From: Adrian Ratiu <adrian.ratiu@collabora.com>
Date: Thu, 27 Nov 2025 14:24:42 GMT
Subject: Re: [PATCH v3 04/10] transport: convert pre-push to hook API
Message-ID: <87qztjimdx.fsf@collabora.com>
In-Reply-To: <xmqqy0nvujlg.fsf@gitster.g>

On Mon, 24 Nov 2025, Junio C Hamano <gitster@pobox.com> wrote:
> Adrian Ratiu <adrian.ratiu@collabora.com> writes: 
> 
>> From: Emily Shaffer <emilyshaffer@google.com> 
>> 
>> Move the pre-push hook from custom run-command invocations to 
>> the new hook API which doesn't require a custom child_process 
>> structure and signal toggling. 
>> 
>> Signed-off-by: Emily Shaffer <emilyshaffer@google.com> 
>> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> 
>> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> --- 
>>  transport.c | 95 
>>  ++++++++++++++++++++++++++++------------------------- 1 file 
>>  changed, 51 insertions(+), 44 deletions(-) 
> 
> So, this completes what 01/10 hinted at when it created a 
> generalized interface modelled after how pre-push hook was run. 
> We used to spawn the pre-push hook and fed its standard input by 
> calling write_in_full().  Now that is largely encapsulated in 
> run_hooks_opt(), but the application specific processing 
> (namely, what we write to the pre-push hook, i.e. the list of 
> ref update status) is given in pre_push_hook_feed_stdin() 
> callback defined here and given to the run_hooks_opt() call. 
> 
> In other words, the mechanisms are very cleanly separated 
> between generic machinery and the client specific processing. 
> Nice. 
> 
> How and where does the pipe we are writing into 
> (i.e. hook_stdin_fd) gets closed when we are done with the 
> child? 
 
That happens in run-command.c:pp_buffer_stdin() which calls the 
feed pipe callback then closes the fd when feeding is finished:

/** 
 * Feed the pipe: *   ret < 0 means error *   ret == 0 means there 
 is more data to be fed *   ret > 0 means feeding finished */
ret = opts->feed_pipe(proc->in, opts->data, pp->children[i].data);
...