How to convert a dynamic dll to static lib?

Question

I write a program helloworld.exe; it depends on a.dll. I don't have the source code of the a.dll, which is a dynamic dll. How can i change it to static library, so I can link it into helloworld.exe?

Nathalienathan

Answer 1

Sorry, but there's no direct way to do so. A DLL is a fully linked executable format file, where a static library is a collection of separate object files collected together. With a little bit of work, you can convert a static library to a DLL, but doing the reverse is non-trivial (to put it mildly).

Rojo

+1 for the only correct answer to the OP's original question. (My answer is just a workaround) – Microhenry

Not just that though, for dll's which arent executables but rather are as they sound: "a dynamically linked library" there are tools to take the .lib and .dll and convert it into a .a (static lib). I've even gotten away with (on a couple of occasions) simply renaming (yes, i have no idea why in the world this worked) and linking against the library and having it work (although, libraries it depended on were still dynamically loaded) – Modernistic

Answer 2

As Jerry said, you cannot do it directly. You can, however, package your program into something like a self extracting RAR file which includes the DLL as part of the single EXE, which automatically extracts the EXE and associated DLLs to a temp folder and starts the main program.

Microhenry

Answer 3

False, it is possible to do this. For example there is a tool called dlltolib which can do it.

Modernistic

In fact it quite clearly states in the description that it only creates an import library: "A .NET command-line app that produces an import library (.lib) from a target dynamic link library (.dll)." – Fogy

@Fogy why do you assume that that is the software that I was talking about and downvote? A quick google search would have showed you binary-soft.com/dll2lib/dll2lib.htm which states on the first line "Convert DLL file into its equivalent static library." – Modernistic

"a quick google search" lead me to the same Github project as Mike. The comment is also about the software mentioned by Mike. The downvote is because your answer is not very clear, especially as it didn't include a link under which to find the tool. But you changed that now, so I'll undownvote. – Fogy

In any case, the linked tool doesn't seem too useful as it is 32-bit only which is quite limiting nowadays. – Fogy

Also, the single user developer license is now $100 as of 09/08/2019 for binary-soft's dll2lib tool. – Betseybetsy

@КонстантинВан no. that tool actually converts the dll and there is no import library. – Modernistic

Answer 4

Perhaps what is being asked is how to create a .LIB file that will permit statically linking to the .DLL. Here are sample commands to achieve this:

set DUMPBIN="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx86\x86\dumpbin.exe"
set LIBX="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx86\x86\lib.exe"
set IN="\MyFolder\MyDll.dll"
set DEF="\MyFolder\MyDll.def"
set LIB="\MyFolder\MyDll.lib"

:: [1] run dumpbin
%DUMPBIN% /EXPORTS /NOLOGO /OUT:%DEF% %IN%

:: [2] edit .DEF file to look proper
:: [3] run LIB
%LIBX% /DEF:%DEF% /OUT:%LIB%

Athey

Answer 5

On windows, you can get the lib file to run your program if you have the corresponding def file. You can use the command prompt window of visual studio to get the lib file. The command line is as follows: lib /def:XXX.def /machine:x64 (or x86 to get 32bit lib)/out:XXX.lib. You need to make sure the def file and dll file are in the same folder and you have changed the directory to the folder.

Interfuse

Aaaaand, that’s an import library, which is a static loader for the DLL. – Nidifugous

Answer 6

To make the long story short - yes, technically it's possible. And yes, it's not that easy as it may seem (not just remove IMAGE_FILE_DLL from characteristics in COFF file).

For example, a DLL can optionally specify an entry-point function which is called automatically whenever a process or thread loads or unloads the DLL. It can be used to perform simple initialization and cleanup tasks. You cannot have something like this in LIB.

Any tool which claims creation of LIB out of DLL just generates a static binding with function declarations only linked to this DLL. You cannot delete DLL and use LIB only - this won't work.

Rechabite

Answer 7

I agree with Jerry, and if it is a deployment problem, you may use Nullsoft Scriptable Install System.

Condign

Answer 8

I am absolutely horrified at the lack of understanding in at least one of the (supposedly popular?) answers.

I have written a linker from the ground up, every line of code. I know everything there is to know about DLLs.

A DLL contains much much more information than a lib, and it does, guaranteed, contain absolutely everything that a lib contains. Every last item.

To convert a dll to a lib, you can follow the simple steps provided in the following well-written article.

https://adrianhenke.wordpress.com/2008/12/05/create-lib-file-from-dll/

(I am not adrian henke, just for information)

The process described allows you to create a lib directly from a dll, without requiring the def file. In fact, it actually allows you to create the def file from the dll, since the dll contains all of this information.

I can guarantee that it works perfectly, since I actually ran the exact same process on a dll and checked the result. The lib is correct, and will allow you to link.

Oh and by the way, it is utterly, completely, totally impossible to convert a lib to a dll.

Pyxis

Don't know what's with the downvotes, but your link is 404. adrianhenke.wordpress.com has been deleted by the user – Betseybetsy

This, like some other answers, seems like it will just create the import .lib, which will still require the .dll in runtime. A real static .lib would contain the code also. – Karisa

No need for the attitude! Here is an archived copied of the now-dead link. As jpa said, that link only says how to make an import library, not a full .lib containing the code. Like you, I don't obviously see what's missing from a .dll that would make it impossible to convert to a lib, except that arranging to call its DllMain would take a bit of effort, but I think you're being a bit over confident in your claims, especially since you haven't presented an actual solution. – Borrero

I wonder why so many negatives, I guess its because you didn't give something easy to CTRL-C + CTRL-V. Its entirely possible, I just disassemble a DLL, it gives me ".s" and then "compile" it again to a ".a". Easily done with standard tooling. – Ahlgren