Re: wait_reading_process_ouput hangs in certain cases (w/ patches)

[Paul Eggert]

Eli Zaretskii wrote:
> > Cc: address@hidden
> > From: Paul Eggert <address@hidden>
> > Date: Sat, 18 Nov 2017 23:07:37 -0800
> >
> > * Fix the bug with carryover that I mentioned in
> > <https://lists.gnu.org/r/emacs-devel/2017-11/msg00283.html>.
>
> Not sure what bug is that, and how would you propose to fix it.

The bug is that with the patch as written, wait_reading_process_output might 
return a positive value even though it didn't read anything (nor did any timers 
or filters).

> >     got_some_output = min (INT_MAX, (wait_proc->infd_num_bytes_read
> >                                      - initial_wait_proc_num_bytes_read));
> If we are using uintmax_t, why limit this by INT_MAX?

Because got_some_output is an int. And it's an int because the function's 
callers (either directly or indirectly) expect int. And the callers don't care 
what the value is, so long as it's positive (this is documented in the comments 
describing wait_reading_process_output etc.).

We could change got_some_output and all its users to employ the type intmax_t 
rather than int, but even then we'd need to limit it to INTMAX_MAX, so why 
bother? It wouldn't fix any bugs.