sigwaitinfo - phpMan

SIGWAITINFO(2)             Linux Programmer’s Manual            SIGWAITINFO(2)



NAME
       sigwaitinfo, sigtimedwait - synchronously wait for queued signals

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 time-
       out);

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 pend-
       ing 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 sigac-
       tion(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 performed: sigtimed-
       wait() 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 number (i.e., a
       value greater than zero).  On failure both calls return -1, with errno set to indi-
       cate the error.

ERRORS
       EAGAIN No  signal  in set was delivered within the timeout period specified to sig-
              timedwait().

       EINVAL timeout was invalid.

       EINTR  The wait was interrupted by a signal handler.  (This handler was for a  sig-
              nal other than one of those in set.)

NOTES
       In  normal usage, the caller blocks the signals in set via a prior call to sigproc-
       mask() (so that the default disposition for these signals does not  occur  if  they
       are  delivered between successive calls to sigwaitinfo()or sigtimedwait()) 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.

CONFORMING TO
       POSIX 1003.1-2001

SEE ALSO
       kill(2), sigaction(2), signal(2), sigpending(2), sigprocmask(2), sigqueue(2),  sig-
       nal(7), sigsetops(3)



Linux 2.4.18                      2002-06-07                    SIGWAITINFO(2)

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