Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!petunia!news
From: jdudeck@polyslo.CalPoly.EDU (John R. Dudeck)
Newsgroups: comp.sys.hp
Subject: About wait(2)...
Message-ID: <281737c1.49d2@petunia.CalPoly.EDU>
Date: 25 Apr 91 20:10:41 GMT
Distribution: usa
Organization: Cal Poly State Univ,CSC Dept,San Luis Obispo,CA 93407
Lines: 49



I am porting an application (the PP X.400 system) from bsd to HP/UX, on
a system running HP/UX ver.  6.5B.  The code includes three daemons.  I am
having problems that seem to be related to the wait(2) call.

The original code defines a wait structure:
  struct wait w;
then later on does a fork and a wait, etc, in the normal fashion.

Then there is a line such as 
  if (WIFEXITED(w)) return w.w_retcode;

This does not compile under HP/UX, with an "operands of cast have
incompatible types" error.  The sys/wait.h file defines WIFEXITED using
a cast of struct to int, as opposed to bsd which does not.

So I changed the above line to
  if (WIFEXITED(w.w_status)) return w.w_retcode;
which compiles ok.

This same scenario exists 5 places in the package.  Now I am at a point
were different parts of the packgage crash with a Bus Error at certain
points in the code.  It doesn't crash in this code, but since this is
the part I changed, I tend to suspect a problem here.  I suspect that
if the code returns the wrong status here, it could provoke a crash
elsewhere in the system.

Furthermore, the daemon isn't cleaning up its zombies like it should.

There also are a couple of wait3() calls in the system, which I didn't
make any changes to.

In the man page for wait(2), there is a line which says:
  "The third parameter to wait3 is currently unused, and must always be
  a null pointer".
In one place this is not null in my code.

My questions are these:

1. Did I do something wrong in the changes I made?
2. Is there a difference in the way wait() works on HP/UX?
3. What happens if the third parameter to wait3 isn't a null pointer?


-- 
John Dudeck                                              "You can only push
jdudeck@Polyslo.CalPoly.Edu                             simplicity so far."
ESL: 62013975 Tel: 805-545-9549                -- AT&T promotional brochure