.\" Written by Michael Haardt, Fri Nov 25 14:51:42 MET 1994
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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 "March 2, 1997" "" "Library functions"
.SH NAME
setjmp, sigsetjmp \- save stack context for non-local goto
.SH SYNOPSIS
.ad l
.B #include <setjmp.h>
.sp
.nf
.BI "int setjmp(jmp_buf " env );
.BI "int sigsetjmp(sigjmp_buf " env ", int " savesigs );
.fi
.ad b
.SH DESCRIPTION
\fBsetjmp()\fP and \fBlongjmp()\fP are useful for dealing with errors
and interrupts encountered in a low-level subroutine of a program.
\fBsetjmp()\fP saves the stack context/environment in \fIenv\fP for
later use by \fBlongjmp()\fP.  The stack context will be invalidated
if the function which called \fBsetjmp()\fP returns.
.P
\fBsigsetjmp()\fP is similar to \fBsetjmp()\fP.  If \fIsavesigs\fP is nonzero,
the set of blocked signals is saved in \fIenv\fP and will be restored
if a \fBsiglongjmp()\fP is later performed with this \fIenv\fP.
.SH "RETURN VALUE"
\fBsetjmp()\fP and \fBsigsetjmp()\fP return 0 if returning directly, and
non-zero when returning from \fBlongjmp()\fP using the saved context.
.SH "CONFORMING TO"
POSIX, ISO 9899
.SH NOTES
POSIX does not specify whether \fBsetjmp\fP will save the
signal context. (In SYSV it will not. In BSD4.3 it will, and there
is a function \fB_setjmp\fP that will not.)
If you want to save signal masks, use \fBsigsetjmp\fP.
.P
\fBsetjmp()\fP and \fBsigsetjmp\fP make programs hard to understand
and maintain.  If possible an alternative should be used.
.SH "SEE ALSO"
.BR longjmp "(3), " siglongjmp (3)