[1/1] libbsd: remove usage of __register_atfork

Message ID 20181003175409.26025-1-fontaine.fabrice@gmail.com
State New
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Series
  • [1/1] libbsd: remove usage of __register_atfork
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Commit Message

Fabrice Fontaine Oct. 3, 2018, 5:54 p.m.
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

Comments

Thomas Petazzoni Oct. 14, 2018, 8:58 a.m. | #1
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

Patch

diff --git a/package/libbsd/0002-Remove-usage-of-__register_atfork.patch b/package/libbsd/0002-Remove-usage-of-__register_atfork.patch
new file mode 100644
index 0000000000..366594bbe8
--- /dev/null
+++ b/package/libbsd/0002-Remove-usage-of-__register_atfork.patch
@@ -0,0 +1,39 @@ 
+From 1220b3b758030f1717558980d60ade9a33628383 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Wed, 3 Oct 2018 19:14:34 +0200
+Subject: [PATCH] Remove usage of __register_atfork
+
+Calling an internal function of glibc is never a good idea.
+This is especially true for __register_atfork which is not defined on
+uClibc with noMMU.
+So remove call to __register_atfork and so always use pthread_atfork
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+[Upstream status:
+https://gitlab.freedesktop.org/libbsd/libbsd/merge_requests/2]
+---
+ src/arc4random_linux.h | 7 -------
+ 1 file changed, 7 deletions(-)
+
+diff --git a/src/arc4random_linux.h b/src/arc4random_linux.h
+index 7a2ca1e..7287b07 100644
+--- a/src/arc4random_linux.h
++++ b/src/arc4random_linux.h
+@@ -31,14 +31,7 @@
+ static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
+ #define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
+ #define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
+-
+-#ifdef __GLIBC__
+-extern void *__dso_handle;
+-extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);
+-#define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)
+-#else
+ #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
+-#endif
+ 
+ static inline void
+ _getentropy_fail(void)
+-- 
+2.17.1
+