Wireshark · Wireshark-dev: Re: [Wireshark-dev] CMake for Windows

[Graham Bloice <graham.bloice@xxxxxxxxxxxxx>]

On 26 June 2013 11:29, Graham Bloice <graham.bloice@xxxxxxxxxxxxx> wrote:

On 26 June 2013 11:07, Roland Knall <rknall@xxxxxxxxx> wrote:

Hi

GLOB and GLOB_RECURSE should normally only catch files, not
directories. (As noted on
http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:file)

Several references found on Google imply that it did return directories as well despite the docs.  My empirical testing seems to show that it doesn't.

 

You should look for ares.h. From the returned path you could deduct
the directory path with STRING.

I'll try this next. 

Alternativly you could look on google for Findcares.cmake, which will
get you some matches for other people, who attempted the same thing.
>From there you can either take their hints or create your own version.

I'm hacking in the  Wireshark copy of that file and all the ones I find on Google are similar.  None of them cater for Windows oddities.

More problematic is finding the library. But you could either use the
built-in function find_library or use the cmake module
FindPackageHandleStandardArgs.cmake (Description in the header of the
file).

Again, it appears that there is nothing in standard CMake to handle the Windows oddities.  There is an existing bug/enhancement for CMake to add VPATHS to find_path et al to cater for the version in the path but it hasn't been progressed since 2010.

My plan was to work out the path under $(PROJECT_LIB_DIR ) for each library and supply that as HINTS to find_path and find_library.

I believe there's another issue as well, on Windows the linker requires access to the import library for linking (e.g. $(PROJECT_LIB_DIR)/c-ares-1.9.1-1-win32ws/lib/libcares-2.lib) and then the dll should be copied to the output directory to load at run-time ($(PROJECT_LIB_DIR)/c-ares-1.9.1-1-win32ws/lib/libcares-2.dll).

I haven't worked out how CMake handles the import library yet.

Allways try to use as many built-in commands as possible, because even
something simple as a little foreach and some paths you set may lead
to cross-compilation mayhem in the future.

I think all the Windows oddities will have to be wrapped in IF(WIN32) or similar to prevent other breaking CMake on other platforms. 

This now works for finding the include path, it appears FILE(GLOB) does locate dirs, where I was going wrong was with round braces instead of curly braces when using CMake vars:

IF (WIN32)

  SET(PROJECT_LIB_DIR "W:/Wireshark/wireshark-win32-libs")

  FILE(GLOB subdir "${PROJECT_LIB_DIR}/*")

  FOREACH(dir ${subdir})

    IF(IS_DIRECTORY ${dir})

      IF("${dir}" MATCHES ".*/c-ares-.*")

        MESSAGE("Found c-ares: ${dir}")

        SET(CARES_HINTS ${dir})

      ENDIF()    

    ENDIF()

  ENDFOREACH()

ENDIF(WIN32)

FIND_PATH(CARES_INCLUDE_DIR ares.h HINTS "${CARES_HINTS}/include")

Note that I still had to add the "/include" suffix to FIND_PATH.  I thought CMake did that automagically.  Shouldn't be too hard to make a macro function to do the search for an aribitrary library string.

Next is fixing the FIND_LIBRARY.  I assume it's looking for the import library to supply to the linker, in this case the library name is .../lib/libcares-2.lib which is different from the unix name and has a version number and a different extension.

Graham