add a way to get an application description for a given externally-handled

scheme, and use it in the confirmation dialog that asks whether to launch such
links.
bug 258802
windows and cross-platform part: r=ere sr=neil,bz
linux part: r=bz sr=bryner

docshell/resources/locale/en-US/appstrings.properties

@@ -52,6 +52,8 @@ deniedPortAccess=Access to the port number given has been disabled for security
 proxyResolveFailure=The proxy server you have configured could not be found. Please check your proxy settings and try again.
 proxyConnectFailure=The connection was refused when attempting to contact the proxy server you have configured. Please check your proxy settings and try again.
 externalProtocolTitle=External Protocol Request
-externalProtocolPrompt=An external application must be launched to handle %1$S: links. Requested link:\n\n\n%2$S\n\n\nIf you were not expecting this request it may be an attempt to exploit a weakness in that other program. Cancel this request unless you are sure it is not malicious.\n
+externalProtocolPrompt=An external application must be launched to handle %1$S: links. Requested link:\n\n\n%2$S\nApplication: %3$S\n\n\nIf you were not expecting this request it may be an attempt to exploit a weakness in that other program. Cancel this request unless you are sure it is not malicious.\n
+#LOCALIZATION NOTE (externalProtocolUnknown): The following string is shown if the application name can't be determined
+externalProtocolUnknown=<Unknown>
 externalProtocolChkMsg=Remember my choice for all links of this type.
 externalProtocolLaunchBtn=Launch application

uriloader/exthandler/nsExternalHelperAppService.cpp

@@ -1067,6 +1067,12 @@ NS_IMETHODIMP nsExternalHelperAppService::LoadUrl(nsIURI * aURL)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
+NS_IMETHODIMP nsExternalHelperAppService::GetApplicationDescription(const nsACString& aScheme, nsAString& _retval)
+{
+  // this method should only be implemented by each OS specific implementation of this service.
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////
 // Methods related to deleting temporary files on exit

uriloader/exthandler/nsExternalProtocolHandler.cpp

@@ -190,6 +190,11 @@ PRBool nsExtProtocolChannel::PromptForScheme(nsIURI* aURI)
     return PR_FALSE;
   }
 
+  nsXPIDLString desc;
+  nsCOMPtr<nsIExternalProtocolService> extProtService (do_GetService(NS_EXTERNALPROTOCOLSERVICE_CONTRACTID));
+  if (extProtService)
+    extProtService->GetApplicationDescription(scheme, desc);
+
   nsCOMPtr<nsIStringBundle> appstrings;
   rv = sbSvc->CreateBundle("chrome://global/locale/appstrings.properties",
                            getter_AddRefs(appstrings));
@@ -213,15 +218,21 @@ PRBool nsExtProtocolChannel::PromptForScheme(nsIURI* aURI)
   appstrings->GetStringFromName(NS_LITERAL_STRING("externalProtocolLaunchBtn").get(),
                                 getter_Copies(launchBtn));
 
+  if (desc.IsEmpty())
+    appstrings->GetStringFromName(NS_LITERAL_STRING("externalProtocolUnknown").get(),
+                                  getter_Copies(desc));
+
+
   nsXPIDLString message;
-  const PRUnichar* msgArgs[] = { utf16scheme.get(), uri.get() };
+  const PRUnichar* msgArgs[] = { utf16scheme.get(), uri.get(), desc.get() };
   appstrings->FormatStringFromName(NS_LITERAL_STRING("externalProtocolPrompt").get(),
                                    msgArgs,
                                    NS_ARRAY_LENGTH(msgArgs),
                                    getter_Copies(message));
 
   if (utf16scheme.IsEmpty() || uri.IsEmpty() || title.IsEmpty() ||
-      checkMsg.IsEmpty() || launchBtn.IsEmpty() || message.IsEmpty())
+      checkMsg.IsEmpty() || launchBtn.IsEmpty() || message.IsEmpty() ||
+      desc.IsEmpty())
     return PR_FALSE;
 
   // all pieces assembled, now we can pose the dialog

uriloader/exthandler/nsIExternalProtocolService.idl

@@ -50,7 +50,7 @@ interface nsIFile;
  * handler for a given protocol scheme. And you can ask it to load 
  * the url using the default handler.
  */
-[scriptable, uuid(100FD4B3-4557-11d4-98D0-001083010E9B)]
+[scriptable, uuid(4F38DF07-0B21-4d40-BED0-08E33EB566FB)]
 interface nsIExternalProtocolService : nsISupports
 {
   /**
@@ -76,5 +76,19 @@ interface nsIExternalProtocolService : nsISupports
    * Used to load a url via an external protocol handler (if one exists)
    * @param aURL The url to load
    */
-  void loadUrl (in nsIURI aURL);  
+  void loadUrl (in nsIURI aURL);
+
+  /**
+   * Gets a human-readable description for the application responsible for
+   * handling a specific protocol.
+   *
+   * @param aScheme The scheme to look up. For example, "mms".
+   *
+   * @throw NS_ERROR_NOT_IMPLEMENTED
+   *        If getting descriptions for protocol helpers is not supported
+   * @throw NS_ERROR_NOT_AVAILABLE
+   *        If no protocol helper exists for this scheme, or if it is not
+   *        possible to get a description for it.
+   */
+  AString getApplicationDescription(in AUTF8String aScheme);
 }; 

uriloader/exthandler/unix/nsGNOMERegistry.cpp

@@ -184,30 +184,50 @@ nsGNOMERegistry::Startup()
   // crash on exit.
 }
 
-/* static */ PRBool
-nsGNOMERegistry::HandlerExists(const char *aProtocolScheme)
+/**
+ * Finds the application for a given protocol.
+ *
+ * @param aProtocolScheme
+ *        Protocol to look up. For example, "ghelp" or "mailto".
+ *
+ * @return UTF-8 string identifying the application. Must be freed with
+ *         g_free.
+ *         NULL on error.
+ */
+static gchar* getAppForScheme(const nsACString& aProtocolScheme)
 {
   if (!gconfLib)
-    return PR_FALSE;
+    return nsnull;
 
   GConfClient *client = _gconf_client_get_default();
   NS_ASSERTION(client, "no gconf client");
 
   nsCAutoString gconfPath(NS_LITERAL_CSTRING("/desktop/gnome/url-handlers/") +
-                          nsDependentCString(aProtocolScheme) +
+                          aProtocolScheme +
                           NS_LITERAL_CSTRING("/command"));
 
   gchar *app = _gconf_client_get_string(client, gconfPath.get(), NULL);
   g_object_unref(G_OBJECT(client));
 
+  return app;
+}
+
+/* static */ PRBool
+nsGNOMERegistry::HandlerExists(const char *aProtocolScheme)
+{
+  gchar *app = getAppForScheme(nsDependentCString(aProtocolScheme));
+
   if (app) {
     g_free(app);
+    GConfClient *client = _gconf_client_get_default();
 
     nsCAutoString enabledPath(NS_LITERAL_CSTRING("/desktop/gnome/url-handlers/") +
                               nsDependentCString(aProtocolScheme) +
                               NS_LITERAL_CSTRING("/enabled"));
     gboolean isEnabled = _gconf_client_get_bool(client, enabledPath.get(), NULL);
 
+    g_object_unref(G_OBJECT(client));
+
     return isEnabled ? PR_TRUE : PR_FALSE;
   }
 
@@ -231,6 +251,19 @@ nsGNOMERegistry::LoadURL(nsIURI *aURL)
   return NS_ERROR_FAILURE;
 }
 
+/* static */ void
+nsGNOMERegistry::GetAppDescForScheme(const nsACString& aScheme,
+                                     nsAString& aDesc)
+{
+  char *app = getAppForScheme(aScheme);
+
+  if (app) {
+    CopyUTF8toUTF16(app, aDesc);
+    g_free(app);
+  }
+}
+
+
 /* static */ already_AddRefed<nsMIMEInfoBase>
 nsGNOMERegistry::GetFromExtension(const char *aFileExt)
 {

uriloader/exthandler/unix/nsGNOMERegistry.h

@@ -49,6 +49,9 @@ class nsGNOMERegistry
 
   static nsresult LoadURL(nsIURI *aURL);
 
+  static void GetAppDescForScheme(const nsACString& aScheme,
+                                  nsAString& aDesc);
+
   static already_AddRefed<nsMIMEInfoBase> GetFromExtension(const char *aFileExt);
 
   static already_AddRefed<nsMIMEInfoBase> GetFromType(const char *aMIMEType);

uriloader/exthandler/unix/nsOSHelperAppService.cpp

@@ -1298,6 +1298,22 @@ NS_IMETHODIMP nsOSHelperAppService::LoadUrl(nsIURI * aURI)
 #endif
 }
 
+NS_IMETHODIMP nsOSHelperAppService::GetApplicationDescription(const nsACString& aScheme, nsAString& _retval)
+{
+  nsCOMPtr<nsIFile> appFile;
+  nsresult rv = GetHandlerAppFromPrefs(PromiseFlatCString(aScheme).get(),
+                                       getter_AddRefs(appFile));
+  if (NS_SUCCEEDED(rv))
+    return appFile->GetLeafName(_retval);
+
+#ifdef MOZ_WIDGET_GTK2
+  nsGNOMERegistry::GetAppDescForScheme(aScheme, _retval);
+  return _retval.IsEmpty() ? NS_ERROR_NOT_AVAILABLE : NS_OK;
+#else
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
 nsresult nsOSHelperAppService::GetFileTokenForPath(const PRUnichar * platformAppPath, nsIFile ** aFile)
 {
   LOG(("-- nsOSHelperAppService::GetFileTokenForPath: '%s'\n",

uriloader/exthandler/unix/nsOSHelperAppService.h

@@ -65,6 +65,7 @@ public:
   // override nsIExternalProtocolService methods
   NS_IMETHOD ExternalProtocolHandlerExists(const char * aProtocolScheme, PRBool * aHandlerExists);
   NS_IMETHOD LoadUrl(nsIURI * aURL);
+  NS_IMETHOD GetApplicationDescription(const nsACString& aScheme, nsAString& _retval);
 
   // GetFileTokenForPath must be implemented by each platform. 
   // platformAppPath --> a platform specific path to an application that we got out of the 

uriloader/exthandler/win/nsOSHelperAppService.cpp

@@ -256,6 +256,20 @@ NS_IMETHODIMP nsOSHelperAppService::LoadUrl(nsIURI * aURL)
   return rv;
 }
 
+NS_IMETHODIMP nsOSHelperAppService::GetApplicationDescription(const nsACString& aScheme, nsAString& _retval)
+{
+  nsCAutoString cmdString(aScheme);
+  cmdString.AppendLiteral("\\shell\\open\\command");
+  HKEY cmd;
+  LONG rc = ::RegOpenKeyEx(HKEY_CLASSES_ROOT, cmdString.get(), 0, KEY_QUERY_VALUE, &cmd);
+  if (rc != ERROR_SUCCESS)
+    return NS_ERROR_NOT_AVAILABLE;
+
+  PRBool found = GetValueString(cmd, NULL, _retval);
+  ::RegCloseKey(cmd);
+  return found ? NS_OK : NS_ERROR_NOT_AVAILABLE;
+}
+
 // GetMIMEInfoFromRegistry: This function obtains the values of some of the nsIMIMEInfo
 // attributes for the mimeType/extension associated with the input registry key.  The default
 // entry for that key is the name of a registry key under HKEY_CLASSES_ROOT.  The default

uriloader/exthandler/win/nsOSHelperAppService.h

@@ -60,6 +60,7 @@ public:
   // override nsIExternalProtocolService methods
   NS_IMETHOD ExternalProtocolHandlerExists(const char * aProtocolScheme, PRBool * aHandlerExists);
   NS_IMETHOD LoadUrl(nsIURI * aURL);
+  NS_IMETHOD GetApplicationDescription(const nsACString& aScheme, nsAString& _retval);
 
   // method overrides for windows registry look up steps....
   already_AddRefed<nsIMIMEInfo> GetMIMEInfoFromOS(const nsACString& aMIMEType, const nsACString& aFileExt, PRBool *aFound);