Add shell_get_file_contents_utf8_sync(), use it instead of gio temporarily

Adding correct annotations to Gio.File.load_contents revealed that gjs
doesn't actually support array+length combinations.  For 3.0 this would
be invasive to fix, so add a method to ShellGlobal which does what
we need.

https://bugzilla.gnome.org/show_bug.cgi?id=646333

js/ui/extensionSystem.js

@@ -67,7 +67,13 @@ function loadExtension(dir, enabled, type) {
         return;
     }
 
-    let [success, metadataContents, len, etag] = metadataFile.load_contents(null);
+    let metadataContents;
+    try {
+        metadataContents = Shell.get_file_contents_utf8_sync(metadataFile.get_path());
+    } catch (e) {
+        global.logError(baseErrorString + 'Failed to load metadata.json: ' + e);
+        return;
+    }
     let meta;
     try {
         meta = JSON.parse(metadataContents);

js/ui/search.js

@@ -274,24 +274,18 @@ OpenSearchSystem.prototype = {
     },
 
     _addProvider: function(fileName) {
-        let file = Gio.file_new_for_path(global.datadir + '/search_providers/' + fileName);
-        let source = '';
-
-        file.load_contents_async(null, Lang.bind(this, function (obj, res) {
-            let [success, source] = file.load_contents_finish(res);
-            if (source) {
-                let [success, name, url, langs, icon_uri] = global.parse_search_provider(source);
-                let provider ={ name: name,
-                                url: url,
-                                id: this._providers.length,
-                                icon_uri: icon_uri,
-                                langs: langs };
-                if (this._checkSupportedProviderLanguage(provider)) {
-                    this._providers.push(provider);
-                    this.emit('changed');
-                }
-            }
-        }));
+        let path = global.datadir + '/search_providers/' + fileName;
+        let source = Shell.get_file_contents_utf8_sync(path);
+        let [success, name, url, langs, icon_uri] = global.parse_search_provider(source);
+        let provider ={ name: name,
+                        url: url,
+                        id: this._providers.length,
+                        icon_uri: icon_uri,
+                        langs: langs };
+        if (this._checkSupportedProviderLanguage(provider)) {
+            this._providers.push(provider);
+            this.emit('changed');
+        }
     },
 
     _refresh: function() {

src/shell-global.c

@@ -2229,3 +2229,36 @@ shell_get_contact_events (TplLogManager *log_manager,
                                              NULL, NULL,
                                              callback, NULL);
 }
+
+
+/**
+ * shell_get_file_contents_utf8_sync:
+ * @path: UTF-8 encoded filename path
+ * @error: a #GError
+ *
+ * Synchronously load the contents of a file as a NUL terminated
+ * string, validating it as UTF-8.  Embedded NUL characters count as
+ * invalid content.
+ *
+ * Returns: (transfer full): File contents
+ */
+char *
+shell_get_file_contents_utf8_sync (const char *path,
+                                   GError    **error)
+{
+  char *contents;
+  gsize len;
+  if (!g_file_get_contents (path, &contents, &len, error))
+    return NULL;
+  if (!g_utf8_validate (contents, len, NULL))
+    {
+      g_free (contents);
+      g_set_error (error,
+                   G_IO_ERROR,
+                   G_IO_ERROR_FAILED,
+                   "File %s contains invalid UTF-8",
+                   path);
+      return NULL;
+    }
+  return contents;
+}

src/shell-global.h

@@ -185,6 +185,9 @@ void shell_get_contact_events (TplLogManager *log_manager,
                                guint num_events,
                                GAsyncReadyCallback callback);
 
+char *shell_get_file_contents_utf8_sync (const char *path,
+                                         GError    **error);
+
 G_END_DECLS
 
 #endif /* __SHELL_GLOBAL_H__ */