[PATCH v2 0/3] posix: Execute file function fixes

[Paul Eggert]

Adhemerval Zanella wrote:
> Execlp can not because since it can be used in following vfork.

I guess that's OK. Please document that execlp has the same limitations that 
execl and execle do, in this area.


> the only missing point is total mmap area of posix_spawn which sets a hard limit for old shell argument handling and posix_spawnp. We can either document these limit or add a logic to calculate total argument list and mmap an area to accommodate all of it.

It's better to not impose hard limits of our own.

One other hard limit is that argc cannot exceed INT_MAX; posix_spawn* should 
ensure that the argc it computes doesn't go past that.