3 files changed, 37 insertions, 60 deletions

diff --git a/edify/edify_parser.cpp b/edify/edify_parser.cpp
index 16ad2ab71..15342d3fa 100644
--- a/edify/edify_parser.cpp
+++ b/edify/edify_parser.cpp
@@ -24,21 +24,20 @@
  * makes the tool less useful. We should either extend the tool or remove it.
  */
 
+#include <errno.h>
 #include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+
+#include <string>
+
+#include <android-base/file.h>
 
 #include "expr.h"
-#include "parser.h"
 
-void ExprDump(int depth, Expr* n, char* script) {
+static void ExprDump(int depth, const Expr* n, const std::string& script) {
     printf("%*s", depth*2, "");
-    char temp = script[n->end];
-    script[n->end] = '\0';
     printf("%s %p (%d-%d) \"%s\"\n",
            n->name == NULL ? "(NULL)" : n->name, n->fn, n->start, n->end,
-           script+n->start);
-    script[n->end] = temp;
+           script.substr(n->start, n->end - n->start).c_str());
     for (int i = 0; i < n->argc; ++i) {
         ExprDump(depth+1, n->argv[i], script);
     }
@@ -53,34 +52,25 @@ int main(int argc, char** argv) {
         return 1;
     }
 
-    FILE* f = fopen(argv[1], "r");
-    if (f == NULL) {
-        printf("%s: %s: No such file or directory\n", argv[0], argv[1]);
+    std::string buffer;
+    if (!android::base::ReadFileToString(argv[1], &buffer)) {
+        printf("%s: failed to read %s: %s\n", argv[0], argv[1], strerror(errno));
         return 1;
     }
-    char buffer[8192];
-    int size = fread(buffer, 1, 8191, f);
-    fclose(f);
-    buffer[size] = '\0';
 
     Expr* root;
     int error_count = 0;
-    int error = parse_string(buffer, &root, &error_count);
+    int error = parse_string(buffer.data(), &root, &error_count);
     printf("parse returned %d; %d errors encountered\n", error, error_count);
     if (error == 0 || error_count > 0) {
 
         ExprDump(0, root, buffer);
 
-        State state;
-        state.cookie = NULL;
-        state.script = buffer;
-        state.errmsg = NULL;
-
+        State state(buffer, nullptr);
         char* result = Evaluate(&state, root);
         if (result == NULL) {
             printf("result was NULL, message is: %s\n",
-                   (state.errmsg == NULL ? "(NULL)" : state.errmsg));
-            free(state.errmsg);
+                   (state.errmsg.empty() ? "(NULL)" : state.errmsg.c_str()));
         } else {
             printf("result is [%s]\n", result);
         }
diff --git a/edify/expr.cpp b/edify/expr.cpp
index ecb1bea1a..aa3a55a87 100644
--- a/edify/expr.cpp
+++ b/edify/expr.cpp
@@ -107,8 +107,7 @@ Value* ConcatFn(const char* name, State* state, int argc, Expr* argv[]) {
 
 Value* IfElseFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 2 && argc != 3) {
-        free(state->errmsg);
-        state->errmsg = strdup("ifelse expects 2 or 3 arguments");
+        state->errmsg = "ifelse expects 2 or 3 arguments";
         return NULL;
     }
     char* cond = Evaluate(state, argv[0]);
@@ -134,11 +133,10 @@ Value* AbortFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc > 0) {
         msg = Evaluate(state, argv[0]);
     }
-    free(state->errmsg);
     if (msg) {
         state->errmsg = msg;
     } else {
-        state->errmsg = strdup("called abort()");
+        state->errmsg = "called abort()";
     }
     return NULL;
 }
@@ -153,15 +151,8 @@ Value* AssertFn(const char* name, State* state, int argc, Expr* argv[]) {
         int b = BooleanString(v);
         free(v);
         if (!b) {
-            int prefix_len;
             int len = argv[i]->end - argv[i]->start;
-            char* err_src = reinterpret_cast<char*>(malloc(len + 20));
-            strcpy(err_src, "assert failed: ");
-            prefix_len = strlen(err_src);
-            memcpy(err_src + prefix_len, state->script + argv[i]->start, len);
-            err_src[prefix_len + len] = '\0';
-            free(state->errmsg);
-            state->errmsg = err_src;
+            state->errmsg = "assert failed: " + state->script.substr(argv[i]->start, len);
             return NULL;
         }
     }
@@ -279,8 +270,7 @@ Value* SequenceFn(const char* name, State* state, int argc, Expr* argv[]) {
 
 Value* LessThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
     if (argc != 2) {
-        free(state->errmsg);
-        state->errmsg = strdup("less_than_int expects 2 arguments");
+        state->errmsg = "less_than_int expects 2 arguments";
         return NULL;
     }
 
@@ -314,8 +304,7 @@ Value* LessThanIntFn(const char* name, State* state, int argc, Expr* argv[]) {
 Value* GreaterThanIntFn(const char* name, State* state,
                         int argc, Expr* argv[]) {
     if (argc != 2) {
-        free(state->errmsg);
-        state->errmsg = strdup("greater_than_int expects 2 arguments");
+        state->errmsg = "greater_than_int expects 2 arguments";
         return NULL;
     }
 
@@ -499,20 +488,12 @@ Value** ReadValueVarArgs(State* state, int argc, Expr* argv[]) {
     return args;
 }
 
-static void ErrorAbortV(State* state, const char* format, va_list ap) {
-    std::string buffer;
-    android::base::StringAppendV(&buffer, format, ap);
-    free(state->errmsg);
-    state->errmsg = strdup(buffer.c_str());
-    return;
-}
-
 // Use printf-style arguments to compose an error message to put into
 // *state.  Returns nullptr.
 Value* ErrorAbort(State* state, const char* format, ...) {
     va_list ap;
     va_start(ap, format);
-    ErrorAbortV(state, format, ap);
+    android::base::StringAppendV(&state->errmsg, format, ap);
     va_end(ap);
     return nullptr;
 }
@@ -520,8 +501,14 @@ Value* ErrorAbort(State* state, const char* format, ...) {
 Value* ErrorAbort(State* state, CauseCode cause_code, const char* format, ...) {
     va_list ap;
     va_start(ap, format);
-    ErrorAbortV(state, format, ap);
+    android::base::StringAppendV(&state->errmsg, format, ap);
     va_end(ap);
     state->cause_code = cause_code;
     return nullptr;
 }
+
+State::State(const std::string& script, void* cookie) :
+    script(script),
+    cookie(cookie) {
+}
+
diff --git a/edify/expr.h b/edify/expr.h
index 886347991..f045d9386 100644
--- a/edify/expr.h
+++ b/edify/expr.h
@@ -18,6 +18,7 @@
 #define _EXPRESSION_H
 
 #include <unistd.h>
+#include <string>
 
 #include "error_code.h"
 #include "yydefs.h"
@@ -26,20 +27,20 @@
 
 typedef struct Expr Expr;
 
-typedef struct {
+struct State {
+    State(const std::string& script, void* cookie);
+
+    // The source of the original script.
+    const std::string& script;
+
     // Optional pointer to app-specific data; the core of edify never
     // uses this value.
     void* cookie;
 
-    // The source of the original script.  Must be NULL-terminated,
-    // and in writable memory (Evaluate may make temporary changes to
-    // it but will restore it when done).
-    char* script;
-
     // The error message (if any) returned if the evaluation aborts.
-    // Should be NULL initially, will be either NULL or a malloc'd
-    // pointer after Evaluate() returns.
-    char* errmsg;
+    // Should be empty initially, will be either empty or a string that
+    // Evaluate() returns.
+    std::string errmsg;
 
     // error code indicates the type of failure (e.g. failure to update system image)
     // during the OTA process.
@@ -50,8 +51,7 @@ typedef struct {
     CauseCode cause_code = kNoCause;
 
     bool is_retry = false;
-
-} State;
+};
 
 #define VAL_STRING  1  // data will be NULL-terminated; size doesn't count null
 #define VAL_BLOB    2