Autosave [was: Improvements to "Recover Emergency File" prompts]

[Richard Heck]

So with Vincent's cleanup, we now have:
Buffer::ReadStatus Buffer::readAutosave(FileName const & fn)
{
    // Now check if autosave file is newer.
    FileName const autosaveFile = getAutosaveFileNameFor(fn);
    if (!autosaveFile.exists()
          || autosaveFile.lastModified() <= fn.lastModified())
        return ReadFileNotFound;

    docstring const file = makeDisplayPath(fn.absFileName(), 20);
    docstring const text = bformat(_("The backup of the document %1$s "
        "is newer.\n\nLoad the backup instead?"), file);
    int const ret = Alert::prompt(_("Load backup?"), text, 0, 2,
        _("&Load backup"), _("Load &original"),    _("&Cancel"));

    switch (ret)
    {
    case 0: {
        ReadStatus const ret_rf = readFile(autosaveFile);
        // the file is not saved if we load the autosave file.
        if (ret_rf == ReadSuccess) {
            markDirty();
            saveCheckSum(fn);
            return ReadSuccess;
        }
        return ReadAutosaveFailure;
    }
    case 1:
        // Here we delete the autosave
        autosaveFile.removeFile();
        return ReadOriginal;
    default:
        break;
    }
    return ReadCancel;
}

As John said, it looks to me as if we remove the autosave file at the 
wrong time: What if the attempt to read the original file fails? It 
seems to me that we should remove it (a) if we read it successfully; (b) 
if we read the original successfully. That would be the attached patch.

Does this seem right?

Richard

Index: src/Buffer.cpp
===================================================================
--- src/Buffer.cpp      (revision 35834)
+++ src/Buffer.cpp      (working copy)
@@ -3693,14 +3693,13 @@
                // the file is not saved if we load the autosave file.
                if (ret_rf == ReadSuccess) {
                        markDirty();
+                       autosaveFile.removeFile();
                        saveCheckSum(fn);
                        return ReadSuccess;
                }
                return ReadAutosaveFailure;
        }
        case 1:
-               // Here we delete the autosave
-               autosaveFile.removeFile();
                return ReadOriginal;
        default:
                break;
@@ -3725,7 +3724,13 @@
        if (ret_ra == ReadSuccess || ret_ra == ReadCancel)
                return ret_ra;
 
-       return readFile(fn);
+       ReadStatus const success = readFile(fn);
+       if (success == ReadSuccess) {
+               FileName const autosaveFile = getAutosaveFileNameFor(fn);
+               if (!autosaveFile.exists())
+                       autosaveFile.removeFile();
+       }
+       return success;
 }