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Re: lib/46661: libpthread shouldn't provide __res_state()
The following reply was made to PR lib/46661; it has been noted by GNATS.
From: christos%zoulas.com@localhost (Christos Zoulas)
To: River Tarnell <river%RT.UK.EU.ORG@localhost>,
Cc: lib-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
Subject: Re: lib/46661: libpthread shouldn't provide __res_state()
Date: Thu, 5 Jul 2012 13:42:30 -0400
On Jul 5, 5:08pm, river%RT.UK.EU.ORG@localhost (River Tarnell) wrote:
-- Subject: Re: lib/46661: libpthread shouldn't provide __res_state()
| So because a program *may* use _res wrongly, *all* programs that use
| _res (and libpthread) are broken, even those that use it correctly?
Define correctly. If a program is linked against -lpthread, nothing
prevents other things that it is linked with to use threads and/or
the resolver functions.
| Postfix is broken in the sense that it doesn't work (e.g. pkg/44656).
| The problem is that it's not clear whose fault it is. Postfix is the
| one calling _res, but it's entirely single-threaded, so there's nothing
| wrong with that. It links against the PostgreSQL client library, libpq.
| libpq does not use _res (it uses the MP-safe resolv interface), but it
| is MP-safe itself, and pulls in libpthread. As a result, Postfix
| doesn't work.
| > This is similar to the issue with have
| > with mutexes: requiring pthread_mutex_init() before using them;
| > other OS's don't and people claim NetBSD is broken.
| The pthread API requires that pthread_mutex_init() be called, doesn't
| it? So, a program not doing so is clearly wrong.
| > If programs want to play with _res from a threaded context, they are
| > broken and should be fixed.
| But the program is single-threaded; it just happens to link against
| libpthread. Why shouldn't that work?
Because it cannot possibly know what other things it calls that use pthreads
are doing. Anyway, the I just fixed postfix, and it will probably get fixed
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