1 files changed, 78 insertions, 0 deletions
diff --git a/devtools/client/shared/devtools-file-watcher.js b/devtools/client/shared/devtools-file-watcher.js
new file mode 100644
index 000000000..59ec1b136
--- /dev/null
+++ b/devtools/client/shared/devtools-file-watcher.js
@@ -0,0 +1,78 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const { Ci } = require("chrome");
+const Services = require("Services");
+const EventEmitter = require("devtools/shared/event-emitter");
+
+loader.lazyImporter(this, "OS", "resource://gre/modules/osfile.jsm");
+
+const HOTRELOAD_PREF = "devtools.loader.hotreload";
+
+function resolveResourcePath(uri) {
+  const handler = Services.io.getProtocolHandler("resource")
+        .QueryInterface(Ci.nsIResProtocolHandler);
+  const resolved = handler.resolveURI(Services.io.newURI(uri, null, null));
+  return resolved.replace(/file:\/\//, "");
+}
+
+function findSourceDir(path) {
+  if (path === "" || path === "/") {
+    return Promise.resolve(null);
+  }
+
+  return OS.File.exists(
+    OS.Path.join(path, "devtools/client/shared/file-watcher.js")
+  ).then(exists => {
+    if (exists) {
+      return path;
+    }
+    return findSourceDir(OS.Path.dirname(path));
+  });
+}
+
+let worker = null;
+const onPrefChange = function () {
+  // We need to figure out a src dir to watch. These are the actual
+  // files the user is working with, not the files in the obj dir. We
+  // do this by walking up the filesystem and looking for the devtools
+  // directories, and falling back to the raw path. This means none of
+  // this will work for users who store their obj dirs outside of the
+  // src dir.
+  //
+  // We take care not to mess with the `devtoolsPath` if that's what
+  // we end up using, because it might be intentionally mapped to a
+  // specific place on the filesystem for loading devtools externally.
+  //
+  // `devtoolsPath` is currently the devtools directory inside of the
+  // obj dir, and we search for `devtools/client`, so go up 2 levels
+  // to skip that devtools dir and start searching for the src dir.
+  if (Services.prefs.getBoolPref(HOTRELOAD_PREF) && !worker) {
+    const devtoolsPath = resolveResourcePath("resource://devtools")
+      .replace(/\/$/, "");
+    const searchPoint = OS.Path.dirname(OS.Path.dirname(devtoolsPath));
+    findSourceDir(searchPoint)
+      .then(srcPath => {
+        const rootPath = srcPath ? OS.Path.join(srcPath, "devtools")
+                                 : devtoolsPath;
+        const watchPath = OS.Path.join(rootPath, "client");
+        const { watchFiles } = require("devtools/client/shared/file-watcher");
+        worker = watchFiles(watchPath, path => {
+          let relativePath = path.replace(rootPath + "/", "");
+          module.exports.emit("file-changed", relativePath, path);
+        });
+      });
+  } else if (worker) {
+    worker.terminate();
+    worker = null;
+  }
+};
+
+Services.prefs.addObserver(HOTRELOAD_PREF, {
+  observe: onPrefChange
+}, false);
+onPrefChange();
+
+EventEmitter.decorate(module.exports);