how can I call a function from a dll in one step?

[2012ZGZYY]

I'm new to Dagu and find it well-suited for my current business needs. However, I have one remaining question: within Dagu's design framework, how can I implement calling a function from a dynamic library and utilizing its return value in a specific step? is there something like a dll executor?

[yottahmd]

@2012ZGZYY There is currently no DLL executor. I believe a DLL is a library, not an executable file, correct? If there is an EXE file on Windows, Dagu can certainly call it, but I'm not sure if that is the solution to your situation. Could you clarify the context a bit more so I can help?

[ghansham]

@2012ZGZYY for native DLLs, you can create a program and compile/link to generate an executable by specifying the library location with -L flag. And also set this library location in the LD_LIBRARY_PATH environment variable in the env section in dagu base.yaml. see following link for reference.

​​https://docs.dagu.cloud/configurations/reference#base-configuration

[2012ZGZYY]

@yottahmd I want to use Dagu to perform some business operations, during which I must call a function from a third-party provided DLL and pass parameters according to its interface. It seems I have to package it as an executable program to integrate it into the Dagu framework.

[yottahmd]

@2012ZGZYY Is the DLL meant to run on Windows? I'm not an expert, but I wonder if it's possible to handle this using PowerShell (pwsh). You can define a script inside the DAG if that helps:

step:
  - name: run_dll
    shell: pwsh
    script: |
      # Example: dotnet mylib.dll or rundll32 mylib.dll, EntryPoint
      Write-Host "Executing DLL..."

[ghansham]

You need not package dll but need to set its path in LD_LIBRARY_PATH.
If you can share a bit of code snippet, we can try to help you more.

[2012ZGZYY]

@ghansham For example, I now have a third-party library third.so (or third.dll), which provides a function called int third_func(double x, int y). I want to load this dynamic library in a step and execute the third_func() function. How should I do this?

[ghansham]

Give me sometime. I will get back to you. It is very much doable. Which language you are using btw?

[2012ZGZYY]

@ghansham c/c++

[ghansham]

Thanks. Very much doable. Give me a day

[JohnMatthiasWabwire]

@2012ZGZYY Link the library to your executable using the MSVC Compiler. In Visual Studio or VS Code, this can be achieved using the User Interface. In GCC and Clang the command would be:

clang main.c -l library.so -o program

The symbols will be exposed after the Dynamically Linked Library is linked to the Executable.