From 2b7fe7e0a1665e079683e2c67d2046aa67517519 Mon Sep 17 00:00:00 2001 From: Chris Denton Date: Fri, 13 Oct 2023 05:54:56 +0100 Subject: [PATCH] Make try_exists return Ok(true) for Windows UDS `fs::try_exists` currently fails on Windows if encountering a Unix Domain Socket (UDS). Fix this by checking for an error code that's returned when there's a failure to use a reparse point. A reparse point is a way to invoke a filesystem filter on a file instead of the file being opened normally. This is used to implement symbolic links (by redirecting to a different path) but also to implement other types of special files such as Unix domain sockets. If the reparse point is not a link type then opening it with `CreateFileW` may fail with `ERROR_CANT_ACCESS_FILE` because the filesystem filter does not implement that operation. This differs from resolving links which may fail with errors such as `ERROR_FILE_NOT_FOUND` or `ERROR_CANT_RESOLVE_FILENAME`. So `ERROR_CANT_ACCESS_FILE` means that the file exists but that we can't open it normally. Still, the file does exist so `try_exists` should report that as `Ok(true)`. --- library/std/src/sys/windows/fs.rs | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/library/std/src/sys/windows/fs.rs b/library/std/src/sys/windows/fs.rs index 0113196b824..6ded683aade 100644 --- a/library/std/src/sys/windows/fs.rs +++ b/library/std/src/sys/windows/fs.rs @@ -1515,6 +1515,13 @@ pub fn try_exists(path: &Path) -> io::Result { // as the file existing. _ if e.raw_os_error() == Some(c::ERROR_SHARING_VIOLATION as i32) => Ok(true), + // `ERROR_CANT_ACCESS_FILE` means that a file exists but that the + // reparse point could not be handled by `CreateFile`. + // This can happen for special files such as: + // * Unix domain sockets which you need to `connect` to + // * App exec links which require using `CreateProcess` + _ if e.raw_os_error() == Some(c::ERROR_CANT_ACCESS_FILE as i32) => Ok(true), + // Other errors such as `ERROR_ACCESS_DENIED` may indicate that the // file exists. However, these types of errors are usually more // permanent so we report them here.