SETJMP(3) BSD Library Functions Manual SETJMP(3)NAME
sigsetjmp, siglongjmp, setjmp, longjmp, _setjmp, _longjmp, longjmperror —
non-local jumps
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <setjmp.h>
int
sigsetjmp(sigjmp_buf env, int savemask);
void
siglongjmp(sigjmp_buf env, int val);
int
setjmp(jmp_buf env);
void
longjmp(jmp_buf env, int val);
int
_setjmp(jmp_buf env);
void
_longjmp(jmp_buf env, int val);
void
longjmperror(void);
DESCRIPTION
The sigsetjmp(), setjmp(), and _setjmp() functions save their calling
environment in env. Each of these functions returns 0.
The corresponding longjmp() functions restore the environment saved by
their most recent respective invocations of the setjmp() function. They
then return so that program execution continues as if the corresponding
invocation of the setjmp() call had just returned the value specified by
val, instead of 0.
Pairs of calls may be intermixed, i.e., both sigsetjmp() and siglongjmp()
and setjmp() and longjmp() combinations may be used in the same program,
however, individual calls may not, e.g. the env argument to setjmp() may
not be passed to siglongjmp().
The longjmp() routines may not be called after the routine which called
the setjmp() routines returns.
All accessible objects have values as of the time longjmp() routine was
called, except that the values of objects of automatic storage invocation
duration that do not have the volatile type and have been changed between
the setjmp() invocation and longjmp() call are indeterminate.
The setjmp()/longjmp() pairs save and restore the signal mask while
_setjmp()/_longjmp() pairs save and restore only the register set and the
stack. (See sigprocmask(2).)
The sigsetjmp()/siglongjmp() function pairs save and restore the signal
mask if the argument savemask is non-zero, otherwise only the register
set and the stack are saved.
ERRORS
If the contents of the env are corrupted, or correspond to an environment
that has already returned, the longjmp() routine calls the routine
longjmperror(3). If longjmperror() returns the program is aborted (see
abort(3)). The default version of longjmperror() prints the message
“longjmp botch” to standard error and returns. User programs wishing to
exit more gracefully should write their own versions of longjmperror().
SEE ALSOsigaction(2), sigaltstack(2), signal(3)STANDARDS
The setjmp() and longjmp() functions conform to ISO/IEC 9899:1990
(“ISO C90”). The sigsetjmp() and siglongjmp() functions conform to IEEE
Std 1003.1-1988 (“POSIX.1”).
BSD June 4, 1993 BSD
