pthread_cleanup_push(3T)       DG/UX R4.11MU05      pthread_cleanup_push(3T)


NAME
       pthread_cleanup_push, pthread_cleanup_pop - establish cleanup
       handlers

SYNOPSIS
       #include <pthread.h>

       void pthread_cleanup_push(void (*routine)(void *arg), void *arg);

       void pthread_cleanup_pop(int execute);

   where:
       routine  A pointer to a cleanup routine
       arg      An argument to be passed to the cleanup routine, if it is
                executed
       execute  An integer (0 = do not run routine, nonzero = run it)

DESCRIPTION
       The pthread_cleanup_push() function pushes the specified routine onto
       the calling thread's cleanup stack.  The cleanup routine is popped
       from the stack and executed with the argument arg when:
         (a)  the thread exits, that is, calls pthread_exit() or returns
              from its start routine
         (b)  the thread acts upon a cancellation request, or
         (c)  the thread calls pthread_cleanup_pop() with a nonzero execute
              argument.

       The pthread_cleanup_pop() function removes the routine at the top of
       the calling thread's cleanup stack and optionally executes it (if
       execute is nonzero).

       In C, these functions can be (and are) implemented as macros and
       shall appear as statements in pairs within the same lexical scope.
       That is, the pthread_cleanup_push() macro is expanded to a string
       whose first character is { with pthread_cleanup_pop() expanding to a
       string whose last character is the corresponding }.

       When a process terminates by an explicit call to exit(2) or by other
       means, no cancellation handlers or destructor functions are invoked.

       The effect of calling longjmp(3C) or siglongjmp(3C) is undefined if
       there have been any calls to pthread_cleanup_push() or
       pthread_cleanup_pop() made without the matching call, since the jump
       buffer was filled.  The effect of calling longjmp(3C) or
       siglongjmp(3C) from inside a cleanup routine is also undefined unless
       the jump buffer was also filled in the cleanup routine.

DIAGNOSTICS
   Return Value
       The pthread_cleanup_push() and pthread_cleanup_pop() functions shall
       be used as statements.  They do not return anything.

   Errors
       These functions never return errors.  Failure to place these
       functions in the same lexical scope will likely result in a compile-
       time error.

SEE ALSO
       pthread_cancel(3T), pthread_setintr(3T).  pthread_setintrtype(3T),
       pthread_exit(3T), threads(5).


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