On 8/14/2022 11:44 AM, Jim Porter wrote:
> On 8/14/2022 11:06 AM, Lars Ingebrigtsen wrote:
>> Some esh-proc tests seem to be failing here:
>>
>> https://hydra.nixos.org/build/187349852/nixlog/1
>>
>> And I've seen the same myself, but intermittently, so it seems like some
>> of the (new) tests there aren't quite stable.
> 
>  From Hydra, it seems that the issue is that there's a broken pipe, so 
> there's probably a timing issue with how the external process runs vs 
> Eshell's internal code. I'll try to reproduce this locally and fix it.

Ok, after stepping away for a bit and letting this bubble around in my 
head, the issue turned out to be pretty simple (I think). Attached is a 
patch that should fix this.

Here's what's going on. Imagine you have a pipeline like 'lisp-command | 
external-command'. It could operate in this order:

   * Start external-command
   * Send output of lisp-command to external-command
   * Finish external-command

That's good. However, it could also do this:

   * Start external-command
   * Finish external-command
   * Send output of lisp-command to external-command -> SIGPIPE!

The fix is to make sure that lisp commands also handle SIGPIPE (aka 
'eshell-broken-pipe'), just like how external commands do.

This is actually a bug introduced from the patch for bug#54062, but 
luckily the tests I added for bug#56025 revealed the issue.