[CMake] Absolute Path linking library

[Laurent Chauvin]

Hello,

I just tried to set the MACOSX_RPATH 1 in the top CMakeLists of MyLib, and
when I now do otool -L libMyLib.dyld, I can indeed see @rpath/libMyLib.dyld.
However, my executable "MyExample" is still not able to find the library at
runtime. When I do otool -L MyExample, I still have libMyLib.dyld, not
@rpath/libMyLib.dyld.
And I have same error (Library not loaded, image not found) when trying to
start the example.

Should I add something more (or remove something) from my CMakeLists
example ?

I'm sorry I'm not really familiar with these mechanisms.

Thank you very much.
-Laurent


On Wed, Sep 4, 2013 at 11:30 AM, Laurent Chauvin
<lchauvin at bwh.harvard.edu>wrote:

> Thank you very much for your answer.
>
> I will try to use the MACOSX_RPATH.
>
> However, I have some questions. As the flag suggests, it's only for mac.
> Is there anything similar for Linux (and eventually Windows systems) ?
>
> Also, the problem to set the full path of the library is, if I compile on
> Windows the extension of library will be dll, on Mac it will be dyld, and
> .a on linux.
> I could make a condition to set the extension at the end of the name of
> the library like libMyLib.(dll, dyld, a) but, I feel like it's not really a
> clean way to do it.
>
> Is there a better way to do it ?
>
> Thank you very much.
> -Laurent
>
>
>
> On Wed, Sep 4, 2013 at 10:57 AM, Clinton Stimpson <clinton at elemtech.com>wrote:
>
>> On Tuesday, September 03, 2013 09:47:45 PM Laurent Chauvin wrote:
>> > Hello everyone,
>> >
>> > I'm working on a library, and I would like the users be able to create
>> their
>> > own program and liking to my library (by specifying path in cmake).
>> >
>> > I created the library and an example to test it.
>> > Everything compiles.
>> >
>> > However, when I try to run my example I have this error:
>> > MyExample:
>> >       libMyLib.1.dylib (compatibility version 1.0.0, current version
>> 1.0.0)
>> >       /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current
>> version
>> > 56.0.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current
>> > version 169.3.0)
>> >
>> > The problem is my example is not in the same directory as my library
>> (not
>> > even in a subdirectory). And it seems it's linking to my library with a
>> > relative path.
>> >
>> > If I add the path of my library in DYLD_LIBRARY_PATH it works, but I
>> would
>> > like the users to be able to compile and link straight forward.
>> >
>> > To link the library to my example I use find_package(MyLib REQUIRED) and
>> > include(${MyLib_USE_FILE}) which basically do a LINK_DIRECTORIES with
>> the
>> > absolute path of the library.
>> >
>> > Then I do add_executable and target_link_libraries(MyExample
>> > ${MyLib_LIBRARIES})
>> >
>> > Compilation is working fine. There is these options:
>> >
>> > -L/Absolute/Path/To/MyLib -lMyLib
>> >
>> > But at runtime, library cannot be found.
>> >
>> > Would it be possible to put the full path of my library when linking in
>> the
>> > CMakeLists ?
>> >
>>
>> You should use the full path to the library instead of LINK_DIRECTORIES.
>> Its easiest if you use install(EXPORT ...) to have CMake generate an
>> export
>> file for you that can be included by your FindMyLib.cmake file.
>> That export file will use the full path, and include any other necessary
>> information about the library.
>>
>> But to solve the problem of finding the library at runtime (specifying a
>> full
>> path won't solve it), CMake 2.8.12 has a new feature to address exactly
>> that
>> problem.  For details: http://www.kitware.com/blog/home/post/510
>>
>> If you can use CMake 2.8.12, then you need to put
>>  set(MACOSX_RPATH 1)
>> in the CMakeLists.txt of MyLib.
>>
>> If the user is using 2.8.12, then any executable they compile with your
>> library will be able to find the library, no matter where it is.
>>
>> By the way, 2.8.12 is in a release candidate stage right now, and right
>> now
>> would be a good time for you to test the new feature that is meant to
>> solve
>> your problem.
>>
>> Clint
>>
>
>
>
> --
> Laurent Chauvin, MS
> Surgical Navigation and Robotics Laboratory, Radiology Department
> Brigham And Women's Hospital, Harvard Medical School
> http://wiki.ncigt.org/index.php/User:Lchauvin
>



-- 
Laurent Chauvin, MS
Surgical Navigation and Robotics Laboratory, Radiology Department
Brigham And Women's Hospital, Harvard Medical School
http://wiki.ncigt.org/index.php/User:Lchauvin
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