.\" Copyright (c) 2005 Michael Kerrisk

.\" based on earlier work by faith@cs.unc.edu and

.\" Mike Battersby <mib@deakin.edu.au>

.\"

.\" %%%LICENSE_START(VERBATIM)

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.\" manual provided the copyright notice and this permission notice are

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.\" entire resulting derived work is distributed under the terms of a

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.\" responsibility for errors or omissions, or for damages resulting from

.\" the use of the information contained herein.  The author(s) may not

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.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2

.\"

.TH SIGPENDING 2 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

sigpending, rt_sigpending \- examine pending signals

.SH SYNOPSIS

.B #include <signal.h>

.PP

.BI "int sigpending(sigset_t *" set );

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

.BR sigpending ():

_POSIX_C_SOURCE

.ad b

.SH DESCRIPTION

.PP

.BR sigpending ()

returns the set of signals that are pending for delivery to the calling

thread (i.e., the signals which have been raised while blocked).

The mask of pending signals is returned in

.IR set .

.SH RETURN VALUE

.BR sigpending ()

returns 0 on success and \-1 on error.

In the event of an error,

.I errno

is set to indicate the cause.

.SH ERRORS

.TP

.B EFAULT

.I set

points to memory which is not a valid part of the process address space.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH NOTES

See

.BR sigsetops (3)

for details on manipulating signal sets.

.PP

If a signal is both blocked and has a disposition of "ignored", it is

.I not

added to the mask of pending signals when generated.

.PP

The set of signals that is pending for a thread

is the union of the set of signals that is pending for that thread

and the set of signals that is pending for the process as a whole; see

.BR signal (7).

.PP

A child created via

.BR fork (2)

initially has an empty pending signal set;

the pending signal set is preserved across an

.BR execve (2).

.\"

.SS C library/kernel differences

The original Linux system call was named

.BR sigpending ().

However, with the addition of real-time signals in Linux 2.2,

the fixed-size, 32-bit

.IR sigset_t

argument supported by that system call was no longer fit for purpose.

Consequently, a new system call,

.BR rt_sigpending (),

was added to support an enlarged

.IR sigset_t

type.

The new system call takes a second argument,

.IR "size_t sigsetsize" ,

which specifies the size in bytes of the signal set in

.IR set .

.\" This argument is currently required to be less than or equal to

.\" .IR sizeof(sigset_t)

.\" (or the error

.\" .B EINVAL

.\" results).

The glibc

.BR sigpending ()

wrapper function hides these details from us, transparently calling

.BR rt_sigpending ()

when the kernel provides it.

.\"

.SH BUGS

In versions of glibc up to and including 2.2.1,

there is a bug in the wrapper function for

.BR sigpending ()

which means that information about pending real-time signals

is not correctly returned.

.SH SEE ALSO

.BR kill (2),

.BR sigaction (2),

.BR signal (2),

.BR sigprocmask (2),

.BR sigsuspend (2),

.BR sigsetops (3),

.BR signal (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.