LONGJMP(3)              Library functions              LONGJMP(3)

NAME
       longjmp, siglongjmp - non-local jump to a saved stack con-
       text

SYNOPSIS
       #include <setjmp.h>

       void longjmp(jmp_buf env, int val);
       void siglongjmp(sigjmp_buf env, int val);

DESCRIPTION
       longjmp() and setjmp() are useful for dealing with  errors
       and  interrupts encountered in a low-level subroutine of a
       program.  longjmp() restores the environment saved by  the
       last call of setjmp() with the corresponding env argument.
       After longjmp() is completed, program execution  continues
       as if the corresponding call of setjmp() had just returned
       the value val.  longjmp() cannot cause 0 to  be  returned.
       If  longjmp is invoked with a second argument of 0, 1 will
       be returned instead.

       siglongjmp() is similar to longjmp() except for  the  type
       of  its  env  argument.   If the sigsetjmp() call that set
       this env used a nonzero savesigs flag,  siglongjmp()  also
       restores the set of blocked signals.

RETURN VALUE
       These functions never return.

CONFORMING TO
       POSIX

NOTES
       POSIX  does  not  specify whether longjmp will restore the
       signal context.  If you want to save  and  restore  signal
       masks, use siglongjmp.

       longjmp()  and  siglongjmp()  make programs hard to under-
       stand and maintain.  If possible an alternative should  be
       used.

SEE ALSO
       setjmp(3), sigsetjmp(3)

                          March 2, 1997                         1