Best way to call functions exported by a dll?

[quandary]

Question:

I have a dll that exports some functions.

Like:
EXPORT char* WINAPI WebServicesGetPluginName()
EXPORT bool WINAPI WebServicesInit(char *szAppTitle, char* szPath, IDispatch* pCALLBACK)
EXPORT int WINAPI WebServicesGetVersion(char *version);

Now to have access to them in an executable that loads the dll via LoadLibrary, I do the following:
1. typedef the function pointer, e.g.: typedef int (WINAPI *WebServicesGetVersion_t)(char *);
2. create a function pointer: WebServicesGetVersion_t WebServicesGetVersion ;
3. get the function address via getproc, e.g. //WebServicesGetVersion = (WebServicesGetVersion_t) GetProcAddress(hModWebServices, "WebServicesGetVersion");


Now if the dll exports some houndred of functions, this is quite much typing work...
Is there a better way (getting the function type, creating a variable)?

[_Superman_]

Do implicit linking using the LIB file that is generated along with the DLL.
In this method give the LIB file as a reference to the linker generating the EXE.

Now you can directly call the exported functions without doing a GetProcAddress on it.

[Paul McKenzie]

Now if the dll exports some houndred of functions, this is quite much typing work...

Declare the functions that you actually use in the program. You don't need to create function pointers for every single exported function.

Regards,

Paul McKenzie

[Igor Vartanov]

Now if the dll exports some houndred of functions, this is quite much typing work...
Is there a better way (getting the function type, creating a variable)?

You know, this is not the most complex problem a programmer typically faces to...

[quandary]

Declare the functions that you actually use in the program. You don't need to create function pointers for every single exported function.

Regards,

Paul McKenzie

Unfortunately, I need most of them!

[quandary]

Do implicit linking using the LIB file that is generated along with the DLL.
In this method give the LIB file as a reference to the linker generating the EXE.

Now you can directly call the exported functions without doing a GetProcAddress on it.

Can I generate a LIB file somehow, if I only have the dll?

[0xC0000005]

If I faced the same task I would write a utility program that reads each line of exported function declarations, parses the information and writes to a text file typedefs, calls to GetProcAddress(), etc. in C++ source code format. I could probably do that in a fraction of the time that it would take to enter all the information manually - and it would not make typing mistakes.

[quandary]

If I faced the same task I would write a utility program that reads each line of exported function declarations, parses the information and writes to a text file typedefs, calls to GetProcAddress(), etc. in C++ source code format. I could probably do that in a fraction of the time that it would take to enter all the information manually - and it would not make typing mistakes.

Good idea, just at the moment, I'm playing with the Microsoft Interface Definition Language Compiler.

[GCDEF]

Can I generate a LIB file somehow, if I only have the dll?

Whoever created the DLL should be able to supply a LIB file. That would be the easiest way to go.

[quandary]

Whoever created the DLL should be able to supply a LIB file. That would be the easiest way to go.

The provider company has filed bankruptcy already some time ago...

[Codeplug]

http://support.microsoft.com/kb/131313

gg

[quandary]

http://support.microsoft.com/kb/131313

gg

Typical Microsoft documentation.
Long, imprecise and useless.

Create .lib file from .dll

search c:\program files\Microsoft Visual Studio for dumpbin.exe

Copy it to your project path
Now run the dumpbin command to get a list of all exported functions of your dll:

dumpbin /exports C:\msys\1.0\home\admin\myproject\mylib.dll


This will print quite a bit of text to the console. However we are only interested in the functions:


 ordinal hint RVA      name

          4    0 00001113 MyDllClose
         19    1 0000112C MyDllConfigureNonModal
          2    2 00001064 MyDllDetect
         20    3 00001122 MyDllDisable
         18    4 00001014 MyDllEnable
          7    5 00001078 MyDllGetChannel
          6    6 000010A0 MyDllGetChannels
         11    7 00001073 MyDllGetErrorText
         14    8 000010EB MyDllGetFrameCount
         13    9 0000104B MyDllGetFrameRate
         10    A 000010AF MyDllGetMaxChannels
         16    B 000010B9 MyDllGetPluginName
          1    C 000010D7 MyDllGetVersion
         17    D 00001069 MyDllInit
          3    E 00001096 MyDllInitializeMode
          8    F 00001055 MyDllSetChannel
          5   10 0000100A MyDllSetChannels
         12   11 0000108C MyDllSetFrameRate
         15   12 0000103C MyDllSetFramesInAverage
          9   13 0000111D MyDllSetMaxChannels
         21   14 0000110E MyDllTerm
...etc

Now copy all those function names (only the names!) and paste them into a new textfile. 
Name the nextfile yourlib.def and put the line EXPORTS at its top. 

My mylib.def file looks like this:

LIBRARY MyDll

EXPORTS
	MyDllGetVersion
	MyDllDetect
	MyDllInitializeMode
	MyDllClose	
	MyDllSetChannels
	MyDllGetChannels
	MyDllGetChannel	
	MyDllSetChannel	
	MyDllSetMaxChannels
	MyDllGetMaxChannels
	MyDllGetErrorText
	MyDllSetFrameRate
	MyDllGetFrameRate
	MyDllGetFrameCount
	MyDllSetFramesInAverage
	MyDllGetPluginName
	MyDllInit	  
	MyDllEnable	  
	MyDllConfigureNonModal
	MyDllDisable	      
	MyDllTerm




Now from that definition file, we can finally create the .lib file. 

search c:\program files\Microsoft Visual Studio for lib.exe
copy it to your project path

run this command in the Command Prompt:
lib /def:C:\msys\1.0\home\admin\myproject\mylib.def /OUT:C:\msys\1.0\home\admin\myproject\mylib.lib


That’s it, happy coding

[Paul McKenzie]

If I faced the same task I would write a utility program

I did a similar thing, only I parsed the header file that came with the library. I would parse the header file and create the entire source code to the function pointers, the call to LoadLibrary() and each call to GetProcAddress().

Regards,

Paul McKenzie

[Codeplug]

>> Copy it to your project path
That's not exactly how you use the command line tools. You should have a "Visual Studio 200x Command Prompt" on your start menu. This sets up the environment variables you need (including PATH) in order to use VS tools on the command line.

gg

[GCDEF]

The provider company has filed bankruptcy already some time ago...

I'd probably look for another source of whatever functionality the DLL provides in that case.