Subject: Re: [PATCH v2] object-file: use real paths when adding alternates

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Tue, 22 Nov 2022 01:56:09 +0100

On Mon, Nov 21 2022, Glen Choo via GitGitGadget wrote:

> From: Glen Choo <[email-masked]>

Aside from some small nits this looks good to me.

>  object-file.c     | 12 ++++++------
>  t/t7700-repack.sh | 18 ++++++++++++++++++
>  2 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/object-file.c b/object-file.c
> index 957790098fa..ef2b762234d 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -508,6 +508,7 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
>  {
>  	struct object_directory *ent;
>  	struct strbuf pathbuf = STRBUF_INIT;
> +	struct strbuf tmp = STRBUF_INIT;
>  	khiter_t pos;
>  
>  	if (!is_absolute_path(entry->buf) && relative_base) {
> @@ -516,12 +517,14 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
>  	}
>  	strbuf_addbuf(&pathbuf, entry);
>  
> -	if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
> +	if (!strbuf_realpath(&tmp, pathbuf.buf, 0)) {
>  		error(_("unable to normalize alternate object path: %s"),
> -		      pathbuf.buf);
> +			pathbuf.buf);

This is a mis-indentation, it was OK in the pre-image, not now.

>  		strbuf_release(&pathbuf);

Doesn't this leak? I've just skimmed strbuf_realpath_1() but e.g. in the
"REALPATH_MANY_MISSING" case it'll have allocated the "resolved" (the
&tmp you pass in here) and then "does a "goto error_out".

It then *resets* the strbuf, but doesn't release it, assuming that
you're going to pass it in again. So in that case we'd leak here, no?

I.e. a NULL return value from strbuf_realpath() doesn't mean that it
didn't allocate in the scratch area passed to it, so we need to
strbuf_release(&tmp) here too.

Perhaps this on top is simpler (but also see below)?:
	
	diff --git a/object-file.c b/object-file.c
	index ef2b762234d..d5d502504bb 100644
	--- a/object-file.c
	+++ b/object-file.c
	@@ -510,6 +510,7 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
	 	struct strbuf pathbuf = STRBUF_INIT;
	 	struct strbuf tmp = STRBUF_INIT;
	 	khiter_t pos;
	+	int ret = -1;
	 
	 	if (!is_absolute_path(entry->buf) && relative_base) {
	 		strbuf_realpath(&pathbuf, relative_base, 1);
	@@ -520,11 +521,9 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
	 	if (!strbuf_realpath(&tmp, pathbuf.buf, 0)) {
	 		error(_("unable to normalize alternate object path: %s"),
	 			pathbuf.buf);
	-		strbuf_release(&pathbuf);
	-		return -1;
	+		goto error;
	 	}
	 	strbuf_swap(&pathbuf, &tmp);
	-	strbuf_release(&tmp);
	 
	 	/*
	 	 * The trailing slash after the directory name is given by
	@@ -533,10 +532,8 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
	 	while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
	 		strbuf_setlen(&pathbuf, pathbuf.len - 1);
	 
	-	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir, &pos)) {
	-		strbuf_release(&pathbuf);
	-		return -1;
	-	}
	+	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir, &pos))
	+		goto error;
	 
	 	CALLOC_ARRAY(ent, 1);
	 	/* pathbuf.buf is already in r->objects->odb_by_path */
	@@ -552,7 +549,11 @@ static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
	 	/* recursively add alternates */
	 	read_info_alternates(r, ent->path, depth + 1);
	 
	-	return 0;
	+	ret = 0;
	+error:
	+	strbuf_release(&tmp);
	+	strbuf_release(&pathbuf);
	+	return ret;
	 }
	 
	 static const char *parse_alt_odb_entry(const char *string,

>  		return -1;
>  	}
> +	strbuf_swap(&pathbuf, &tmp);
> +	strbuf_release(&tmp);
>  
>  	/*
>  	 * The trailing slash after the directory name is given by
> @@ -596,10 +599,7 @@ static void link_alt_odb_entries(struct repository *r, const char *alt,
>  		return;
>  	}
>  
> -	strbuf_add_absolute_path(&objdirbuf, r->objects->odb->path);
> -	if (strbuf_normalize_path(&objdirbuf) < 0)
> -		die(_("unable to normalize object directory: %s"),
> -		    objdirbuf.buf);
> +	strbuf_realpath(&objdirbuf, r->objects->odb->path, 1);
>  
>  	while (*alt) {
>  		alt = parse_alt_odb_entry(alt, sep, &entry);
> diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
> index 5be483bf887..ce1954d0977 100755
> --- a/t/t7700-repack.sh
> +++ b/t/t7700-repack.sh
> @@ -90,6 +90,24 @@ test_expect_success 'loose objects in alternate ODB are not repacked' '
>  	test_has_duplicate_object false
>  '
>  
> +test_expect_success '--local keeps packs when alternate is objectdir ' '
> +	git init alt_symlink &&
> +	(
> +		cd alt_symlink &&
> +		git init &&

The tests pass without this re-"git init", left over from development?

> +		echo content >file4 &&
> +		git add file4 &&
> +		git commit -m commit_file4 &&
> +		git repack -a &&
> +		ls .git/objects/pack/*.pack >../expect &&
> +		ln -s objects .git/alt_objects &&
> +		echo "$(pwd)/.git/alt_objects" >.git/objects/info/alternates &&
> +		git repack -a -d -l &&
> +		ls .git/objects/pack/*.pack >../actual
> +	) &&
> +	test_cmp expect actual
> +'
> +

I think this is better squashed in:
	
	diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
	index ce1954d0977..79eef5b4aa7 100755
	--- a/t/t7700-repack.sh
	+++ b/t/t7700-repack.sh
	@@ -91,13 +91,11 @@ test_expect_success 'loose objects in alternate ODB are not repacked' '
	 '
	 
	 test_expect_success '--local keeps packs when alternate is objectdir ' '
	-	git init alt_symlink &&
	+	test_when_finished "rm -rf repo" &&
	+	git init repo &&
	+	test_commit -C repo A &&
	 	(
	-		cd alt_symlink &&
	-		git init &&
	-		echo content >file4 &&
	-		git add file4 &&
	-		git commit -m commit_file4 &&
	+		cd repo &&
	 		git repack -a &&
	 		ls .git/objects/pack/*.pack >../expect &&
	 		ln -s objects .git/alt_objects &&

Because:

 * If it's not a setup for a later test let's call it "repo" and clean
   it up at the end.

 * The "file4" you're creating doesn't go with the existing pattern, the
   file{1..3} are created in the top-level .git, here you're making a
   file4 in another repo.

   This just calls it "A.t", and makes it with test_commit, since all
   you need is a dummy commit.

 * I think we typically use "find .. -type f", not "ls", see
   e.g. t5351-unpack-large-objects.sh, but I left it in-place. I think
   aside from that test there's some other "let's compare the packed
   before & after" in the test suite, but I can't remember offhand...