ccan dependencies seems to break external projects

[Andrew Bartlett]

On Sun, 2012-02-12 at 19:08 +0100, Jelmer Vernooij wrote:
> On 02/12/2012 06:57 PM, Matthieu Patou wrote:
> > On 02/12/2012 04:52 AM, Jelmer Vernooij wrote:
> >> On Sat, Feb 11, 2012 at 02:49:20PM -0800, Matthieu Patou wrote:
> >>> I'm trying to compile openchange as described here : 
> >>> http://tracker.openchange.org/projects/openchange/wiki/HowTo_Install_OpenChange_From_Source
> >>>
> >>> I'm using the latest git tree instead of alpha17, after a couple of
> >>> tweak in the script that setup the prerequisits I have a samba4 with
> >>> using system talloc/tdb/tevent and ldb.
> >>>
> >>> Then I try to build openchange and got:
> >>>
> >>>
> >>> /usr/local/src/openchange$ make
> >>> Linking sample application bin/libmapixx-test
> >>> g++ -I.  -O3 -Wall -g3 -fstrict-aliasing -Wp,-D_FORTIFY_SOURCE=2
> >>> -DHAVE_IMMEDIATE_STRUCTURES=1 -D_GNU_SOURCE=1
> >>> -Wl,-rpath,/usr/local/samba/lib -I/usr/local/samba/include
> >>>     -I/usr/local/samba/include   -I/usr/local/samba/include
> >>> -I/usr/local/samba/include     -o bin/libmapixx-test
> >>> libmapi++/tests/test.cpp libmapipp.so.0.11 libmapi.so.0
> >>> .11 -Wl,-rpath,/usr/local/samba/lib -L/usr/local/samba/lib -ldcerpc
> >>> -ldcerpc-binding -lndr -lsamba-hostconfig -lsamba-util -ltevent
> >>> -ltalloc   -Wl,-rpath,/usr/local/samb
> >>> a/lib -L/usr/local/samba/lib -lldb -ltalloc
> >>> -Wl,-rpath,/usr/local/samba/lib -L/usr/local/samba/lib -ltalloc
> >>> -lpthread
> >>> /usr/local/samba/lib/libsmbconf.so.0: undefined reference to
> >>> `hash_any at SAMBA_4.0.0ALPHA18_GIT_0B3A262'
> >>>
> >>>
> >>> The hash_any symbol comes from the ccan library and is included in
> >>> libsmbconf.so via source3/util/
> >>>
> >>> I suspect there is a symbols collision when you build samba 4 with
> >>> system libs as ldb has its own version of ccan but obviously with a
> >>> different version although it seems that ldb didn't directly need
> >>> ccan (no ccan in the output of ldd libldb.so), the following command
> >>> ls /usr/local/systemsamba/lib/ldb/libccan.so.0* output this:
> >>>
> >>> /usr/local/systemsamba/lib/ldb/libccan.so.0
> >>> /usr/local/systemsamba/lib/ldb/libccan.so.0.1-init-1161-g661d41f
> >>>
> >>> There is no way to have a system ccan and it seems that there is no
> >>> easy way to use the one built for ldb as the "system" ccan.
> >>>
> >>> I don't know what can be done, the cheapest is to have a
> >>> source3/util not to depend on ccan if --disable-tdb2 was specified
> >>> on the command line.
> >> Does ccan really have to be a separate library? Its goal seems to be
> >> the same as the 'samba-util' library.
> >>
> >> If I understand correctly ccan isn't really meant as a shared library
> >> with utility functions but rather as a collection of C files that you
> >> can pick a few useful ones from.
> >>
> >> Would it perhaps be possible to just include the relevant files from
> >> ccan in libsamba-util?
> > I'm not sure how this will fix the problem.
> > Let say that we have ccan in samba-util, instead of depending on ccan, 
> > ldb will depend on samba-util.
> > It means if I understand well that we will have a libsambautil.so with 
> > a version 1.4.1 (the version of ldb) but as it seems that we have no 
> > way to use a system samba-util library when building samba4 will have 
> > also a version of this library SAMBA_4.0.0ALPHA...
> tdb can include whatever it needs from ccan in the same way as 
> samba-util does (AFAIK it only uses a single macro from ccan at the moment).
> 
> ccan doesn't have a well-defined ABI. The problem with the way you're 
> building ldb and Samba is that you end up with two versions of the ccan 
> library - one which does have hash_any and one which doesn't. The linker 
> only tries to load one and not the other, because it remembers it has 
> already loaded ccan.

Does removing the 'vnum' line from ccan/wscript fix any of this?

It seems odd to be forcing the vnum from the upstream ccan if this
really is a private library?

Also, shouldn't we be putting a -samba4 prefix on the end of the name of
all the private and bundled libraries?  (We do it when bundling
Heimdal).

Andrew Bartlett

-- 
Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org