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Date: Mon, 13 Nov 2023 20:07:44 +0100
From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: Bruno Haible <bruno@clisp.org>
Cc: cygwin@cygwin.com
Subject: Re: random is not multithread-safe in Cygwin
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On Nov 13 19:04, Bruno Haible via Cygwin wrote:
> Corinna Vinschen wrote:
> > > And indeed glibc, musl libc, AIX, Android, and even NetBSD implement it in a
> > > multithread-safe way.
> > 
> > Our code is from FreeBSD, originally.  I checked the latest code from
> > FreeBSD.  It doesn't lock anything in random() and generates the same
> > error when running the same test app.
> > 
> > Why is that ok for FreeBSD?
> 
> It is not OK in FreeBSD, either. This is what I noted in the Gnulib manual:
> https://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=doc/posix-functions/random.texi
> 
> But it is MT-safe in NetBSD (in the '#ifndef SMALL_RANDOM' branch):
> http://cvsweb.netbsd.org/bsdweb.cgi/src/common/lib/libc/stdlib/random.c?rev=1.7&content-type=text/x-cvsweb-markup

Ok, I pushed a patch(*) to make the random(3) functions thread-safe, more
or less following NetBSDs lead.  If you get a chance, give the next test
release cygwin-3.5.0-0.459.gd223f095905a a try.

The patch will be part of the next release, 3.4.10.


Thanks,
Corinna

(*) https://sourceware.org/git/?p=newlib-cygwin.git;a=commit;h=06e463223b95