I'm building a dll to use PocoNetSSL to get some data via an HTTPS endpoint. I need to call that dll via C# in Unity which runs an old version of Mono.
I am using mingw-w64 shell to build my dll. There is a package of the Poco libraries available via the package manager pacman and I am using that.
$ pacman -Qs 'poco'
local/mingw-w64-x86_64-poco 1.6.0-2
POrtable COmponents C++ Libraries (mingw-w64)
I can build an executable and it builds fine & runs fine hitting the https endpoint. I have openssl installed somewhere or it may have come with mingw.
My problem is that I cannot open the dll with LoadLibrary. I get a null pointer and I'm guessing it's a dependency problem. Here's my build commands and a snapshot of dependency walker. Is there anything I am missing here. I think I should be able to do this but maybe not?
sburke#sburke-pc MINGW64 ~/sandbox/hitaws
$ scons
scons: Reading SConscript files ...
msys
scons: done reading SConscript files.
scons: Building targets ...
g++ -o gdoaws.os -c -Wall -DPOCO_WIN32_UTF8 -I/mingw64/include gdoaws.cpp
g++ -o gdoaws.dll -Wl,-no-undefined -shared -Wl,--out-implib=libgdoaws.dll.a -Wl,--export-all-symbols -Wl,--enable-auto-import -Wl,--whole-archive gdoaws.os -Wl,--no-whole-archive -L/mingw64/lib -lPocoNetSSL.dll -lPocoNet.dll -lPocoUtil.dll -lPocoFoundation.dll
scons: done building targets.
Assuming your loading a dynamic library code is correct your app is very likely trying to load different version of openssl dlls than Poco was built against.
In msys2 you can check a dynamic library dependencies by:
ldd /mingw64/bin/libPocoNetSSL.dll
which depends on:
LIBEAY32.dll => /mingw64/bin/LIBEAY32.dll
SSLEAY32.dll => /mingw64/bin/SSLEAY32.dll
Is this what you see in dependency walker?
The best workround for this problem is to copy above dlls to the folder where your executable is and always distribute them with your software.
Related
I need to build a shared library on windows (dll) in 32bit and 64bit.
The build is controlled with cmake, the compiler is mingw64
This is my cmake file:
#64Bit Build (works fine)
ADD_LIBRARY(mylib SHARED mylib.c)
SET_TARGET_PROPERTIES(mylib PROPERTIES PREFIX "")
target_link_options(mylib PUBLIC -Wl,--exclude-all-symbols -s -Wl,--gc-sections -Wl,-Map=output.map )
#32Bit Build (linking issues)
ADD_LIBRARY(mylib32 SHARED mylib.c)
SET_TARGET_PROPERTIES(mylib32 PROPERTIES PREFIX "" COMPILE_FLAGS "-m32" LINK_FLAGS "-m32")
target_link_options(mylib32 PUBLIC --verbose -Wl,--exclude-all-symbols -s -Wl,--gc-sections -Wl,-Map=output.map)
I get a lot of complaints during linking due to 32Bit incomatibility of many linked libraries.
I can reduce the amount of complaints, when I am specifically add 32Bit libraries to the search path like this:
target_link_options(mylib32 PUBLIC --verbose -Wl,--exclude-all-symbols -s -Wl,--gc-sections -Wl,-Map=output.map -L/msys64/mingw32/lib -L/msys64/mingw32/i686-w64-mingw32/lib -L/msys64/mingw32/lib/gcc/i686-w64-mingw32/10.3.0)
But there are still some incompatibilities left: like the dllcrt.a which is always linked from the 64Bit mingw path,
which seems kind of hard coded into gcc/ld.
I even tried to use an empty spec fiel, which gave nor results:
target_link_options(mylib32 PUBLIC -specs=myspe --verbose -Wl,--exclude-all-symbols -s -Wl,--gc-sections -Wl,-Map=output.map -L/msys64/mingw32/lib -L/msys64/mingw32/i686-w64-mingw32/lib -L/msys64/mingw32/lib/gcc/i686-w64-mingw32/10.3.0)
Typical error message I get:
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: i386:x86-64 architecture of input file `C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/lib/dllcrt2.o' is incompatible with i386 output
I just figured out a solution for my case:
the crt* stuff is startup code, which is not needed in the case of libraries.
So I added the -nostartfiles flag, and my library links fine.
I guess in case off an application one can probably link the 32bit startfiles manualy as a workaround.
SET_TARGET_PROPERTIES(amprio_seednkey32 PROPERTIES PREFIX "" COMPILE_FLAGS "-m32 -nostartfiles" LINK_FLAGS "-m32 -nostartfiles")
Anyhow, this all feels like a dirty Workaround, I still wonder what is the best way to link 32Bit and 64Bit using mingw-w64.
I'm trying to use the ncurses library on AIX 7.1 to make use of panels which aren't included in the curses library that is standard on AIX. I have the ncurses library installed. The compile,link, and execute work fine with:
xlc ngoodbye.c -lncurses
The actual ncurses library is libncurses.a, which I understand is a static library. However, when I move the executable to another AIX host and execute I get:
Dependent module libncurses.a(libncurses.so.5) could not be loaded. Could not load module libncurses.a(libncurses.so.5). System error: No such file or directory.
How can I link the ncurses library so that the program will execute on other hosts where the ncurses library isn't installed? Note I'm using xlc on AIX, not gcc.
I've tried -bstatic but get link errors at compile time. Note that I'm not a developer so my experience in this area is limited. Thanks.
Both static and shared libraries in AIX are built as position independent (PIC). So even a "shared" library can be statically bound to an executable. You were on the right track with -bstatic, you just need to switch back to dynamic binding for the rest of the libraries you're linking to.
So try this for your final link:
xlc -o myexe myexe.o <other objects as needed> -bstatic -lncurses -bdynamic -lm <and other other libraries as needed>
I do this all the time to make sure that my production environment matches my development one.
Normally ".a" does mean a static library. However, in adapting the initial report (in 2008) describing the AIX 5 shared library configuration there was some miscommunication and ".a" was used for both static and shared libraries. That was finally corrected last year (see changelog).
AIX 4, by the way, used a much more complicated scheme, so shared libraries for ncurses were first implemented on AIX 5.
Packagers prefer shared libraries. So what you have is a shared library named libncurses.a (legal, but not conventional). This is not created with the archiver ar, but using the loader ld. To see that they are different, you can try
ar tv libncurses.a
(with the appropriate directory). Likely ar will say something like
ar: 0707-108 File libncurses.a is not an archive file.
while file may give a more informative message:
libncurses.a: executable (RISC System/6000) or object module not stripped
You can however build ncurses from source. In that case (no matter what version), the default builds static libraries. You need not install those into the system area, but can configure ncurses using the --prefix option to install into a different directory.
As suggested in another answer, there is a workaround using the -bdynamic and -bstatic options of AIX's ld (loader), e.g., changing
xlc -o foo foo.c -lncurses
to
xlc -o foo foo.c -bstatic -lncurses -ldynamic
However, this is partly dependent upon the loader's search path and the name of the archive. If the archive is named libncurses.a, the command works as given. If it is named libncurses.so (as in current sources), then this command is needed to link against the shared library:
xlc -o foo foo.c -brtl -lncurses
But this command (which one might suppose to provide the static linkage using the libncurses.so file) does not succeed:
xlc -o foo foo.c -brtl -bstatic -lncurses -bdynamic
I've been trying to create a CMake-based build-system for a project that is supposed to use SDL2_image library. I do not want to force user to install any libraries to the system to be able to build the project, so I took advantage of the CMake's ability to download and build dependencies (freetype, SDL2 and SDL2_image) from source code as External Projects.
Everything is fine with freetype and SDL2 (which both include CMakeLists.txt files out of the box), but I've ran out of ideas how to make it work for SDL2_image. CMake's external projects support custom configuration and building settings which I used in different variants with no success.
The CMake file itself can be found here, but the problematic part is this:
# SDL_image library
ExternalProject_Add(sdl2_image_project
URL https://www.libsdl.org/projects/SDL_image/release/SDL2_image-2.0.0.tar.gz
DEPENDS sdl2_project
PREFIX ${LIBS_DIR}/SDL2_image
CONFIGURE_COMMAND LDFLAGS=-L${SDL2_BIN} CFLAGS=-I${SDL2_SRC}/include SDL2_CONFIG=${SDL2_BIN}/sdl2-config <SOURCE_DIR>/configure --prefix=<INSTALL_DIR> --enable-shared=no
BUILD_COMMAND make
INSTALL_COMMAND ""
)
An error occurs while building sdl2_image_project. Some trivial research discovered that the error is generated by the undefined references to parts of libdl. Here is a tiny part of the hole error:
libtool: link: gcc -I/home/snikitin/_src/img_glypher/libs/SDL2/src/sdl2_project/include -I/usr/local/include/SDL2 -D_REENTRANT -o showimage showimage.o -Wl,-rpath -Wl,/usr/local/lib -pthread -L/home/snikitin/_src/img_glypher/libs/SDL2/src/sdl2_project-build ./.libs/libSDL2_image.a -L/usr/local/lib -lSDL2 -pthread
/home/snikitin/_src/img_glypher/libs/SDL2/src/sdl2_project-build/libSDL2.a(SDL_dynapi.c.o): In function `get_sdlapi_entry':
/home/snikitin/_src/img_glypher/libs/SDL2/src/sdl2_project/src/dynapi/SDL_dynapi.c:227: undefined reference to `dlopen'
I think the problem takes place due to the fact that linker tries to create a shared version of SDL2_image library while linking it to a static libSDL2.a. The thing is - if this is right - SDL2 building step creates both static and shared versions of itself so one would assume that linker would use libSDL2-2.0.so instead (I do not actually need a shared library - just the static one, but I do not know how to prevent the build system from trying to create it apart from passing --enable-shared=no to SDL2_image configure script, which does not help in this case).
After a lot of googling I've discovered that the possible source of the problem is that sdl2-config (which is called to get some flags for compiler during SDL_image building) may be called with wrong arguments and produces wrong cflags which confuse everything else. But I'm not sure that is the case and also I do not know how to influence sdl2_config call from CMake (configure --help does not seem to unveil any useful options for this situation).
I am running Ubuntu 14.04 x64 if it matters in any way. Would appreciate any advice!
Looks like you need to link some libraries like m and dl. It can be fixed by providing
custom sdl2-config file. Copy sdl2-config from extracted archive and substitute --libs result:
--libs)
echo -L${exec_prefix}/lib -Wl,-rpath,${libdir} -pthread -lSDL2 -lm -ldl
;;
Note that order is important (that's why just modifying LIBS not works for me).
Now this file can be used in your ExternalProject_Add command instead of SDL2_CONFIG=${SDL2_BIN}/sdl2-config:
...
... CFLAGS=-I${SDL2_SRC}/include SDL2_CONFIG=${CMAKE_CURRENT_LIST_DIR}/sdl2-config <SOURCE_DIR>/configure
...
I've tried official howto but failed. I got error:
"The procedure entry point InterlockedCompareExchange#12 could not be located in the dynamic link library libstdc++-6.dll"
The problem was due the old gcc compiler, bundled with DevKit from rubyinstaller.org (4.5 vs 4.8 on my PC). Use MSYS instead. Assume we have zeromq source inside D:\libs\zeromq, then the procedure is:
Download GUI MinGW installer.
Install base and MSYS (if you already have working gcc compiler you probably only need MSYS).
Launch MSYS environment by executing C:\MinGW\msys\1.0\msys.bat.
Follow Using MSYS with MinGW section:
mount c:/mingw /mingw
cd /d/libs/zeromq
./configure --prefix=/mingw
make
Copy /d/libs/zeromq/src/.libs/libzmq.dll to your desired place.
In fact I needed to use ZeroMQ with C++, so I downloaded zmq.hpp, moved it to include directory, and compiled hwserver.cpp to test it:
C:\MinGW\bin\g++.exe -o hwserver hwserver.cpp -L. -lzmq -ID:\libs\zeromq\include
It worked, but when I launch it I got:
Assertion failed!
Program: D:\tmp\zmq\hwserver.exe
File: D:\libs\zeromq\include/zmq.hpp, Line 280
Expression: rc == 0
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
I've managed to get rid of this failure by commenting lines 279, 280. Similar issue
After installing Mono, I need to setup environment variable as follows.
PKG_CONFIG_PATH="/Library/Frameworks/Mono.framework/Versions/2.8/
What's the purpose of pkgconfig files (or .pc files) that are installed in /Library/Frameworks/Mono.framework/Versions/2.8/lib/pkgconfig?
There are two main kind of uses:
providing compiler and linking flags for compiling the mono runtime inside your own application (embedding): mono-2.pc is an example. These are generally used as follows:
gcc myprogram.c `pkg-config --cflags --libs mono-2`
providing default lists of managed assemblies for particular subsystems: dotnet.pc provides the assemblies that are normally loaded by default by csc on Windows, gtk-sharp-2.0.pc lists the assemblies of the Gtk+ binding, etc. These are generally used as follows:
gmcs -pkg:gtk-sharp-2.0 myprogram.cs
If you look inside the files, they have a Description field that should explain what each file is used for.