MySQL Bugs: #39288: MySQL Embedded server (libmysqld.a) is built without -fPIC flag

Bug #39288	MySQL Embedded server (libmysqld.a) is built without -fPIC flag
Submitted:	6 Sep 2008 17:06	Modified:	14 Jan 2013 11:06
Reporter:	Edward Hades	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Compiling	Severity:	S2 (Serious)
Version:	5.1.26-rc, 5.0, 5.1 bzr	OS:	Linux
Assigned to:	Joerg Bruehe	CPU Architecture:	Any
Tags:	Contribution

Description:
The MySQL Embedded library is not built with -fPIC flag (even when ./configure is called with --with-pic). This makes creating shared libraries using libmysqld report warning or even impossible on certain architectures.

How to repeat:
Configure MySQL sources with --with-pic
Build it
Try to link a shared library against libmysqld.a

Thank you for the report.

Verified as described.

Workaround: `export CFLAGS='-fPIC'` before running configure

I looked through a build log of 5.0.60 and determined that the only library built with PIC, even when --with-pic is enabled by the configure script, is libmysqlclient.a .  libmysqld.a is gathered from:

libmysqld_int.a
libregex.a
libmyisam.a
libmyisamrg.a
libheap.a
libmysys.a
libmystrings.a
libdbug.a
libvio.a

All of these need to be built with PIC.  The CFLAGS="-fPIC" temporary workaround does work for me, though.

As a larger question in this, why is the submitter trying to link a shared library against a static one (esp one as large s libmysqld)? libmysqld should be provided in a shared library form as well for linking against I think.

Well, yes, linking against libmysqld.so can solve all our problems.

The problem is, there is no libmysqld.so, neither built by mysql's build system, nor available in any distribution to my knowledge.

Sveta: Any plans to make a shared libmsqld.so to solve this properly?

Is there any progress on this? Any plans on including this in a future mysql release, or anyone working on it?

Robin, Ingmar,

target version is 6.0, so bug should be fixed in version 6.0 sometime.

I don't agree on setting the target version of this to 6.0. We finally re-enabled the embedded Server in 5.1, so I think it deserves to be built properly.

This change is not affecting any source code at all, it does not introduce any change in behavior. It just requires the surrounding build scripts and Makefiles to be fixed. Why is such a trivial change being postponed to 6.0?

I am fine with postponing the creation of a shared library version of the MySQL embedded server to a future version, if it's too intrusive to do (I now submitted WL#4650 about this).

But not building the static libraries with PIC is a bug that needs to be fixed ASAP, as it is a roadblock for the adoption of MySQL Embedded.

Any updates on this? I think it's important and trivial enough to have it fixed soon.

Requesting a re-triage of this one.

I have tried to modify the makefiles myself in order to create a shared libmysqld. The smaller libraries that libmysqld depends on (mysys, strings, regex, vio...) can easily be changed to use libtool. However, libmysqld has a special treatment for Metrowerks on MacOS (a few object files seem to be linked in twice). Is this really necessary (don't have a mac)? 
And wouldn't it be cleaner to depend on the sources directly and let libtool do the work? This way, the problem of including object files more than once wouldn't exist. Anyway, there might be some problem with the build process that I don't see.

Please take a look at the bugreport [1] filed at the Gentoo bugtracker.
There are a lot details about the whole problem + a partially working patch [2] for the MySQL makefiles.

[1] Bugreport: http://bugs.gentoo.org/show_bug.cgi?id=238487
[2] Patch: http://bugs.gentoo.org/show_bug.cgi?id=238487#c47

Regards, Elias P.

There is a new (at least for me) working patch against mysql in gentoo's bugzilla:

Bug: http://bugs.gentoo.org/show_bug.cgi?id=238487
Patch: http://bugs.gentoo.org/attachment.cgi?id=186704

Perhaps it is worth a review?

Following up on the last comment, if you want to check the patches for mysql-5.0.76 and mysql-community-5.0.77, here are the direct links:

mysql-5.0.76 - http://git.overlays.gentoo.org/gitweb/?p=proj/mysql-extras.git;a=blob_plain;f=0204_all_emb...

mysql-community-5.0.77 - http://git.overlays.gentoo.org/gitweb/?p=proj/mysql-extras.git;a=blob_plain;f=0204_all_emb...

Unfortunately, the Gentoo patch doesn't work properly.

When the patch is applied, regardless of whether you're running on x86 or x86_64, if you try to run Amarok (the one app I know of that's currently using libmysqld) it can't find its library linked against libmysqld unless Amarok is compiled *with* -Wl,--as-needed.  No one seems to have figured out why, yet.  The Gentoo people hacked around this by forcing -Wl,--as-needed on in their Amarok ebuild, but there is clearly something wrong.

Please make libmysqld a proper shared library! The performance issues talked about in http://lists.mysql.com/internals/35950 really seem questionable after reading various posts in http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=508406#52 and the following 3-4 postings. On the other hand, static libraries are a PITA when it comes to security updates from which MySQL  has had more than one in the past.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/102373

3126 Vladislav Vaintroub	2010-03-04
      Bug#39288 : create a shared libmysqld.so.
       
      Plugins are unlikely to work with libmysqld.so, as we do
      _not_ force plugin to export all symbols. Exporting all symbols is definitely possible, on some platforms with  whole-archive, -rdynamic or similar hacks. However, it makes much more sense to finish the "Server API" so neither mysqld nor libmysqld needs to export anything.

Possible patch for 5.1: http://dev.gentoo.org/~reavertm/mysql-5.1.50-use-libtool.patch

Another related bug report in the Gentoo Bug tracker:

https://bugs.gentoo.org/show_bug.cgi?id=306315

Here is a direct link to the patch for this that is now included in Gentoo:

http://git.overlays.gentoo.org/gitweb/?p=proj/mysql-extras.git;a=blob;f=02040_all_embedded...

Bug #59104 was marked as duplicate of this one.

Message from Danny:
Old e-mail from 2010 indicates that this bug is fixed in 5.5+. Does it still need to be fixed in 5.1? Building all the objects that go into the library archive with -fPIC is not a minor change and affects all other binaries.

-ramesh

Closing on behalf of Ramesh.