From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Date: Sun, 14 Oct 2018 10:58:13 +0200
Subject: [Buildroot] [PATCH 1/1] libbsd: remove usage of
 __register_atfork
In-Reply-To: <20181003175409.26025-1-fontaine.fabrice@gmail.com>
References: <20181003175409.26025-1-fontaine.fabrice@gmail.com>
Message-ID: <20181014105813.7123ba04@windsurf>
List-Id: <buildroot.busybox.net>
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To: buildroot@busybox.net

Hello,

+Arnout in Cc.

On Wed,  3 Oct 2018 19:54:09 +0200, Fabrice Fontaine wrote:
> The following error is raised by minizip:
> 
> [100%] Linking C executable minizip
> /home/peko/autobuild/instance-0/output/host/m68k-buildroot-uclinux-uclibc/sysroot/usr/lib/libbsd.a(arc4random.o): In function `_rs_init.part.1':
> arc4random.c:(.text+0xaa): undefined reference to `__register_atfork'
> collect2: error: ld returned 1 exit status
> 
> As specified in openssl/Config.in, uClibc on noMMU doesn't provide
> __register_atfork() so, as suggested by Arnout during review of minizip
> patch (https://patchwork.ozlabs.org/patch/978000), remove usage of this
> function from libbsd to always use pthread_atfork
> 
> Fixes:
>  - http://autobuild.buildroot.org/results/df2dcbdceaa01a2ae37bf09140e4dbef0a5b9489
> 
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> ---
>  ...02-Remove-usage-of-__register_atfork.patch | 39 +++++++++++++++++++
>  1 file changed, 39 insertions(+)
>  create mode 100644 package/libbsd/0002-Remove-usage-of-__register_atfork.patch

With this change, the build fails in the CI of libbsd:
https://gitlab.freedesktop.org/ffontaine/libbsd/-/jobs/26984:

../src/.libs/libbsd.so: undefined reference to `pthread_atfork'

I guess that's because pthread_atfork() requires linking against
libpthread ?

Also, pthread_atfork() does not have the dso_handle argument that
__register_atfork() has. Is this important in the context of libbsd ?
See
https://gitlab.com/gnutls/gnutls/commit/84b1a7ac383bf1db4c73b8f044170446deca8b2e
for example. I would assume no, because there was already a fallback on
pthread_atfork() in libbsd.

Also, Arnout said __register_atfork() is an internal function, but
it is documented in LSB:
http://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/baselib--register-atfork.html.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com