tmedicci opened a new pull request, #8985: URL: https://github.com/apache/nuttx/pull/8985
## Summary Nowadays, opening a FIFO for write-only (with `O_NONBLOCK` cleared) won't block even if there are no readers. Only opening for read-only (with no writers) would block. This is not a POSIX-compliant behavior. According to https://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html > When opening a FIFO with O_RDONLY or O_WRONLY set: > * If O_NONBLOCK is set, an open() for reading-only shall return without delay. An open() for writing-only shall return an error if no process currently has the file open for reading. > > * If O_NONBLOCK is clear, an open() for reading-only shall block the calling thread until a thread opens the file for writing. An open() for writing-only shall block the calling thread until a thread opens the file for reading. This commit has an equivalent on nuttx-apps: `EXAMPLES_PIPE` app was updated to check pipes and named pipes behavior. ## Impact It would be a _possible_ breaking change if any application was written specifically to expect an `open` for write-only (and `O_NONBLOCK` cleared, of course) to be non-blocking even if there are no readers. Being able to port POSIX-compliant applications that expect `open` to block when opening for write-only with no readers would enhance NuttX's objective of "to achieve a high degree of standards compliance. The primary governing standards are POSIX and ANSI standards". That is the case for [RTP Tools](https://github.com/apache/nuttx-apps/pull/1651), for instance. ## Testing `sim:citest`, running [`pipe` app]() and [RTP Tools](https://github.com/apache/nuttx-apps/pull/1651) on ESP32-LyraT v4.1 with `rtpdump`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@nuttx.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
