Add modifyCmdFunc to Scanner and WithModifyCmdFunc option

[process0]

This PR adds support for modifying the exec.Cmd instance

[Ullaakut]

Hi @process0 !

Thanks for this PR. Could you explain what is your use case here? What changes do you need to apply to exec.Cmd?

I'm fine with the idea but I feel like the naming of WithModifyCmdFunc might be too long/complex. WDYT? Do you have suggestions for another name for it?

[process0]

Use cases for me are setting SysProcAttr, i.e. cmd.SysProcAttr.Pdeathsig = syscall.SIGKILL, which forces killing the child process when the parent process dies. There are likely other use cases here beyond other SysProcAttr serttings (env vars, dir, etc), so a modify function fits best imo.

I can change the name to WithModifyCmd if that is simpler.

[elivlo]

Hi @process0 @Ullaakut

For me it was quite confusing at the first time I looked at the function name. Nearly all current functions that begin with With... only change nmap cli arguments. Nevertheless I think we should rename the function to something like WithCustomSysProcAttrs. I have nothing against modifying the exec.Cmd but we need to make sure that nobody misunderstand what it does.

Additionally we should only change this single attribute SysProcAttrs to prevent users accidentally overriding arguments or other options.

[process0]

@elivlo There are WithFilterHost, WithFilterPort, WithBinaryPath, WithContext that do more than set arguments. I was under the assumption that the With prefix is used due to the functional arguments choice.

Limiting functionality to SysProcAttr is fine for me, though i wonder if there would be any need for setting env vars or a working directory, or even having access to the process itself. I do think a strong warning should be added, like in WithCustomArgs.

[elivlo]

@process0 You're right. I just wanted to point out that I became a little perplexed. But it is fine for me to name the function like this. My opinion is that we should cover the command as best we can when there is currently no need for it.

I am fine with functions that modify SysProcAttr, Env and Dir so feel free to add them :)
If someone later needs to access more than these args, we'll open a new PR.

[process0]

@elivlo Understood. I've updated the PR to support custom SysProcAttr only, as that is my need.

[elivlo]

Alright. I'll approve it.