bug#12980: 24.3.50; Zombie process left after call-process

[Paul Eggert <eggert@cs.ucla.edu>]

On 11/29/12 10:04, Eli Zaretskii wrote:

>> +      /* CHILD must be a child process that has not been reaped, and
>> +         STATUS and OPTIONS must be valid.  */
>> +      eassert (errno == EINTR);
> 
> Are we sure that either CHILD will have exited at this point, or else
> OPTIONS won't include WNOHANG?

It's unlikely that CHILD will have exited at this point.  That can
happen only if CHILD exited after the immediately-preceding waitpid
call and before this eassert.  In such a case, CHILD has exited but
has not been reaped.

It's common for OPTIONS to not include WNOHANG (wait_for_termination
does this), and when that happens it's almost always the case that
CHILD has not exited at this point.

> Can this function be ever called if
> neither of these conditions is true?

By "this function" I assume you mean get_child_status.  Yes, it's
quite common.  For example, Fcall_process invokes wait_for_termination,
and it's common for wait_for_termination to invoke get_child_status
before CHILD has exited, and without WNOHANG in OPTIONS.