281343 show an error message when filenames are too long; and convert that error

to an nsresult
patch by Son Le <son.le0@gmail.com> r=biesi sr=darin

dom/locales/en-US/chrome/nsWebBrowserPersist.properties

@@ -44,3 +44,5 @@ accessError=%S could not be saved, because you cannot change the contents of tha
 helperAppNotFound=%S could not be opened, because the associated helper application does not exist. Change the association in your preferences.
 noMemory=There is not sufficient memory to complete the action you requested.\n\nQuit some applications and try again.
 title=Downloading %S
+fileAlreadyExistsError=%S could not be saved, because a file already exists with the same name as the '_files' directory.\n\nTry saving to a different location.
+fileNameTooLongError=%S could not be saved, because the file name was too long.\n\nTry saving with a shorter file name.

embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp

@@ -1033,6 +1033,14 @@ nsresult nsWebBrowserPersist::SendErrorStatusChange(
     nsAutoString msgId;
     switch(aResult)
     {
+    case NS_ERROR_FILE_NAME_TOO_LONG:
+        // File name too long.
+        msgId.AssignLiteral("fileNameTooLongError");
+        break;
+    case NS_ERROR_FILE_ALREADY_EXISTS:
+        // File exists with same name as directory.
+        msgId.AssignLiteral("fileAlreadyExistsError");
+        break;
     case NS_ERROR_FILE_DISK_FULL:
     case NS_ERROR_FILE_NO_DEVICE_SPACE:
         // Out of space on target volume.
@@ -1584,9 +1592,13 @@ nsresult nsWebBrowserPersist::SaveDocumentInternal(
                 {
                     localDataPath->IsDirectory(&haveDir);
                 }
-                if (!haveDir && NS_SUCCEEDED(localDataPath->Create(nsILocalFile::DIRECTORY_TYPE, 0755)))
+                if (!haveDir)
                 {
-                    haveDir = PR_TRUE;
+                    rv = localDataPath->Create(nsILocalFile::DIRECTORY_TYPE, 0755);
+                    if (NS_SUCCEEDED(rv))
+                        haveDir = PR_TRUE;
+                    else
+                        SendErrorStatusChange(PR_FALSE, rv, nsnull, aFile);
                 }
                 if (!haveDir)
                 {

xpcom/io/nsLocalFileWin.cpp

@@ -254,10 +254,15 @@ static nsresult ConvertWinError(DWORD winErr)
         case ERROR_CANNOT_MAKE:
             rv = NS_ERROR_FILE_ALREADY_EXISTS;
             break;
+        case ERROR_FILENAME_EXCED_RANGE:
+            rv = NS_ERROR_FILE_NAME_TOO_LONG;
+            break;
         case 0:
             rv = NS_OK;
+            break;
         default:
             rv = NS_ERROR_FAILURE;
+            break;
     }
     return rv;
 }