diff --git a/edify/edify_parser.cpp b/edify/edify_parser.cpp
index 16ad2ab..15342d3 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 @@
         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 ecb1bea..aa3a55a 100644
--- a/edify/expr.cpp
+++ b/edify/expr.cpp
@@ -107,8 +107,7 @@
 
 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 @@
     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 @@
         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* 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* 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 @@
     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, 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 8863479..f045d93 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 @@
     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
diff --git a/tests/component/edify_test.cpp b/tests/component/edify_test.cpp
index ded8540..ede2ecb 100644
--- a/tests/component/edify_test.cpp
+++ b/tests/component/edify_test.cpp
@@ -25,10 +25,7 @@
     int error_count;
     EXPECT_EQ(parse_string(expr_str, &e, &error_count), 0);
 
-    State state;
-    state.cookie = nullptr;
-    state.errmsg = nullptr;
-    state.script = strdup(expr_str);
+    State state(expr_str, nullptr);
 
     char* result = Evaluate(&state, e);
 
@@ -38,8 +35,6 @@
         EXPECT_STREQ(result, expected);
     }
 
-    free(state.errmsg);
-    free(state.script);
     free(result);
 }
 
diff --git a/updater/updater.cpp b/updater/updater.cpp
index c222cee..74a4048 100644
--- a/updater/updater.cpp
+++ b/updater/updater.cpp
@@ -14,22 +14,24 @@
  * limitations under the License.
  */
 
+#include "updater.h"
+
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "edify/expr.h"
-#include "updater.h"
-#include "install.h"
-#include "blockimg.h"
-#include "minzip/Zip.h"
-#include "minzip/SysUtil.h"
-#include "config.h"
-
+#include <android-base/strings.h>
 #include <selinux/label.h>
 #include <selinux/selinux.h>
 
+#include "config.h"
+#include "edify/expr.h"
+#include "blockimg.h"
+#include "install.h"
+#include "minzip/Zip.h"
+#include "minzip/SysUtil.h"
+
 // Generated by the makefile, this function defines the
 // RegisterDeviceExtensions() function, which calls all the
 // registration functions for device-specific extensions.
@@ -140,10 +142,7 @@
     updater_info.package_zip_addr = map.addr;
     updater_info.package_zip_len = map.length;
 
-    State state;
-    state.cookie = &updater_info;
-    state.script = script;
-    state.errmsg = NULL;
+    State state(script, &updater_info);
 
     if (argc == 5) {
         if (strcmp(argv[4], "retry") == 0) {
@@ -160,22 +159,21 @@
     }
 
     if (result == NULL) {
-        if (state.errmsg == NULL) {
+        if (state.errmsg.empty()) {
             printf("script aborted (no error message)\n");
             fprintf(cmd_pipe, "ui_print script aborted (no error message)\n");
         } else {
-            printf("script aborted: %s\n", state.errmsg);
-            char* line = strtok(state.errmsg, "\n");
-            while (line) {
+            printf("script aborted: %s\n", state.errmsg.c_str());
+            const std::vector<std::string> lines = android::base::Split(state.errmsg, "\n");
+            for (const std::string& line : lines) {
                 // Parse the error code in abort message.
                 // Example: "E30: This package is for bullhead devices."
-                if (*line == 'E') {
-                    if (sscanf(line, "E%u: ", &state.error_code) != 1) {
-                         printf("Failed to parse error code: [%s]\n", line);
+                if (!line.empty() && line[0] == 'E') {
+                    if (sscanf(line.c_str(), "E%u: ", &state.error_code) != 1) {
+                         printf("Failed to parse error code: [%s]\n", line.c_str());
                     }
                 }
-                fprintf(cmd_pipe, "ui_print %s\n", line);
-                line = strtok(NULL, "\n");
+                fprintf(cmd_pipe, "ui_print %s\n", line.c_str());
             }
             fprintf(cmd_pipe, "ui_print\n");
         }
@@ -189,7 +187,6 @@
             }
         }
 
-        free(state.errmsg);
         return 7;
     } else {
         fprintf(cmd_pipe, "ui_print script succeeded: result was [%s]\n", result);