3 files changed, 40 insertions, 68 deletions

diff --git a/install.cpp b/install.cpp
index ce3d4f6ad..9d8943f7d 100644
--- a/install.cpp
+++ b/install.cpp
@@ -395,12 +395,8 @@ static int try_update_binary(const std::string& package, ZipArchiveHandle zip, b
   //   update attempt.
   //
 
-  // Convert the vector to a NULL-terminated char* array suitable for execv.
-  const char* chr_args[args.size() + 1];
-  chr_args[args.size()] = nullptr;
-  for (size_t i = 0; i < args.size(); i++) {
-    chr_args[i] = args[i].c_str();
-  }
+  // Convert the std::string vector to a NULL-terminated char* vector suitable for execv.
+  auto chr_args = StringVectorToNullTerminatedArray(args);
 
   pid_t pid = fork();
 
@@ -415,7 +411,7 @@ static int try_update_binary(const std::string& package, ZipArchiveHandle zip, b
   if (pid == 0) {
     umask(022);
     close(pipefd[0]);
-    execv(chr_args[0], const_cast<char**>(chr_args));
+    execv(chr_args[0], chr_args.data());
     // Bug: 34769056
     // We shouldn't use LOG/PLOG in the forked process, since they may cause
     // the child process to hang. This deadlock results from an improperly
diff --git a/roots.cpp b/roots.cpp
index e988da0a8..6db0ca519 100644
--- a/roots.cpp
+++ b/roots.cpp
@@ -28,7 +28,6 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include <algorithm>
 #include <iostream>
 #include <string>
 #include <vector>
@@ -44,6 +43,7 @@
 #include <fs_mgr_dm_linear.h>
 
 #include "otautil/mounts.h"
+#include "otautil/sysutil.h"
 
 static Fstab fstab;
 
@@ -90,12 +90,8 @@ int ensure_path_unmounted(const std::string& path) {
 }
 
 static int exec_cmd(const std::vector<std::string>& args) {
-  CHECK_NE(static_cast<size_t>(0), args.size());
-
-  std::vector<char*> argv(args.size());
-  std::transform(args.cbegin(), args.cend(), argv.begin(),
-                 [](const std::string& arg) { return const_cast<char*>(arg.c_str()); });
-  argv.push_back(nullptr);
+  CHECK(!args.empty());
+  auto argv = StringVectorToNullTerminatedArray(args);
 
   pid_t child;
   if ((child = fork()) == 0) {
diff --git a/updater/install.cpp b/updater/install.cpp
index ccde409df..0e1028bd1 100644
--- a/updater/install.cpp
+++ b/updater/install.cpp
@@ -393,17 +393,20 @@ Value* UnmountFn(const char* name, State* state, const std::vector<std::unique_p
   return StringValue(mount_point);
 }
 
-static int exec_cmd(const char* path, char* const argv[]) {
+static int exec_cmd(const std::vector<std::string>& args) {
+  CHECK(!args.empty());
+  auto argv = StringVectorToNullTerminatedArray(args);
+
   pid_t child;
   if ((child = vfork()) == 0) {
-    execv(path, argv);
+    execv(argv[0], argv.data());
     _exit(EXIT_FAILURE);
   }
 
   int status;
   waitpid(child, &status, 0);
   if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-    LOG(ERROR) << path << " failed with status " << WEXITSTATUS(status);
+    LOG(ERROR) << args[0] << " failed with status " << WEXITSTATUS(status);
   }
   return WEXITSTATUS(status);
 }
@@ -453,62 +456,52 @@ Value* FormatFn(const char* name, State* state, const std::vector<std::unique_pt
   }
 
   if (fs_type == "ext4") {
-    const char* mke2fs_argv[] = { "/system/bin/mke2fs", "-t",    "ext4", "-b", "4096",
-                                  location.c_str(),     nullptr, nullptr };
-    std::string size_str;
+    std::vector<std::string> mke2fs_args = {
+      "/system/bin/mke2fs", "-t", "ext4", "-b", "4096", location
+    };
     if (size != 0) {
-      size_str = std::to_string(size / 4096LL);
-      mke2fs_argv[6] = size_str.c_str();
+      mke2fs_args.push_back(std::to_string(size / 4096LL));
     }
 
-    int status = exec_cmd(mke2fs_argv[0], const_cast<char**>(mke2fs_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd(mke2fs_args); status != 0) {
       LOG(ERROR) << name << ": mke2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
-    const char* e2fsdroid_argv[] = { "/system/bin/e2fsdroid", "-e",   "-a", mount_point.c_str(),
-                                     location.c_str(),        nullptr };
-    status = exec_cmd(e2fsdroid_argv[0], const_cast<char**>(e2fsdroid_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd({ "/system/bin/e2fsdroid", "-e", "-a", mount_point, location });
+        status != 0) {
       LOG(ERROR) << name << ": e2fsdroid failed (" << status << ") on " << location;
       return StringValue("");
     }
     return StringValue(location);
-  } else if (fs_type == "f2fs") {
+  }
+
+  if (fs_type == "f2fs") {
     if (size < 0) {
       LOG(ERROR) << name << ": fs_size can't be negative for f2fs: " << fs_size;
       return StringValue("");
     }
-    std::string num_sectors = std::to_string(size / 512);
-
-    const char* f2fs_path = "/sbin/mkfs.f2fs";
-    const char* f2fs_argv[] = { "mkfs.f2fs",
-                                "-g", "android",
-                                "-w", "512",
-                                location.c_str(),
-                                (size < 512) ? nullptr : num_sectors.c_str(),
-                                nullptr };
-    int status = exec_cmd(f2fs_path, const_cast<char**>(f2fs_argv));
-    if (status != 0) {
+    std::vector<std::string> f2fs_args = {
+      "/sbin/mkfs.f2fs", "-g", "android", "-w", "512", location
+    };
+    if (size >= 512) {
+      f2fs_args.push_back(std::to_string(size / 512));
+    }
+    if (auto status = exec_cmd(f2fs_args); status != 0) {
       LOG(ERROR) << name << ": mkfs.f2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
-    const char* sload_argv[] = { "/sbin/sload.f2fs", "-t", mount_point.c_str(), location.c_str(),
-                                 nullptr };
-    status = exec_cmd(sload_argv[0], const_cast<char**>(sload_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd({ "/sbin/sload.f2fs", "-t", mount_point, location }); status != 0) {
       LOG(ERROR) << name << ": sload.f2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
     return StringValue(location);
-  } else {
-    LOG(ERROR) << name << ": unsupported fs_type \"" << fs_type << "\" partition_type \""
-               << partition_type << "\"";
   }
 
+  LOG(ERROR) << name << ": unsupported fs_type \"" << fs_type << "\" partition_type \""
+             << partition_type << "\"";
   return nullptr;
 }
 
@@ -675,17 +668,12 @@ Value* RunProgramFn(const char* name, State* state, const std::vector<std::uniqu
     return ErrorAbort(state, kArgsParsingFailure, "%s() Failed to parse the argument(s)", name);
   }
 
-  char* args2[argv.size() + 1];
-  for (size_t i = 0; i < argv.size(); i++) {
-    args2[i] = &args[i][0];
-  }
-  args2[argv.size()] = nullptr;
-
-  LOG(INFO) << "about to run program [" << args2[0] << "] with " << argv.size() << " args";
+  auto exec_args = StringVectorToNullTerminatedArray(args);
+  LOG(INFO) << "about to run program [" << exec_args[0] << "] with " << argv.size() << " args";
 
   pid_t child = fork();
   if (child == 0) {
-    execv(args2[0], args2);
+    execv(exec_args[0], exec_args.data());
     PLOG(ERROR) << "run_program: execv failed";
     _exit(EXIT_FAILURE);
   }
@@ -909,20 +897,12 @@ Value* Tune2FsFn(const char* name, State* state, const std::vector<std::unique_p
     return ErrorAbort(state, kArgsParsingFailure, "%s() could not read args", name);
   }
 
-  char* args2[argv.size() + 1];
-  // Tune2fs expects the program name as its args[0]
-  args2[0] = const_cast<char*>(name);
-  if (args2[0] == nullptr) {
-    return nullptr;
-  }
-  for (size_t i = 0; i < argv.size(); ++i) {
-    args2[i + 1] = &args[i][0];
-  }
+  // tune2fs expects the program name as its first arg.
+  args.insert(args.begin(), "tune2fs");
+  auto tune2fs_args = StringVectorToNullTerminatedArray(args);
 
-  // tune2fs changes the file system parameters on an ext2 file system; it
-  // returns 0 on success.
-  int result = tune2fs_main(argv.size() + 1, args2);
-  if (result != 0) {
+  // tune2fs changes the filesystem parameters on an ext2 filesystem; it returns 0 on success.
+  if (auto result = tune2fs_main(tune2fs_args.size() - 1, tune2fs_args.data()); result != 0) {
     return ErrorAbort(state, kTune2FsFailure, "%s() returned error code %d", name, result);
   }
   return StringValue("t");