I noticed that both my compiler (MinGW) and the Windows 8 SDK come with the same libraries, save the naming conventions (i.e. win32.lib on the Windows 8 SDK is libwin32.a in the MinGW libraries).
Do all compilers come with libraries such as these?
Are these libraries for multiple operating systems?
What is the difference (if any) between the libraries that come with the Windows 8 SDK and those that come with the compiler?
There are two kinds of libraries:
Import libraries:
These libraries only list where to find references to variables/functions/etc., but they don't contain the code itself.
"Normal" libraries (which contain object files that contain machine code):
These libraries contain object files, which contain the actual machine code.
The libraries that ship with an operating system are generally import libraries.
The actual code, after all, is in the operating system itself; the import libraries merely tell you how to use the code provided in the operating system.
Why is this necessary? Because there is no way for a program to "discover" the libraries available on an operating system while it is running, so the program has to know what will be available when it is compiled.
Those that come with a compiler are generally code libraries; they contain code that the compiler requires (which varies depending on your particular compiler) in order to comple your program.
However, there is no single "standard format" for a library; Microsoft uses COFF, but *nix tools use ELF.
So when Microsoft ships the import libraries for a system, it only ships them in COFF format, which is great for the Visual C++ compiler -- but not so useful for other compilers.
This causes compiler vendors such as MinGW to be forced to create their own import libraries for the operating systems which they intended to target -- the purpose of these libraries is exactly the same as as those provided by the operating system vendor (such as Microsoft), but their format is different.
That's why you see seemingly similar libraries provided in multiple ways.
MinGW comes with its own set of SDK libraries for the simple reason that MinGW is intended to provide a freely available compiler implementation that can produce Windows programs, but the Windows SDK is not freely available in the sense that the MinGW developers want/need. Because of the license on the Microsoft Windows SDK, it is not something that can simply be distributed with the MinGW compiler. So a significant part of the MinGW development effort is a set of headers and libraries that provide the Windows SDK functionality without infringing on Microsoft's licensing terms.
A fair bit of the MinGW WinSDK is public domain (maybe even most or all of it). All of it is freely distributable open source.
There may also be compatibility issues with MinGW using MS object files and libraries, but I was surprised to find that MinGW can often link to object files and libraries produced by MS compilers (though I'm not sure if there are any guarantees that it is supported).
A related issue is that MinGW relies heavily on the msvcrt.dll C runtime DLL provided by Microsoft. But that DLL is not distributed by MinGW - it's a part of every Windows OS, so MinGW relies on it simply being present as a base OS facility.
Related
This is a possible duplicate to this question but the answer is not solving my problem...
I want to use third party software delivered by c++ headers, libraries (.lib) and dlls for a project. Because it will run on a BeagleBone, I am writing this project for Linux. Is there any proper way to link dlls for Linux applications?
Highly unlikely to ever work:
Windows uses a different file-format for executable files (and DLL's are essentially executable files - same for shared libraries in Linux). This means that relocation information and symbol linkage is different.
Even if you manage to load and relocate the DLL, you most likely will need many other DLL's (such as the compiler runtime and system runtime [kernel32.dll for example]) to actually run the application. And of course, those dependent files need to have a correct interface to work on Linux (see #3)
There's nothing stopping a Windows DLL from making system calls directly in the shared library - these won't work in Linux.
Your best choices are:
Request Linux versions from the supplier of those libraries. Depending on what the functionality is, it may or may not be an easy task for the supplier to produce alternatives for different architectures.
Run the application inside the WINE (WINdows Emulator) package.
Run a Windows virtual machine, and run the application inside that.
Write your own replacement libraries, or find others already available out there.
Assuming the code compiled is actually portable (just using standard library stuff or whatever), could I use the same .lib for my projects across multiple platforms, or can they only run on the platform they were compiled on?
I'm porting my C++ project from Windows to Linux and I use a few 3rd party libraries including openAL, FreeType and FreeImage, and I would like to know if I have to get/recompile new library files.
The dynamic linkers on Windows and Linux work in completely different ways. On Linux the linker will expect elf format .so files. Windows however uses .lib and .dll files which are in a different, incompatible format.
Even if you were to find a way around this, the default calling conventions between the two OSes are different. C function calls place the arguments into different registers so it would be impossible to call functions in these lib files without having the compiler use a custom calling convention, however this would prevent any other code from calling your libraries.
The Wine Project has created a compatibility layer to allow Windows binaries to call into libraries compiled for Linux, however there is a significant performance and complexity penalty to such a layer.
In short, you would be best off in nearly every case to recompile the project for both OSes separately. The libraries you mention (afaik) are all available for Linux also so porting should be a breeze.
The entire purpose of languages like C++ is to provide a platform-agnostic source code abstraction that is portable, because the code created by compiling your C++ is not.
You shall have to rebuild it for your target platform.
.lib files contain platform-specific object code. You will need different ones for each platform.
You will have to recompile the other libraries on each platform you port to.
I want to create a light-weight portable application in C/C++ for Windows. I don't want to statically link everything because I want to keep the size of exe as small as possible. I also use Dependency Walker to track the DLL dependencies of my exe file.
My question is that what are the list of DLL dependencies that an application can have and stay portable across different versions of Windows? With this list at hand I can check the output from Dependency Walker with the list and choose which libraries to link statically and which to link dynamically. I prefer the list contain OSes from Windows XP higher, but having Windows 98 in mind is also interesting.
Create a basic Win32 application in something like Visual Studio and check the dependencies with Dependency Walker. Those are your base dependencies. All of the standard Win32 DLL files will be required, including user32.dll, kernel32.dll, and so on. (Although some of this varies, depending on what you want the application to do. In some cases, you can get away with only kernel32.dll, but you won't be able to show a window on the screen. Probably a fairly useless app.)
Keep in mind that the last version of Visual Studio that can compile applications that run on Windows 98 is Visual Studio 2005. Visual Studio 2008 can target a minimum of Windows 2000, while VS 2010 can target a minimum of Windows XP SP2. You'll need to either use an older version of the compiler, or edit the executable file's PE header manually to change the subsystem field.
If you're really into things like this (although it's honestly a waste of time) you should investigate Matt Pietrek's LIBCTINY, originally from an article published in MSDN Magazine back in January of 2001. This little library makes it theoretically possible to use the /NODEFAULTLIB compiler flag in order to avoid linking to the CRT.
If you are linking to standard Windows DLLs then there's no issue because the DLLs are already present on the target systems.
For other DLLs, if you have to distribute the DLL then your total executable code size will be greater than if you had used static linking. You only end up with smaller executable code size if you have multiple applications that use common libraries.
In other words, although dynamic linking sounds seductive, old fashioned static linking may be better for you.
Now, if you are concerned about linking to a C runtime then you could consider using mingw which can link against the Windows C runtime which is present on all systems.
I'm assuming you're using VC. Microsoft provides the list you're looking for in MSDN. See:
Redistributing Visual C++ Files
Determining Which DLLs to Redistribute
Note that the list changes based on VC's version (you can choose yours on the top of the pages). Also, on modern versions of Windows, it is advised to properly install the runtime dlls using VCRedist_*.exe - it would probably make your programs less portable than you wish, but it's a one-time installation of (sort of) system components, that no-one will ever have to uninstall.
I know that if I link my c++ program to a dynamic library (DLL) that was built with a different version of Visual Studio, it won't work because of the binary compatibility issue.
(I have experienced this with Boost library and VS 2005 and 2008)
But my question is: is this true for all versions of MSVS? Does this apply to static libraries(LIB) as well? Is this an issue with GCC & Linux as well? and finally how about linking in VS to a DLL built with MinGW?
By the way aside from cross-platform or cross-compiler, why can't two version of the same compiler(VS) be compatibile?
Hi. I know that if I link my c++ program to a dynamic library (DLL) that was built with a different version of Visual Studio, it won't work because of the binary compatibility issue. (I have experienced this with Boost library and VS 2005 and 2008)
I do not remember ever seeing MS changing the ABI, so technically different versions of the compiler will produce the same output (given the same flags (see below)).
Therefore I don't think this is not incompatibilities in Dev Studio but changes in Boost.
Different versions of boost are not backwards compatible (in binary, source they are backward compatible).
But my question is: is this true for all versions of MSVS?
I don't believe there is a problem. Now if you use different flags you can make the object files incompatible. This is why debug/release binaries are built into separate directories and linked against different versions of the standard run-time.
Does this apply to static libraries(LIB) as well?
You must link against the correct static library. But once the static library is in your code it is stuck there all resolved names will not be re-resolved at a later date.
Is this an issue with GCC & Linux as well?
Yes. GCC has broken backwards compatability in the ABI a couple of times (several on purpose (some by mistake)). This is not a real issue as on Linux code is usually distributed as source and you compile it on your platform and it will work.
and finally how about linking in VS to a DLL built with MinGW?
Sorry I don't know.
By the way aside from cross-platform or cross-compiler, why can't two version of the same compiler(VS) be compatibile?
Well fully optimized code objects may be compressed more thus alignment is different. Other compiler flags may affect the way code is generated that is incompatible with other binary objects (changing the way functions are called (all parameters on the stack or some parameters in registers)). Technically only objects compiled with exactly the same flags should be linked together (technically it is a bit looser than that as a lot of flags don't affect the binary compatibility).
Note some libraries are released with multiple versions of the same library that are compiled in different ways. You usually distinguish the library by the extension on the end. At my last job we used the following convention.
libASR.dll // A Sincgle threaded Relase version lib
libASD.dll // A Single threaded Debug version
libAMR.dll // A Multi threaded Release version
libAMD.dll // A Multi threaded Debug version
If properly built, DLLs should be programming-language and version neutral. You can link to DLLs built with VB, C, C++, etc.
You can use dependency walker to examine the exported functions in the dll.
To answer part of your question, GCC/Linux does not have this problem. At least, not as often. libstdc++ and glibc are the standard C++/C libraries on GNU systems, and the authors of those libraries go to efforts to avoid breaking compatibility. glibc is pretty much always backward compatible, but libstdc++ has broken ABI several times in the past and probably will again in the future.
It is very difficult to write stable ABIs in C++ compared to C, because the automatic features in C++ take away some of the control you need to maintain an ABI. Especially once you get into templates and inline functions, where some of the code gets embedded in your application rather than staying contained in the shared library. That means that the object's structure can't ever change without requiring a recompilation of the application.
In practice, it isn't a huge deal on Windows. It would be fantastic if Microsoft just made the MSI installer know how to grab Microsoft-provided DLLs from Windows Update when an app is installed that needs them, but simply adding the redistributable to an InnoSetup-generated installer works well enough.
I am creating a open-source C++ library using Visual Studio 2005. I would like to provide prebuilt libs along with the source code. Are these libs, built with VS2005, also going to work with newer versions of Visual Studio (esp VS Express Edition 2008)? Or do I need to provide separate libs per VS version?
Not normally, no. Libraries built with the VS tools are linked into the 'Microsoft C Runtime' (called MSVCRT followed by a version number) which provides C and C++ standard library functions, and if you attempt to run a program that requires two different versions of this runtime then errors will occur.
On top of this, different compiler versions churn out different compiled code and the code from one compiler version frequently isn't compatible with another apart from in the most trivial cases (and if they churned out the same code then there would be no point having different versions :))
If you are distributing static libraries, you may be able to distribute version-independent libraries, depending on exactly what you are doing. If you are only making calls to the OS, then you may be OK. C RTL functions, maybe. But if you use any C++ Standard Library functions, classes, or templates, then probably not.
If distributing DLLs, you will need separate libraries for each VS version. Sometimes you even need separate libraries for various service-pack levels. And as mentioned by VolkerK, users of your library will have to use compatible compiler and linker settings. And even if you do everything right, users may need to link with other libraries that are somehow incompatible with yours.
Due to these issues, instead of spending time trying to build all these libraries for your users, I'd spend the time making them as easy to build as possible, so that users can can build them on their own with minimal fuss.
Generally it's not possible to link against libraries built with different compilers, different versions of the same compiler, and even different settings of the same compiler version and get a working application. (Although it might work for specific subsets of the language and std library.) There is no standard binary interface for C++ - not even one for some common platform as there are in C.
To achieve that, you either need to wrap your library in a C API or you will have to ship a binary for every compiler, compiler version, and compiler setting you want to support.
If your library project is a static library, then, you'll have to supply a build for every Visual Studio version that you want your users to be in. In the example you gave, that equates to providing both a VS2005 and a VS2008 library.
If your library project is a dynamic library, then, you evade the problems somewhat, but, it means that users will need to make sure that they use the 'Microsoft C Runtime' that's compatible with your build environment. You can eliminate that criteria should you statically link the 'Microsoft C Runtime' into your dynamic library.