Add startup permissions checks (#1596)

Some files in the extension dir need to be executable for proper
operation, and some packaging methods (GitHub Actions Artifacts)
may create extension bundles with the executable bits removed.
So, on startup we check those files, and make them executable if
necessary. (Only if we're installed as a user extension.)

Author: ferdnyc

src/extension.js

@@ -364,6 +364,14 @@ var serviceIndicator = null;
 var lockscreenInput = null;
 
 function init() {
+    // If installed as a user extension, this checks the permissions
+    // on certain critical files in the extension directory
+    // to ensure that they have the executable bit set,
+    // and makes them executable if not. Some packaging methods
+    // (particularly GitHub Actions artifacts) automatically remove
+    // executable bits from all contents, presumably for security.
+    Utils.ensurePermissions();
+
     // If installed as a user extension, this will install the Desktop entry,
     // DBus and systemd service files necessary for DBus activation and
     // GNotifications. Since there's no uninit()/uninstall() hook for extensions

src/shell/utils.js

@@ -128,6 +128,55 @@ function _installResource(dirname, basename, relativePath) {
     }
 }
 
+/**
+ * Use Gio.File to ensure a file's executable bits are set.
+ *
+ * @param {string} filepath - An absolute path to a file
+ * @returns {boolean} - True if the file already was, or is now, executable
+ */
+function _setExecutable(filepath) {
+    try {
+        const file = Gio.File.new_for_path(filepath);
+        const finfo = file.query_info(
+            `${Gio.FILE_ATTRIBUTE_STANDARD_TYPE},${Gio.FILE_ATTRIBUTE_UNIX_MODE}`,
+            Gio.FileQueryInfoFlags.NO_FOLLOW_SYMLINKS,
+            null);
+
+        if (!finfo.has_attribute(Gio.FILE_ATTRIBUTE_UNIX_MODE))
+            return false;
+
+        const mode = finfo.get_attribute_uint32(
+            Gio.FILE_ATTRIBUTE_UNIX_MODE);
+        const new_mode = (mode | 0o111);
+        if (mode === new_mode)
+            return true;
+
+        return file.set_attribute_uint32(
+            Gio.FILE_ATTRIBUTE_UNIX_MODE,
+            new_mode,
+            Gio.FileQueryInfoFlags.NO_FOLLOW_SYMLINKS,
+            null);
+    } catch (e) {
+        logError(e, 'GSConnect');
+        return false;
+    }
+}
+
+/**
+ * Ensure critical files in the extension directory have the
+ * correct permissions.
+ */
+function ensurePermissions() {
+    if (Config.IS_USER) {
+        const executableFiles = [
+            'gsconnect-preferences',
+            'service/daemon.js',
+            'service/nativeMessagingHost.js',
+        ];
+        for (const file of executableFiles)
+            _setExecutable(GLib.build_filenamev([Extension.path, file]));
+    }
+}
 
 /**
  * Install the files necessary for the GSConnect service to run.
@@ -221,4 +270,3 @@ function installService() {
             GLib.unlink(GLib.build_filenamev([manifest[0], manifestFile]));
     }
 }
-