[CMake] library path stripping

[Eric Noulard]

2011/6/8 Andreas Naumann <Andreas-Naumann at gmx.net>:
> Am 08.06.2011 11:56, schrieb Eric Noulard:
>>
>> 2011/6/8 Andreas Naumann<Andreas-Naumann at gmx.net>:
>>
>>>
>>> Hi @all,
>>>
>>> I have some problem with the library usage in cmake.
>>>
>>> It seems to me, that cmake removes the full path of the library, if the
>>> path
>>> is in the environment variable LIBRARY_PATH.
>>> This behaviour cause problems at our system, such that the linker links
>>> against the wrong library.
>>>
>>> Is there an option to avoid this splitting?
>>>
>>
>> Did you read that:
>> http://www.cmake.org/Wiki/CMake_RPATH_handling
>>
>> Which version of CMake are you using?
>> On which system ?
>>
>>
>>
>
> We are using version 2.8.2 and 2.8.4 on Debian and Suse Linux.
>
> I've read the hints on RPATH handling, but there it is said, that:
> "By default if you don't change any RPATH related settings, CMake will link
> the executables and shared libraries with full RPATH to all used libraries
> in the build tree"

Yes.
And you did not mention it but the probleme you have occurs when using
the executable **directly from the build dir** right?

> This means, if I don't set anything related to RPATH, cmake should not strip
> the path from the library, should it?

No it shoudn't for the binary in the buitd tree but...
if you do "make install" the installed binaries will have no RPATH unless
you set

SET(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")

# add the automatically determined parts of the RPATH
# which point to directories outside the build tree to the install RPATH
SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)

> I played with the example and it was a bit hard to understand, when the path
> is stripped from the library.
> The problem arises before linking the executable.

This is a different issue.
Could you copy/paste the

add_executable
and
target_link_libraries

statement you use for the offending executable?

> We link to a library, which exists in two different directories:
> /usr/lib64
> and
> somewhere/lib/

This should be resolved by YOU inside CMakeLists.txt by

target_link_libraries(exename /path/to/appropriate/lib/lbname.so)

the
/path/to/appropriate/lib/lbname.so could be the result of an appropriate
find_library
call.

> At the same time, the environment variable LIBRARY_PATH is set to
> somewhere/lib. In this case, cmake removes the path from the library name,
> but does not append it as -L to the linker search paths.
> Now it is up to the linker to choose the right library, which is really bad!
> In our case (gcc 4.1.2 on Suse) it selects the wrong library.
>
> Is there any possibility to avoid this "environmentvariable dependent"
> splitting?

Yes full RPATH should be the solution.


-- 
Erk
Membre de l'April - « promouvoir et défendre le logiciel libre » -
http://www.april.org