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glibc/misc/pselect.c
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/* Copyright (C) 1996-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <signal.h> | |
#include <stddef.h> /* For NULL. */ | |
#include <sys/time.h> | |
#include <sys/select.h> | |
#include <sysdep-cancel.h> | |
/* Check the first NFDS descriptors each in READFDS (if not NULL) for read | |
readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS | |
(if not NULL) for exceptional conditions. If TIMEOUT is not NULL, time out | |
after waiting the interval specified therein. Additionally set the sigmask | |
SIGMASK for this call. Returns the number of ready descriptors, or -1 for | |
errors. */ | |
int | |
__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, | |
const struct timespec *timeout, const sigset_t *sigmask) | |
{ | |
struct timeval tval; | |
int retval; | |
sigset_t savemask; | |
/* Change nanosecond number to microseconds. This might mean losing | |
precision and therefore the `pselect` should be available. But | |
for now it is hardly found. */ | |
if (timeout != NULL) | |
{ | |
/* Catch bugs which would be hidden by the TIMESPEC_TO_TIMEVAL | |
computations. The division by 1000 truncates values. */ | |
if (__glibc_unlikely (timeout->tv_nsec < 0)) | |
{ | |
__set_errno (EINVAL); | |
return -1; | |
} | |
TIMESPEC_TO_TIMEVAL (&tval, timeout); | |
} | |
/* The setting and restoring of the signal mask and the select call | |
should be an atomic operation. This can't be done without kernel | |
help. */ | |
if (sigmask != NULL) | |
__sigprocmask (SIG_SETMASK, sigmask, &savemask); | |
/* Note the pselect() is a cancellation point. But since we call | |
select() which itself is a cancellation point we do not have | |
to do anything here. */ | |
retval = __select (nfds, readfds, writefds, exceptfds, | |
timeout != NULL ? &tval : NULL); | |
if (sigmask != NULL) | |
__sigprocmask (SIG_SETMASK, &savemask, NULL); | |
return retval; | |
} | |
#ifndef __pselect | |
weak_alias (__pselect, pselect) | |
/* __select handles cancellation. */ | |
LIBC_CANCEL_HANDLED (); | |
#endif |