[unix-history] / usr / src / man / man3 / setjmp.3

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)setjmp.3	6.2 (Berkeley) 1/9/86
.\"
.TH SETJMP 3 "January 9, 1986"
.UC 4
.SH NAME
setjmp, longjmp \- non-local goto
.SH SYNOPSIS
.nf
.B #include <setjmp.h>
.PP
.B setjmp(env)
.B jmp_buf env;
.PP
.B longjmp(env, val)
.B jmp_buf env;
.PP
.B _setjmp(env)
.B jmp_buf env;
.PP
.B _longjmp(env, val)
.B jmp_buf env;
.fi
.SH DESCRIPTION
These routines are useful for dealing with errors 
and interrupts encountered in
a low-level subroutine of a program.
.PP
.I Setjmp 
saves its stack environment in
.I env
for later use by
.I longjmp.
It returns value 0.
.PP
.I Longjmp
restores the environment saved by the last call of
.IR setjmp .
It then returns in such a way that execution
continues as if the call of 
.I setjmp
had just returned the value
.I val
to the function that invoked
.I setjmp,
which must not itself have returned in the interim.
All accessible data have values as of the time
.I longjmp
was called.
.PP
.I Setjmp
and
.I longjmp
save and restore the signal mask
.IR sigmask (2),
while
.I _setjmp
and
.I _longjmp
manipulate only the C stack and registers.
.SH ERRORS
.PP
If the contents of the
.B jmp_buf
are corrupted, or correspond to an environment that has already returned,
.I longjmp
calls the routine 
.IR longjmperror .
If
.I longjmperror
returns the program is aborted.
The default version of 
.I longjmperror
prints the message ``longjmp botch'' to standard error and returns.
User programs wishing to exit more gracefully can write their own
versions of 
.IR longjmperror .
.SH "SEE ALSO"
sigvec(2), sigstack(2), signal(3)
Commit	Line	Data
c7eaf808 KM	1	.\" Copyright (c) 1980 Regents of the University of California.
	2	.\" All rights reserved. The Berkeley software License Agreement
	3	.\" specifies the terms and conditions for redistribution.
	4	.\"
95f51977	5	.\" @(#)setjmp.3 6.2 (Berkeley) 1/9/86
c7eaf808	6	.\"
95f51977	7	.TH SETJMP 3 "January 9, 1986"
c7eaf808 KM	8	.UC 4
	9	.SH NAME
	10	setjmp, longjmp \- non-local goto
	11	.SH SYNOPSIS
	12	.nf
	13	.B #include <setjmp.h>
	14	.PP
	15	.B setjmp(env)
	16	.B jmp_buf env;
	17	.PP
	18	.B longjmp(env, val)
	19	.B jmp_buf env;
e04f0ee2 KM	20	.PP
	21	.B _setjmp(env)
	22	.B jmp_buf env;
	23	.PP
	24	.B _longjmp(env, val)
	25	.B jmp_buf env;
c7eaf808 KM	26	.fi
	27	.SH DESCRIPTION
	28	These routines are useful for dealing with errors
	29	and interrupts encountered in
	30	a low-level subroutine of a program.
	31	.PP
	32	.I Setjmp
	33	saves its stack environment in
	34	.I env
	35	for later use by
	36	.I longjmp.
	37	It returns value 0.
	38	.PP
	39	.I Longjmp
	40	restores the environment saved by the last call of
	41	.IR setjmp .
	42	It then returns in such a way that execution
	43	continues as if the call of
	44	.I setjmp
	45	had just returned the value
	46	.I val
	47	to the function that invoked
	48	.I setjmp,
	49	which must not itself have returned in the interim.
	50	All accessible data have values as of the time
	51	.I longjmp
	52	was called.
e04f0ee2 KM	53	.PP
	54	.I Setjmp
	55	and
	56	.I longjmp
	57	save and restore the signal mask
	58	.IR sigmask (2),
	59	while
	60	.I _setjmp
	61	and
	62	.I _longjmp
	63	manipulate only the C stack and registers.
93a6fb6f KM	64	.SH ERRORS
	65	.PP
	66	If the contents of the
	67	.B jmp_buf
	68	are corrupted, or correspond to an environment that has already returned,
	69	.I longjmp
	70	calls the routine
	71	.IR longjmperror .
	72	If
	73	.I longjmperror
	74	returns the program is aborted.
	75	The default version of
	76	.I longjmperror
	77	prints the message ``longjmp botch'' to standard error and returns.
	78	User programs wishing to exit more gracefully can write their own
	79	versions of
	80	.IR longjmperror .
c7eaf808	81	.SH "SEE ALSO"
e04f0ee2	82	sigvec(2), sigstack(2), signal(3)