sigtimedwait


SYNOPSIS
       #include <signal.h>

       int sigwaitinfo(const sigset_t *set, siginfo_t *info);

       int sigtimedwait(const sigset_t *set, siginfo_t *info,
                        const struct timespec *timeout);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sigwaitinfo(), sigtimedwait(): _POSIX_C_SOURCE >= 199309L

DESCRIPTION
       sigwaitinfo() suspends execution of the calling thread until one of the
       signals in set is delivered.  (If one of the signals in set is  already
       pending  for  the calling thread, sigwaitinfo() will return immediately
       with information about that signal.)

       sigwaitinfo() removes the delivered signal from the set of pending sig-
       nals 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 thread 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.

RETURN VALUE
       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().

       EINTR  The  wait  was  interrupted  by a signal handler; see signal(7).
              (This handler was for a signal other than one of those in set.)

       thread other than the one calling sigwaitinfo() or sigtimedwait()).

       The set of signals that is pending for a given thread is the  union  of
       the set of signals that is pending specifically for that thread and the
       set of signals that is pending for the process as  a  whole  (see  sig-
       nal(7)).

       Attempts to wait for SIGKILL and SIGSTOP are silently ignored.

       If  multiple threads of a process are blocked waiting for the same sig-
       nal(s) in sigwaitinfo() or sigtimedwait(),  then  exactly  one  of  the
       threads  will  actually  receive  the  signal if it is delivered to the
       process as a whole; which of the threads receives the signal  is  inde-
       terminate.

       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.

       On Linux, sigwaitinfo() is a library function  implemented  on  top  of
       sigtimedwait().

SEE ALSO
       kill(2),  sigaction(2), signal(2), signalfd(2), sigpending(2), sigproc-
       mask(2), sigqueue(3), sigsetops(3), sigwait(3), signal(7), time(7)

COLOPHON
       This page is part of release 3.35 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://man7.org/linux/man-pages/.



Linux                             2011-10-03                    SIGWAITINFO(2)
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