.TH SETJMP 3
.SH NAME
setjmp, longjmp \- non-local goto
.SH SYNOPSIS
.B #include <setjmp.h>
.PP
.B setjmp(env)
.br
.B jmp_buf env;
.PP
.B longjmp(env, val)
.br
.B jmp_buf env;
.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.
.SH "SEE ALSO"
signal(2)
.SH BUGS
The values of the register variables are not saved.
Thus, the function that calls
.I setjmp
should not use register declarations
for variables that might be accessed after the
.IR longjmp .