Subject: Re: What's cooking in git.git (Dec 2025, #03)

From: Junio C Hamano <[email-masked]>
Date: Thu, 18 Dec 2025 11:57:30 +0900

Aaron Plattner <[email-masked]> writes:

> I'm pretty sure the problem is when do_oid_object_info_extended() 
> substitutes the blank oi here:
>
> 	if (!oi)
> 		oi = &blank_oi;
>
> and then packfile_store_read_object_info() compares it to its own local 
> blank oi:
>
> 	static struct object_info blank_oi = OBJECT_INFO_INIT;

Ahh, that's an unusual mistake.

The following was done on top of 'seen', but would it help?  We
shouldn't have to use the stand-in "blank" thing to begin with.

Besides, explicitly handling the NULL case would reduce the
potential chance of errors that somebody accidentally writes into
blank_oi, making its contents dirty.

 object-file.c |  8 ++++----
 odb.c         | 29 +++++++++++++----------------
 packfile.c    |  3 +--
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git c/object-file.c w/object-file.c
index af1c3f972d..6280e42f34 100644
--- c/object-file.c
+++ w/object-file.c
@@ -426,7 +426,7 @@ int odb_source_loose_read_object_info(struct odb_source *source,
 	unsigned long size_scratch;
 	enum object_type type_scratch;
 
-	if (oi->delta_base_oid)
+	if (oi && oi->delta_base_oid)
 		oidclr(oi->delta_base_oid, source->odb->repo->hash_algo);
 
 	/*
@@ -437,13 +437,13 @@ int odb_source_loose_read_object_info(struct odb_source *source,
 	 * return value implicitly indicates whether the
 	 * object even exists.
 	 */
-	if (!oi->typep && !oi->sizep && !oi->contentp) {
+	if (!oi || (!oi->typep && !oi->sizep && !oi->contentp)) {
 		struct stat st;
-		if (!oi->disk_sizep && (flags & OBJECT_INFO_QUICK))
+		if ((!oi || !oi->disk_sizep) && (flags & OBJECT_INFO_QUICK))
 			return quick_has_loose(source->loose, oid) ? 0 : -1;
 		if (stat_loose_object(source->loose, oid, &st, &path) < 0)
 			return -1;
-		if (oi->disk_sizep)
+		if (oi && oi->disk_sizep)
 			*oi->disk_sizep = st.st_size;
 		return 0;
 	}
diff --git c/odb.c w/odb.c
index 01a9d2e70f..8278ef39a0 100644
--- c/odb.c
+++ w/odb.c
@@ -680,34 +680,31 @@ static int do_oid_object_info_extended(struct object_database *odb,
 				       const struct object_id *oid,
 				       struct object_info *oi, unsigned flags)
 {
-	static struct object_info blank_oi = OBJECT_INFO_INIT;
 	const struct cached_object *co;
 	const struct object_id *real = oid;
 	int already_retried = 0;
 
-
 	if (flags & OBJECT_INFO_LOOKUP_REPLACE)
 		real = lookup_replace_object(odb->repo, oid);
 
 	if (is_null_oid(real))
 		return -1;
 
-	if (!oi)
-		oi = &blank_oi;
-
 	co = find_cached_object(odb, real);
 	if (co) {
-		if (oi->typep)
-			*(oi->typep) = co->type;
-		if (oi->sizep)
-			*(oi->sizep) = co->size;
-		if (oi->disk_sizep)
-			*(oi->disk_sizep) = 0;
-		if (oi->delta_base_oid)
-			oidclr(oi->delta_base_oid, odb->repo->hash_algo);
-		if (oi->contentp)
-			*oi->contentp = xmemdupz(co->buf, co->size);
-		oi->whence = OI_CACHED;
+		if (oi) {
+			if (oi->typep)
+				*(oi->typep) = co->type;
+			if (oi->sizep)
+				*(oi->sizep) = co->size;
+			if (oi->disk_sizep)
+				*(oi->disk_sizep) = 0;
+			if (oi->delta_base_oid)
+				oidclr(oi->delta_base_oid, odb->repo->hash_algo);
+			if (oi->contentp)
+				*oi->contentp = xmemdupz(co->buf, co->size);
+			oi->whence = OI_CACHED;
+		}
 		return 0;
 	}
 
diff --git c/packfile.c w/packfile.c
index ce6716fbea..3ffd6c7240 100644
--- c/packfile.c
+++ w/packfile.c
@@ -2132,7 +2132,6 @@ int packfile_store_read_object_info(struct packfile_store *store,
 				    struct object_info *oi,
 				    unsigned flags UNUSED)
 {
-	static struct object_info blank_oi = OBJECT_INFO_INIT;
 	struct pack_entry e;
 	int rtype;
 
@@ -2143,7 +2142,7 @@ int packfile_store_read_object_info(struct packfile_store *store,
 	 * We know that the caller doesn't actually need the
 	 * information below, so return early.
 	 */
-	if (oi == &blank_oi)
+	if (!oi)
 		return 0;
 
 	rtype = packed_object_info(store->source->odb->repo, e.p, e.offset, oi);