.\" Copyright (c) 2005 Michael Kerrisk
-.\" based on earlier work by faith@cs.unc.edu and
+.\" based on earlier work by faith@cs.unc.edu and
.\" Mike Battersby <mib@deakin.edu.au>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
-.\"
+.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
-.\"
+.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
.\"
-.TH SIGPENDING 2 2005-09-15 "Linux 2.6.13" "Linux Programmer's Manual"
+.TH SIGPENDING 2 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
-sigpending \- examine pending signals
+sigpending, rt_sigpending \- examine pending signals
.SH SYNOPSIS
.B #include <signal.h>
-.sp
+.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 ()
thread (i.e., the signals which have been raised while blocked).
The mask of pending signals is returned in
.IR set .
-.SH "RETURN VALUE"
+.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
-.IR set
+.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.
-.SH "CONFORMING TO"
-POSIX.1-2001.
+.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
+which means that information about pending real-time signals
is not correctly returned.
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR kill (2),
.BR sigaction (2),
.BR signal (2),
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