| .\" 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 SIGSUSPEND 2 2015-03-29 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| sigsuspend, rt_sigsuspend \- wait for a signal |
| .SH SYNOPSIS |
| .B #include <signal.h> |
| .sp |
| .BI "int sigsuspend(const sigset_t *" mask ); |
| .sp |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .sp |
| .ad l |
| .BR sigsuspend (): |
| _POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE |
| .ad b |
| .SH DESCRIPTION |
| .BR sigsuspend () |
| temporarily replaces the signal mask of the calling process with the |
| mask given by |
| .I mask |
| and then suspends the process until delivery of a signal whose |
| action is to invoke a signal handler or to terminate a process. |
| |
| If the signal terminates the process, then |
| .BR sigsuspend () |
| does not return. |
| If the signal is caught, then |
| .BR sigsuspend () |
| returns after the signal handler returns, |
| and the signal mask is restored to the state before the call to |
| .BR sigsuspend (). |
| |
| It is not possible to block |
| .B SIGKILL |
| or |
| .BR SIGSTOP ; |
| specifying these signals in |
| .IR mask , |
| has no effect on the process's signal mask. |
| .SH RETURN VALUE |
| .BR sigsuspend () |
| always returns \-1, with |
| .I errno |
| set to indicate the error (normally, |
| .BR EINTR ). |
| .SH ERRORS |
| .TP |
| .B EFAULT |
| .I mask |
| points to memory which is not a valid part of the process address space. |
| .TP |
| .B EINTR |
| The call was interrupted by a signal. |
| .SH CONFORMING TO |
| POSIX.1-2001. |
| .SH NOTES |
| .PP |
| Normally, |
| .BR sigsuspend () |
| is used in conjunction with |
| .BR sigprocmask (2) |
| in order to prevent delivery of a signal during the execution of a |
| critical code section. |
| The caller first blocks the signals with |
| .BR sigprocmask (2). |
| When the critical code has completed, the caller then waits for the |
| signals by calling |
| .BR sigsuspend () |
| with the signal mask that was returned by |
| .BR sigprocmask (2) |
| (in the |
| .I oldset |
| argument). |
| .PP |
| See |
| .BR sigsetops (3) |
| for details on manipulating signal sets. |
| .\" |
| .SS C library/kernel ABI differences |
| The original Linux system call was named |
| .BR sigsuspend (). |
| However, with the addition of real-time signals in Linux 2.2, |
| the fixed-size, 32-bit |
| .IR sigset_t |
| type supported by that system call was no longer fit for purpose. |
| Consequently, a new system call, |
| .BR rt_sigsuspend (), |
| 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 mask . |
| This argument is currently required to have the value |
| .IR sizeof(sigset_t) |
| (or the error |
| .B EINVAL |
| results). |
| The glibc |
| .BR sigsuspend () |
| wrapper function hides these details from us, transparently calling |
| .BR rt_sigsuspend () |
| when the kernel provides it. |
| .\" |
| .SH SEE ALSO |
| .BR kill (2), |
| .BR pause (2), |
| .BR sigaction (2), |
| .BR signal (2), |
| .BR sigprocmask (2), |
| .BR sigwaitinfo (2), |
| .BR sigsetops (3), |
| .BR sigwait (3), |
| .BR signal (7) |