sigwaitinfo, sigtimedwait, rt_sigtimedwait - synchronously wait for queued signals
#include <signal.h>
int sigwaitinfo(const sigset_t *restrict set,
siginfo_t *_Nullable restrict info);
int sigtimedwait(const sigset_t *restrict set,
siginfo_t *_Nullable restrict info,
const struct timespec *restrict timeout);Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sigwaitinfo() suspends execution of the calling
thread until one of the signals in set is pending (If one of
the signals in set is already pending for the calling thread,
sigwaitinfo() will return immediately.)
sigwaitinfo() removes the signal from the set of
pending signals and returns the signal number as its function result. If
the info argument is not NULL, then the buffer that it points
to is used to return a structure of type siginfo_t (see
sigaction(2)) containing information about the
signal.
If multiple signals in set are pending for the caller, the
signal that is retrieved by sigwaitinfo() is determined
according to the usual ordering rules; see signal(7)
for further details.
sigtimedwait() operates in exactly the same way as
sigwaitinfo() except that it has an additional
argument, timeout, which specifies the interval for which the
thread is suspended waiting for a signal. (This interval will be rounded
up to the system clock granularity, and kernel scheduling delays mean
that the interval may overrun by a small amount.) This argument is a
timespec(3) structure.
If both fields of this structure are specified as 0, a poll is
performed: sigtimedwait() returns immediately, either
with information about a signal that was pending for the caller, or with
an error if none of the signals in set was pending.
On success, both sigwaitinfo() and
sigtimedwait() return a signal number (i.e., a value
greater than zero). On failure both calls return -1, with errno
set to indicate the error.