⚡ Add API: IsDefaultProtocolClient

atom/browser/api/atom_api_app.cc

@@ -451,6 +451,8 @@ void App::BuildPrototype(
                  base::Bind(&Browser::ClearRecentDocuments, browser))
       .SetMethod("setAppUserModelId",
                  base::Bind(&Browser::SetAppUserModelID, browser))
+      .SetMethod("isDefaultProtocolClient",
+                 base::Bind(&Browser::IsDefaultProtocolClient, browser))
       .SetMethod("setAsDefaultProtocolClient",
                  base::Bind(&Browser::SetAsDefaultProtocolClient, browser))
       .SetMethod("removeAsDefaultProtocolClient",

atom/browser/browser.h

@@ -82,6 +82,9 @@ class Browser : public WindowListObserver {
   // Set as default handler for a protocol.
   bool SetAsDefaultProtocolClient(const std::string& protocol);
 
+  // Query the current state of default handler for a protocol.
+  bool IsDefaultProtocolClient(const std::string& protocol);
+
 #if defined(OS_MACOSX)
   // Hide the application.
   void Hide();

atom/browser/browser_linux.cc

@@ -42,6 +42,10 @@ bool Browser::SetAsDefaultProtocolClient(const std::string& protocol) {
   return false;
 }
 
+bool Browser::IsDefaultProtocolClient(const std::string& protocol) {
+  return false;
+}
+
 std::string Browser::GetExecutableFileVersion() const {
   return brightray::GetApplicationVersion();
 }

atom/browser/browser_mac.mm

@@ -60,6 +60,30 @@ bool Browser::SetAsDefaultProtocolClient(const std::string& protocol) {
   return return_code == noErr;
 }
 
+bool Browser::IsDefaultProtocolClient(const std::string& protocol) {
+  if (protocol.empty())
+    return false;
+
+  NSString* identifier = [base::mac::MainBundle() bundleIdentifier];
+  if (!identifier)
+    return false;
+
+  NSString* protocol_ns = [NSString stringWithUTF8String:protocol.c_str()];
+  
+  CFStringRef bundle =
+      LSCopyDefaultHandlerForURLScheme(base::mac::NSToCFCast(protocol_ns));
+  NSString* bundleId = static_cast<NSString*>(
+      base::mac::CFTypeRefToNSObjectAutorelease(bundle));
+  if (!bundleId)
+    return false;
+
+  // Ensure the comparison is case-insensitive 
+  // as LS does not persist the case of the bundle id.
+  NSComparisonResult result =
+      [bundleId caseInsensitiveCompare:identifier];
+  return result == NSOrderedSame;
+}
+
 void Browser::SetAppUserModelID(const base::string16& name) {
 }
 

atom/browser/browser_win.cc

@@ -225,6 +225,50 @@ bool Browser::SetAsDefaultProtocolClient(const std::string& protocol) {
   return true;
 }
 
+bool Browser::IsDefaultProtocolClient(const std::string& protocol) {
+  if (protocol.empty())
+    return false;
+
+  base::FilePath path;
+  if (!PathService::Get(base::FILE_EXE, &path)) {
+    LOG(ERROR) << "Error getting app exe path";
+    return false;
+  }
+
+  // Main Registry Key
+  HKEY root = HKEY_CURRENT_USER;
+  std::string keyPathStr = "Software\\Classes\\" + protocol;
+  std::wstring keyPath = std::wstring(keyPathStr.begin(), keyPathStr.end());
+
+  // Command Key
+  std::string cmdPathStr = keyPathStr + "\\shell\\open\\command";
+  std::wstring cmdPath = std::wstring(cmdPathStr.begin(), cmdPathStr.end());
+
+  base::win::RegKey key;
+  base::win::RegKey commandKey;
+  if (FAILED(key.Open(root, keyPath.c_str(), KEY_ALL_ACCESS)))
+    // Key doesn't exist, we can confirm that it is not set
+    return false;
+
+  if (FAILED(commandKey.Open(root, cmdPath.c_str(), KEY_ALL_ACCESS)))
+    // Key doesn't exist, we can confirm that it is not set
+    return false;
+
+  std::wstring keyVal;
+  if (FAILED(commandKey.ReadValue(L"", &keyVal)))
+    // Default value not set, we can confirm that it is not set
+    return false;
+
+  std::wstring exePath(path.value());
+  std::wstring exe = L"\"" + exePath + L"\" \"%1\"";
+  if (keyVal == exe) {
+    // Default value is the same as current file path
+    return true;
+  } else {
+    return false;
+  }
+}
+
 PCWSTR Browser::GetAppUserModelID() {
   if (app_user_model_id_.empty()) {
     SetAppUserModelID(base::ReplaceStringPlaceholders(

docs/api/app.md

@@ -384,6 +384,18 @@ This method checks if the current executable as the default handler for a protoc
 **Note:** On OS X, removing the app will automatically remove the app as the
 default protocol handler.
 
+### `app.isDefaultProtocolClient(protocol)` _OS X_ _Windows_
+
+* `protocol` String - The name of your protocol, without `://`. 
+
+This method checks if the current executable is the default handler for a protocol
+(aka URI scheme). If so, it will return true. Otherwise, it will return false. 
+
+**Note:** On OS X, you can use this method to check if the app has been registered as the default protocol handler for a protocol. You can also verify this by checking `~/Library/Preferences/com.apple.LaunchServices.plist` on the OS X machine. 
+Please refer to [Apple's documentation][LSCopyDefaultHandlerForURLScheme] for details.
+
+The API uses the Windows Registry and LSCopyDefaultHandlerForURLScheme internally.
+
 ### `app.setUserTasks(tasks)` _Windows_
 
 * `tasks` Array - Array of `Task` objects
@@ -556,3 +568,5 @@ Sets the `image` associated with this dock icon.
 [tasks]:http://msdn.microsoft.com/en-us/library/windows/desktop/dd378460(v=vs.85).aspx#tasks
 [app-user-model-id]: https://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx
 [CFBundleURLTypes]: https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html#//apple_ref/doc/uid/TP40009249-102207-TPXREF115
+[LSCopyDefaultHandlerForURLScheme]: 
+https://developer.apple.com/library/mac/documentation/Carbon/Reference/LaunchServicesReference/#//apple_ref/c/func/LSCopyDefaultHandlerForURLScheme