setjmp - set jump point for a non-local goto
int setjmp(jmp_buf env);
[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.1-2017 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.
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.
No errors are defined.
In general, sigsetjmp() is more useful in dealing with errors and interrupts encountered in a low-level subroutine of a program.
First released in Issue 1. Derived from Issue 1 of the SVID.
The normative text is updated to avoid use of the term "must" for application requirements.
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