"; %d\n", curr->filename, ret);
-        return NULL;
+  EndIteration(cookie);
+
+  if (include_pseudo_chunk) {
+    chunks->emplace_back(CHUNK_NORMAL, 0, zip_file, zip_file->size());
+  }
+
+  size_t pos = 0;
+  size_t nextentry = 0;
+  while (pos < zip_file->size()) {
+    if (nextentry < temp_entries.size() &&
+        static_cast<off64_t>(pos) == temp_entries[nextentry].second.offset) {
+      // compose the next deflate chunk.
+      std::string entryname = temp_entries[nextentry].first;
+      size_t uncompressed_len = temp_entries[nextentry].second.uncompressed_length;
+      std::vector<uint8_t> uncompressed_data(uncompressed_len);
+      if ((ret = ExtractToMemory(handle, &temp_entries[nextentry].second, uncompressed_data.data(),
+                                 uncompressed_len)) != 0) {
+        printf("failed to extract %s with size %zu: %s\n", entryname.c_str(), uncompressed_len,
+               ErrorCodeString(ret));
+        CloseArchive(handle);
+        return false;
       }
 
-      inflateEnd(&strm);
+      size_t compressed_len = temp_entries[nextentry].second.compressed_length;
+      ImageChunk curr(CHUNK_DEFLATE, pos, zip_file, compressed_len);
+      curr.SetEntryName(std::move(entryname));
+      curr.SetUncompressedData(std::move(uncompressed_data));
+      chunks->push_back(curr);
 
-      pos += curr->deflate_len;
+      pos += compressed_len;
       ++nextentry;
-      ++*num_chunks;
-      ++curr;
       continue;
     }
 
-    // use a normal chunk to take all the data up to the start of the
-    // next deflate section.
-
-    curr->type = CHUNK_NORMAL;
-    curr->start = pos;
-    if (nextentry < entrycount) {
-      curr->len = temp_entries[nextentry].data_offset - pos;
+    // Use a normal chunk to take all the data up to the start of the next deflate section.
+    size_t raw_data_len;
+    if (nextentry < temp_entries.size()) {
+      raw_data_len = temp_entries[nextentry].second.offset - pos;
     } else {
-      curr->len = st.st_size - pos;
+      raw_data_len = zip_file->size() - pos;
     }
-    curr->data = img + pos;
-    curr->filename = NULL;
-    curr->I = NULL;
-    pos += curr->len;
+    chunks->emplace_back(CHUNK_NORMAL, pos, zip_file, raw_data_len);
 
-    ++*num_chunks;
-    ++curr;
+    pos += raw_data_len;
   }
 
-  free(temp_entries);
-  return img;
+  CloseArchive(handle);
+  return true;
 }
 
-/*
- * Read the given file and break it up into chunks, putting the number
- * of chunks and their info in *num_chunks and **chunks,
- * respectively.  Returns a malloc'd block of memory containing the
- * contents of the file; various pointers in the output chunk array
- * will point into this block of memory.  The caller should free the
- * return value when done with all the chunks.  Returns NULL on
- * failure.
- */
-unsigned char* ReadImage(const char* filename,
-                         int* num_chunks, ImageChunk** chunks) {
+// Read the given file and break it up into chunks, and putting the data in to a vector.
+static bool ReadImage(const char* filename, std::vector<ImageChunk>* chunks,
+                      std::vector<uint8_t>* img) {
+  CHECK(chunks != nullptr && img != nullptr);
+
+  android::base::unique_fd fd(open(filename, O_RDONLY));
+  if (fd == -1) {
+    printf("failed to open \"%s\" %s\n", filename, strerror(errno));
+    return false;
+  }
   struct stat st;
-  if (stat(filename, &st) != 0) {
+  if (fstat(fd, &st) != 0) {
     printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
-    return NULL;
+    return false;
   }
 
   size_t sz = static_cast<size_t>(st.st_size);
-  unsigned char* img = reinterpret_cast<unsigned char*>(malloc(sz + 4));
-  FILE* f = fopen(filename, "rb");
-  if (fread(img, 1, sz, f) != sz) {
+  img->resize(sz);
+  if (!android::base::ReadFully(fd, img->data(), sz)) {
     printf("failed to read \"%s\" %s\n", filename, strerror(errno));
-    fclose(f);
-    return NULL;
+    return false;
   }
-  fclose(f);
-
-  // append 4 zero bytes to the data so we can always search for the
-  // four-byte string 1f8b0800 starting at any point in the actual
-  // file data, without special-casing the end of the data.
-  memset(img+sz, 0, 4);
 
   size_t pos = 0;
 
-  *num_chunks = 0;
-  *chunks = NULL;
-
   while (pos < sz) {
-    unsigned char* p = img+pos;
-
-    bool processed_deflate = false;
-    if (sz - pos >= 4 &&
-        p[0] == 0x1f && p[1] == 0x8b &&
-        p[2] == 0x08 &&    // deflate compression
-        p[3] == 0x00) {    // no header flags
+    // 0x00 no header flags, 0x08 deflate compression, 0x1f8b gzip magic number
+    if (sz - pos >= 4 && get_unaligned<uint32_t>(img->data() + pos) == 0x00088b1f) {
       // 'pos' is the offset of the start of a gzip chunk.
       size_t chunk_offset = pos;
 
-      *num_chunks += 3;
-      *chunks = reinterpret_cast<ImageChunk*>(realloc(*chunks,
-          *num_chunks * sizeof(ImageChunk)));
-      ImageChunk* curr = *chunks + (*num_chunks-3);
-
-      // create a normal chunk for the header.
-      curr->start = pos;
-      curr->type = CHUNK_NORMAL;
-      curr->len = GZIP_HEADER_LEN;
-      curr->data = p;
-      curr->I = NULL;
-
-      pos += curr->len;
-      p += curr->len;
-      ++curr;
-
-      curr->type = CHUNK_DEFLATE;
-      curr->filename = NULL;
-      curr->I = NULL;
+      // The remaining data is too small to be a gzip chunk; treat them as a normal chunk.
+      if (sz - pos < GZIP_HEADER_LEN + GZIP_FOOTER_LEN) {
+        chunks->emplace_back(CHUNK_NORMAL, pos, img, sz - pos);
+        break;
+      }
 
-      // We must decompress this chunk in order to discover where it
-      // ends, and so we can put the uncompressed data and its length
-      // into curr->data and curr->len.
+      // We need three chunks for the deflated image in total, one normal chunk for the header,
+      // one deflated chunk for the body, and another normal chunk for the footer.
+      chunks->emplace_back(CHUNK_NORMAL, pos, img, GZIP_HEADER_LEN);
+      pos += GZIP_HEADER_LEN;
 
-      size_t allocated = 32768;
-      curr->len = 0;
-      curr->data = reinterpret_cast<unsigned char*>(malloc(allocated));
-      curr->start = pos;
-      curr->deflate_data = p;
+      // We must decompress this chunk in order to discover where it ends, and so we can update
+      // the uncompressed_data of the image body and its length.
 
       z_stream strm;
       strm.zalloc = Z_NULL;
       strm.zfree = Z_NULL;
       strm.opaque = Z_NULL;
       strm.avail_in = sz - pos;
-      strm.next_in = p;
+      strm.next_in = img->data() + pos;
 
       // -15 means we are decoding a 'raw' deflate stream; zlib will
       // not expect zlib headers.
       int ret = inflateInit2(&strm, -15);
+      if (ret < 0) {
+        printf("failed to initialize inflate: %d\n", ret);
+        return false;
+      }
 
+      size_t allocated = BUFFER_SIZE;
+      std::vector<uint8_t> uncompressed_data(allocated);
+      size_t uncompressed_len = 0, raw_data_len = 0;
       do {
-        strm.avail_out = allocated - curr->len;
-        strm.next_out = curr->data + curr->len;
+        strm.avail_out = allocated - uncompressed_len;
+        strm.next_out = uncompressed_data.data() + uncompressed_len;
         ret = inflate(&strm, Z_NO_FLUSH);
         if (ret < 0) {
-          if (!processed_deflate) {
-            // This is the first chunk, assume that it's just a spurious
-            // gzip header instead of a real one.
-            break;
-          }
-          printf("Error: inflate failed [%s] at file offset [%zu]\n"
-                 "imgdiff only supports gzip kernel compression,"
-                 " did you try CONFIG_KERNEL_LZO?\n",
+          printf("Warning: inflate failed [%s] at offset [%zu], treating as a normal chunk\n",
                  strm.msg, chunk_offset);
-          free(img);
-          return NULL;
+          break;
         }
-        curr->len = allocated - strm.avail_out;
+        uncompressed_len = allocated - strm.avail_out;
         if (strm.avail_out == 0) {
           allocated *= 2;
-          curr->data = reinterpret_cast<unsigned char*>(realloc(curr->data, allocated));
+          uncompressed_data.resize(allocated);
         }
-        processed_deflate = true;
       } while (ret != Z_STREAM_END);
 
-      curr->deflate_len = sz - strm.avail_in - pos;
+      raw_data_len = sz - strm.avail_in - pos;
       inflateEnd(&strm);
-      pos += curr->deflate_len;
-      p += curr->deflate_len;
-      ++curr;
 
-      // create a normal chunk for the footer
+      if (ret < 0) {
+        continue;
+      }
+
+      ImageChunk body(CHUNK_DEFLATE, pos, img, raw_data_len);
+      uncompressed_data.resize(uncompressed_len);
+      body.SetUncompressedData(std::move(uncompressed_data));
+      chunks->push_back(body);
 
-      curr->type = CHUNK_NORMAL;
-      curr->start = pos;
-      curr->len = GZIP_FOOTER_LEN;
-      curr->data = img+pos;
-      curr->I = NULL;
+      pos += raw_data_len;
 
-      pos += curr->len;
-      p += curr->len;
-      ++curr;
+      // create a normal chunk for the footer
+      chunks->emplace_back(CHUNK_NORMAL, pos, img, GZIP_FOOTER_LEN);
+
+      pos += GZIP_FOOTER_LEN;
 
       // The footer (that we just skipped over) contains the size of
       // the uncompressed data.  Double-check to make sure that it
       // matches the size of the data we got when we actually did
       // the decompression.
-      size_t footer_size = Read4(p-4);
-      if (footer_size != curr[-2].len) {
-        printf("Error: footer size %zu != decompressed size %zu\n",
-            footer_size, curr[-2].len);
-        free(img);
-        return NULL;
+      size_t footer_size = get_unaligned<uint32_t>(img->data() + pos - 4);
+      if (footer_size != body.DataLengthForPatch()) {
+        printf("Error: footer size %zu != decompressed size %zu\n", footer_size,
+               body.GetRawDataLength());
+        return false;
       }
     } else {
-      // Reallocate the list for every chunk; we expect the number of
-      // chunks to be small (5 for typical boot and recovery images).
-      ++*num_chunks;
-      *chunks = reinterpret_cast<ImageChunk*>(realloc(*chunks, *num_chunks * sizeof(ImageChunk)));
-      ImageChunk* curr = *chunks + (*num_chunks-1);
-      curr->start = pos;
-      curr->I = NULL;
-
-      // 'pos' is not the offset of the start of a gzip chunk, so scan
-      // forward until we find a gzip header.
-      curr->type = CHUNK_NORMAL;
-      curr->data = p;
-
-      for (curr->len = 0; curr->len < (sz - pos); ++curr->len) {
-        if (p[curr->len] == 0x1f &&
-            p[curr->len+1] == 0x8b &&
-            p[curr->len+2] == 0x08 &&
-            p[curr->len+3] == 0x00) {
+      // Use a normal chunk to take all the contents until the next gzip chunk (or EOF); we expect
+      // the number of chunks to be small (5 for typical boot and recovery images).
+
+      // Scan forward until we find a gzip header.
+      size_t data_len = 0;
+      while (data_len + pos < sz) {
+        if (data_len + pos + 4 <= sz &&
+            get_unaligned<uint32_t>(img->data() + pos + data_len) == 0x00088b1f) {
           break;
         }
+        data_len++;
       }
-      pos += curr->len;
-    }
-  }
+      chunks->emplace_back(CHUNK_NORMAL, pos, img, data_len);
 
-  return img;
-}
-
-#define BUFFER_SIZE 32768
-
-/*
- * Takes the uncompressed data stored in the chunk, compresses it
- * using the zlib parameters stored in the chunk, and checks that it
- * matches exactly the compressed data we started with (also stored in
- * the chunk).  Return 0 on success.
- */
-int TryReconstruction(ImageChunk* chunk, unsigned char* out) {
-  size_t p = 0;
-
-#if 0
-  printf("trying %d %d %d %d %d\n",
-          chunk->level, chunk->method, chunk->windowBits,
-          chunk->memLevel, chunk->strategy);
-#endif
-
-  z_stream strm;
-  strm.zalloc = Z_NULL;
-  strm.zfree = Z_NULL;
-  strm.opaque = Z_NULL;
-  strm.avail_in = chunk->len;
-  strm.next_in = chunk->data;
-  int ret;
-  ret = deflateInit2(&strm, chunk->level, chunk->method, chunk->windowBits,
-                     chunk->memLevel, chunk->strategy);
-  do {
-    strm.avail_out = BUFFER_SIZE;
-    strm.next_out = out;
-    ret = deflate(&strm, Z_FINISH);
-    size_t have = BUFFER_SIZE - strm.avail_out;
-
-    if (memcmp(out, chunk->deflate_data+p, have) != 0) {
-      // mismatch; data isn't the same.
-      deflateEnd(&strm);
-      return -1;
+      pos += data_len;
     }
-    p += have;
-  } while (ret != Z_STREAM_END);
-  deflateEnd(&strm);
-  if (p != chunk->deflate_len) {
-    // mismatch; ran out of data before we should have.
-    return -1;
-  }
-  return 0;
-}
-
-/*
- * Verify that we can reproduce exactly the same compressed data that
- * we started with.  Sets the level, method, windowBits, memLevel, and
- * strategy fields in the chunk to the encoding parameters needed to
- * produce the right output.  Returns 0 on success.
- */
-int ReconstructDeflateChunk(ImageChunk* chunk) {
-  if (chunk->type != CHUNK_DEFLATE) {
-    printf("attempt to reconstruct non-deflate chunk\n");
-    return -1;
   }
 
-  size_t p = 0;
-  unsigned char* out = reinterpret_cast<unsigned char*>(malloc(BUFFER_SIZE));
-
-  // We only check two combinations of encoder parameters:  level 6
-  // (the default) and level 9 (the maximum).
-  for (chunk->level = 6; chunk->level <= 9; chunk->level += 3) {
-    chunk->windowBits = -15;  // 32kb window; negative to indicate a raw stream.
-    chunk->memLevel = 8;      // the default value.
-    chunk->method = Z_DEFLATED;
-    chunk->strategy = Z_DEFAULT_STRATEGY;
-
-    if (TryReconstruction(chunk, out) == 0) {
-      free(out);
-      return 0;
-    }
-  }
-
-  free(out);
-  return -1;
+  return true;
 }
 
 /*
- * Given source and target chunks, compute a bsdiff patch between them
- * by running bsdiff in a subprocess.  Return the patch data, placing
- * its length in *size.  Return NULL on failure.  We expect the bsdiff
- * program to be in the path.
+ * Given source and target chunks, compute a bsdiff patch between them.
+ * Store the result in the patch_data.
+ * |bsdiff_cache| can be used to cache the suffix array if the same |src| chunk
+ * is used repeatedly, pass nullptr if not needed.
  */
-unsigned char* MakePatch(ImageChunk* src, ImageChunk* tgt, size_t* size) {
-  if (tgt->type == CHUNK_NORMAL) {
-    if (tgt->len <= 160) {
-      tgt->type = CHUNK_RAW;
-      *size = tgt->len;
-      return tgt->data;
-    }
+static bool MakePatch(const ImageChunk* src, ImageChunk* tgt, std::vector<uint8_t>* patch_data,
+                      saidx_t** bsdiff_cache) {
+  if (tgt->ChangeChunkToRaw(0)) {
+    size_t patch_size = tgt->DataLengthForPatch();
+    patch_data->resize(patch_size);
+    std::copy(tgt->DataForPatch(), tgt->DataForPatch() + patch_size, patch_data->begin());
+    return true;
   }
 
+#if defined(__ANDROID__)
+  char ptemp[] = "/data/local/tmp/imgdiff-patch-XXXXXX";
+#else
   char ptemp[] = "/tmp/imgdiff-patch-XXXXXX";
-  int fd = mkstemp(ptemp);
+#endif
 
+  int fd = mkstemp(ptemp);
   if (fd == -1) {
-    printf("MakePatch failed to create a temporary file: %s\n",
-           strerror(errno));
-    return NULL;
+    printf("MakePatch failed to create a temporary file: %s\n", strerror(errno));
+    return false;
   }
-  close(fd); // temporary file is created and we don't need its file
-             // descriptor
+  close(fd);
 
-  int r = bsdiff(src->data, src->len, &(src->I), tgt->data, tgt->len, ptemp);
+  int r = bsdiff::bsdiff(src->DataForPatch(), src->DataLengthForPatch(), tgt->DataForPatch(),
+                         tgt->DataLengthForPatch(), ptemp, bsdiff_cache);
   if (r != 0) {
     printf("bsdiff() failed: %d\n", r);
-    return NULL;
+    return false;
   }
 
+  android::base::unique_fd patch_fd(open(ptemp, O_RDONLY));
+  if (patch_fd == -1) {
+    printf("failed to open %s: %s\n", ptemp, strerror(errno));
+    return false;
+  }
   struct stat st;
-  if (stat(ptemp, &st) != 0) {
-    printf("failed to stat patch file %s: %s\n",
-            ptemp, strerror(errno));
-    return NULL;
+  if (fstat(patch_fd, &st) != 0) {
+    printf("failed to stat patch file %s: %s\n", ptemp, strerror(errno));
+    return false;
   }
 
   size_t sz = static_cast<size_t>(st.st_size);
-  // TODO: Memory leak on error return.
-  unsigned char* data = reinterpret_cast<unsigned char*>(malloc(sz));
-
-  if (tgt->type == CHUNK_NORMAL && tgt->len <= sz) {
+  // Change the chunk type to raw if the patch takes less space that way.
+  if (tgt->ChangeChunkToRaw(sz)) {
     unlink(ptemp);
-
-    tgt->type = CHUNK_RAW;
-    *size = tgt->len;
-    return tgt->data;
-  }
-
-  *size = sz;
-
-  FILE* f = fopen(ptemp, "rb");
-  if (f == NULL) {
-    printf("failed to open patch %s: %s\n", ptemp, strerror(errno));
-    return NULL;
+    size_t patch_size = tgt->DataLengthForPatch();
+    patch_data->resize(patch_size);
+    std::copy(tgt->DataForPatch(), tgt->DataForPatch() + patch_size, patch_data->begin());
+    return true;
   }
-  if (fread(data, 1, sz, f) != sz) {
-    printf("failed to read patch %s: %s\n", ptemp, strerror(errno));
-    return NULL;
+  patch_data->resize(sz);
+  if (!android::base::ReadFully(patch_fd, patch_data->data(), sz)) {
+    printf("failed to read \"%s\" %s\n", ptemp, strerror(errno));
+    return false;
   }
-  fclose(f);
 
   unlink(ptemp);
+  tgt->SetSourceInfo(*src);
 
-  tgt->source_start = src->start;
-  switch (tgt->type) {
-    case CHUNK_NORMAL:
-      tgt->source_len = src->len;
-      break;
-    case CHUNK_DEFLATE:
-      tgt->source_len = src->deflate_len;
-      tgt->source_uncompressed_len = src->len;
-      break;
-  }
-
-  return data;
-}
-
-/*
- * Cause a gzip chunk to be treated as a normal chunk (ie, as a blob
- * of uninterpreted data).  The resulting patch will likely be about
- * as big as the target file, but it lets us handle the case of images
- * where some gzip chunks are reconstructible but others aren't (by
- * treating the ones that aren't as normal chunks).
- */
-void ChangeDeflateChunkToNormal(ImageChunk* ch) {
-  if (ch->type != CHUNK_DEFLATE) return;
-  ch->type = CHUNK_NORMAL;
-  free(ch->data);
-  ch->data = ch->deflate_data;
-  ch->len = ch->deflate_len;
-}
-
-/*
- * Return true if the data in the chunk is identical (including the
- * compressed representation, for gzip chunks).
- */
-int AreChunksEqual(ImageChunk* a, ImageChunk* b) {
-    if (a->type != b->type) return 0;
-
-    switch (a->type) {
-        case CHUNK_NORMAL:
-            return a->len == b->len && memcmp(a->data, b->data, a->len) == 0;
-
-        case CHUNK_DEFLATE:
-            return a->deflate_len == b->deflate_len &&
-                memcmp(a->deflate_data, b->deflate_data, a->deflate_len) == 0;
-
-        default:
-            printf("unknown chunk type %d\n", a->type);
-            return 0;
-    }
+  return true;
 }
 
 /*
@@ -740,137 +809,103 @@ int AreChunksEqual(ImageChunk* a, ImageChunk* b) {
  * a single chunk.  (Such runs can be produced when deflate chunks are
  * changed to normal chunks.)
  */
-void MergeAdjacentNormalChunks(ImageChunk* chunks, int* num_chunks) {
-  int out = 0;
-  int in_start = 0, in_end;
-  while (in_start < *num_chunks) {
-    if (chunks[in_start].type != CHUNK_NORMAL) {
-      in_end = in_start+1;
-    } else {
-      // in_start is a normal chunk.  Look for a run of normal chunks
-      // that constitute a solid block of data (ie, each chunk begins
-      // where the previous one ended).
-      for (in_end = in_start+1;
-           in_end < *num_chunks && chunks[in_end].type == CHUNK_NORMAL &&
-             (chunks[in_end].start ==
-              chunks[in_end-1].start + chunks[in_end-1].len &&
-              chunks[in_end].data ==
-              chunks[in_end-1].data + chunks[in_end-1].len);
-           ++in_end);
+static void MergeAdjacentNormalChunks(std::vector<ImageChunk>* chunks) {
+  size_t merged_last = 0, cur = 0;
+  while (cur < chunks->size()) {
+    // Look for normal chunks adjacent to the current one. If such chunk exists, extend the
+    // length of the current normal chunk.
+    size_t to_check = cur + 1;
+    while (to_check < chunks->size() && chunks->at(cur).IsAdjacentNormal(chunks->at(to_check))) {
+      chunks->at(cur).MergeAdjacentNormal(chunks->at(to_check));
+      to_check++;
     }
 
-    if (in_end == in_start+1) {
-#if 0
-      printf("chunk %d is now %d\n", in_start, out);
-#endif
-      if (out != in_start) {
-        memcpy(chunks+out, chunks+in_start, sizeof(ImageChunk));
-      }
-    } else {
-#if 0
-      printf("collapse normal chunks %d-%d into %d\n", in_start, in_end-1, out);
-#endif
-
-      // Merge chunks [in_start, in_end-1] into one chunk.  Since the
-      // data member of each chunk is just a pointer into an in-memory
-      // copy of the file, this can be done without recopying (the
-      // output chunk has the first chunk's start location and data
-      // pointer, and length equal to the sum of the input chunk
-      // lengths).
-      chunks[out].type = CHUNK_NORMAL;
-      chunks[out].start = chunks[in_start].start;
-      chunks[out].data = chunks[in_start].data;
-      chunks[out].len = chunks[in_end-1].len +
-        (chunks[in_end-1].start - chunks[in_start].start);
+    if (merged_last != cur) {
+      chunks->at(merged_last) = std::move(chunks->at(cur));
     }
-
-    ++out;
-    in_start = in_end;
+    merged_last++;
+    cur = to_check;
+  }
+  if (merged_last < chunks->size()) {
+    chunks->erase(chunks->begin() + merged_last, chunks->end());
   }
-  *num_chunks = out;
 }
 
-ImageChunk* FindChunkByName(const char* name,
-                            ImageChunk* chunks, int num_chunks) {
-  int i;
-  for (i = 0; i < num_chunks; ++i) {
-    if (chunks[i].type == CHUNK_DEFLATE && chunks[i].filename &&
-        strcmp(name, chunks[i].filename) == 0) {
-      return chunks+i;
+static ImageChunk* FindChunkByName(const std::string& name, std::vector<ImageChunk>& chunks) {
+  for (size_t i = 0; i < chunks.size(); ++i) {
+    if (chunks[i].GetType() == CHUNK_DEFLATE && chunks[i].GetEntryName() == name) {
+      return &chunks[i];
     }
   }
-  return NULL;
+  return nullptr;
 }
 
-void DumpChunks(ImageChunk* chunks, int num_chunks) {
-    for (int i = 0; i < num_chunks; ++i) {
-        printf("chunk %d: type %d start %zu len %zu\n",
-               i, chunks[i].type, chunks[i].start, chunks[i].len);
-    }
+static void DumpChunks(const std::vector<ImageChunk>& chunks) {
+  for (size_t i = 0; i < chunks.size(); ++i) {
+    printf("chunk %zu: ", i);
+    chunks[i].Dump();
+  }
 }
 
-int main(int argc, char** argv) {
-  int zip_mode = 0;
+int imgdiff(int argc, const char** argv) {
+  bool zip_mode = false;
 
   if (argc >= 2 && strcmp(argv[1], "-z") == 0) {
-    zip_mode = 1;
+    zip_mode = true;
     --argc;
     ++argv;
   }
 
-  size_t bonus_size = 0;
-  unsigned char* bonus_data = NULL;
+  std::vector<uint8_t> bonus_data;
   if (argc >= 3 && strcmp(argv[1], "-b") == 0) {
-    struct stat st;
-    if (stat(argv[2], &st) != 0) {
-      printf("failed to stat bonus file %s: %s\n", argv[2], strerror(errno));
+    android::base::unique_fd fd(open(argv[2], O_RDONLY));
+    if (fd == -1) {
+      printf("failed to open bonus file %s: %s\n", argv[2], strerror(errno));
       return 1;
     }
-    bonus_size = st.st_size;
-    bonus_data = reinterpret_cast<unsigned char*>(malloc(bonus_size));
-    FILE* f = fopen(argv[2], "rb");
-    if (f == NULL) {
-      printf("failed to open bonus file %s: %s\n", argv[2], strerror(errno));
+    struct stat st;
+    if (fstat(fd, &st) != 0) {
+      printf("failed to stat bonus file %s: %s\n", argv[2], strerror(errno));
       return 1;
     }
-    if (fread(bonus_data, 1, bonus_size, f) != bonus_size) {
+
+    size_t bonus_size = st.st_size;
+    bonus_data.resize(bonus_size);
+    if (!android::base::ReadFully(fd, bonus_data.data(), bonus_size)) {
       printf("failed to read bonus file %s: %s\n", argv[2], strerror(errno));
       return 1;
     }
-    fclose(f);
 
     argc -= 2;
     argv += 2;
   }
 
   if (argc != 4) {
-    usage:
     printf("usage: %s [-z] [-b <bonus-file>] <src-img> <tgt-img> <patch-file>\n",
             argv[0]);
     return 2;
   }
 
-  int num_src_chunks;
-  ImageChunk* src_chunks;
-  int num_tgt_chunks;
-  ImageChunk* tgt_chunks;
-  int i;
+  std::vector<ImageChunk> src_chunks;
+  std::vector<ImageChunk> tgt_chunks;
+  std::vector<uint8_t> src_file;
+  std::vector<uint8_t> tgt_file;
 
   if (zip_mode) {
-    if (ReadZip(argv[1], &num_src_chunks, &src_chunks, 1) == NULL) {
+    if (!ReadZip(argv[1], &src_chunks, &src_file, true)) {
       printf("failed to break apart source zip file\n");
       return 1;
     }
-    if (ReadZip(argv[2], &num_tgt_chunks, &tgt_chunks, 0) == NULL) {
+    if (!ReadZip(argv[2], &tgt_chunks, &tgt_file, false)) {
       printf("failed to break apart target zip file\n");
       return 1;
     }
   } else {
-    if (ReadImage(argv[1], &num_src_chunks, &src_chunks) == NULL) {
+    if (!ReadImage(argv[1], &src_chunks, &src_file)) {
       printf("failed to break apart source image\n");
       return 1;
     }
-    if (ReadImage(argv[2], &num_tgt_chunks, &tgt_chunks) == NULL) {
+    if (!ReadImage(argv[2], &tgt_chunks, &tgt_file)) {
       printf("failed to break apart target image\n");
       return 1;
     }
@@ -878,51 +913,47 @@ int main(int argc, char** argv) {
     // Verify that the source and target images have the same chunk
     // structure (ie, the same sequence of deflate and normal chunks).
 
-    if (!zip_mode) {
-        // Merge the gzip header and footer in with any adjacent
-        // normal chunks.
-        MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
-        MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
-    }
+    // Merge the gzip header and footer in with any adjacent normal chunks.
+    MergeAdjacentNormalChunks(&tgt_chunks);
+    MergeAdjacentNormalChunks(&src_chunks);
 
-    if (num_src_chunks != num_tgt_chunks) {
+    if (src_chunks.size() != tgt_chunks.size()) {
       printf("source and target don't have same number of chunks!\n");
       printf("source chunks:\n");
-      DumpChunks(src_chunks, num_src_chunks);
+      DumpChunks(src_chunks);
       printf("target chunks:\n");
-      DumpChunks(tgt_chunks, num_tgt_chunks);
+      DumpChunks(tgt_chunks);
       return 1;
     }
-    for (i = 0; i < num_src_chunks; ++i) {
-      if (src_chunks[i].type != tgt_chunks[i].type) {
-        printf("source and target don't have same chunk "
-                "structure! (chunk %d)\n", i);
+    for (size_t i = 0; i < src_chunks.size(); ++i) {
+      if (src_chunks[i].GetType() != tgt_chunks[i].GetType()) {
+        printf("source and target don't have same chunk structure! (chunk %zu)\n", i);
         printf("source chunks:\n");
-        DumpChunks(src_chunks, num_src_chunks);
+        DumpChunks(src_chunks);
         printf("target chunks:\n");
-        DumpChunks(tgt_chunks, num_tgt_chunks);
+        DumpChunks(tgt_chunks);
         return 1;
       }
     }
   }
 
-  for (i = 0; i < num_tgt_chunks; ++i) {
-    if (tgt_chunks[i].type == CHUNK_DEFLATE) {
+  for (size_t i = 0; i < tgt_chunks.size(); ++i) {
+    if (tgt_chunks[i].GetType() == CHUNK_DEFLATE) {
       // Confirm that given the uncompressed chunk data in the target, we
       // can recompress it and get exactly the same bits as are in the
       // input target image.  If this fails, treat the chunk as a normal
       // non-deflated chunk.
-      if (ReconstructDeflateChunk(tgt_chunks+i) < 0) {
-        printf("failed to reconstruct target deflate chunk %d [%s]; "
-               "treating as normal\n", i, tgt_chunks[i].filename);
-        ChangeDeflateChunkToNormal(tgt_chunks+i);
+      if (!tgt_chunks[i].ReconstructDeflateChunk()) {
+        printf("failed to reconstruct target deflate chunk %zu [%s]; treating as normal\n", i,
+               tgt_chunks[i].GetEntryName().c_str());
+        tgt_chunks[i].ChangeDeflateChunkToNormal();
         if (zip_mode) {
-          ImageChunk* src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
-          if (src) {
-            ChangeDeflateChunkToNormal(src);
+          ImageChunk* src = FindChunkByName(tgt_chunks[i].GetEntryName(), src_chunks);
+          if (src != nullptr) {
+            src->ChangeDeflateChunkToNormal();
           }
         } else {
-          ChangeDeflateChunkToNormal(src_chunks+i);
+          src_chunks[i].ChangeDeflateChunkToNormal();
         }
         continue;
       }
@@ -935,16 +966,16 @@ int main(int argc, char** argv) {
       // data.
       ImageChunk* src;
       if (zip_mode) {
-        src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks);
+        src = FindChunkByName(tgt_chunks[i].GetEntryName(), src_chunks);
       } else {
-        src = src_chunks+i;
+        src = &src_chunks[i];
       }
 
-      if (src == NULL || AreChunksEqual(tgt_chunks+i, src)) {
-        ChangeDeflateChunkToNormal(tgt_chunks+i);
-        if (src) {
-          ChangeDeflateChunkToNormal(src);
-        }
+      if (src == nullptr) {
+        tgt_chunks[i].ChangeDeflateChunkToNormal();
+      } else if (tgt_chunks[i] == *src) {
+        tgt_chunks[i].ChangeDeflateChunkToNormal();
+        src->ChangeDeflateChunkToNormal();
       }
     }
   }
@@ -954,14 +985,15 @@ int main(int argc, char** argv) {
     // For zips, we only need to do this to the target:  deflated
     // chunks are matched via filename, and normal chunks are patched
     // using the entire source file as the source.
-    MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
+    MergeAdjacentNormalChunks(&tgt_chunks);
+
   } else {
     // For images, we need to maintain the parallel structure of the
     // chunk lists, so do the merging in both the source and target
     // lists.
-    MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
-    MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
-    if (num_src_chunks != num_tgt_chunks) {
+    MergeAdjacentNormalChunks(&tgt_chunks);
+    MergeAdjacentNormalChunks(&src_chunks);
+    if (src_chunks.size() != tgt_chunks.size()) {
       // This shouldn't happen.
       printf("merging normal chunks went awry\n");
       return 1;
@@ -971,35 +1003,43 @@ int main(int argc, char** argv) {
   // Compute bsdiff patches for each chunk's data (the uncompressed
   // data, in the case of deflate chunks).
 
-  DumpChunks(src_chunks, num_src_chunks);
+  DumpChunks(src_chunks);
 
-  printf("Construct patches for %d chunks...\n", num_tgt_chunks);
-  unsigned char** patch_data = reinterpret_cast<unsigned char**>(malloc(
-      num_tgt_chunks * sizeof(unsigned char*)));
-  size_t* patch_size = reinterpret_cast<size_t*>(malloc(num_tgt_chunks * sizeof(size_t)));
-  for (i = 0; i < num_tgt_chunks; ++i) {
+  printf("Construct patches for %zu chunks...\n", tgt_chunks.size());
+  std::vector<std::vector<uint8_t>> patch_data(tgt_chunks.size());
+  saidx_t* bsdiff_cache = nullptr;
+  for (size_t i = 0; i < tgt_chunks.size(); ++i) {
     if (zip_mode) {
       ImageChunk* src;
-      if (tgt_chunks[i].type == CHUNK_DEFLATE &&
-          (src = FindChunkByName(tgt_chunks[i].filename, src_chunks,
-                                 num_src_chunks))) {
-        patch_data[i] = MakePatch(src, tgt_chunks+i, patch_size+i);
+      if (tgt_chunks[i].GetType() == CHUNK_DEFLATE &&
+          (src = FindChunkByName(tgt_chunks[i].GetEntryName(), src_chunks))) {
+        if (!MakePatch(src, &tgt_chunks[i], &patch_data[i], nullptr)) {
+          printf("Failed to generate patch for target chunk %zu: ", i);
+          return 1;
+        }
       } else {
-        patch_data[i] = MakePatch(src_chunks, tgt_chunks+i, patch_size+i);
+        if (!MakePatch(&src_chunks[0], &tgt_chunks[i], &patch_data[i], &bsdiff_cache)) {
+          printf("Failed to generate patch for target chunk %zu: ", i);
+          return 1;
+        }
       }
     } else {
-      if (i == 1 && bonus_data) {
-        printf("  using %zu bytes of bonus data for chunk %d\n", bonus_size, i);
-        src_chunks[i].data = reinterpret_cast<unsigned char*>(realloc(src_chunks[i].data,
-            src_chunks[i].len + bonus_size));
-        memcpy(src_chunks[i].data+src_chunks[i].len, bonus_data, bonus_size);
-        src_chunks[i].len += bonus_size;
-     }
-
-      patch_data[i] = MakePatch(src_chunks+i, tgt_chunks+i, patch_size+i);
+      if (i == 1 && !bonus_data.empty()) {
+        printf("  using %zu bytes of bonus data for chunk %zu\n", bonus_data.size(), i);
+        src_chunks[i].SetBonusData(bonus_data);
+      }
+
+      if (!MakePatch(&src_chunks[i], &tgt_chunks[i], &patch_data[i], nullptr)) {
+        printf("Failed to generate patch for target chunk %zu: ", i);
+        return 1;
+      }
     }
-    printf("patch %3d is %zu bytes (of %zu)\n",
-           i, patch_size[i], tgt_chunks[i].source_len);
+    printf("patch %3zu is %zu bytes (of %zu)\n", i, patch_data[i].size(),
+           src_chunks[i].GetRawDataLength());
+  }
+
+  if (bsdiff_cache != nullptr) {
+    free(bsdiff_cache);
   }
 
   // Figure out how big the imgdiff file header is going to be, so
@@ -1007,77 +1047,38 @@ int main(int argc, char** argv) {
   // within the file.
 
   size_t total_header_size = 12;
-  for (i = 0; i < num_tgt_chunks; ++i) {
-    total_header_size += 4;
-    switch (tgt_chunks[i].type) {
-      case CHUNK_NORMAL:
-        total_header_size += 8*3;
-        break;
-      case CHUNK_DEFLATE:
-        total_header_size += 8*5 + 4*5;
-        break;
-      case CHUNK_RAW:
-        total_header_size += 4 + patch_size[i];
-        break;
-    }
+  for (size_t i = 0; i < tgt_chunks.size(); ++i) {
+    total_header_size += tgt_chunks[i].GetHeaderSize(patch_data[i].size());
   }
 
   size_t offset = total_header_size;
 
-  FILE* f = fopen(argv[3], "wb");
+  android::base::unique_fd patch_fd(open(argv[3], O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR));
+  if (patch_fd == -1) {
+    printf("failed to open \"%s\": %s\n", argv[3], strerror(errno));
+    return 1;
+  }
 
   // Write out the headers.
-
-  fwrite("IMGDIFF2", 1, 8, f);
-  Write4(num_tgt_chunks, f);
-  for (i = 0; i < num_tgt_chunks; ++i) {
-    Write4(tgt_chunks[i].type, f);
-
-    switch (tgt_chunks[i].type) {
-      case CHUNK_NORMAL:
-        printf("chunk %3d: normal   (%10zu, %10zu)  %10zu\n", i,
-               tgt_chunks[i].start, tgt_chunks[i].len, patch_size[i]);
-        Write8(tgt_chunks[i].source_start, f);
-        Write8(tgt_chunks[i].source_len, f);
-        Write8(offset, f);
-        offset += patch_size[i];
-        break;
-
-      case CHUNK_DEFLATE:
-        printf("chunk %3d: deflate  (%10zu, %10zu)  %10zu  %s\n", i,
-               tgt_chunks[i].start, tgt_chunks[i].deflate_len, patch_size[i],
-               tgt_chunks[i].filename);
-        Write8(tgt_chunks[i].source_start, f);
-        Write8(tgt_chunks[i].source_len, f);
-        Write8(offset, f);
-        Write8(tgt_chunks[i].source_uncompressed_len, f);
-        Write8(tgt_chunks[i].len, f);
-        Write4(tgt_chunks[i].level, f);
-        Write4(tgt_chunks[i].method, f);
-        Write4(tgt_chunks[i].windowBits, f);
-        Write4(tgt_chunks[i].memLevel, f);
-        Write4(tgt_chunks[i].strategy, f);
-        offset += patch_size[i];
-        break;
-
-      case CHUNK_RAW:
-        printf("chunk %3d: raw      (%10zu, %10zu)\n", i,
-               tgt_chunks[i].start, tgt_chunks[i].len);
-        Write4(patch_size[i], f);
-        fwrite(patch_data[i], 1, patch_size[i], f);
-        break;
-    }
+  if (!android::base::WriteStringToFd("IMGDIFF2", patch_fd)) {
+    printf("failed to write \"IMGDIFF2\" to \"%s\": %s\n", argv[3], strerror(errno));
+    return 1;
+  }
+  Write4(patch_fd, static_cast<int32_t>(tgt_chunks.size()));
+  for (size_t i = 0; i < tgt_chunks.size(); ++i) {
+    printf("chunk %zu: ", i);
+    offset = tgt_chunks[i].WriteHeaderToFd(patch_fd, patch_data[i], offset);
   }
 
   // Append each chunk's bsdiff patch, in order.
-
-  for (i = 0; i < num_tgt_chunks; ++i) {
-    if (tgt_chunks[i].type != CHUNK_RAW) {
-      fwrite(patch_data[i], 1, patch_size[i], f);
+  for (size_t i = 0; i < tgt_chunks.size(); ++i) {
+    if (tgt_chunks[i].GetType() != CHUNK_RAW) {
+      if (!android::base::WriteFully(patch_fd, patch_data[i].data(), patch_data[i].size())) {
+        CHECK(false) << "failed to write " << patch_data[i].size() << " bytes patch for chunk "
+                     << i;
+      }
     }
   }
 
-  fclose(f);
-
   return 0;
 }
diff --git a/applypatch/imgdiff_main.cpp b/applypatch/imgdiff_main.cpp
new file mode 100644
index 000000000..7d5bdf9aa
--- /dev/null
+++ b/applypatch/imgdiff_main.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "applypatch/imgdiff.h"
+
+int main(int argc, char** argv) {
+  return imgdiff(argc, const_cast<const char**>(argv));
+}
diff --git a/applypatch/imgpatch.cpp b/applypatch/imgpatch.cpp
index d175d6385..adcc61fd6 100644
--- a/applypatch/imgpatch.cpp
+++ b/applypatch/imgpatch.cpp
@@ -14,31 +14,41 @@
  * limitations under the License.
  */
 
-// See imgdiff.c in this directory for a description of the patch file
+// See imgdiff.cpp in this directory for a description of the patch file
 // format.
 
+#include <applypatch/imgpatch.h>
+
+#include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/cdefs.h>
 #include <sys/stat.h>
-#include <errno.h>
 #include <unistd.h>
-#include <string.h>
 
+#include <string>
 #include <vector>
 
-#include "zlib.h"
-#include "openssl/sha.h"
-#include "applypatch.h"
-#include "imgdiff.h"
-#include "utils.h"
+#include <applypatch/applypatch.h>
+#include <applypatch/imgdiff.h>
+#include <android-base/memory.h>
+#include <openssl/sha.h>
+#include <zlib.h>
+
+static inline int64_t Read8(const void *address) {
+  return android::base::get_unaligned<int64_t>(address);
+}
+
+static inline int32_t Read4(const void *address) {
+  return android::base::get_unaligned<int32_t>(address);
+}
 
 int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
                     const unsigned char* patch_data, ssize_t patch_size,
                     SinkFn sink, void* token) {
-  Value patch = {VAL_BLOB, patch_size,
-      reinterpret_cast<char*>(const_cast<unsigned char*>(patch_data))};
-  return ApplyImagePatch(
-      old_data, old_size, &patch, sink, token, nullptr, nullptr);
+  Value patch(VAL_BLOB, std::string(reinterpret_cast<const char*>(patch_data), patch_size));
+
+  return ApplyImagePatch(old_data, old_size, &patch, sink, token, nullptr, nullptr);
 }
 
 /*
@@ -47,203 +57,204 @@ int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
  * file, and update the SHA context with the output data as well.
  * Return 0 on success.
  */
-int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
-                    const Value* patch,
-                    SinkFn sink, void* token, SHA_CTX* ctx,
-                    const Value* bonus_data) {
-    ssize_t pos = 12;
-    char* header = patch->data;
-    if (patch->size < 12) {
-        printf("patch too short to contain header\n");
-        return -1;
+int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size, const Value* patch,
+                    SinkFn sink, void* token, SHA_CTX* ctx, const Value* bonus_data) {
+  if (patch->data.size() < 12) {
+    printf("patch too short to contain header\n");
+    return -1;
+  }
+
+  // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
+  // (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
+  // CHUNK_GZIP.)
+  size_t pos = 12;
+  const char* header = &patch->data[0];
+  if (memcmp(header, "IMGDIFF2", 8) != 0) {
+    printf("corrupt patch file header (magic number)\n");
+    return -1;
+  }
+
+  int num_chunks = Read4(header + 8);
+
+  for (int i = 0; i < num_chunks; ++i) {
+    // each chunk's header record starts with 4 bytes.
+    if (pos + 4 > patch->data.size()) {
+      printf("failed to read chunk %d record\n", i);
+      return -1;
     }
+    int type = Read4(&patch->data[pos]);
+    pos += 4;
 
-    // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
-    // (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
-    // CHUNK_GZIP.)
-    if (memcmp(header, "IMGDIFF2", 8) != 0) {
-        printf("corrupt patch file header (magic number)\n");
+    if (type == CHUNK_NORMAL) {
+      const char* normal_header = &patch->data[pos];
+      pos += 24;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d normal header data\n", i);
         return -1;
-    }
+      }
 
-    int num_chunks = Read4(header+8);
+      size_t src_start = static_cast<size_t>(Read8(normal_header));
+      size_t src_len = static_cast<size_t>(Read8(normal_header + 8));
+      size_t patch_offset = static_cast<size_t>(Read8(normal_header + 16));
 
-    int i;
-    for (i = 0; i < num_chunks; ++i) {
-        // each chunk's header record starts with 4 bytes.
-        if (pos + 4 > patch->size) {
-            printf("failed to read chunk %d record\n", i);
-            return -1;
+      if (src_start + src_len > static_cast<size_t>(old_size)) {
+        printf("source data too short\n");
+        return -1;
+      }
+      ApplyBSDiffPatch(old_data + src_start, src_len, patch, patch_offset, sink, token, ctx);
+    } else if (type == CHUNK_RAW) {
+      const char* raw_header = &patch->data[pos];
+      pos += 4;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d raw header data\n", i);
+        return -1;
+      }
+
+      ssize_t data_len = Read4(raw_header);
+
+      if (pos + data_len > patch->data.size()) {
+        printf("failed to read chunk %d raw data\n", i);
+        return -1;
+      }
+      if (ctx) SHA1_Update(ctx, &patch->data[pos], data_len);
+      if (sink(reinterpret_cast<const unsigned char*>(&patch->data[pos]), data_len, token) !=
+          data_len) {
+        printf("failed to write chunk %d raw data\n", i);
+        return -1;
+      }
+      pos += data_len;
+    } else if (type == CHUNK_DEFLATE) {
+      // deflate chunks have an additional 60 bytes in their chunk header.
+      const char* deflate_header = &patch->data[pos];
+      pos += 60;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d deflate header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = static_cast<size_t>(Read8(deflate_header));
+      size_t src_len = static_cast<size_t>(Read8(deflate_header + 8));
+      size_t patch_offset = static_cast<size_t>(Read8(deflate_header + 16));
+      size_t expanded_len = static_cast<size_t>(Read8(deflate_header + 24));
+      size_t target_len = static_cast<size_t>(Read8(deflate_header + 32));
+      int level = Read4(deflate_header + 40);
+      int method = Read4(deflate_header + 44);
+      int windowBits = Read4(deflate_header + 48);
+      int memLevel = Read4(deflate_header + 52);
+      int strategy = Read4(deflate_header + 56);
+
+      if (src_start + src_len > static_cast<size_t>(old_size)) {
+        printf("source data too short\n");
+        return -1;
+      }
+
+      // Decompress the source data; the chunk header tells us exactly
+      // how big we expect it to be when decompressed.
+
+      // Note: expanded_len will include the bonus data size if
+      // the patch was constructed with bonus data.  The
+      // deflation will come up 'bonus_size' bytes short; these
+      // must be appended from the bonus_data value.
+      size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->data.size() : 0;
+
+      std::vector<unsigned char> expanded_source(expanded_len);
+
+      // inflate() doesn't like strm.next_out being a nullptr even with
+      // avail_out being zero (Z_STREAM_ERROR).
+      if (expanded_len != 0) {
+        z_stream strm;
+        strm.zalloc = Z_NULL;
+        strm.zfree = Z_NULL;
+        strm.opaque = Z_NULL;
+        strm.avail_in = src_len;
+        strm.next_in = old_data + src_start;
+        strm.avail_out = expanded_len;
+        strm.next_out = expanded_source.data();
+
+        int ret = inflateInit2(&strm, -15);
+        if (ret != Z_OK) {
+          printf("failed to init source inflation: %d\n", ret);
+          return -1;
         }
-        int type = Read4(patch->data + pos);
-        pos += 4;
-
-        if (type == CHUNK_NORMAL) {
-            char* normal_header = patch->data + pos;
-            pos += 24;
-            if (pos > patch->size) {
-                printf("failed to read chunk %d normal header data\n", i);
-                return -1;
-            }
-
-            size_t src_start = Read8(normal_header);
-            size_t src_len = Read8(normal_header+8);
-            size_t patch_offset = Read8(normal_header+16);
-
-            if (src_start + src_len > static_cast<size_t>(old_size)) {
-                printf("source data too short\n");
-                return -1;
-            }
-            ApplyBSDiffPatch(old_data + src_start, src_len,
-                             patch, patch_offset, sink, token, ctx);
-        } else if (type == CHUNK_RAW) {
-            char* raw_header = patch->data + pos;
-            pos += 4;
-            if (pos > patch->size) {
-                printf("failed to read chunk %d raw header data\n", i);
-                return -1;
-            }
-
-            ssize_t data_len = Read4(raw_header);
-
-            if (pos + data_len > patch->size) {
-                printf("failed to read chunk %d raw data\n", i);
-                return -1;
-            }
-            if (ctx) SHA1_Update(ctx, patch->data + pos, data_len);
-            if (sink((unsigned char*)patch->data + pos,
-                     data_len, token) != data_len) {
-                printf("failed to write chunk %d raw data\n", i);
-                return -1;
-            }
-            pos += data_len;
-        } else if (type == CHUNK_DEFLATE) {
-            // deflate chunks have an additional 60 bytes in their chunk header.
-            char* deflate_header = patch->data + pos;
-            pos += 60;
-            if (pos > patch->size) {
-                printf("failed to read chunk %d deflate header data\n", i);
-                return -1;
-            }
-
-            size_t src_start = Read8(deflate_header);
-            size_t src_len = Read8(deflate_header+8);
-            size_t patch_offset = Read8(deflate_header+16);
-            size_t expanded_len = Read8(deflate_header+24);
-            int level = Read4(deflate_header+40);
-            int method = Read4(deflate_header+44);
-            int windowBits = Read4(deflate_header+48);
-            int memLevel = Read4(deflate_header+52);
-            int strategy = Read4(deflate_header+56);
-
-            if (src_start + src_len > static_cast<size_t>(old_size)) {
-                printf("source data too short\n");
-                return -1;
-            }
-
-            // Decompress the source data; the chunk header tells us exactly
-            // how big we expect it to be when decompressed.
-
-            // Note: expanded_len will include the bonus data size if
-            // the patch was constructed with bonus data.  The
-            // deflation will come up 'bonus_size' bytes short; these
-            // must be appended from the bonus_data value.
-            size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->size : 0;
-
-            std::vector<unsigned char> expanded_source(expanded_len);
-
-            // inflate() doesn't like strm.next_out being a nullptr even with
-            // avail_out being zero (Z_STREAM_ERROR).
-            if (expanded_len != 0) {
-                z_stream strm;
-                strm.zalloc = Z_NULL;
-                strm.zfree = Z_NULL;
-                strm.opaque = Z_NULL;
-                strm.avail_in = src_len;
-                strm.next_in = (unsigned char*)(old_data + src_start);
-                strm.avail_out = expanded_len;
-                strm.next_out = expanded_source.data();
-
-                int ret;
-                ret = inflateInit2(&strm, -15);
-                if (ret != Z_OK) {
-                    printf("failed to init source inflation: %d\n", ret);
-                    return -1;
-                }
-
-                // Because we've provided enough room to accommodate the output
-                // data, we expect one call to inflate() to suffice.
-                ret = inflate(&strm, Z_SYNC_FLUSH);
-                if (ret != Z_STREAM_END) {
-                    printf("source inflation returned %d\n", ret);
-                    return -1;
-                }
-                // We should have filled the output buffer exactly, except
-                // for the bonus_size.
-                if (strm.avail_out != bonus_size) {
-                    printf("source inflation short by %zu bytes\n", strm.avail_out-bonus_size);
-                    return -1;
-                }
-                inflateEnd(&strm);
-
-                if (bonus_size) {
-                    memcpy(expanded_source.data() + (expanded_len - bonus_size),
-                           bonus_data->data, bonus_size);
-                }
-            }
-
-            // Next, apply the bsdiff patch (in memory) to the uncompressed
-            // data.
-            std::vector<unsigned char> uncompressed_target_data;
-            if (ApplyBSDiffPatchMem(expanded_source.data(), expanded_len,
-                                    patch, patch_offset,
-                                    &uncompressed_target_data) != 0) {
-                return -1;
-            }
-
-            // Now compress the target data and append it to the output.
-
-            // we're done with the expanded_source data buffer, so we'll
-            // reuse that memory to receive the output of deflate.
-            if (expanded_source.size() < 32768U) {
-                expanded_source.resize(32768U);
-            }
-
-            {
-                std::vector<unsigned char>& temp_data = expanded_source;
-
-                // now the deflate stream
-                z_stream strm;
-                strm.zalloc = Z_NULL;
-                strm.zfree = Z_NULL;
-                strm.opaque = Z_NULL;
-                strm.avail_in = uncompressed_target_data.size();
-                strm.next_in = uncompressed_target_data.data();
-                int ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
-                if (ret != Z_OK) {
-                    printf("failed to init uncompressed data deflation: %d\n", ret);
-                    return -1;
-                }
-                do {
-                    strm.avail_out = temp_data.size();
-                    strm.next_out = temp_data.data();
-                    ret = deflate(&strm, Z_FINISH);
-                    ssize_t have = temp_data.size() - strm.avail_out;
-
-                    if (sink(temp_data.data(), have, token) != have) {
-                        printf("failed to write %ld compressed bytes to output\n",
-                               (long)have);
-                        return -1;
-                    }
-                    if (ctx) SHA1_Update(ctx, temp_data.data(), have);
-                } while (ret != Z_STREAM_END);
-                deflateEnd(&strm);
-            }
-        } else {
-            printf("patch chunk %d is unknown type %d\n", i, type);
-            return -1;
+
+        // Because we've provided enough room to accommodate the output
+        // data, we expect one call to inflate() to suffice.
+        ret = inflate(&strm, Z_SYNC_FLUSH);
+        if (ret != Z_STREAM_END) {
+          printf("source inflation returned %d\n", ret);
+          return -1;
+        }
+        // We should have filled the output buffer exactly, except
+        // for the bonus_size.
+        if (strm.avail_out != bonus_size) {
+          printf("source inflation short by %zu bytes\n", strm.avail_out - bonus_size);
+          return -1;
         }
+        inflateEnd(&strm);
+
+        if (bonus_size) {
+          memcpy(expanded_source.data() + (expanded_len - bonus_size), &bonus_data->data[0],
+                 bonus_size);
+        }
+      }
+
+      // Next, apply the bsdiff patch (in memory) to the uncompressed data.
+      std::vector<unsigned char> uncompressed_target_data;
+      // TODO(senj): Remove the only usage of ApplyBSDiffPatchMem here,
+      // replace it with ApplyBSDiffPatch with a custom sink function that
+      // wraps the given sink function to stream output to save memory.
+      if (ApplyBSDiffPatchMem(expanded_source.data(), expanded_len, patch, patch_offset,
+                              &uncompressed_target_data) != 0) {
+        return -1;
+      }
+      if (uncompressed_target_data.size() != target_len) {
+        printf("expected target len to be %zu, but it's %zu\n", target_len,
+               uncompressed_target_data.size());
+        return -1;
+      }
+
+      // Now compress the target data and append it to the output.
+
+      // we're done with the expanded_source data buffer, so we'll
+      // reuse that memory to receive the output of deflate.
+      if (expanded_source.size() < 32768U) {
+        expanded_source.resize(32768U);
+      }
+
+      {
+        std::vector<unsigned char>& temp_data = expanded_source;
+
+        // now the deflate stream
+        z_stream strm;
+        strm.zalloc = Z_NULL;
+        strm.zfree = Z_NULL;
+        strm.opaque = Z_NULL;
+        strm.avail_in = uncompressed_target_data.size();
+        strm.next_in = uncompressed_target_data.data();
+        int ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
+        if (ret != Z_OK) {
+          printf("failed to init uncompressed data deflation: %d\n", ret);
+          return -1;
+        }
+        do {
+          strm.avail_out = temp_data.size();
+          strm.next_out = temp_data.data();
+          ret = deflate(&strm, Z_FINISH);
+          ssize_t have = temp_data.size() - strm.avail_out;
+
+          if (sink(temp_data.data(), have, token) != have) {
+            printf("failed to write %zd compressed bytes to output\n", have);
+            return -1;
+          }
+          if (ctx) SHA1_Update(ctx, temp_data.data(), have);
+        } while (ret != Z_STREAM_END);
+        deflateEnd(&strm);
+      }
+    } else {
+      printf("patch chunk %d is unknown type %d\n", i, type);
+      return -1;
     }
+  }
 
-    return 0;
+  return 0;
 }
diff --git a/applypatch/applypatch.h b/applypatch/include/applypatch/applypatch.h
index f392c5534..4489decb6 100644
--- a/applypatch/applypatch.h
+++ b/applypatch/include/applypatch/applypatch.h
@@ -17,11 +17,15 @@
 #ifndef _APPLYPATCH_H
 #define _APPLYPATCH_H
 
+#include <stdint.h>
 #include <sys/stat.h>
 
+#include <memory>
+#include <string>
 #include <vector>
 
-#include "openssl/sha.h"
+#include <openssl/sha.h>
+
 #include "edify/expr.h"
 
 struct FileContents {
@@ -39,33 +43,28 @@ struct FileContents {
 
 typedef ssize_t (*SinkFn)(const unsigned char*, ssize_t, void*);
 
-// applypatch.c
+// applypatch.cpp
 int ShowLicenses();
 size_t FreeSpaceForFile(const char* filename);
 int CacheSizeCheck(size_t bytes);
 int ParseSha1(const char* str, uint8_t* digest);
 
-int applypatch_flash(const char* source_filename, const char* target_filename,
-                     const char* target_sha1_str, size_t target_size);
 int applypatch(const char* source_filename,
                const char* target_filename,
                const char* target_sha1_str,
                size_t target_size,
-               int num_patches,
-               char** const patch_sha1_str,
-               Value** patch_data,
-               Value* bonus_data);
+               const std::vector<std::string>& patch_sha1_str,
+               const std::vector<std::unique_ptr<Value>>& patch_data,
+               const Value* bonus_data);
 int applypatch_check(const char* filename,
-                     int num_patches,
-                     char** const patch_sha1_str);
+                     const std::vector<std::string>& patch_sha1_str);
+int applypatch_flash(const char* source_filename, const char* target_filename,
+                     const char* target_sha1_str, size_t target_size);
 
 int LoadFileContents(const char* filename, FileContents* file);
 int SaveFileContents(const char* filename, const FileContents* file);
-void FreeFileContents(FileContents* file);
-int FindMatchingPatch(uint8_t* sha1, char* const * const patch_sha1_str,
-                      int num_patches);
 
-// bsdiff.cpp
+// bspatch.cpp
 void ShowBSDiffLicense();
 int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
                      const Value* patch, ssize_t patch_offset,
diff --git a/applypatch/imgdiff.h b/applypatch/include/applypatch/imgdiff.h
index f2069b4f3..22cbd4fa0 100644
--- a/applypatch/imgdiff.h
+++ b/applypatch/include/applypatch/imgdiff.h
@@ -14,17 +14,26 @@
  * limitations under the License.
  */
 
+#ifndef _APPLYPATCH_IMGDIFF_H
+#define _APPLYPATCH_IMGDIFF_H
+
+#include <stddef.h>
+
 // Image patch chunk types
-#define CHUNK_NORMAL   0
-#define CHUNK_GZIP     1   // version 1 only
-#define CHUNK_DEFLATE  2   // version 2 only
-#define CHUNK_RAW      3   // version 2 only
+#define CHUNK_NORMAL 0
+#define CHUNK_GZIP 1     // version 1 only
+#define CHUNK_DEFLATE 2  // version 2 only
+#define CHUNK_RAW 3      // version 2 only
 
 // The gzip header size is actually variable, but we currently don't
 // support gzipped data with any of the optional fields, so for now it
 // will always be ten bytes.  See RFC 1952 for the definition of the
 // gzip format.
-#define GZIP_HEADER_LEN   10
+static constexpr size_t GZIP_HEADER_LEN = 10;
 
 // The gzip footer size really is fixed.
-#define GZIP_FOOTER_LEN   8
+static constexpr size_t GZIP_FOOTER_LEN = 8;
+
+int imgdiff(int argc, const char** argv);
+
+#endif  // _APPLYPATCH_IMGDIFF_H
diff --git a/applypatch/include/applypatch/imgpatch.h b/applypatch/include/applypatch/imgpatch.h
index 64d9aa9eb..6549f79f0 100644
--- a/applypatch/include/applypatch/imgpatch.h
+++ b/applypatch/include/applypatch/imgpatch.h
@@ -14,13 +14,15 @@
  * limitations under the License.
  */
 
-#ifndef _IMGPATCH_H
-#define _IMGPATCH_H
+#ifndef _APPLYPATCH_IMGPATCH_H
+#define _APPLYPATCH_IMGPATCH_H
 
-typedef ssize_t (*SinkFn)(const unsigned char*, ssize_t, void*);
+#include <sys/types.h>
+
+using SinkFn = ssize_t (*)(const unsigned char*, ssize_t, void*);
 
 int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
                     const unsigned char* patch_data, ssize_t patch_size,
                     SinkFn sink, void* token);
 
-#endif  //_IMGPATCH_H
+#endif  // _APPLYPATCH_IMGPATCH_H
diff --git a/applypatch/libimgpatch.pc b/applypatch/libimgpatch.pc
new file mode 100644
index 000000000..e5002934f
--- /dev/null
+++ b/applypatch/libimgpatch.pc
@@ -0,0 +1,6 @@
+# This file is for libimgpatch in Chrome OS.
+
+Name: libimgpatch
+Description: Apply imgdiff patch
+Version: 0.0.1
+Libs: -limgpatch -lbz2 -lz
diff --git a/applypatch/utils.cpp b/applypatch/utils.cpp
deleted file mode 100644
index 4a80be75f..000000000
--- a/applypatch/utils.cpp
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <stdio.h>
-
-#include "utils.h"
-
-/** Write a 4-byte value to f in little-endian order. */
-void Write4(int value, FILE* f) {
-  fputc(value & 0xff, f);
-  fputc((value >> 8) & 0xff, f);
-  fputc((value >> 16) & 0xff, f);
-  fputc((value >> 24) & 0xff, f);
-}
-
-/** Write an 8-byte value to f in little-endian order. */
-void Write8(long long value, FILE* f) {
-  fputc(value & 0xff, f);
-  fputc((value >> 8) & 0xff, f);
-  fputc((value >> 16) & 0xff, f);
-  fputc((value >> 24) & 0xff, f);
-  fputc((value >> 32) & 0xff, f);
-  fputc((value >> 40) & 0xff, f);
-  fputc((value >> 48) & 0xff, f);
-  fputc((value >> 56) & 0xff, f);
-}
-
-int Read2(void* pv) {
-    unsigned char* p = reinterpret_cast<unsigned char*>(pv);
-    return (int)(((unsigned int)p[1] << 8) |
-                 (unsigned int)p[0]);
-}
-
-int Read4(void* pv) {
-    unsigned char* p = reinterpret_cast<unsigned char*>(pv);
-    return (int)(((unsigned int)p[3] << 24) |
-                 ((unsigned int)p[2] << 16) |
-                 ((unsigned int)p[1] << 8) |
-                 (unsigned int)p[0]);
-}
-
-long long Read8(void* pv) {
-    unsigned char* p = reinterpret_cast<unsigned char*>(pv);
-    return (long long)(((unsigned long long)p[7] << 56) |
-                       ((unsigned long long)p[6] << 48) |
-                       ((unsigned long long)p[5] << 40) |
-                       ((unsigned long long)p[4] << 32) |
-                       ((unsigned long long)p[3] << 24) |
-                       ((unsigned long long)p[2] << 16) |
-                       ((unsigned long long)p[1] << 8) |
-                       (unsigned long long)p[0]);
-}