NAME

setjmp — set jump point for a non-local goto

SYNOPSIS

#include <setjmp.h>

int setjmp(jmp_buf env);


DESCRIPTION

^[CX] 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.1-2024 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.

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

XBD <setjmp.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The normative text is updated to avoid use of the term "must" for application requirements.