[stdlib] Adds functionality to spawn and manage processes from exec. file

[izo0x90]

• Adds vfork, execvp, kill system call utils. to Mojos cLib binds

• Adds utility struct. to allow spawning and managing child processes
  from an executable file

  • run factory method that creates process and returns "management"
    object
  • Instance methods to send signals to child process, INT, HUP, KILL

Ex.:

import os

fn main():
 p = os.Process.run("ls", List[String]("-lha"))
 p. interrupt()

[owenhilyard]

Good work so far, just a few fixes.

[owenhilyard]

https://docs.modular.com/mojo/stdlib/testing/testing/assert_raises/

[izo0x90]

The issue here from what I understand seems to be that I am rasing the exception in the forked child process when we don't find the executable file ... which try actually handles gracefully ... so this works fine:

try:
  _ = Process.run("file_does_not_exist", List[String]())
except e:
 print(e)

But for some reason (I assume related to the raise being in a different process) when try to validate the raise with:

with assert_raise():
  _ = Process.run("file_does_not_exist", List[String]())

It crashed the test suite with a no such process error. 🤔

[owenhilyard]

I think that raises in a fork pre-exec is unsound, you'll need to check before you fork.