setjmp(3)



SETJMP(3)                      Library functions                     SETJMP(3)

NAME
       setjmp, sigsetjmp - save stack context for non-local goto

SYNOPSIS
       #include <setjmp.h>

       int setjmp(jmp_buf env);
       int sigsetjmp(sigjmp_buf env, int savesigs);

DESCRIPTION
       setjmp()  and  longjmp()  are useful for dealing with errors and inter-
       rupts encountered in a low-level subroutine  of  a  program.   setjmp()
       saves  the stack context/environment in env for later use by longjmp().
       The stack context will be invalidated  if  the  function  which  called
       setjmp() returns.

       sigsetjmp()  is  similar to setjmp().  If savesigs is non-zero, the set
       of blocked signals is saved in env and  will  be  restored  if  a  sig-
       longjmp() is later performed with this env.

RETURN VALUE
       setjmp()  and  sigsetjmp() return 0 if returning directly, and non-zero
       when returning from longjmp() using the saved context.

CONFORMING TO
       POSIX.1-2001, C99

NOTES
       POSIX does not specify whether setjmp() will save the  signal  context.
       (In  System  V  it will not. In 4.3BSD it will, and there is a function
       _setjmp that will  not.)   If  you  want  to  save  signal  masks,  use
       sigsetjmp().

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

SEE ALSO
       longjmp(3), siglongjmp(3)

                                  1997-03-02                         SETJMP(3)

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