LONGJMP(P) POSIX Programmer's Manual LONGJMP(P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMElongjmp - non-local goto
SYNOPSIS
#include <setjmp.h>
void longjmp(jmp_buf env, int val);
DESCRIPTION
The longjmp() function shall restore the environment saved by the most
recent invocation of setjmp() in the same thread, with the correspond‐
ing jmp_buf argument. If there is no such invocation, or if the func‐
tion containing the invocation of setjmp() has terminated execution in
the interim, or if the invocation of setjmp() was within the scope of
an identifier with variably modified type and execution has left that
scope in the interim, the behavior is undefined. It is unspecified
whether longjmp() restores the signal mask, leaves the signal mask
unchanged, or restores it to its value at the time setjmp() was called.
All accessible objects have values, and all other components of the
abstract machine have state (for example, floating-point status flags
and open files), as of the time longjmp() was called, except that the
values of objects of automatic storage duration are unspecified if they
meet all the following conditions:
* They are local to the function containing the corresponding setjmp()
invocation.
* They do not have volatile-qualified type.
* They are changed between the setjmp() invocation and longjmp() call.
As it bypasses the usual function call and return mechanisms, longjmp()
shall execute correctly in contexts of interrupts, signals, and any of
their associated functions. However, if longjmp() is invoked from a
nested signal handler (that is, from a function invoked as a result of
a signal raised during the handling of another signal), the behavior is
undefined.
The effect of a call to longjmp() where initialization of the jmp_buf
structure was not performed in the calling thread is undefined.
RETURN VALUE
After longjmp() is completed, program execution continues as if the
corresponding invocation of setjmp() had just returned the value speci‐
fied by val. The longjmp() function shall not cause setjmp() to return
0; if val is 0, setjmp() shall return 1.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
Applications whose behavior depends on the value of the signal mask
should not use longjmp() and setjmp(), since their effect on the signal
mask is unspecified, but should instead use the siglongjmp() and
sigsetjmp() functions (which can save and restore the signal mask under
application control).
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOsetjmp() , sigaction() , siglongjmp() , sigsetjmp() , the Base Defini‐
tions volume of IEEE Std 1003.1-2001, <setjmp.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 LONGJMP(P)
