Re: [PATCH 2/3] cat-file: add mailmap support to -s option
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Sep 16, 2022, 22:22 UTC
- Message-ID
- <xmqq8rmjez7h.fsf@gitster.g>
- In-Reply-To
- <20220916205946.178925-3-siddharthasthana31@gmail.com>
Siddharth Asthana <siddharthasthana31@gmail.com> writes:
Show 11 quoted lines
> Using `git cat-file --use-mailmap` with `-s` option, like the following is > allowed: > > git cat-file --use-mailmap -s <commit/tag object sha> > > The current implementation will return the same object size irrespective > of the mailmap option, which is not as useful as it could be. > When we > use the mailmap mechanism to replace the idents, the size of the object > can change and `-s` option would be more useful if it shows the size of > the changed object. This patch implements that.
Simply put, the current implementation is BUGGY, in other words, no?
The above sounds like a quite roundabout way to say that. "the following is allowed" (but it does not work, really). "is not as useful as it could be" (it is pretty much useless, in fact).
If I were doing this step, I'd summarize it into a single three-line paragraph, like so:
Even though the cat-file command with -s option does not complain
when --use-mailmap option is given, it is ignored. Compute the size
of the object after replacing the idents and report it instead.Show 6 quoted lines
> -s:: > Instead of the content, show the object size identified by > - `<object>`. > + `<object>`. If used with `--use-mailmap` option, will show the > + size of updated object after replacing idents using the mailmap > + mechanism.
We are not modifying the object in the object database, so it would be preferrable to avoid a misleading phrasing "updated object", if we can. The size that the object would have had, if the idents recorded in it were the ones "corrected" by the mailmap, is what we report.
Show 26 quoted lines
> diff --git a/builtin/cat-file.c b/builtin/cat-file.c
> index 989eee0bb4..9942b93867 100644
> --- a/builtin/cat-file.c
> +++ b/builtin/cat-file.c
> @@ -132,8 +132,21 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
>
> case 's':
> oi.sizep = &size;
> +
> + if (use_mailmap) {
> + oi.typep = &type;
> + oi.contentp = (void**)&buf;
> + }
> +
> if (oid_object_info_extended(the_repository, &oid, &oi, flags) < 0)
> die("git cat-file: could not get object info");
> +
> + if (use_mailmap && (type == OBJ_COMMIT || type == OBJ_TAG)) {
> + size_t s = size;
> + buf = replace_idents_using_mailmap(buf, &s);
> + size = cast_size_t_to_ulong(s);
> + }
> +
> printf("%"PRIuMAX"\n", (uintmax_t)size);
> ret = 0;
> goto cleanup;We did not grab the object contents but just asked the API to fill oi.sizep but now we grab the contents in oi.contentp, and possibly munge it via mailmap.
Are we merely borrowing the object contents from somebody so we do not have to release anything before jumping to "cleanup" here? What's the memory ownership around replace_idents_using_mailmap()? You pass "buf" to it, and overwrite "buf" with what it returns. If you were responsible for releasing the original "buf" you obtained from oid_object_info_extended(), have you lost the only pointer to it that you may have wanted to use to release it by doing so?
... goes and looks ...
OK, replace_idents_using_mailmap() assumes that object_buf is owned by the caller and the caller is willing to let it go. That is why it attaches it to a strbuf, calls apply_mailmap_to_header() to munge the strbuf, and detaches. The net effect is that the original "buf" we took from oid_object_info_extended() may be freed inside it, and the returned value may be a newly allocated one to replace it, so overwriting buf is OK.
We still need to free "buf", but the function assumes that all cases "buf" would be populated (or left to NULL) and it is OK to free it at cleanup: label, so we are not leaking anything here.
Good.
Show 19 quoted lines
> diff --git a/t/t4203-mailmap.sh b/t/t4203-mailmap.sh > index cd1cab3e54..59513e7c57 100755 > --- a/t/t4203-mailmap.sh > +++ b/t/t4203-mailmap.sh > @@ -1022,4 +1022,14 @@ test_expect_success '--mailmap enables mailmap in cat-file for annotated tag obj > test_cmp expect actual > ' > > +test_expect_success 'git cat-file -s returns correct size with --use-mailmap' ' > + test_when_finished "rm .mailmap" && > + cat >.mailmap <<-EOF && > + C O Mitter <committer@example.com> Orig <orig@example.com> > + EOF > + echo "220" >expect && > + git cat-file --use-mailmap -s HEAD >actual && > + test_cmp expect actual > +' > + > test_done