On a .NET project, I have a couple of functions imported from native DLLs.
Currently to add the native DLLs to the project, they are copied to the root of the C# project and their property Build action is set to Copy to output directory.
Is there a better workflow for bundling native DLLs?
One option, which is particularly useful if you want single exe deployment, is to embed the DLL(s) into your manifest as Resources. This is a similar approach to what is often used to create "universal binaries" which can run on either X86 or X64 platforms from a single file. In that case you embed the 64-bit version inside the 32-bit version and extract it at runtime when needed. You can see that in action with the Sysinternals binaries.
In your case, you would embed a native binary within the managed executable, then either load it as an IO stream at runtime or extract it and reference it from the extracted path. In either case, you never have to worry about "losing" the resource because it's part of your project.
If you decide to go that route, the answer to how to do it has been provided several times over. Here's one such question:
Embedding unmanaged dll into a managed C# dll
Related
Is C++ source code required to build a .NET wrapper or static libraries *.lib files are just enough?
We plan to use SWIG.
Thanks.
w.r.t. your question asking specifically about static-libraries *.lib:
Is C++ source code required to build a .NET wrapper or static libraries *.lib files are just enough?
I doubt you actually intend to wrap a static-lib: Statically-linked libraries generally aren't redistributable nor portable (e.g. the authors of closed-source static libraries need to build them every time a new supported compiler comes out, e.g. you can't use a GCC lib with VisualC++ 2017, and an x64 VisualC++ 2017 lib won't be compatible with an x86 VisualC++ 2015 project) - and even if you loaded a *.lib into your process' memory and jumped into a known function address inside the lib's image, it would immediately break because the static library's code will have references to certain memory addresses (e.g. of string-constants) which aren't yet relocated - you'll get an segfault (or "Access violation" on Windows) crash if you're lucky (if not, it'll definitely corrupt your process' memory space before being detected).
P/Invoke in .NET Framework and .NET on Windows (i.e. using [DllImport]) only supports DLLs (Dynamically Linked Libraries), not statically-linked libraries.
You can also call into native code if the native code is available as a COM object, or can be accessed through platform features like OLE, WMIC, ADSI, etc (assuming your code's process is the same ISA as the native code you want to call, as it will still be loaded into your process, which is why you can't use 64-bit Office Excel to open databases where only a 32-bit OLE-DB or ODBC driver is available).
When a library is available as a *.lib then you need to make your own native host first - a simple C/C++ Win32 (PE) EXE or DLL that re-exports all of the useful functions from that *.lib will be sufficient - because then those exports can be imported by C#/.NET.
But in general:
If you are exporting COM objects to .NET then you don't need both the source-code files (*.c, *.cpp) or header files (*.h and *.hpp), only the IDL files or *.tlb (Type-lib) which the compiler will generate for you.
If your native code is also available through other platform features like OLE, ActiveX, COM Automation (IDispatch), ODBC, OLE-DB, ADSI, WMI, etc then you wouldn't be using [DllImport], and those platforms all either provide a standard interface (like ODBC and OLE-DB)
But generally speaking, no - you do not need the source-code (i.e. both *.c and *.h files) to create a .NET wrapper around native code exported from a native DLL and imported into .NET using [DllImport].
But you will need the header files (*.h) from a C/C++ project in addition to knowing the compiler settings (for finding out things like calling-convention, parameter marshaling info, etc) and a PE inspector (to verify the exported functions are at least present in the DLL you want to load).
Don't forget to ensure you provide both x86 and x64 native DLLs for all functionality if you're compiling your C#/.NET code for AnyCPU (tip: Using a 32bit or 64bit dll in C# DllImport )
I've read many questions and answers indicating that if I want to link my C# project against native libraries, I can't use AnyCPU platform target but must make separate 32- and 64-bit builds, each linked against the native DLL of the appropriate bitness.
This makes me wonder how the .NET Framework assemblies themselves are, or at least appear to be, built for AnyCPU. That is, when adding a reference to my GUI application, why don't I have to pick the 32-bit or 64-bit version of System.Windows.Forms? I thought this might just be some Visual Studio magic that would resolve to the appropriate GAC subdirectory (GAC_32 or GAC_64), but I searched for System.Windows.Forms.dll in the GAC and found it in:
C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll
Note the "GAC_MSIL". So how does this DLL manage to wrap a native 32-bit API yet remain linkable in a 64-bit application? And why can't I use a similar strategy to make a single C# DLL that links against a native 32-bit library yet remains runnable in 64-bit mode?
Option 1: In GAC you may register 2 versions of assembly one 32 and one 64 bit with exactly same names. Oracle DB Driver for .NET uses this strategy.
Option 2: With your assembly that will be AnyCPU deploy two versions of native DLL and choose proper DLL at runtime (SQLite works like that). As it turns out .NET Framework is intelligent enough to load proper version of native DLL via P/Invoke (Using a 32bit or 64bit dll in C# DllImport)
I had the same problem and ended up using Fody Costura
DLL Files will be shipped as embedded ressources and the lib takes care of the bitness.
You could find an example for SQLite here
The problem I have encountered was that your application needs to have access to the Windows Temp folder to create the assemblies from the ressource. If you dont need it, you could disable it using a config setting createtemporaryassemblies
I have a source file written in C++, performing some simulation. I would like to create a user interface for this in C#. How can I have both C++ and C# in a single Visual Studio solution?
What I did so far was I created a .NET C# project and solution, and then a native project as a DLL library. I have marked the C# project as "Depends on" the C++ dll. I have provided the necessary dllexport directives and imported using DllImport. Everything compiles fine, but when I execute the application, the dll is not found:
Unable to load DLL 'xxxx.dll': The specified module could not be found.
It is no surprise the DLL is not found, as the application is run from its output directory and the output directories are different for the C# and C++ projects. I do not want to write an explicit path as my import like `"..\..\Debug\xxxxx.dll".
Is there some common way how to structure a solution containing native a Dll and C# app so that the C# app can call the native Dll?
If you know that after deployment your C++ DLL will be in the same folder as your C# DLL (or executable), then on simple way to solve the problem is to use the PostBuild event (Project properties, Build events).
You can add a copy command that will put your C++ DLL into the C# output folder.
I found a very comfortable way, which might have some unexpected drawbacks, but I do not see any so far: I can enable CLR for the C++ DLL project, making it "mixed", even if it in fact does not contain any managed code, and then the project building it can be made a Reference in the C# .NET project.
To make the project mixed mode set Configuration Properties / General / Common Language Runtime Support to Common Language Runtime Support (/clr).
After this the build system copies the DLL into the application output folder automatically.
My application includes SQLite.dll. How I make a single-executable application in C# WPF without installing via ClickOnce Application or any installation file setup.
How can I bundle System.Data.SQLite into my project so I can produce a single-executable application with no tag-along DLLs?
for the System.Data.SQLite.dll assembly you can embed it as a resource and then use Reflection.Load from the resource before it's used by any of your code so it's ready to go. Or handle when AssemblyResolve is called, then you load it from the resource.
With the SQLite.Interop.dll thats the hard part because it actually makes all the calls to the SQLLite C++ libraries, and the method used by the System.Data.SQLite assembly makes calls to the correct DLL based on X86 or x64. You could possibly couple the 1st part of this with this article to create a memory based load of the 2nd DLL but you'd need to replicate the initial checks for x64/x86 and .NET dll performs and then load the correct one. (You'd just embed both and load the correct one)
I know I'm not the first person to ask this question on Stack Overflow and I'm sure I won't be the last. But, after spending hours researching how to do this and then physically trying to do it, I'm near ready to give up.
I have a .NET Framework 4, C#, WinForms application that builds to an executable. I rely on many many many dlls. The dlls fall into multiple categories.
Libraries I have written with no dependencies of their own
Libraries I have written with dependencies on other libraries I've written
Libraries I have written with dependencies on third party dlls
Third party stand alone dlls
Third party dlls with their own dependencies on other dlls
So after I compile my application I have a directory with an executable and approximately 15 dlls.
I want to pack all the dlls into a single executable so that I can simply distribute a single executable.
I know that IlMerge is the typically suggested application to use for this, but I'm curious if there is something easier to use that is more intuitive and works accross both WinForms and WPF.
The problem here is that ILMerge only can merge .Net assemblies. Your file lame_enc.dll isn't a .Net assembly but a standard Windows dll and therefore can't be loaded by ILMerge.
To get around this you could embed lame_enc.dll in your assembly and then extract it when needed in your application. Check out this article for more info on that.
http://weblogs.asp.net/ralfw/archive/2007/02/04/single-assembly-deployment-of-managed-and-unmanaged-code.aspx
In the end, I went an entirely different direction.
I decided to use the Costura Visual Studio Extensions located here.
These extensions use a combination of two methods
Jeffrey Richter's suggestion of using embedded resources as a method of merging assemblies
Einar Egilsson's suggestion using cecil to create module initializers
What's nice here is that you simply install the extensions into Visual Studio. After doing that, for any project where you want to pack your DLLs into a single executable, simply select the project, click Project on the menu bar, Costura, Configure, and then OK. It will ask you to reload the project - click yes. Now whenever you build the project it will create just a single executable (or DLL if you are doing it on a library). Couldn't be more easy.
ILMerge only combines pure (not mixed-mode) CLR assemblies. It works by extracting all of the CIL modules and then relinking them into a single new assembly. Assembly resources are also recombined.
ILMerge cannot merge native executable code. lame_enc.dll is a native DLL file and does not contain any CIL modules, that's why you can't combine it.
If you want to pack your application into a single executable a workaround is to include lame_enc.dll as an assembly resource, then save lame_enc.dll to disk in a temp folder perhaps, and add the folder it was saved in to your application's PATH, so your [DllImport] runtime linker will be able to access it.
To address your exact issue, verify that the file C:\Release\lame_enc.dll exists and that it is in fact a .NET file. ILMerge can only merge .NET assemblies.
Now if you are only worried about distribution of your application, you may consider creating an installer to install all of the binaries, and not worry about merging them using ILMerge.
Another alternative to using ILMerge is to embed the binaries in an assembly as desribed here.