On Fri, May 16, 2025 at 04:39:57PM +0200, Vincent Lefevre wrote: > On 2025-05-16 09:05:47 -0400, Rich Felker wrote: > > FWIW musl adopted the EINPROGRESS as soon as we were made aware of the > > issue, and later changed it to returning 0 since applications > > (particularly, any written prior to this interpretation) are prone to > > interpret EINPROGRESS as an error condition rather than success and > > possibly misinterpret it as meaning the fd is still open and valid to > > pass to close again. > > If I understand correctly, this is a poor choice. POSIX.1-2024 says: > > ERRORS > The close() and posix_close() functions shall fail if: > [...] > [EINPROGRESS] > The function was interrupted by a signal and fildes was closed > but the close operation is continuing asynchronously. > > But this does not mean that the asynchronous close operation will > succeed. There are no asynchronous behaviors specified for there to be a conformance distinction here. The only observable behaviors happen instantly, mainly the release of the file descriptor and the process's handle on the underlying resource. Abstractly, there is no async operation that could succeed or fail. > So the application could incorrectly deduce that the close operation > was done without any error. This deduction is correct, not incorrect. Rather, failing with EINPROGRESS would make the application incorrectly deduce that there might be some error it missed (even if it's aware of the new error code), and absolutely does make all existing applications written prior to the new text in POSIX 2024 unable to determine if the fd was even released and needs to be passed to close again or not. Rich
