Date: Wed, 9 Jul 2003 22:47:10 -0400 (EDT) From: Daniel Eischen <eischen@vigrid.com> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: freebsd-threads@freebsd.org Subject: Re: null pthread_t Message-ID: <Pine.GSO.4.10.10307092242350.9055-100000@pcnet5.pcnet.com> In-Reply-To: <20030710001744.GA7135@Odin.AC.HMC.Edu>
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On Wed, 9 Jul 2003, Brooks Davis wrote:
> I've got some Linux pthread code that goes something like this that I'm
> porting to FreeBSD:
>
> ------
> pthread_t tid;
>
> tid = -1;
>
> /* Do stuff including maybe creating a thread. */
>
> if (tid != -1) {
> pthread_cancel(tid);
> pthread_join(tid, NULL);
> }
> ------
>
> Since FreeBSD uses pointers instead of integers for pthread_t's, this
> generates warnings which go away if you replace -1 with NULL, but
> it seems like that is likely to do bad things on linux. Is there a
> portable NULL-equivalent pthread_t? I'm not seeing anything jump out at
> me in the headers.
The code in question shouldn't be doing that. If it needs to know
whether a thread id is valid, it should have a separate flag for
it (tid_valid) or possibly use pthread_kill(tid, 0) and checking
the return value (sending signal 0 to a thread is akin to sending
a process signal 0; the signal isn't delivered but the process id
is checked for validity).
--
Dan Eischen
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