Index Index for
Section 3
Index Alphabetical
listing for S
Bottom of page Bottom of
page		 

sigwait(3)


NAME

  sigwait, sigwaitinfo, sigtimedwait - Suspend a calling thread until a
  signal arrives


SYNOPSIS

  #include <signal.h>

  int sigwait(
	  const sigset_t *set,
	  int *signal );

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

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


LIBRARY

  Threads Library (libpthread.so):  sigwait()

  Realtime Library (librt.a, librt.so): sigwaitinfo(), sigtimedwait()


PARAMETERS

  set Specifies the set of signals to wait for.

  signal
      Returns the signal number of the selected signal. (See the DESCRIPTION
      section for information about the selected signal.)

  info
      Specifies a pointer to a siginfo structure that is receiving data
      describing the signal, including any application-defined data specified
      when the signal was posted.

  timeout
      Specifies a timeout for the wait. If timeout is null, the argument is
      ignored.


DESCRIPTION

  The sigwait functions suspend the calling thread until at least one of the
  signals in the set parameter is in the caller's set of pending signals.
  When this happens, one of those signals is automatically selected and
  removed from the set of pending signals.  The signal number identifying
  that signal is then returned.

  For the sigwait() function, the signal number is stored in the signal
  argument. For the sigwaitinfo() and sigtimedwait() functions, if the info
  argument is specified, the selected signal number is stored in the si_signo
  member of siginfo structure, and the cause of the signal is stored in the
  si_code member. If any value is queued to the selected signal, the first
  queued value is dequeued and stored in the si_value member of info. If no
  value is queued, the content of the si_value member is undefined.

  For sigtimedwait(), if the timeout parameter is specified, the function
  waits for the specified time interval.  If the timespec structure specified
  contains a timeout value of zero (0), and if none of the signals specified
  by set are pending, then sigtimedwait() returns immediately with an error.

  The effect is unspecified if any signals in the set parameter are not
  blocked when the sigwait functions are called.

  The set parameter is created using the set manipulation functions
  sigemptyset(), sigfillset(), sigaddset(), and sigdelset().

  If, while the sigwait functions are waiting, a signal occurs that is
  eligible for delivery (that is, not blocked by the signal mask), that
  signal is handled asynchronously and the wait is interrupted.


RETURN VALUES

  Upon successful completion, the sigwait() function returns 0 (zero). The
  other functions return the number of the selected signal.

  On failure, sigwait() returns the errno value for the failure. The other
  functions return -1 and set errno to indicate the error.


ERRORS

  If the sigwait functions fail, errno is set to one of the following values:

  [EINVAL]
      The value of the set parameter contains an invalid or unsupported
      signal number.

  [EINVAL]
      The timeout argument specified a tv_nsec value that is less than 0 or
      greater than or equal to 1,000,000,000.

  [EINTR]
      The wait was interrupted by an unblocked, caught signal.

  [EAGAIN]
      No signal specified by set was delivered within the specified timeout
      period.


SEE ALSO

  Headers: siginfo(5)

  Functions: sigaction(2), sigpending(2), sigsuspend(2)

  Routines: sigaddset(3), sigdelset(3), sigemptyset(3), sigfillset(3)

Index Index for
Section 3
Index Alphabetical
listing for S
Top of page Top of
page