NAME
_longjmp, _setjmp,
longjmp, longjmperror,
setjmp, siglongjmp,
sigsetjmp —
non-local jumps
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<setjmp.h>
void
_longjmp(jmp_buf env,
int val);
int
_setjmp(jmp_buf env);
void
longjmp(jmp_buf env,
int val);
void
longjmperror(void);
int
setjmp(jmp_buf env);
void
siglongjmp(sigjmp_buf env,
int val);
int
sigsetjmp(sigjmp_buf env,
int savemask);
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 ALSO
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”).