1 files changed, 49 insertions, 0 deletions
diff --git a/browser/components/attribution/MacAttribution.sys.mjs b/browser/components/attribution/MacAttribution.sys.mjs
new file mode 100644
index 0000000000..09ec083a44
--- /dev/null
+++ b/browser/components/attribution/MacAttribution.sys.mjs
@@ -0,0 +1,49 @@
+/* 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/. */
+
+const NUL = 0x0;
+const TAB = 0x9;
+
+export var MacAttribution = {
+  /**
+   * The file path to the `.app` directory.
+   */
+  get applicationPath() {
+    // On macOS, `GreD` is like "App.app/Contents/macOS".  Return "App.app".
+    return Services.dirsvc.get("GreD", Ci.nsIFile).parent.parent.path;
+  },
+
+  async setAttributionString(aAttrStr, path = this.applicationPath) {
+    return IOUtils.setMacXAttr(
+      path,
+      "com.apple.application-instance",
+      new TextEncoder().encode(`__MOZCUSTOM__${aAttrStr}`)
+    );
+  },
+
+  async getAttributionString(path = this.applicationPath) {
+    let promise = IOUtils.getMacXAttr(path, "com.apple.application-instance");
+    return promise.then(bytes => {
+      // We need to process the extended attribute a little bit to isolate
+      // the attribution string:
+      // - nul bytes and tabs may be present in raw attribution strings, but are
+      //   never part of the attribution data
+      // - attribution data is expected to be preceeded by the string `__MOZCUSTOM__`
+      let attrStr = new TextDecoder().decode(
+        bytes.filter(b => b != NUL && b != TAB)
+      );
+
+      if (attrStr.startsWith("__MOZCUSTOM__")) {
+        // Return everything after __MOZCUSTOM__
+        return attrStr.slice(13);
+      }
+
+      throw new Error(`No attribution data found in ${path}`);
+    });
+  },
+
+  async delAttributionString(path = this.applicationPath) {
+    return IOUtils.delMacXAttr(path, "com.apple.application-instance");
+  },
+};