nsExternalHelperAppService::ExternalProtocolHandlerExists (almost) always sets aHandlerExists to PR_TRUE, enabling gnomevfs protocols (bug 389632), patch by Karl Tomlinson <mozbugs@karlt.net>, r+sr=biesi,dmose; a=roc

uriloader/exthandler/beos/nsOSHelperAppService.cpp

@@ -240,7 +240,8 @@ nsOSHelperAppService::GetProtocolInfoFromOS(const nsACString &aScheme)
   PRBool exists;
   nsresult rv = OSProtocolHandlerExists(nsPromiseFlatCString(aScheme).get(),
                                         &exists);
-  NS_ENSURE_SUCCESS(rv, nsnull);
+  if (NS_FAILED(rv) || !exists)
+    return nsnull;
 
   nsMIMEInfoBeOS *handlerInfo =
 	new nsMIMEInfoBeOS(aScheme, nsMIMEInfoBase::eProtocolInfo);

uriloader/exthandler/mac/nsOSHelperAppService.cpp

@@ -323,7 +323,8 @@ nsOSHelperAppService::GetProtocolInfoFromOS(const nsACString &aScheme)
   PRBool exists;
   nsresult rv = OSProtocolHandlerExists(nsPromiseFlatCString(aScheme).get(),
                                         &exists);
-  NS_ENSURE_SUCCESS(rv, nsnull);
+  if (NS_FAILED(rv) || !exists)
+    return nsnull;
 
   nsMIMEInfoMac *handlerInfo =
     new nsMIMEInfoMac(aScheme, nsMIMEInfoBase::eProtocolInfo);

uriloader/exthandler/nsExternalProtocolHandler.cpp

@@ -584,8 +584,10 @@ NS_IMETHODIMP nsExternalProtocolHandler::NewURI(const nsACString &aSpec,
 
 NS_IMETHODIMP nsExternalProtocolHandler::NewChannel(nsIURI *aURI, nsIChannel **_retval)
 {
-  // only try to return a channel if we have a protocol handler for the url
-
+  // Only try to return a channel if we have a protocol handler for the url.
+  // nsOSHelperAppService::LoadUriInternal relies on this to check trustedness
+  // for some platforms at least.  (win uses ::ShellExecute and unix uses
+  // gnome_url_show.)
   PRBool haveExternalHandler = HaveExternalProtocolHandler(aURI);
   if (haveExternalHandler)
   {

uriloader/exthandler/unix/nsGNOMERegistry.cpp

@@ -242,6 +242,14 @@ nsGNOMERegistry::HandlerExists(const char *aProtocolScheme)
   return PR_FALSE;
 }
 
+// XXX Check HandlerExists() before calling LoadURL.
+//
+// If there is not a registered handler for the protocol, gnome_url_show()
+// falls back to using gnomevfs modules.  See bug 389632.  We don't want
+// this fallback to happen as we are not sure of the safety of all gnomevfs
+// modules and MIME-default applications.  (gnomevfs should be handled in
+// nsGnomeVFSProtocolHandler.)
+
 /* static */ nsresult
 nsGNOMERegistry::LoadURL(nsIURI *aURL)
 {

uriloader/exthandler/unix/nsOSHelperAppService.cpp

@@ -1639,10 +1639,14 @@ nsOSHelperAppService::GetProtocolInfoFromOS(const nsACString &aScheme)
 {
   NS_ASSERTION(!aScheme.IsEmpty(), "No scheme was specified!");
 
+  // We must check that a registered handler exists so that gnome_url_show
+  // doesn't fallback to gnomevfs.
+  // See nsGNOMERegistry::LoadURL and bug 389632.
   PRBool exists;
   nsresult rv = OSProtocolHandlerExists(nsPromiseFlatCString(aScheme).get(),
                                         &exists);
-  NS_ENSURE_SUCCESS(rv, nsnull);
+  if (NS_FAILED(rv) || !exists)
+    return nsnull;
 
   nsMIMEInfoUnix *handlerInfo =
     new nsMIMEInfoUnix(aScheme, nsMIMEInfoBase::eProtocolInfo);

uriloader/exthandler/win/nsOSHelperAppService.cpp

@@ -561,7 +561,8 @@ nsOSHelperAppService::GetProtocolInfoFromOS(const nsACString &aScheme)
   PRBool exists;
   nsresult rv = OSProtocolHandlerExists(nsPromiseFlatCString(aScheme).get(),
                                         &exists);
-  NS_ENSURE_SUCCESS(rv, nsnull);
+  if (NS_FAILED(rv) || !exists)
+    return nsnull;
 
   nsMIMEInfoWin *handlerInfo =
     new nsMIMEInfoWin(aScheme, nsMIMEInfoBase::eProtocolInfo);