fix file argument changing before callback in async_wget; fixes #2349

2 files changed, 18 insertions, 4 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index 44e8c473..57fe1f9f 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -688,15 +688,22 @@ mergeInto(LibraryManager.library, {
   emscripten_async_wget: function(url, file, onload, onerror) {
     var _url = Pointer_stringify(url);
     var _file = Pointer_stringify(file);
+    function doCallback(callback) {
+      if (callback) {
+        var stack = Runtime.stackSave();
+        Runtime.dynCall('vi', callback, [allocate(intArrayFromString(_file), 'i8', ALLOC_STACK)]);
+        Runtime.stackRestore(stack);
+      }
+    }
     FS.createPreloadedFile(
       PATH.dirname(_file),
       PATH.basename(_file),
       _url, true, true,
       function() {
-        if (onload) Runtime.dynCall('vi', onload, [file]);
+        doCallback(onload);
       },
       function() {
-        if (onerror) Runtime.dynCall('vi', onerror, [file]);
+        doCallback(onerror);
       }
     );
   },
@@ -727,7 +734,11 @@ mergeInto(LibraryManager.library, {
     http.onload = function http_onload(e) {
       if (http.status == 200) {
         FS.createDataFile( _file.substr(0, index), _file.substr(index + 1), new Uint8Array(http.response), true, true);
-        if (onload) Runtime.dynCall('vii', onload, [arg, file]);
+        if (onload) {
+          var stack = Runtime.stackSave();
+          Runtime.dynCall('vii', onload, [arg, allocate(intArrayFromString(_file), 'i8', ALLOC_STACK)]);
+          Runtime.stackRestore(stack);
+        }
       } else {
         if (onerror) Runtime.dynCall('vii', onerror, [arg, http.status]);
       }
diff --git a/tests/emscripten_fs_api_browser.cpp b/tests/emscripten_fs_api_browser.cpp
index 0355287a..1410ba3c 100644
--- a/tests/emscripten_fs_api_browser.cpp
+++ b/tests/emscripten_fs_api_browser.cpp
@@ -107,11 +107,14 @@ int main() {
     onLoaded,
     onError);
 
+  char name[40];
+  strcpy(name, "/tmp/screen_shot.png"); // test for issue #2349, name being free'd
   emscripten_async_wget(
     "http://localhost:8888/screenshot.png", 
-    "/tmp/screen_shot.png",
+    name,
     onLoaded,
     onError);
+  memset(name, 0, 30);
 
   emscripten_set_main_loop(wait_wgets, 0, 0);