SETJMP(3)                  POSIX Programmer's Manual                 SETJMP(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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 .



IEEE/The Open Group                  2017                            SETJMP(3)
