Content-type: text/html Man page of sigwait

sigwait

Section: C Library Functions (3)
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NAME

sigwait, sigwaitinfo, sigtimedwait - Suspends a calling thread until a signal arrives.  

LIBRARY

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

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);  

PARAMETERS

Specifies the set of signals to wait for. Returns the signal number of the selected signal. (See the DESCRIPTION section for information about the selected signal.) 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. 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.
 

RELATED INFORMATION

Headers: siginfo(5)

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

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


 

Index

NAME
LIBRARY
SYNOPSIS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:41:04 GMT, October 02, 2010