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setjmp, sigsetjmp - save stack context for non-local goto
int setjmp(jmp_buf env);
int sigsetjmp(sigjmp_buf env, int savesigs);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
setjmp(): see NOTES.
sigsetjmp(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_C_SOURCE
setjmp() and longjmp(3) are useful for dealing with errors and
interrupts encountered in a low-level subroutine of a program.
setjmp() saves the stack context/environment in env for later use by
longjmp(3). The stack context will be invalidated if the function
which called setjmp() returns.
sigsetjmp() is similar to setjmp(). If, and only if, savesigs is non-
zero, the process’s current signal mask is saved in env and will be
restored if a siglongjmp(3) is later performed with this env.
setjmp() and sigsetjmp() return 0 if returning directly, and non-zero
when returning from longjmp(3) using the saved context.
C89, C99, and POSIX.1-2001 specify setjmp(). POSIX.1-2001 specifies
POSIX does not specify whether setjmp() will save the signal signal
mask. In System V it will not. In 4.3BSD it will, and there is a
function _setjmp that will not. By default, Linux/glibc follows the
System V behavior, but the BSD behavior is provided if the _BSD_SOURCE
feature test macro is defined and none of _POSIX_SOURCE,
_POSIX_C_SOURCE, _XOPEN_SOURCE, _XOPEN_SOURCE_EXTENDED, _GNU_SOURCE, or
_SVID_SOURCE is defined.
If you want to portably save and restore signal masks, use sigsetjmp()
setjmp() and sigsetjmp() make programs hard to understand and maintain.
If possible an alternative should be used.
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