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       setjmp, sigsetjmp - save stack context for nonlocal goto


       #include <setjmp.h>

       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 nonzero,  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 nonzero when  returning  from
       longjmp(3) or siglongjmp(3) using the saved context.


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue   │
       │setjmp(), sigsetjmp() │ Thread safety │ MT-Safe │


       setjmp(): POSIX.1-2001, POSIX.1-2008, C89, C99.

       sigsetjmp(): POSIX.1-2001, POSIX.1-2008.


       POSIX  does  not  specify whether setjmp() will save the signal mask (to be later restored
       during longjmp(3)).  In System V it will not.  In 4.3BSD it will, and there is a  function
       _setjmp  that  will  not.   On Linux with glibc versions before 2.19, setjmp() follows the
       System V behavior by default, 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.   Since  glibc  2.19,
       <setjmp.h>  exposes  only  the  System  V version of setjmp().  Programs that need the BSD
       semantics should replace calls to setjmp()  with  calls  to  sigsetjmp()  with  a  nonzero
       savesigs argument.

       If you want to portably save and restore signal masks, use sigsetjmp() and siglongjmp(3).

       setjmp()  and  sigsetjmp() make programs hard to understand and maintain.  If possible, an
       alternative should be used.


       longjmp(3), siglongjmp(3)


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                                            2015-08-08                                  SETJMP(3)