Reduce network file hanging issue due to win32API GetFileAttributes cache (unsynchronized).
STR:
1. Open a network file.
2. Close Notepad++ to have it in the session.
3. Disconnect the network, and launch Notepad++ immediately.
4. Around more than 1 minute's delay, then the "Error" dialog displayed.
The reason for the hanging is that the network file was incorrectly detected by doesFileExist (GetFileAttributesEx) as present, leading Notepad++ to attempt opening a non-existent file with _wfopen. This issue seems to stem from a caching mechanism within the IO function (GetFileAttributesEx). When the network disconnects, the cache is not immediately cleared, causing GetFileAttributesEx to falsely report that the file exists. Consequently, when Notepad++ is launched after a network disconnection, GetFileAttributesEx retains its cache, indicating the file exists, while _wfopen fails to locate the network resource, resulting in a hang.
Unfortunately, there's no efficient solution for this problem. The commit's remedy is to check if the file is on the network and whether its directory still exists. If the directory doesn't exist, we avoid calling _wfopen. We verify the directory's existence instead of the file itself because the cache issue with GetFileAttributesEx occurs before _wfopen is executed. Checking the directory avoids the cache problem due to the identical argument being used.
I've tested this remedy in debug mode, and it works fine. However, the problem persists in release mode. Despite this, I believe it's worth keeping this solution, as it provides some protection in a variable network environment, potentially mitigating the issue when it arises.
Ref: https://github.com/notepad-plus-plus/notepad-plus-plus/pull/15658#issuecomment-2386662974
Improve #4306, #6178, #8055, #11388, #12553, #15540, close#15701
Don Ho
1 month ago