SIGWAITINFO(2) Linux Programmer's Manual SIGWAITINFO(2)
NAME
sigwaitinfo, sigtimedwait - synchronously wait for queued signals
SYNOPSIS
#include<signal.h>
intsigwaitinfo(constsigset_t*set,siginfo_t*info);
intsigtimedwait(constsigset_t*set,siginfo_t*info,conststruct
timespec timeout);
DESCRIPTION
sigwaitinfo() suspends execution of the calling process until one of
the signals in set is delivered. (If one of the signals in set is
already pending for the calling process, sigwaitinfo() will return
immediately with information about that signal.)
sigwaitinfo() removes the delivered signal from the calling process's
list of pending signals and returns the signal number as its function
result. If the info argument is not NULL, then it returns a structure
of type siginfo_t (see sigaction(2)) containing information about the
signal.
Signals returned via sigwaitinfo() are delivered in the usual order;
see signal(7) for further details.
sigtimedwait() operates in exactly the same way as sigwaitinfo() except
that it has an additional argument, timeout, which enables an upper
bound to be placed on the time for which the process is suspended.
This argument is of the following type:
struct timespec {
long tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
}
If both fields of this structure are specified as 0, a poll is per-
formed: 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.
RETURNVALUE
On success, both sigwaitinfo() and sigtimedwait() return a signal num-
ber (i.e., a value greater than zero). On failure both calls return
-1, with errno set to indicate the error.
ERRORS
EAGAIN No signal in set was delivered within the timeout period speci-
fied to sigtimedwait().
EINVAL timeout was invalid.
EINTR The wait was interrupted by a signal handler. (This handler was
for a signal other than one of those in set.)
NOTES
In normal usage, the caller blocks the signals in set via a prior call
to sigprocmask() (so that the default disposition for these signals
does not occur if they are delivered between successive calls to sig-
waitinfo()orsigtimedwait()) and does not establish handlers for these
signals.
POSIX leaves the meaning of a NULL value for the timeout argument of
sigtimedwait() unspecified, permitting the possibility that this has
the same meaning as a call to sigwaitinfo(), and indeed this is what is
done on Linux.
CONFORMINGTO
POSIX 1003.1-2001
SEEALSO
kill(2), sigaction(2), signal(2), sigpending(2), sigprocmask(2),
sigqueue(2), signal(7), sigsetops(3)
Linux 2.4.18 2002-06-07 SIGWAITINFO(2)
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