Ultimately, after exec(), a process only inherits a limited number of things from before exec(). Those things should be directly configurable from the parent process before Start(), using the Turing complete language of the parent process, in my proposal.
If you, say, want to open a socket that will be persisted after exec(), you can open the socket in the original process and pass it in the list of open FDs of the Process object returned by CreateProcess(). After StartProcess() is called, the newly created process should see this open FD as one of its already opened FDs, just like if you had opened it between fork() and exec().
What am I missing? What could you do after fork() in the child that would persist after exec() but not be easily configurable from the outside in principle?
In practice, I can of course imagine that the kernel has all sorts of assumptions about who gets to access certain internal process data structures that it would be very hard to modify today.
