1 files changed, 88 insertions, 0 deletions
diff --git a/toolkit/modules/WindowsRegistry.sys.mjs b/toolkit/modules/WindowsRegistry.sys.mjs
new file mode 100644
index 0000000000..7bc6c77ae1
--- /dev/null
+++ b/toolkit/modules/WindowsRegistry.sys.mjs
@@ -0,0 +1,88 @@
+/* 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/. */
+
+export var WindowsRegistry = {
+  /**
+   * Safely reads a value from the registry.
+   *
+   * @param aRoot
+   *        The root registry to use.
+   * @param aPath
+   *        The registry path to the key.
+   * @param aKey
+   *        The key name.
+   * @param [aRegistryNode=0]
+   *        Optionally set to nsIWindowsRegKey.WOW64_64 (or nsIWindowsRegKey.WOW64_32)
+   *        to access a 64-bit (32-bit) key from either a 32-bit or 64-bit application.
+   * @return The key value or undefined if it doesn't exist.  If the key is
+   *         a REG_MULTI_SZ, an array is returned.
+   */
+  readRegKey(aRoot, aPath, aKey, aRegistryNode = 0) {
+    const kRegMultiSz = 7;
+    const kMode = Ci.nsIWindowsRegKey.ACCESS_READ | aRegistryNode;
+    let registry = Cc["@mozilla.org/windows-registry-key;1"].createInstance(
+      Ci.nsIWindowsRegKey
+    );
+    try {
+      registry.open(aRoot, aPath, kMode);
+      if (registry.hasValue(aKey)) {
+        let type = registry.getValueType(aKey);
+        switch (type) {
+          case kRegMultiSz:
+            // nsIWindowsRegKey doesn't support REG_MULTI_SZ type out of the box.
+            let str = registry.readStringValue(aKey);
+            return str.split("\0").filter(v => v);
+          case Ci.nsIWindowsRegKey.TYPE_STRING:
+            return registry.readStringValue(aKey);
+          case Ci.nsIWindowsRegKey.TYPE_INT:
+            return registry.readIntValue(aKey);
+          default:
+            throw new Error("Unsupported registry value.");
+        }
+      }
+    } catch (ex) {
+    } finally {
+      registry.close();
+    }
+    return undefined;
+  },
+
+  /**
+   * Safely removes a key from the registry.
+   *
+   * @param aRoot
+   *        The root registry to use.
+   * @param aPath
+   *        The registry path to the key.
+   * @param aKey
+   *        The key name.
+   * @param [aRegistryNode=0]
+   *        Optionally set to nsIWindowsRegKey.WOW64_64 (or nsIWindowsRegKey.WOW64_32)
+   *        to access a 64-bit (32-bit) key from either a 32-bit or 64-bit application.
+   * @return True if the key was removed or never existed, false otherwise.
+   */
+  removeRegKey(aRoot, aPath, aKey, aRegistryNode = 0) {
+    let registry = Cc["@mozilla.org/windows-registry-key;1"].createInstance(
+      Ci.nsIWindowsRegKey
+    );
+    let result = false;
+    try {
+      let mode =
+        Ci.nsIWindowsRegKey.ACCESS_QUERY_VALUE |
+        Ci.nsIWindowsRegKey.ACCESS_SET_VALUE |
+        aRegistryNode;
+      registry.open(aRoot, aPath, mode);
+      if (registry.hasValue(aKey)) {
+        registry.removeValue(aKey);
+        result = !registry.hasValue(aKey);
+      } else {
+        result = true;
+      }
+    } catch (ex) {
+    } finally {
+      registry.close();
+    }
+    return result;
+  },
+};