SETJMP(3P)

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.

NAME
setjmp — set jump point for a non-local goto

SYNOPSIS

#include <setjmp.h>

int setjmp(jmp_buf env);

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.1-2017 defers to the ISO C standard.

A call to setjmp() shall save the calling environment in its env argument for later use by longjmp().

It is unspecified whether setjmp() is a macro or a function. If a macro definition is suppressed in order to access an actual function, or a program defines an external identifier with the name setjmp, the behavior is undefined.

An application shall ensure that an invocation of setjmp() appears in one of the following contexts only:

*   The entire controlling expression of a selection or iteration statement

*   One operand of a relational or equality operator with the other operand an integral constant expression, with the resulting expression being the entire controlling expression of a selection or iteration statement

*   The operand of a unary '!' operator with the resulting expression being the entire controlling expression of a selection or iteration

*   The entire expression of an expression statement (possibly cast to void)

If the invocation appears in any other context, the behavior is undefined.

RETURN VALUE
If the return is from a direct invocation, setjmp() shall return 0. If the return is from a call to longjmp(), setjmp() shall return a non-zero value.

ERRORS
No errors are defined.

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
In general, sigsetjmp() is more useful in dealing with errors and interrupts encountered in a low-level subroutine of a program.

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
longjmp(), sigsetjmp()

The Base Definitions volume of POSIX.1-2017, <setjmp.h>

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

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 .