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This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface
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NAME
longjmp — non-local goto
SYNOPSIS
#include <setjmp.h> void longjmp(jmp_buf env, int val);
DESCRIPTION
The functionality described on this reference page is aligned with the ISO C standard. Any conflict
between the requirements described here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The longjmp() function shall restore the environment saved by the most recent invocation of setjmp() in
the same process, with the corresponding jmp_buf argument. If the most recent invocation of setjmp() with
the corresponding jmp_buf occurred in another thread, or if there is no such invocation, or if the
function 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 specified 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 ALSO
setjmp(), sigaction(), siglongjmp(), sigsetjmp()
The Base Definitions volume of POSIX.1‐2008, <setjmp.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .