Compiling a library (redland) in Cygwin using gcc and using the output in Visual Studio (c++)

Question

I'm currently trying to compile redland (librdf http://librdf.org/) under Windows. According to their website it should build under Windows. As i don't want to spend my time fixing the .sln I thought about compiling librdf (and the necessary projects) in cygwin and then use the library in visual studio.

So my question is: Is it possible to use librarys compile in cygwin in windows application? And if so how?

As I am a windows developer I don't know if there is any difference from the created .a files to .dlls. I already read up to the topic and it will be necessary to include the cygwin1.dll in the project but this won't be a problem.

Or does anyone have any better idea how I can get redland compiled as windows dlls? I thought about using mingw but until now I didn't manage to compile it.

Any help will be appreciated.

Thanks

Update:

Thanks to the help of Yaakov (And his pretty cool cygwin ports) I meanwhile managed to compile raptor (which is a prerequisite for librdf). All I had to do was include another argument for configure: --with-xml2-config=/usr/x86_64-w64-mingw32/sys-root/mingw/bin/xml2-config

Now I'm trying to compile rasqal which is another requesite and is also depending on raptor2. For it to work I had to export PKG_CONFIG_PATH="/usr/x86_64-w64-mingw32/sys-root/mingw/lib/pkgconfig/" for pkg-config to find the correct raptor installation.

So configure for rasqal worked but when I try to make it I get the following error:

Making all in src
make[1]: Entering directory `/home/Stefan/workspace/rasqal/src'
make  all-am
make[2]: Entering directory `/home/Stefan/workspace/rasqal/src'
/bin/sh ../libtool  --tag=CC    --mode=compile x86_64-w64-mingw32-gcc -DHAVE_CONFIG_H  -I.   -DRASQAL_INTERNAL=1   -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/raptor2       -g -O2   -DMTWIST_CONFIG -I../libmtwist -g -O2 -MT rasqal_algebra.lo -MD -MP -MF .deps/rasqal_algebra.Tpo -c -o rasqal_algebra.lo rasqal_algebra.c
libtool: compile:  x86_64-w64-mingw32-gcc -DHAVE_CONFIG_H -I. -DRASQAL_INTERNAL=1 -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/raptor2 -g -O2 -DMTWIST_CONFIG -I../libmtwist -g -O2 -MT rasqal_algebra.lo -MD -MP -MF .deps/rasqal_algebra.Tpo -c rasqal_algebra.c  -DDLL_EXPORT -DPIC -o .libs/rasqal_algebra.o
In file included from /usr/x86_64-w64-mingw32/sys-root/mingw/include/sys/time.h:10:0,
                 from rasqal.h:116,
                 from rasqal_algebra.c:39:
/usr/x86_64-w64-mingw32/sys-root/mingw/include/time.h:260:8: error: redefinition of 'struct timezone'
./win32_rasqal_config.h:62:8: note: originally defined here
Makefile:1045: recipe for target `rasqal_algebra.lo' failed
make[2]: *** [rasqal_algebra.lo] Error 1
make[2]: Leaving directory `/home/Stefan/workspace/rasqal/src'
Makefile:720: recipe for target `all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/Stefan/workspace/rasqal/src'
Makefile:484: recipe for target `all-recursive' failed
make: *** [all-recursive] Error 1

Which I can't get my head around I'm not really into cross compiling. Can someone point me into the right direction?

Answer 1

The MSVC and Cygwin runtimes are incompatible, so you cannot use a Cygwin-compiled binary within VS. However, you can use Cygwin to cross-compile a library for Windows, which for C libraries, should be compatible with VS. (C++ is very compiler-specific, particularly with symbol mangling, but IIRC these libraries are all in C.)

To get started, you need to install the mingw64-i686-gcc-core, mingw64-i686-headers, and mingw64-i686-runtime packages, plus all dependencies, via Cygwin's setup.exe installer. Then, beginning with the "bottom" of the dependency chain, build each library with e.g.:

./configure --prefix=/usr/i686-w64-mingw32/sys-root/mingw --host=i686-w64-mingw32

Then run make followed by make install. For Windows x64, substitute all the i686s above with x86_64.

Keep in mind that librdf has a lot of (sub)dependencies, but I don't remember now how many are optional. Some, but not all, of these are available from the Cygwin Ports repository; those should at least help you get started.

Answer 2

I recommend you to build raptor2 using Visual Studio. I did this successfully for Visual Studio 2017 x64 this way:

Install libxml2 and libxslt

Open PowerShell:

git clone https://github.com/Microsoft/vcpkg
cd vcpkg
.\bootstrap-vcpkg.bat
.\vcpkg install libxml2:x64-windows
.\vcpkg install libxslt:x64-windows

Build raptor2

Download raptor: http://librdf.org/raptor/ (http://download.librdf.org/source/raptor2-2.0.15.tar.gz)

Change raptor2-2.015/CMakeLists.txt, line 258:

ADD_DEFINITIONS(-DHAVE_CONFIG_H)
->
ADD_DEFINITIONS(-DHAVE_CONFIG_H -DYY_NO_UNISTD_H)

change raptor2-2.015/src/CMakeLists.txt, line 118:

ADD_LIBRARY(raptor2
    raptor_avltree.c
    ...
->
ADD_LIBRARY(raptor2
    raptor_escaped.c
    sort_r.c
    raptor_ntriples.c
    raptor_avltree.c
    ...

open cmake: set LIBXML2_INCLUDE_DIR to: path/to/vcpkg/installed/x64-windows/include set LIBXML2_LIBRARIES to: path/to/vcpkg/installed/x64-windows/lib/libxml2.lib

set LIBXSLT_INCLUDE_DIR to: path/to/vcpkg/installed/x64-windows/include
set LIBXSLT_LIBRARIES to: path/to/vcpkg/installed/x64-windows/lib/libxlst.lib
set LIBXSLT_EXSLT_LIBRARY to: path/to/vcpkg/installed/x64-windows/lib/libexlst.lib

Deployment:

Set CMAKE_INSTALL_PREFIX to your deplyoment path e.g. C:\thirdparty\vs2017\x64\raptor2

Execute the INSTALL target in Visual Studio.

If you do not like to execute this steps manually you can just download a prebuild version here.