Draft: Try to identify the scenario that causes stat throw EINVAL in OSX

[jozkee]

Related to #57221

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Issue Details

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Related to #57221

Author:	Jozkee
Assignees:	-
Labels:	area-Extensions-FileSystem
Milestone:	-

[adamsitnik]

which syscall gives us an EINVAL?

[jozkee]

@adamsitnik I suspect is stat since the call-stack in #57221 is related to validation of lstat and stat caches in FileSystem.Unix.cs. However I find it strange since there is no documentation stating that stat is capable of throwing EINVAL. You can look at the conversation I had with Dan for context #57221 (comment). I also find it very strange that it only fails in macOS/OSX.

[jozkee]

Based on the latest helix log, I think we can be more certain that the issue is in the stat performed in FileSystemInfo.Refresh().

Unhandled exception. System.IO.IOException: Invalid argument : '/var/folders/4m/hrs4drf17cxbyfbbkbhtxczh0000gy/T/afbguk0e.avl/UsePollingFileWatcher_UseActivePolling_HasChanged_SymbolicLink_TargetDeleted_133_4d15e445'
   at System.IO.FileStatus.ThrowOnCacheInitializationError(ReadOnlySpan`1 path) in /_/src/libraries/System.Private.CoreLib/src/System/IO/FileStatus.Unix.cs:line 418
   at System.IO.FileStatus.GetLastWriteTime(ReadOnlySpan`1 path, Boolean continueOnError) in /_/src/libraries/System.Private.CoreLib/src/System/IO/FileStatus.Unix.cs:line 284
   at System.IO.FileSystemInfo.get_LastWriteTimeUtc() in /_/src/libraries/System.Private.CoreLib/src/System/IO/FileSystemInfo.cs:line 115
   at Microsoft.Extensions.FileProviders.Physical.PollingFileChangeToken.GetLastWriteTimeUtc() in /_/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PollingFileChangeToken.cs:line 61
   at Microsoft.Extensions.FileProviders.Physical.PollingFileChangeToken.get_HasChanged() in /_/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PollingFileChangeToken.cs:line 108
   at Microsoft.Extensions.FileProviders.Physical.PhysicalFilesWatcher.RaiseChangeEvents(Object state) in /_/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs:line 455
   at System.Threading.TimerQueueTimer.Fire(Boolean isThreadPool) in /_/src/libraries/System.Private.CoreLib/src/System/Threading/Timer.cs:line 673
   at System.Threading.TimerQueue.FireNextTimers() in /_/src/libraries/System.Private.CoreLib/src/System/Threading/Timer.cs:line 327

And judging by the filename which shows the test in which is being created (UsePollingFileWatcher_UseActivePolling_HasChanged_SymbolicLink_TargetDeleted_133_4d15e445), it might have something to do with the symlink ceasing to exist between lstat (line 354) and stat (line 365). cc @carlossanlop

runtime/src/libraries/System.Private.CoreLib/src/System/IO/FileStatus.Unix.cs

Lines 345 to 369 in c0fc818

	internal void RefreshCaches(ReadOnlySpan<char> path)
	{
	_isDirectory = false;
	path = Path.TrimEndingDirectorySeparator(path);
	// Retrieve the file cache (lstat) to get the details on the object, without following symlinks.
	// If it is a symlink, then subsequently get details on the target of the symlink,
	// storing those results separately. We only report failure if the initial
	// lstat fails, as a broken symlink should still report info on exists, attributes, etc.
	if (!TryRefreshFileCache(path))
	{
	_exists = false;
	return;
	}
	// Do an initial check in case the main path is pointing to a directory
	_isDirectory = CacheHasDirectoryFlag(_fileCache);
	// We also need to check if the main path is a symbolic link,
	// in which case, we retrieve the symbolic link data
	if (!_isDirectory && HasSymbolicLinkFlag && TryRefreshSymbolicLinkCache(path))
	{
	// and check again if the symlink path is a directory
	_isDirectory = CacheHasDirectoryFlag(_symlinkCache);
	}

I'm still curious why this happens only on macOS 1014 and 1015, I've stressed calling stat with multiple invalid paths on macOS BigSur 11.5.2 but none has returned me the error "Invalid argument"/EINVAL.

[jozkee]

Closing as I was finally able to repro locally, see #57221 (comment).