| .\" Written by Michael Haardt, Fri Nov 25 14:51:42 MET 1994 |
| .\" |
| .\" This is free documentation; you can redistribute it and/or |
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| .\" Added sigsetjmp, Sun Mar 2 22:03:05 EST 1997, jrv@vanzandt.mv.com |
| .\" Modifications, Sun Feb 26 14:39:45 1995, faith@cs.unc.edu |
| .\" " |
| .TH SETJMP 3 2009-06-26 "" "Linux Programmer's Manual" |
| .SH NAME |
| setjmp, sigsetjmp \- save stack context for nonlocal goto |
| .SH SYNOPSIS |
| .B #include <setjmp.h> |
| .sp |
| .nf |
| .BI "int setjmp(jmp_buf " env ); |
| |
| .BI "int sigsetjmp(sigjmp_buf " env ", int " savesigs ); |
| .fi |
| .sp |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .sp |
| .BR setjmp (): |
| see NOTES. |
| .br |
| .BR sigsetjmp (): |
| _POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_C_SOURCE |
| .SH DESCRIPTION |
| .BR setjmp () |
| and |
| .BR longjmp (3) |
| are useful for dealing with errors |
| and interrupts encountered in a low-level subroutine of a program. |
| .BR setjmp () |
| saves the stack context/environment in \fIenv\fP for |
| later use by |
| .BR longjmp (3). |
| The stack context will be invalidated |
| if the function which called |
| .BR setjmp () |
| returns. |
| .P |
| .BR sigsetjmp () |
| is similar to |
| .BR setjmp (). |
| If, and only if, \fIsavesigs\fP is nonzero, |
| the process's current signal mask is saved in \fIenv\fP |
| and will be restored if a |
| .BR siglongjmp (3) |
| is later performed with this \fIenv\fP. |
| .SH "RETURN VALUE" |
| .BR setjmp () |
| and |
| .BR sigsetjmp () |
| return 0 if returning directly, and |
| nonzero when returning from |
| .BR longjmp (3) |
| or |
| .BR siglongjmp (3) |
| using the saved context. |
| .SH "CONFORMING TO" |
| C89, C99, and POSIX.1-2001 specify |
| .BR setjmp (). |
| POSIX.1-2001 specifies |
| .BR sigsetjmp (). |
| .SH NOTES |
| POSIX does not specify whether |
| .BR setjmp () |
| will save the signal mask. |
| In System V it will not. |
| In 4.3BSD it will, and there |
| is a function \fB_setjmp\fP that will not. |
| By default, Linux/glibc follows the System V behavior, |
| but the BSD behavior is provided if the |
| .BR _BSD_SOURCE |
| feature test macro is defined and none of |
| .BR _POSIX_SOURCE , |
| .BR _POSIX_C_SOURCE , |
| .BR _XOPEN_SOURCE , |
| .BR _XOPEN_SOURCE_EXTENDED , |
| .BR _GNU_SOURCE , |
| or |
| .B _SVID_SOURCE |
| is defined. |
| |
| If you want to portably save and restore signal masks, use |
| .BR sigsetjmp () |
| and |
| .BR siglongjmp (3). |
| .P |
| .BR setjmp () |
| and |
| .BR sigsetjmp () |
| make programs hard to understand |
| and maintain. |
| If possible an alternative should be used. |
| .SH "SEE ALSO" |
| .BR longjmp (3), |
| .BR siglongjmp (3) |
