init: use init's property expansion code for setprop/write

Change-Id: I3c284860cc8d5106ac2b086e62baeb6263873935
Signed-off-by: Dima Zavin <dima@android.com>

init/builtins.c

@@ -31,6 +31,7 @@
 #include <sys/resource.h>
 #include <linux/loop.h>
 #include <cutils/partition_utils.h>
+#include <sys/system_properties.h>
 
 #include "init.h"
 #include "keywords.h"
@@ -448,22 +449,15 @@ int do_setprop(int nargs, char **args)
 {
     const char *name = args[1];
     const char *value = args[2];
+    char prop_val[PROP_VALUE_MAX];
+    int ret;
 
-    if (value[0] == '$') {
-        /* Use the value of a system property if value starts with '$' */
-        value++;
-        if (value[0] != '$') {
-            value = property_get(value);
-            if (!value) {
-                ERROR("property %s has no value for assigning to %s\n", value, name);
-                return -EINVAL;
-            }
-        } /* else fall through to support double '$' prefix for setting properties
-           * to string literals that start with '$'
-           */
+    ret = expand_props(prop_val, value, sizeof(prop_val));
+    if (ret) {
+        ERROR("cannot expand '%s' while assigning to '%s'\n", value, name);
+        return -EINVAL;
     }
-
-    property_set(name, value);
+    property_set(name, prop_val);
     return 0;
 }
 
@@ -547,21 +541,15 @@ int do_write(int nargs, char **args)
 {
     const char *path = args[1];
     const char *value = args[2];
-    if (value[0] == '$') {
-        /* Write the value of a system property if value starts with '$' */
-        value++;
-        if (value[0] != '$') {
-            value = property_get(value);
-            if (!value) {
-                ERROR("property %s has no value for writing to %s\n", value, path);
-                return -EINVAL;
-            }
-        } /* else fall through to support double '$' prefix for writing
-           * string literals that start with '$'
-           */
-    }
+    char prop_val[PROP_VALUE_MAX];
+    int ret;
 
-    return write_file(path, value);
+    ret = expand_props(prop_val, value, sizeof(prop_val));
+    if (ret) {
+        ERROR("cannot expand '%s' while writing to '%s'\n", value, path);
+        return -EINVAL;
+    }
+    return write_file(path, prop_val);
 }
 
 int do_copy(int nargs, char **args)

init/init_parser.c

@@ -176,7 +176,7 @@ static int push_chars(char **dst, int *len, const char *chars, int cnt)
     return 0;
 }
 
-static int expand_props(char *dst, const char *src, int dst_size)
+int expand_props(char *dst, const char *src, int dst_size)
 {
     int cnt = 0;
     char *dst_ptr = dst;

init/init_parser.h

@@ -31,5 +31,6 @@ void queue_all_property_triggers();
 void queue_builtin_action(int (*func)(int nargs, char **args), char *name);
 
 int init_parse_config_file(const char *fn);
+int expand_props(char *dst, const char *src, int len);
 
 #endif