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Load DLL from block of memory - how to use?

I found a block with functions that allow loading DLLs directly from memory, but I don't know how to use it.

This is the unit: http://www.delphibasics.info/home/delphibasicssnippets/udllfrommem-loadadllfrommemory

I know that the function:

function memLoadLibrary(FileBase : Pointer) : Pointer;

But I don't know how I can use it, what is the FileBase I need to define, etc.

Can anyone help me?

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2 answers


You just need to put the DLL in memory and pass memLoadLibrary a pointer to the location of the DLL in memory.

For example, from a resource:



hRes := LoadResource(HInstance, 'MYRESNAME');
if hres=0 then
  RaiseLastOSError;
BaseAddress := LockResource(hRes);
if BaseAddress=nil then
  RaiseLastOSError;
lib := memLoadLibrary(BaseAddress);
.....
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Let's say you have both a procedure and a function in your DLL that you want to load from memory in order to use them:

    ** GLOBAL ** (both, exe -> dll)
    type
      TTest1Proc = record
        Proc: procedure; StdCall;
        hLib: THandle;
      end;

      TTest2Func = record
        Func: function: Boolean; StdCall;
        hLib: THandle;
      end;

    ** DLL **

    procedure Test1; StdCall;
    begin
      ShowMessage('Test proc');
    end;

    function Test2: Boolean; StdCall;
    begin
      Result := True;
    end;

    exports
      Test1.
      Test2;

This is how you can load the dll and use both methods (procedures and functions) in the .EXE project:



    procedure Test1;
    var
      Test1Proc: TTest1Proc;
    begin
      with Test1Proc do
      begin
        hLib := LoadLibrary(PChar('DLL_PATH.dll'));
        if hLib <> 0 then
        begin
          @Proc := GetProcAddress(hLib, 'Test1');
          if Assigned(Proc) then
          try
            Proc; //will execute dll procedure Test1
          finally
            FreeLibrary(hLib);
          end
          else
          ShowMessage('Procedure not found on DLL');
        end
        else
        ShowMessage('DLL not found.');
      end;
    end;

And as a function:

    function Test2: Boolean;
    var
      Test2Func: TTest2Func;
    begin
      Result := False;
      with Test2Func do
      begin
        hLib := LoadLibrary(PChar('DLL_PATH.dll'));
        if hLib <> 0 then
        begin
          @Func := GetProcAddress(hLib, 'Test2');
          if Assigned(Func) then
          try
            Result := Func; //will execute the function Test2
          finally
            FreeLibrary(hLib);
          end
          else
          ShowMessage('Function not found on DLL.');
        end
        else
        ShowMessage('DLL not found.');
      end;
    end;
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