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/* Copyright (C) 1996-1998,2001,2002,2003,2006 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 <features.h>
#ifdef __USE_XOPEN2K
#include <sys/syscall.h>
#include <sys/select.h>
#include <sys/time.h>
#include <signal.h>
#include <cancel.h>
static int __NC(pselect)(int nfds, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, const struct timespec *timeout,
const sigset_t *sigmask)
{
#ifdef __NR_pselect6
#define NSEC_PER_SEC 1000000000L
struct timespec _ts, *ts = 0;
if (timeout) {
/* The Linux kernel can in some situations update the timeout value.
* We do not want that so use a local variable.
*/
_ts = *timeout;
/* GNU extension: allow for timespec values where the sub-sec
* field is equal to or more than 1 second. The kernel will
* reject this on us, so take care of the time shift ourself.
* Some applications (like readline and linphone) do this.
* See 'clarification on select() type calls and invalid timeouts'
* on the POSIX general list for more information.
*/
if (_ts.tv_nsec >= NSEC_PER_SEC) {
_ts.tv_sec += _ts.tv_nsec / NSEC_PER_SEC;
_ts.tv_nsec %= NSEC_PER_SEC;
}
ts = &_ts;
}
/* The pselect6 syscall API is strange. It wants a 7th arg to be
* the sizeof(*sigmask). However syscalls with > 6 arguments aren't
* supported on linux. So arguments 6 and 7 are stuffed in a struct
* and a pointer to that struct is passed as the 6th argument to
* the syscall.
* Glibc stuffs arguments 6 and 7 in a ulong[2]. Linux reads
* them as if there were a struct { sigset_t*; size_t } in
* userspace. There woudl be trouble if userspace and the kernel are
* compiled differently enough that size_t isn't the same as ulong,
* but not enough to trigger the compat layer in linux. I can't
* think of such a case, so I'm using linux's struct.
* Furthermore Glibc sets the sigsetsize to _NSIG/8. However linux
* checks for sizeof(sigset_t), which internally is a ulong array.
* This means that if _NSIG isn't a multiple of BITS_PER_LONG then
* linux will refuse glibc's value. So I prefer sizeof(sigset_t) for
* the value of sigsetsize.
*/
struct {
const sigset_t *sigmask;
size_t sigsetsize;
} args67 = {
sigmask,
sizeof(sigset_t),
};
return INLINE_SYSCALL(pselect6, 6, nfds, readfds, writefds, exceptfds, ts, &args67);
#else
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)
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);
/* The comment below does not apply on uClibc, since we use __select_nocancel */
/* 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 = __NC(select)(nfds, readfds, writefds, exceptfds,
timeout != NULL ? &tval : NULL);
if (sigmask != NULL)
sigprocmask (SIG_SETMASK, &savemask, NULL);
return retval;
#endif
}
CANCELLABLE_SYSCALL(int, pselect, (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
const struct timespec *timeout, const sigset_t *sigmask),
(nfds, readfds, writefds, exceptfds, timeout, sigmask))
#endif
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