Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!pasteur!ucbvax!decwrl!sun!pitstop!sundc!seismo!uunet!mcvax!hp4nl!philmds!leo
From: leo@philmds.UUCP (Leo de Wit)
Newsgroups: comp.lang.c
Subject: Re: Any way to catch exit()?
Keywords: _cleanup
Message-ID: <771@philmds.UUCP>
Date: 28 Aug 88 06:28:50 GMT
References: <8808261432.AA11635@ucbvax.Berkeley.EDU> <967@cbnews.ATT.COM>
Reply-To: leo@philmds.UUCP (Leo de Wit)
Organization: Philips I&E DTS Eindhoven
Lines: 43

In article <967@cbnews.ATT.COM> lvc@cbnews.ATT.COM (Lawrence V. Cipriani) writes:
>One solution that I have employed is to define my own exit routine.
>When the program terminates my exit routine is called, and does what
>I want.
>
>	void exit(e)
>		int e;
>	{
>		...whatever...
>		_exit(e);	/* still need this sucker */
>	}
>
>This probably is non-portable but should solve your problem (if I
>understood it correctly).

One of the problems looming up is that exit() should flush stdio buffers.
(this should be part of ...whatever...). I don't know how that can be
done in a portable manner. Ultrix seems to use _cleanup() at this point.
There is a funny thing about _cleanup():
It is called without parameters. If I run the following program through adb:

main()
{
    exit(0);
}

then _cleanup() does just: ret.

If I run the following however:

main()
{
    printf("12345");
    exit(0);
}

then _cleanup() does a lot of stuff. It seems that if stdio is not used
a simple version of _cleanup is used; if it IS used, a complicated one
is used that does a _filewalk() or something. Probably has something to
do with keeping binary sizes small, but I can't figure out how you can
have several _cleanup() 's in one library. Anyone knows?

                               Leo.