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

[Paul Eggert]

On 11/14/2017 06:58 AM, Matthias Dahl wrote:
> If during an active
> call to wait_... all recursive calls happen to read exactly 2**32 (or
> whatever bit depths EMACS_UINT is) bytes back, then we will miss it
> completely and stall.

First, this means that the companion idea of subtracting the two 
counters to yield a byte count is also buggy because the byte count will 
be wrong for this call. This would be a bug that could happen whenever a 
successful recursive call occurs, which apparently is quite common. So 
if we stick with the current approach, we definitely should be dropping 
the requirement that Eli was thinking of, which says that a positive 
number returned by wait_reading_process_output indicates the number of 
bytes read for this call.

Second, I don't leaving a known bug in the code, even if the bug is 
unlikely. Too often, these extreme cases occur anyway (e.g., due to a 
network attack). I'd prefer a slightly-more-complicated solution where 
the bug cannot occur. It can't be that hard to fix.