table of contents
SIGTIMEDWAIT(2) | System Calls Manual | SIGTIMEDWAIT(2) |
NAME¶
sigtimedwait
, sigwaitinfo
—
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include <signal.h>
int
sigtimedwait
(const sigset_t *restrict
set, siginfo_t *restrict info,
const struct timespec *restrict timeout);
int
sigwaitinfo
(const
sigset_t * restrict set,
siginfo_t * restrict
info);
DESCRIPTION¶
Thesigtimedwait
() system call is equivalent to
sigwaitinfo
() except that if none of the signals
specified by set are pending,
sigtimedwait
() waits for the time interval specified
in the timespec structure referenced by
timeout. If the timespec structure
pointed to by timeout is zero-valued and if none of the
signals specified by set are pending, then
sigtimedwait
() returns immediately with an error. If
timeout is the NULL
pointer, the
behavior is unspecified. CLOCK_MONOTONIC
clock is used
to measure the time interval specified by the timeout
argument.
The sigwaitinfo
() system call selects the
pending signal from the set specified by set. Should
any of multiple pending signals in the range
SIGRTMIN
to SIGRTMAX
be
selected, it shall be the lowest numbered one. The selection order between
realtime and non-realtime signals, or between multiple pending non-realtime
signals, is unspecified. If no signal in set is
pending at the time of the call, the calling thread is suspended until one
or more signals in set become pending or until it is
interrupted by an unblocked, caught signal.
The sigwaitinfo
() system call is
equivalent to the sigwait
() system call if the
info argument is NULL
. If the
info argument is non-NULL
, the
sigwaitinfo
() function is equivalent to
sigwait
(), except that the selected signal number
shall be stored in the si_signo member, and the cause
of the signal shall be stored in the si_code member.
Besides this, the sigwaitinfo
() and
sigtimedwait
() system calls may return
EINTR
if interrupted by signal, which is not allowed
for the sigwait
() function.
If any value is queued to the selected signal, the first such
queued value is dequeued and, if the info argument is
non-NULL
, the value is stored in the
si_value member of info. The
system resource used to queue the signal is released and returned to the
system for other use. If no value is queued, the content of the
si_value member is zero-valued. If no further signals
are queued for the selected signal, the pending indication for that signal
is reset.
RETURN VALUES¶
Upon successful completion (that is, one of the signals specified by set is pending or is generated)sigwaitinfo
() and
sigtimedwait
() return the selected signal number.
Otherwise, the functions return a value of -1 and set the global variable
errno to indicate the error.
ERRORS¶
Thesigtimedwait
() system call will fail if:
- [
EAGAIN
] - No signal specified by set was generated within the specified timeout period.
The sigtimedwait
() and
sigwaitinfo
() system calls fail if:
- [
EINTR
] - The wait was interrupted by an unblocked, caught signal.
The sigtimedwait
() system call may also
fail if:
- [
EINVAL
] - The timeout argument specified a tv_nsec value less than zero or greater than or equal to 1000 million. Kernel only checks for this error if no signal is pending in set and it is necessary to wait.
SEE ALSO¶
sigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigwait(2), pause(3), pthread_sigmask(3), siginfo(3)STANDARDS¶
Thesigtimedwait
() and
sigwaitinfo
() system calls conform to
ISO/IEC 9945-1:1996 (“POSIX.1”).
September 27, 2012 | Linux 4.9.0-9-amd64 |