[CMake] Creating relocatable packages

Mon Oct 19 17:35:45 EDT 2015

Hi Dan,

On a second read, it seems Zac's problem was actually finding the
dependency (libpcap) of a dependency. Or rather, making if findable,
because the second depenency contains an absolute path which is broken due
to cross-compilation.

I have never used it but this page contains information on how to fix the
paths in the config file to be relative instead of absolute. That should
fix the problem:

https://cmake.org/Wiki/CMake/Tutorials/How_to_create_a_ProjectConfig.cmake_file

On Mon, Oct 19, 2015 at 11:15 PM, Dan Kegel <dank at kegel.com> wrote:

> Well, that's one answer.  But if you want to use system libpcap, it's not
> a very satisfying one.
>
> It's odd that pcap doesn't ship with a .pc file.
> I guess the pcap folks are hostile to pkgconfig because it's LGPL; see
> https://github.com/the-tcpdump-group/libpcap/issues/374
> - Dan
>
>
>
> On Mon, Oct 19, 2015 at 2:04 PM, Pau Garcia i Quiles <pgquiles at elpauer.org
> > wrote:
>
>> Hello,
>>
>> Use ExternalProject to build libpcap as part of your project. Make sure
>> you use $ORIGIN in rpath everywhere. Install your application (and your
>> bundled libpcap) to /opt to avoid polluting the system.
>>
>> On Mon, Oct 19, 2015 at 10:37 PM, Zac Bergquist <zbergquist99 at gmail.com>
>> wrote:
>>
>>> Thank you for your reply, Guillaume.
>>>
>>> I understand that this is the expected behavior.  I even linked to the
>>> documentation that says this is the expected behavior.  What I don't
>>> understand is how to resolve it.  Are you saying it is not possible to
>>> create a relocatable package unless all dependencies are also using CMake?
>>> That doesn't seem right.
>>>
>>> Should I be trying to write a package config file for libpcap, or is
>>> there a better way to approach this?
>>>
>>> On Sat, Oct 17, 2015 at 8:19 AM, Guillaume Dumont <
>>> dumont.guillaume at gmail.com> wrote:
>>>
>>>> What you are seeing is the expected behavior. You can get a relocatable
>>>> package if all your dependencies (in your case libcap) have themselves
>>>> relocatable package config files with exported targets. Then you package
>>>> should make use of find_dependency macro.
>>>>
>>>> On Fri, Oct 16, 2015 at 4:56 PM, Zac Bergquist <zbergquist99 at gmail.com>
>>>> wrote:
>>>>
>>>>> I've created a sample project to replicate my issue in hopes that it
>>>>> would make it easier to troubleshoot.
>>>>>
>>>>> Thanks for any help,
>>>>> Zac
>>>>>
>>>>> https://github.com/zmb3/cmaketest
>>>>>
>>>>> On Mon, Oct 12, 2015 at 8:53 AM, Zac Bergquist <zbergquist99 at gmail.com
>>>>> > wrote:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I'm trying to fix a project so that its output is relocatable.  The
>>>>>> project is a library that itself depends on libpcap.  My goal is to be able
>>>>>> to import the library into my CMake application and have CMake
>>>>>> automatically link libpcap with it.
>>>>>>
>>>>>> I'm using a toolchain file that invokes an ARM cross compiler, sets
>>>>>> CMAKE_INSTALL_PREFIX and appends it to CMAKE_FIND_ROOT_PATH.  This all
>>>>>> seems to work well.
>>>>>>
>>>>>> What I'm seeing is that the exported files that get installed to
>>>>>> CMAKE_INSTALL_PREFIX contain absolute paths to libpcap on my machine, which
>>>>>> make them useless to other team members.
>>>>>>
>>>>>> The first thing I changed was to use CONFIGURE_PACKAGE_CONFIG_FILE
>>>>>> instead of CONFIGURE_FILE.  This got rid of absolute paths in the generated
>>>>>> CMake config file.
>>>>>>
>>>>>> However, I still have absolute paths in the CMake target import file
>>>>>> that gets generated.  The IMPORTED_LINK_INTERFACE_LIBRARIES target property
>>>>>> has an absolute path instead of one relative to CMAKE_INSTALL_PREFIX.
>>>>>>
>>>>>> I've read the "Creating Relocatable Packages" [1] section of the
>>>>>> CMake packages documentation. I'm pretty sure this is what I'm running
>>>>>> into, but I don't quite understand how to solve it.  The documentation says
>>>>>> that I should be using imported targets, but I'm not sure how to do so.
>>>>>> The library is just using its own FindPCAP.cmake file to locate libpcap.
>>>>>>
>>>>>> Does anyone know of an example of a CMake package that imports other
>>>>>> libraries?  I could also try to create a minimal example project with this
>>>>>> setup if it would be helpful.
>>>>>>
>>>>>> Thanks,
>>>>>> Zac
>>>>>>
>>>>>> [1]:
>>>>>> https://cmake.org/cmake/help/v3.3/manual/cmake-packages.7.html#creating-relocatable-packages
>>>>>>
>>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Powered by www.kitware.com
>>>>>
>>>>> Please keep messages on-topic and check the CMake FAQ at:
>>>>> http://www.cmake.org/Wiki/CMake_FAQ
>>>>>
>>>>> Kitware offers various services to support the CMake community. For
>>>>> more information on each offering, please visit:
>>>>>
>>>>> CMake Support: http://cmake.org/cmake/help/support.html
>>>>> CMake Consulting: http://cmake.org/cmake/help/consulting.html
>>>>> CMake Training Courses: http://cmake.org/cmake/help/training.html
>>>>>
>>>>> Visit other Kitware open-source projects at
>>>>> http://www.kitware.com/opensource/opensource.html
>>>>>
>>>>> Follow this link to subscribe/unsubscribe:
>>>>> http://public.kitware.com/mailman/listinfo/cmake
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Guillaume Dumont
>>>> =========================
>>>> dumont.guillaume at gmail.com
>>>>
>>>
>>>
>>> --
>>>
>>> Powered by www.kitware.com
>>>
>>> Please keep messages on-topic and check the CMake FAQ at:
>>> http://www.cmake.org/Wiki/CMake_FAQ
>>>
>>> Kitware offers various services to support the CMake community. For more
>>> information on each offering, please visit:
>>>
>>> CMake Support: http://cmake.org/cmake/help/support.html
>>> CMake Consulting: http://cmake.org/cmake/help/consulting.html
>>> CMake Training Courses: http://cmake.org/cmake/help/training.html
>>>
>>> Visit other Kitware open-source projects at
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Follow this link to subscribe/unsubscribe:
>>> http://public.kitware.com/mailman/listinfo/cmake
>>>
>>
>>
>>
>> --
>> Pau Garcia i Quiles
>> http://www.elpauer.org
>> (Due to my workload, I may need 10 days to answer)
>>
>> --
>>
>> Powered by www.kitware.com
>>
>> Please keep messages on-topic and check the CMake FAQ at:
>> http://www.cmake.org/Wiki/CMake_FAQ
>>
>> Kitware offers various services to support the CMake community. For more
>> information on each offering, please visit:
>>
>> CMake Support: http://cmake.org/cmake/help/support.html
>> CMake Consulting: http://cmake.org/cmake/help/consulting.html
>> CMake Training Courses: http://cmake.org/cmake/help/training.html
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/cmake
>>
>
>

-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/cmake/attachments/20151019/61bf15cc/attachment-0001.html>