Messages in this thread |  | | | From | KOSAKI Motohiro <> | | Subject | poll never return EBADF? | | Date | Tue, 26 May 2009 18:09:32 +0900 (JST) |
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Hi
I have one stupid question.
"man poll" describe this error code.
>ERRORS > EBADF An invalid file descriptor was given in one of the sets.
but current kernel implementation ignore invalid file descriptor, not return EBADF.
================ cut code ======================================== static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) { unsigned int mask; int fd; mask = 0; fd = pollfd->fd; if (fd >= 0) { //// here int fput_needed; struct file * file; file = fget_light(fd, &fput_needed); mask = POLLNVAL; if (file != NULL) { //// and here mask = DEFAULT_POLLMASK; if (file->f_op && file->f_op->poll) mask = file->f_op->poll(file, pwait); /* Mask out unneeded events. */ mask &= pollfd->events | POLLERR | POLLHUP; fput_light(file, fput_needed); } } ================ end code ======================================== In the other hand, SUSv3 talk about
> POLLNVAL > The specified fd value is invalid. This flag is only valid in the > revents member; it shall ignored in the events member.
and
> If the value of fd is less than 0, events shall be ignored, and revents > shall be set to 0 in that entry on return from poll().
but, no desribe EBADF. (see http://www.opengroup.org/onlinepubs/009695399/functions/poll.html)
So, I think the implementation is correct.
Why don't we remove EBADF description?
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