| .\" Copyright (c) 2005 Michael Kerrisk |
| .\" based on earlier work by faith@cs.unc.edu and |
| .\" Mike Battersby <mib@deakin.edu.au> |
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| .\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2 |
| .\" |
| .TH SIGPENDING 2 2021-03-22 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| sigpending, rt_sigpending \- examine pending signals |
| .SH SYNOPSIS |
| .nf |
| .B #include <signal.h> |
| .PP |
| .BI "int sigpending(sigset_t *" set ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR sigpending (): |
| .nf |
| _POSIX_C_SOURCE |
| .fi |
| .SH DESCRIPTION |
| .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. |
| On failure, \-1 is returned and |
| .I errno |
| is set to indicate the error. |
| .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) |