On Fri, Feb 18 2022, Taylor Blau wrote:
> On Fri, Feb 18, 2022 at 09:43:52PM +0100, Ævar Arnfjörð Bjarmason wrote:
>> diff --git a/builtin/commit.c b/builtin/commit.c
>> index b9ed0374e30..bc5d34bc31f 100644
>> --- a/builtin/commit.c
>> +++ b/builtin/commit.c
>> @@ -725,11 +725,13 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>> int clean_message_contents = (cleanup_mode != COMMIT_MSG_CLEANUP_NONE);
>> int old_display_comment_prefix;
>> int merge_contains_scissors = 0;
>> + int invoked_hook;
>>
>> /* This checks and barfs if author is badly specified */
>> determine_author_info(author_ident);
>>
>> - if (!no_verify && run_commit_hook(use_editor, index_file, "pre-commit", NULL))
>> + if (!no_verify && run_commit_hook(use_editor, index_file, &invoked_hook,
>> + "pre-commit", NULL))
>> return 0;
>>
>> if (squash_message) {
>> @@ -1052,10 +1054,10 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>> return 0;
>> }
>>
>> - if (!no_verify && hook_exists("pre-commit")) {
>> + if (!no_verify && invoked_hook) {
>> /*
>> - * Re-read the index as pre-commit hook could have updated it,
>> - * and write it out as a tree. We must do this before we invoke
>> + * Re-read the index as the pre-commit-commit hook was invoked
>> + * and could have updated it. We must do this before we invoke
>> * the editor and after we invoke run_status above.
>> */
>> discard_cache();
>
> Sanity checking my own understating of this race: if we ran the
> pre-commit hook and it modified the index, but hook_exists() returns
> false later on (e.g., because the hook itself went away, the directory
> became unreadable, etc.), then we won't call discard_cache() when we
> should have?
Yes, it's that obscure.
> If so, OK. This definitely seems like a pretty niche race, but
> independent of that I think the change here is an improvement in
> readability, and makes it clearer that calling discard_cache() depends
> on whether or not we *ran* the pre-commit hook, not whether we (still)
> *have* a pre-commit hook.
Yeah, that's the main reason to do it. I found this really hard to
follow before, why didn't we just remember if we have/ran the thing? Now
we do.
