From bbea0ddeb9bd9eefe568a9f4456cccf630704d8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:23 +0100
Subject: [PATCH 01/12] object-file.c: split up declaration of unrelated
 variables
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Split up the declaration of the "ret" and "re_allocated"
variables. It's not our usual style to group variable declarations
simply because they share a type, we'd only prefer to do so when the
two are closely related (e.g. "int i, j"). This change makes a
subsequent and meaningful change's diff smaller.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 object-file.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/object-file.c b/object-file.c
index 8be57f48de..ecc7797329 100644
--- a/object-file.c
+++ b/object-file.c
@@ -2118,7 +2118,8 @@ static int index_mem(struct index_state *istate,
 		     enum object_type type,
 		     const char *path, unsigned flags)
 {
-	int ret, re_allocated = 0;
+	int ret;
+	int re_allocated = 0;
 	int write_object = flags & HASH_WRITE_OBJECT;
 
 	if (!type)

From 63e05f90562cc8db5c450dbceeab6677b6e5351f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:24 +0100
Subject: [PATCH 02/12] object-file API: return "void", not "int" from
 hash_object_file()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The hash_object_file() function added in abdc3fc8421 (Add
hash_sha1_file(), 2006-10-14) did not have a meaningful return value,
and it never has.

One was seemingly added to avoid adding braces to the "ret = "
assignments being modified here. Let's instead assign "0" to the "ret"
variables at the beginning of the relevant functions, and have them
return "void".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 object-file.c  | 16 ++++++++--------
 object-store.h |  6 +++---
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/object-file.c b/object-file.c
index ecc7797329..eeb6814780 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1836,14 +1836,13 @@ static int write_buffer(int fd, const void *buf, size_t len)
 	return 0;
 }
 
-int hash_object_file(const struct git_hash_algo *algo, const void *buf,
+void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 		     unsigned long len, const char *type,
 		     struct object_id *oid)
 {
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
 	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
-	return 0;
 }
 
 /* Finalize a file on disk, and close it. */
@@ -2118,7 +2117,7 @@ static int index_mem(struct index_state *istate,
 		     enum object_type type,
 		     const char *path, unsigned flags)
 {
-	int ret;
+	int ret = 0;
 	int re_allocated = 0;
 	int write_object = flags & HASH_WRITE_OBJECT;
 
@@ -2148,8 +2147,9 @@ static int index_mem(struct index_state *istate,
 	if (write_object)
 		ret = write_object_file(buf, size, type_name(type), oid);
 	else
-		ret = hash_object_file(the_hash_algo, buf, size,
-				       type_name(type), oid);
+		hash_object_file(the_hash_algo, buf, size, type_name(type),
+				 oid);
+
 	if (re_allocated)
 		free(buf);
 	return ret;
@@ -2161,7 +2161,7 @@ static int index_stream_convert_blob(struct index_state *istate,
 				     const char *path,
 				     unsigned flags)
 {
-	int ret;
+	int ret = 0;
 	const int write_object = flags & HASH_WRITE_OBJECT;
 	struct strbuf sbuf = STRBUF_INIT;
 
@@ -2175,8 +2175,8 @@ static int index_stream_convert_blob(struct index_state *istate,
 		ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
 					oid);
 	else
-		ret = hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
-				       type_name(OBJ_BLOB), oid);
+		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
+				 type_name(OBJ_BLOB), oid);
 	strbuf_release(&sbuf);
 	return ret;
 }
diff --git a/object-store.h b/object-store.h
index 6f89482df0..44f6868cc9 100644
--- a/object-store.h
+++ b/object-store.h
@@ -245,9 +245,9 @@ static inline void *repo_read_object_file(struct repository *r,
 /* Read and unpack an object file into memory, write memory to an object file */
 int oid_object_info(struct repository *r, const struct object_id *, unsigned long *);
 
-int hash_object_file(const struct git_hash_algo *algo, const void *buf,
-		     unsigned long len, const char *type,
-		     struct object_id *oid);
+void hash_object_file(const struct git_hash_algo *algo, const void *buf,
+		      unsigned long len, const char *type,
+		      struct object_id *oid);
 
 int write_object_file_flags(const void *buf, unsigned long len,
 			    const char *type, struct object_id *oid,

From b04cdea46cf5ae60066fa6dd12d5449bf3ef283f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:25 +0100
Subject: [PATCH 03/12] object-file API: add a format_object_header() function
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Add a convenience function to wrap the xsnprintf() command that
generates loose object headers. This code was copy/pasted in various
parts of the codebase, let's define it in one place and re-use it from
there.

All except one caller of it had a valid "enum object_type" for us,
it's only write_object_file_prepare() which might need to deal with
"git hash-object --literally" and a potential garbage type. Let's have
the primary API use an "enum object_type", and define a *_literally()
function that can take an arbitrary "const char *" for the type.

See [1] for the discussion that prompted this patch, i.e. new code in
object-file.c that wanted to copy/paste the xsnprintf() invocation.

In the case of fast-import.c the callers unfortunately need to cast
back & forth between "unsigned char *" and "char *", since
format_object_header() ad encode_in_pack_object_header() take
different signedness.

1. https://lore.kernel.org/git/211213.86bl1l9bfz.gmgdl@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fast-import.c |  6 +++---
 builtin/index-pack.c  |  3 +--
 bulk-checkin.c        |  4 ++--
 http-push.c           |  2 +-
 object-file.c         | 23 ++++++++++++++++++++---
 object-store.h        |  8 ++++++++
 6 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index 2b2e28bad7..123df7d9a5 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -937,8 +937,8 @@ static int store_object(
 	git_hash_ctx c;
 	git_zstream s;
 
-	hdrlen = xsnprintf((char *)hdr, sizeof(hdr), "%s %lu",
-			   type_name(type), (unsigned long)dat->len) + 1;
+	hdrlen = format_object_header((char *)hdr, sizeof(hdr), type,
+				      dat->len);
 	the_hash_algo->init_fn(&c);
 	the_hash_algo->update_fn(&c, hdr, hdrlen);
 	the_hash_algo->update_fn(&c, dat->buf, dat->len);
@@ -1091,7 +1091,7 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 	hashfile_checkpoint(pack_file, &checkpoint);
 	offset = checkpoint.offset;
 
-	hdrlen = xsnprintf((char *)out_buf, out_sz, "blob %" PRIuMAX, len) + 1;
+	hdrlen = format_object_header((char *)out_buf, out_sz, OBJ_BLOB, len);
 
 	the_hash_algo->init_fn(&c);
 	the_hash_algo->update_fn(&c, out_buf, hdrlen);
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 3c2e6aee3c..01574378ce 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -449,8 +449,7 @@ static void *unpack_entry_data(off_t offset, unsigned long size,
 	int hdrlen;
 
 	if (!is_delta_type(type)) {
-		hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX,
-				   type_name(type),(uintmax_t)size) + 1;
+		hdrlen = format_object_header(hdr, sizeof(hdr), type, size);
 		the_hash_algo->init_fn(&c);
 		the_hash_algo->update_fn(&c, hdr, hdrlen);
 	} else
diff --git a/bulk-checkin.c b/bulk-checkin.c
index 8785b2ac80..85b3ebaf97 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -220,8 +220,8 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
 	if (seekback == (off_t) -1)
 		return error("cannot find the current offset");
 
-	header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX,
-			       type_name(type), (uintmax_t)size) + 1;
+	header_len = format_object_header((char *)obuf, sizeof(obuf),
+					  type, size);
 	the_hash_algo->init_fn(&ctx);
 	the_hash_algo->update_fn(&ctx, obuf, header_len);
 
diff --git a/http-push.c b/http-push.c
index 3309aaf004..f0c044dcf7 100644
--- a/http-push.c
+++ b/http-push.c
@@ -363,7 +363,7 @@ static void start_put(struct transfer_request *request)
 	git_zstream stream;
 
 	unpacked = read_object_file(&request->obj->oid, &type, &len);
-	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1;
+	hdrlen = format_object_header(hdr, sizeof(hdr), type, len);
 
 	/* Set it up */
 	git_deflate_init(&stream, zlib_compression_level);
diff --git a/object-file.c b/object-file.c
index eeb6814780..3fcd46cf9e 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1049,6 +1049,23 @@ void *xmmap(void *start, size_t length,
 	return ret;
 }
 
+static int format_object_header_literally(char *str, size_t size,
+					  const char *type, size_t objsize)
+{
+	return xsnprintf(str, size, "%s %"PRIuMAX, type, (uintmax_t)objsize) + 1;
+}
+
+int format_object_header(char *str, size_t size, enum object_type type,
+			 size_t objsize)
+{
+	const char *name = type_name(type);
+
+	if (!name)
+		BUG("could not get a type name for 'enum object_type' value %d", type);
+
+	return format_object_header_literally(str, size, name, objsize);
+}
+
 /*
  * With an in-core object data in "map", rehash it to make sure the
  * object name actually matches "oid" to detect object corruption.
@@ -1077,7 +1094,7 @@ int check_object_signature(struct repository *r, const struct object_id *oid,
 		return -1;
 
 	/* Generate the header */
-	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(obj_type), (uintmax_t)size) + 1;
+	hdrlen = format_object_header(hdr, sizeof(hdr), obj_type, size);
 
 	/* Sha1.. */
 	r->hash_algo->init_fn(&c);
@@ -1777,7 +1794,7 @@ static void write_object_file_prepare(const struct git_hash_algo *algo,
 	git_hash_ctx c;
 
 	/* Generate the header */
-	*hdrlen = xsnprintf(hdr, *hdrlen, "%s %"PRIuMAX , type, (uintmax_t)len)+1;
+	*hdrlen = format_object_header_literally(hdr, *hdrlen, type, len);
 
 	/* Sha1.. */
 	algo->init_fn(&c);
@@ -2051,7 +2068,7 @@ int force_object_loose(const struct object_id *oid, time_t mtime)
 	buf = read_object(the_repository, oid, &type, &len);
 	if (!buf)
 		return error(_("cannot read object for %s"), oid_to_hex(oid));
-	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1;
+	hdrlen = format_object_header(hdr, sizeof(hdr), type, len);
 	ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime, 0);
 	free(buf);
 
diff --git a/object-store.h b/object-store.h
index 44f6868cc9..8b4413d0ce 100644
--- a/object-store.h
+++ b/object-store.h
@@ -331,6 +331,14 @@ int repo_has_object_file_with_flags(struct repository *r,
  */
 int has_loose_object_nonlocal(const struct object_id *);
 
+/**
+ * format_object_header() is a thin wrapper around s xsnprintf() that
+ * writes the initial "<type> <obj-len>" part of the loose object
+ * header. It returns the size that snprintf() returns + 1.
+ */
+int format_object_header(char *str, size_t size, enum object_type type,
+			 size_t objsize);
+
 void assert_oid_type(const struct object_id *oid, enum object_type expect);
 
 /*

From c80d226a046170b1c8dd82ef72a27373ddd5880e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:26 +0100
Subject: [PATCH 04/12] object-file API: have write_object_file() take "enum
 object_type"
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change the write_object_file() function to take an "enum object_type"
instead of a "const char *type". Its callers either passed
{commit,tree,blob,tag}_type and can pass the corresponding OBJ_* type
instead, or were hardcoding strings like "blob".

This avoids the back & forth fragility where the callers of
write_object_file() would have the enum type, and convert it
themselves via type_name(). We do have to now do that conversion
ourselves before calling write_object_file_prepare(), but those
codepaths will be similarly adjusted in subsequent commits.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 apply.c                  |  8 ++++----
 builtin/checkout.c       |  2 +-
 builtin/mktag.c          |  2 +-
 builtin/mktree.c         |  2 +-
 builtin/notes.c          |  2 +-
 builtin/receive-pack.c   |  2 +-
 builtin/replace.c        |  2 +-
 builtin/tag.c            |  2 +-
 builtin/unpack-objects.c |  6 +++---
 cache-tree.c             |  2 +-
 commit.c                 |  2 +-
 match-trees.c            |  2 +-
 merge-ort.c              |  4 ++--
 merge-recursive.c        |  2 +-
 notes-cache.c            |  2 +-
 notes.c                  |  8 ++++----
 object-file.c            | 10 +++++-----
 object-store.h           |  4 ++--
 read-cache.c             |  2 +-
 19 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/apply.c b/apply.c
index 7ffadc3b17..e82a7c30f0 100644
--- a/apply.c
+++ b/apply.c
@@ -3589,7 +3589,7 @@ static int try_threeway(struct apply_state *state,
 
 	/* Preimage the patch was prepared for */
 	if (patch->is_new)
-		write_object_file("", 0, blob_type, &pre_oid);
+		write_object_file("", 0, OBJ_BLOB, &pre_oid);
 	else if (get_oid(patch->old_oid_prefix, &pre_oid) ||
 		 read_blob_object(&buf, &pre_oid, patch->old_mode))
 		return error(_("repository lacks the necessary blob to perform 3-way merge."));
@@ -3605,7 +3605,7 @@ static int try_threeway(struct apply_state *state,
 		return -1;
 	}
 	/* post_oid is theirs */
-	write_object_file(tmp_image.buf, tmp_image.len, blob_type, &post_oid);
+	write_object_file(tmp_image.buf, tmp_image.len, OBJ_BLOB, &post_oid);
 	clear_image(&tmp_image);
 
 	/* our_oid is ours */
@@ -3618,7 +3618,7 @@ static int try_threeway(struct apply_state *state,
 			return error(_("cannot read the current contents of '%s'"),
 				     patch->old_name);
 	}
-	write_object_file(tmp_image.buf, tmp_image.len, blob_type, &our_oid);
+	write_object_file(tmp_image.buf, tmp_image.len, OBJ_BLOB, &our_oid);
 	clear_image(&tmp_image);
 
 	/* in-core three-way merge between post and our using pre as base */
@@ -4346,7 +4346,7 @@ static int add_index_file(struct apply_state *state,
 			}
 			fill_stat_cache_info(state->repo->index, ce, &st);
 		}
-		if (write_object_file(buf, size, blob_type, &ce->oid) < 0) {
+		if (write_object_file(buf, size, OBJ_BLOB, &ce->oid) < 0) {
 			discard_cache_entry(ce);
 			return error(_("unable to create backing store "
 				       "for newly created file %s"), path);
diff --git a/builtin/checkout.c b/builtin/checkout.c
index cc804ba8e1..24cc235939 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -298,7 +298,7 @@ static int checkout_merged(int pos, const struct checkout *state,
 	 * (it also writes the merge result to the object database even
 	 * when it may contain conflicts).
 	 */
-	if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
+	if (write_object_file(result_buf.ptr, result_buf.size, OBJ_BLOB, &oid))
 		die(_("Unable to add merge result for '%s'"), path);
 	free(result_buf.ptr);
 	ce = make_transient_cache_entry(mode, &oid, path, 2, ce_mem_pool);
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 3b2dbbb37e..96a3686af5 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -100,7 +100,7 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 	if (verify_object_in_tag(&tagged_oid, &tagged_type))
 		die(_("tag on stdin did not refer to a valid object"));
 
-	if (write_object_file(buf.buf, buf.len, tag_type, &result) < 0)
+	if (write_object_file(buf.buf, buf.len, OBJ_TAG, &result) < 0)
 		die(_("unable to write tag file"));
 
 	strbuf_release(&buf);
diff --git a/builtin/mktree.c b/builtin/mktree.c
index ae78ca1c02..a1213aaa96 100644
--- a/builtin/mktree.c
+++ b/builtin/mktree.c
@@ -58,7 +58,7 @@ static void write_tree(struct object_id *oid)
 		strbuf_add(&buf, ent->oid.hash, the_hash_algo->rawsz);
 	}
 
-	write_object_file(buf.buf, buf.len, tree_type, oid);
+	write_object_file(buf.buf, buf.len, OBJ_TREE, oid);
 	strbuf_release(&buf);
 }
 
diff --git a/builtin/notes.c b/builtin/notes.c
index 05d60483e8..4cc84dfa76 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -199,7 +199,7 @@ static void prepare_note_data(const struct object_id *object, struct note_data *
 
 static void write_note_data(struct note_data *d, struct object_id *oid)
 {
-	if (write_object_file(d->buf.buf, d->buf.len, blob_type, oid)) {
+	if (write_object_file(d->buf.buf, d->buf.len, OBJ_BLOB, oid)) {
 		int status = die_message(_("unable to write note object"));
 
 		if (d->edit_path)
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 9f4a0b816c..231d576927 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -762,7 +762,7 @@ static void prepare_push_cert_sha1(struct child_process *proc)
 		int bogs /* beginning_of_gpg_sig */;
 
 		already_done = 1;
-		if (write_object_file(push_cert.buf, push_cert.len, "blob",
+		if (write_object_file(push_cert.buf, push_cert.len, OBJ_BLOB,
 				      &push_cert_oid))
 			oidclr(&push_cert_oid);
 
diff --git a/builtin/replace.c b/builtin/replace.c
index 6ff1734d58..995ca68330 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -474,7 +474,7 @@ static int create_graft(int argc, const char **argv, int force, int gentle)
 		return -1;
 	}
 
-	if (write_object_file(buf.buf, buf.len, commit_type, &new_oid)) {
+	if (write_object_file(buf.buf, buf.len, OBJ_COMMIT, &new_oid)) {
 		strbuf_release(&buf);
 		return error(_("could not write replacement commit for: '%s'"),
 			     old_ref);
diff --git a/builtin/tag.c b/builtin/tag.c
index 134b3f1edf..31e6b155c0 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -238,7 +238,7 @@ static int build_tag_object(struct strbuf *buf, int sign, struct object_id *resu
 {
 	if (sign && do_sign(buf) < 0)
 		return error(_("unable to sign the tag"));
-	if (write_object_file(buf->buf, buf->len, tag_type, result) < 0)
+	if (write_object_file(buf->buf, buf->len, OBJ_TAG, result) < 0)
 		return error(_("unable to write tag file"));
 	return 0;
 }
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 4a9466295b..808041551f 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -177,7 +177,7 @@ static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 	struct object_id oid;
 
 	if (write_object_file(obj_buf->buffer, obj_buf->size,
-			      type_name(obj->type), &oid) < 0)
+			      obj->type, &oid) < 0)
 		die("failed to write object %s", oid_to_hex(&obj->oid));
 	obj->flags |= FLAG_WRITTEN;
 }
@@ -243,7 +243,7 @@ static void write_object(unsigned nr, enum object_type type,
 			 void *buf, unsigned long size)
 {
 	if (!strict) {
-		if (write_object_file(buf, size, type_name(type),
+		if (write_object_file(buf, size, type,
 				      &obj_list[nr].oid) < 0)
 			die("failed to write object");
 		added_object(nr, type, buf, size);
@@ -251,7 +251,7 @@ static void write_object(unsigned nr, enum object_type type,
 		obj_list[nr].obj = NULL;
 	} else if (type == OBJ_BLOB) {
 		struct blob *blob;
-		if (write_object_file(buf, size, type_name(type),
+		if (write_object_file(buf, size, type,
 				      &obj_list[nr].oid) < 0)
 			die("failed to write object");
 		added_object(nr, type, buf, size);
diff --git a/cache-tree.c b/cache-tree.c
index 65ca993361..fdbbd191d2 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -440,7 +440,7 @@ static int update_one(struct cache_tree *it,
 	} else if (dryrun) {
 		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
 				 tree_type, &it->oid);
-	} else if (write_object_file_flags(buffer.buf, buffer.len, tree_type,
+	} else if (write_object_file_flags(buffer.buf, buffer.len, OBJ_TREE,
 					   &it->oid, flags & WRITE_TREE_SILENT
 					   ? HASH_SILENT : 0)) {
 		strbuf_release(&buffer);
diff --git a/commit.c b/commit.c
index a348f085b2..6cc0ba9c11 100644
--- a/commit.c
+++ b/commit.c
@@ -1567,7 +1567,7 @@ int commit_tree_extended(const char *msg, size_t msg_len,
 		goto out;
 	}
 
-	result = write_object_file(buffer.buf, buffer.len, commit_type, ret);
+	result = write_object_file(buffer.buf, buffer.len, OBJ_COMMIT, ret);
 out:
 	strbuf_release(&buffer);
 	return result;
diff --git a/match-trees.c b/match-trees.c
index df413989fa..49398e599f 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -235,7 +235,7 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,
 		rewrite_with = oid2;
 	}
 	hashcpy(rewrite_here, rewrite_with->hash);
-	status = write_object_file(buf, sz, tree_type, result);
+	status = write_object_file(buf, sz, OBJ_TREE, result);
 	free(buf);
 	return status;
 }
diff --git a/merge-ort.c b/merge-ort.c
index c319797021..d4ba2955f1 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1888,7 +1888,7 @@ static int handle_content_merge(struct merge_options *opt,
 
 		if (!ret &&
 		    write_object_file(result_buf.ptr, result_buf.size,
-				      blob_type, &result->oid))
+				      OBJ_BLOB, &result->oid))
 			ret = err(opt, _("Unable to add %s to database"),
 				  path);
 
@@ -3343,7 +3343,7 @@ static void write_tree(struct object_id *result_oid,
 	}
 
 	/* Write this object file out, and record in result_oid */
-	write_object_file(buf.buf, buf.len, tree_type, result_oid);
+	write_object_file(buf.buf, buf.len, OBJ_TREE, result_oid);
 	strbuf_release(&buf);
 }
 
diff --git a/merge-recursive.c b/merge-recursive.c
index d9457797db..e0cbbf2d02 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1373,7 +1373,7 @@ static int merge_mode_and_contents(struct merge_options *opt,
 
 			if (!ret &&
 			    write_object_file(result_buf.ptr, result_buf.size,
-					      blob_type, &result->blob.oid))
+					      OBJ_BLOB, &result->blob.oid))
 				ret = err(opt, _("Unable to add %s to database"),
 					  a->path);
 
diff --git a/notes-cache.c b/notes-cache.c
index 2473314d68..9dfd251a81 100644
--- a/notes-cache.c
+++ b/notes-cache.c
@@ -92,7 +92,7 @@ int notes_cache_put(struct notes_cache *c, struct object_id *key_oid,
 {
 	struct object_id value_oid;
 
-	if (write_object_file(data, size, "blob", &value_oid) < 0)
+	if (write_object_file(data, size, OBJ_BLOB, &value_oid) < 0)
 		return -1;
 	return add_note(&c->tree, key_oid, &value_oid, NULL);
 }
diff --git a/notes.c b/notes.c
index f87dac4068..7452e71cc8 100644
--- a/notes.c
+++ b/notes.c
@@ -675,7 +675,7 @@ static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
 		ret = tree_write_stack_finish_subtree(n);
 		if (ret)
 			return ret;
-		ret = write_object_file(n->buf.buf, n->buf.len, tree_type, &s);
+		ret = write_object_file(n->buf.buf, n->buf.len, OBJ_TREE, &s);
 		if (ret)
 			return ret;
 		strbuf_release(&n->buf);
@@ -836,7 +836,7 @@ int combine_notes_concatenate(struct object_id *cur_oid,
 	free(new_msg);
 
 	/* create a new blob object from buf */
-	ret = write_object_file(buf, buf_len, blob_type, cur_oid);
+	ret = write_object_file(buf, buf_len, OBJ_BLOB, cur_oid);
 	free(buf);
 	return ret;
 }
@@ -916,7 +916,7 @@ int combine_notes_cat_sort_uniq(struct object_id *cur_oid,
 				 string_list_join_lines_helper, &buf))
 		goto out;
 
-	ret = write_object_file(buf.buf, buf.len, blob_type, cur_oid);
+	ret = write_object_file(buf.buf, buf.len, OBJ_BLOB, cur_oid);
 
 out:
 	strbuf_release(&buf);
@@ -1192,7 +1192,7 @@ int write_notes_tree(struct notes_tree *t, struct object_id *result)
 	ret = for_each_note(t, flags, write_each_note, &cb_data) ||
 	      write_each_non_note_until(NULL, &cb_data) ||
 	      tree_write_stack_finish_subtree(&root) ||
-	      write_object_file(root.buf.buf, root.buf.len, tree_type, result);
+	      write_object_file(root.buf.buf, root.buf.len, OBJ_TREE, result);
 	strbuf_release(&root.buf);
 	return ret;
 }
diff --git a/object-file.c b/object-file.c
index 3fcd46cf9e..59eb793e0a 100644
--- a/object-file.c
+++ b/object-file.c
@@ -2014,7 +2014,7 @@ static int freshen_packed_object(const struct object_id *oid)
 }
 
 int write_object_file_flags(const void *buf, unsigned long len,
-			    const char *type, struct object_id *oid,
+			    enum object_type type, struct object_id *oid,
 			    unsigned flags)
 {
 	char hdr[MAX_HEADER_LEN];
@@ -2023,7 +2023,7 @@ int write_object_file_flags(const void *buf, unsigned long len,
 	/* Normally if we have it in the pack then we do not bother writing
 	 * it out into .git/objects/??/?{38} file.
 	 */
-	write_object_file_prepare(the_hash_algo, buf, len, type, oid, hdr,
+	write_object_file_prepare(the_hash_algo, buf, len, type_name(type), oid, hdr,
 				  &hdrlen);
 	if (freshen_packed_object(oid) || freshen_loose_object(oid))
 		return 0;
@@ -2162,7 +2162,7 @@ static int index_mem(struct index_state *istate,
 	}
 
 	if (write_object)
-		ret = write_object_file(buf, size, type_name(type), oid);
+		ret = write_object_file(buf, size, type, oid);
 	else
 		hash_object_file(the_hash_algo, buf, size, type_name(type),
 				 oid);
@@ -2189,7 +2189,7 @@ static int index_stream_convert_blob(struct index_state *istate,
 				 get_conv_flags(flags));
 
 	if (write_object)
-		ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
+		ret = write_object_file(sbuf.buf, sbuf.len, OBJ_BLOB,
 					oid);
 	else
 		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
@@ -2313,7 +2313,7 @@ int index_path(struct index_state *istate, struct object_id *oid,
 		if (!(flags & HASH_WRITE_OBJECT))
 			hash_object_file(the_hash_algo, sb.buf, sb.len,
 					 blob_type, oid);
-		else if (write_object_file(sb.buf, sb.len, blob_type, oid))
+		else if (write_object_file(sb.buf, sb.len, OBJ_BLOB, oid))
 			rc = error(_("%s: failed to insert into database"), path);
 		strbuf_release(&sb);
 		break;
diff --git a/object-store.h b/object-store.h
index 8b4413d0ce..eab1e2a967 100644
--- a/object-store.h
+++ b/object-store.h
@@ -250,10 +250,10 @@ void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 		      struct object_id *oid);
 
 int write_object_file_flags(const void *buf, unsigned long len,
-			    const char *type, struct object_id *oid,
+			    enum object_type type, struct object_id *oid,
 			    unsigned flags);
 static inline int write_object_file(const void *buf, unsigned long len,
-				    const char *type, struct object_id *oid)
+				    enum object_type type, struct object_id *oid)
 {
 	return write_object_file_flags(buf, len, type, oid, 0);
 }
diff --git a/read-cache.c b/read-cache.c
index cbe73f14e5..b8ae30a0e7 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -735,7 +735,7 @@ static struct cache_entry *create_alias_ce(struct index_state *istate,
 void set_object_name_for_intent_to_add_entry(struct cache_entry *ce)
 {
 	struct object_id oid;
-	if (write_object_file("", 0, blob_type, &oid))
+	if (write_object_file("", 0, OBJ_BLOB, &oid))
 		die(_("cannot create an empty blob in the object database"));
 	oidcpy(&ce->oid, &oid);
 }

From 73182b2d84e3348ab87ef5ecbe3315881381c29c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:27 +0100
Subject: [PATCH 05/12] object API: correct "buf" v.s. "map" mismatch in *.c
 and *.h
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change the name of the second argument to check_object_signature() to
be "buf" in object-file.c, making it consistent with the prototype in
cache.h

This fixes an inconsistency that's been with us since 2ade9340262 (Add
"check_sha1_signature()" helper function, 2005-04-08), and makes a
subsequent commit's diff smaller, as we'll move these API docs to
cache.h.

While we're at it fix a small grammar error in the documentation,
dropping an "an" before "in-core object-data".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 object-file.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/object-file.c b/object-file.c
index 59eb793e0a..271acf4dd1 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1067,13 +1067,13 @@ int format_object_header(char *str, size_t size, enum object_type type,
 }
 
 /*
- * With an in-core object data in "map", rehash it to make sure the
+ * With in-core object data in "buf", rehash it to make sure the
  * object name actually matches "oid" to detect object corruption.
- * With "map" == NULL, try reading the object named with "oid" using
+ * With "buf" == NULL, try reading the object named with "oid" using
  * the streaming interface and rehash it to do the same.
  */
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *map, unsigned long size, const char *type,
+			   void *buf, unsigned long size, const char *type,
 			   struct object_id *real_oidp)
 {
 	struct object_id tmp;
@@ -1084,8 +1084,8 @@ int check_object_signature(struct repository *r, const struct object_id *oid,
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen;
 
-	if (map) {
-		hash_object_file(r->hash_algo, map, size, type, real_oid);
+	if (buf) {
+		hash_object_file(r->hash_algo, buf, size, type, real_oid);
 		return !oideq(oid, real_oid) ? -1 : 0;
 	}
 

From cdcaaec9a6028f53f9b44efb6dce9f15bb394b45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:28 +0100
Subject: [PATCH 06/12] object API docs: move check_object_signature() docs to
 cache.h
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Move the API documentation for check_object_signature() to cache.h,
where its prototype is declared. This is in preparation for adding a
companion function.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 cache.h       | 6 ++++++
 object-file.c | 6 ------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/cache.h b/cache.h
index 281f00ab1b..98d1ef0857 100644
--- a/cache.h
+++ b/cache.h
@@ -1319,6 +1319,12 @@ enum unpack_loose_header_result unpack_loose_header(git_zstream *stream,
 struct object_info;
 int parse_loose_header(const char *hdr, struct object_info *oi);
 
+/**
+ * With in-core object data in "buf", rehash it to make sure the
+ * object name actually matches "oid" to detect object corruption.
+ * With "buf" == NULL, try reading the object named with "oid" using
+ * the streaming interface and rehash it to do the same.
+ */
 int check_object_signature(struct repository *r, const struct object_id *oid,
 			   void *buf, unsigned long size, const char *type,
 			   struct object_id *real_oidp);
diff --git a/object-file.c b/object-file.c
index 271acf4dd1..44e0b32d71 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1066,12 +1066,6 @@ int format_object_header(char *str, size_t size, enum object_type type,
 	return format_object_header_literally(str, size, name, objsize);
 }
 
-/*
- * With in-core object data in "buf", rehash it to make sure the
- * object name actually matches "oid" to detect object corruption.
- * With "buf" == NULL, try reading the object named with "oid" using
- * the streaming interface and rehash it to do the same.
- */
 int check_object_signature(struct repository *r, const struct object_id *oid,
 			   void *buf, unsigned long size, const char *type,
 			   struct object_id *real_oidp)

From ee213de22d15e801ba3712be0cb8ecbf7415fa1d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:29 +0100
Subject: [PATCH 07/12] object API users + docs: check <0, not !0 with
 check_object_signature()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change those users of the object API that misused
check_object_signature() by assuming it returned any non-zero when the
OID didn't match the expected value to check <0 instead. In practice
all of this code worked before, but it wasn't consistent with rest of
the users of the API.

Let's also clarify what the <0 return value means in API docs.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/index-pack.c | 5 ++---
 builtin/mktag.c      | 2 +-
 cache.h              | 3 +++
 object-file.c        | 2 +-
 pack-check.c         | 2 +-
 5 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 01574378ce..416f60a98c 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1412,9 +1412,8 @@ static void fix_unresolved_deltas(struct hashfile *f)
 		if (!data)
 			continue;
 
-		if (check_object_signature(the_repository, &d->oid,
-					   data, size,
-					   type_name(type), NULL))
+		if (check_object_signature(the_repository, &d->oid, data, size,
+					   type_name(type), NULL) < 0)
 			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
 
 		/*
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 96a3686af5..98d1e66f32 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -97,7 +97,7 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 				&tagged_oid, &tagged_type))
 		die(_("tag on stdin did not pass our strict fsck check"));
 
-	if (verify_object_in_tag(&tagged_oid, &tagged_type))
+	if (verify_object_in_tag(&tagged_oid, &tagged_type) < 0)
 		die(_("tag on stdin did not refer to a valid object"));
 
 	if (write_object_file(buf.buf, buf.len, OBJ_TAG, &result) < 0)
diff --git a/cache.h b/cache.h
index 98d1ef0857..5d08195212 100644
--- a/cache.h
+++ b/cache.h
@@ -1324,6 +1324,9 @@ int parse_loose_header(const char *hdr, struct object_info *oi);
  * object name actually matches "oid" to detect object corruption.
  * With "buf" == NULL, try reading the object named with "oid" using
  * the streaming interface and rehash it to do the same.
+ *
+ * A negative value indicates an error, usually that the OID is not
+ * what we expected, but it might also indicate another error.
  */
 int check_object_signature(struct repository *r, const struct object_id *oid,
 			   void *buf, unsigned long size, const char *type,
diff --git a/object-file.c b/object-file.c
index 44e0b32d71..d628f58c0d 100644
--- a/object-file.c
+++ b/object-file.c
@@ -2613,7 +2613,7 @@ int read_loose_object(const char *path,
 		}
 		if (check_object_signature(the_repository, expected_oid,
 					   *contents, *size,
-					   oi->type_name->buf, real_oid))
+					   oi->type_name->buf, real_oid) < 0)
 			goto out;
 	}
 
diff --git a/pack-check.c b/pack-check.c
index 3f418e3a6a..48d818ee7b 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -143,7 +143,7 @@ static int verify_packfile(struct repository *r,
 				    oid_to_hex(&oid), p->pack_name,
 				    (uintmax_t)entries[i].offset);
 		else if (check_object_signature(r, &oid, data, size,
-						type_name(type), NULL))
+						type_name(type), NULL) < 0)
 			err = error("packed %s from %s is corrupt",
 				    oid_to_hex(&oid), p->pack_name);
 		else if (fn) {

From 0f156dbb04b434d95ce5465e6b07d8869d55e8e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:30 +0100
Subject: [PATCH 08/12] object-file API: split up and simplify
 check_object_signature()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Split up the check_object_signature() function into that non-streaming
version (it accepts an already filled "buf"), and a new
stream_object_signature() which will retrieve the object from storage,
and hash it on-the-fly.

All of the callers of check_object_signature() were effectively
calling two different functions, if we go by cyclomatic
complexity. I.e. they'd either take the early "if (map)" branch and
return early, or not. This has been the case since the "if (map)"
condition was added in 090ea12671b (parse_object: avoid putting whole
blob in core, 2012-03-07).

We can then further simplify the resulting check_object_signature()
function since only one caller wanted to pass a non-NULL "buf" and a
non-NULL "real_oidp". That "read_loose_object()" codepath used by "git
fsck" can instead use hash_object_file() followed by oideq().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fast-export.c |  2 +-
 builtin/index-pack.c  |  2 +-
 builtin/mktag.c       |  5 ++---
 cache.h               | 12 ++++++++----
 object-file.c         | 32 ++++++++++++++++++--------------
 object.c              |  4 ++--
 pack-check.c          |  9 ++++++---
 7 files changed, 38 insertions(+), 28 deletions(-)

diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 9f1c730e58..319859db30 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -300,7 +300,7 @@ static void export_blob(const struct object_id *oid)
 		if (!buf)
 			die("could not read blob %s", oid_to_hex(oid));
 		if (check_object_signature(the_repository, oid, buf, size,
-					   type_name(type), NULL) < 0)
+					   type_name(type)) < 0)
 			die("oid mismatch in blob %s", oid_to_hex(oid));
 		object = parse_object_buffer(the_repository, oid, type,
 					     size, buf, &eaten);
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 416f60a98c..e1927205a7 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1413,7 +1413,7 @@ static void fix_unresolved_deltas(struct hashfile *f)
 			continue;
 
 		if (check_object_signature(the_repository, &d->oid, data, size,
-					   type_name(type), NULL) < 0)
+					   type_name(type)) < 0)
 			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
 
 		/*
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 98d1e66f32..4d28eceeba 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -61,9 +61,8 @@ static int verify_object_in_tag(struct object_id *tagged_oid, int *tagged_type)
 		    type_name(*tagged_type), type_name(type));
 
 	repl = lookup_replace_object(the_repository, tagged_oid);
-	ret = check_object_signature(the_repository, repl,
-				     buffer, size, type_name(*tagged_type),
-				     NULL);
+	ret = check_object_signature(the_repository, repl, buffer, size,
+				     type_name(*tagged_type));
 	free(buffer);
 
 	return ret;
diff --git a/cache.h b/cache.h
index 5d08195212..c068f99c79 100644
--- a/cache.h
+++ b/cache.h
@@ -1322,15 +1322,19 @@ int parse_loose_header(const char *hdr, struct object_info *oi);
 /**
  * With in-core object data in "buf", rehash it to make sure the
  * object name actually matches "oid" to detect object corruption.
- * With "buf" == NULL, try reading the object named with "oid" using
- * the streaming interface and rehash it to do the same.
  *
  * A negative value indicates an error, usually that the OID is not
  * what we expected, but it might also indicate another error.
  */
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *buf, unsigned long size, const char *type,
-			   struct object_id *real_oidp);
+			   void *buf, unsigned long size, const char *type);
+
+/**
+ * A streaming version of check_object_signature().
+ * Try reading the object named with "oid" using
+ * the streaming interface and rehash it to do the same.
+ */
+int stream_object_signature(struct repository *r, const struct object_id *oid);
 
 int finalize_object_file(const char *tmpfile, const char *filename);
 
diff --git a/object-file.c b/object-file.c
index d628f58c0d..f985492274 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1067,22 +1067,25 @@ int format_object_header(char *str, size_t size, enum object_type type,
 }
 
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *buf, unsigned long size, const char *type,
-			   struct object_id *real_oidp)
+			   void *buf, unsigned long size, const char *type)
 {
-	struct object_id tmp;
-	struct object_id *real_oid = real_oidp ? real_oidp : &tmp;
+	struct object_id real_oid;
+
+	hash_object_file(r->hash_algo, buf, size, type, &real_oid);
+
+	return !oideq(oid, &real_oid) ? -1 : 0;
+}
+
+int stream_object_signature(struct repository *r, const struct object_id *oid)
+{
+	struct object_id real_oid;
+	unsigned long size;
 	enum object_type obj_type;
 	struct git_istream *st;
 	git_hash_ctx c;
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen;
 
-	if (buf) {
-		hash_object_file(r->hash_algo, buf, size, type, real_oid);
-		return !oideq(oid, real_oid) ? -1 : 0;
-	}
-
 	st = open_istream(r, oid, &obj_type, &size, NULL);
 	if (!st)
 		return -1;
@@ -1105,9 +1108,9 @@ int check_object_signature(struct repository *r, const struct object_id *oid,
 			break;
 		r->hash_algo->update_fn(&c, buf, readlen);
 	}
-	r->hash_algo->final_oid_fn(real_oid, &c);
+	r->hash_algo->final_oid_fn(&real_oid, &c);
 	close_istream(st);
-	return !oideq(oid, real_oid) ? -1 : 0;
+	return !oideq(oid, &real_oid) ? -1 : 0;
 }
 
 int git_open_cloexec(const char *name, int flags)
@@ -2611,9 +2614,10 @@ int read_loose_object(const char *path,
 			git_inflate_end(&stream);
 			goto out;
 		}
-		if (check_object_signature(the_repository, expected_oid,
-					   *contents, *size,
-					   oi->type_name->buf, real_oid) < 0)
+		hash_object_file(the_repository->hash_algo,
+				 *contents, *size, oi->type_name->buf,
+				 real_oid);
+		if (!oideq(expected_oid, real_oid))
 			goto out;
 	}
 
diff --git a/object.c b/object.c
index c37501fc12..d07678ef6d 100644
--- a/object.c
+++ b/object.c
@@ -279,7 +279,7 @@ struct object *parse_object(struct repository *r, const struct object_id *oid)
 	if ((obj && obj->type == OBJ_BLOB && repo_has_object_file(r, oid)) ||
 	    (!obj && repo_has_object_file(r, oid) &&
 	     oid_object_info(r, oid, NULL) == OBJ_BLOB)) {
-		if (check_object_signature(r, repl, NULL, 0, NULL, NULL) < 0) {
+		if (stream_object_signature(r, repl) < 0) {
 			error(_("hash mismatch %s"), oid_to_hex(oid));
 			return NULL;
 		}
@@ -290,7 +290,7 @@ struct object *parse_object(struct repository *r, const struct object_id *oid)
 	buffer = repo_read_object_file(r, oid, &type, &size);
 	if (buffer) {
 		if (check_object_signature(r, repl, buffer, size,
-					   type_name(type), NULL) < 0) {
+					   type_name(type)) < 0) {
 			free(buffer);
 			error(_("hash mismatch %s"), oid_to_hex(repl));
 			return NULL;
diff --git a/pack-check.c b/pack-check.c
index 48d818ee7b..d8d8f91de6 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -127,7 +127,7 @@ static int verify_packfile(struct repository *r,
 
 		if (type == OBJ_BLOB && big_file_threshold <= size) {
 			/*
-			 * Let check_object_signature() check it with
+			 * Let stream_object_signature() check it with
 			 * the streaming interface; no point slurping
 			 * the data in-core only to discard.
 			 */
@@ -142,8 +142,11 @@ static int verify_packfile(struct repository *r,
 			err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 				    oid_to_hex(&oid), p->pack_name,
 				    (uintmax_t)entries[i].offset);
-		else if (check_object_signature(r, &oid, data, size,
-						type_name(type), NULL) < 0)
+		else if (data && check_object_signature(r, &oid, data, size,
+							type_name(type)) < 0)
+			err = error("packed %s from %s is corrupt",
+				    oid_to_hex(&oid), p->pack_name);
+		else if (!data && stream_object_signature(r, &oid) < 0)
 			err = error("packed %s from %s is corrupt",
 				    oid_to_hex(&oid), p->pack_name);
 		else if (fn) {

From 0ff7b4f976b78ab38313356b3e0582e5fa9a3bcc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:31 +0100
Subject: [PATCH 09/12] object API: rename hash_object_file_literally() to
 write_*()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before 0c3db67cc81 (hash-object --literally: fix buffer overrun with
extra-long object type, 2015-05-04) the hash-object code being changed
here called write_sha1_file() to both hash and write a loose
object. Before that we'd use hash_sha1_file() to if "-w" wasn't
provided, and otherwise call write_sha1_file().

Now we'll always call the same function for both writing. Let's rename
it from hash_*_literally() to write_*_literally(). Even though the
write_*() might not actually write if HASH_WRITE_OBJECT isn't in
"flags", having it be more similar to write_object_file_flags() than
hash_object_file(), but carrying a name that would suggest that it's a
variant of the latter is confusing.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/hash-object.c | 2 +-
 object-file.c         | 6 +++---
 object-store.h        | 6 +++---
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/builtin/hash-object.c b/builtin/hash-object.c
index c7b3ad74c6..f4cbd9c4ae 100644
--- a/builtin/hash-object.c
+++ b/builtin/hash-object.c
@@ -25,7 +25,7 @@ static int hash_literally(struct object_id *oid, int fd, const char *type, unsig
 	if (strbuf_read(&buf, fd, 4096) < 0)
 		ret = -1;
 	else
-		ret = hash_object_file_literally(buf.buf, buf.len, type, oid,
+		ret = write_object_file_literally(buf.buf, buf.len, type, oid,
 						 flags);
 	strbuf_release(&buf);
 	return ret;
diff --git a/object-file.c b/object-file.c
index f985492274..9e5b849693 100644
--- a/object-file.c
+++ b/object-file.c
@@ -2027,9 +2027,9 @@ int write_object_file_flags(const void *buf, unsigned long len,
 	return write_loose_object(oid, hdr, hdrlen, buf, len, 0, flags);
 }
 
-int hash_object_file_literally(const void *buf, unsigned long len,
-			       const char *type, struct object_id *oid,
-			       unsigned flags)
+int write_object_file_literally(const void *buf, unsigned long len,
+				const char *type, struct object_id *oid,
+				unsigned flags)
 {
 	char *header;
 	int hdrlen, status = 0;
diff --git a/object-store.h b/object-store.h
index eab1e2a967..29169d117f 100644
--- a/object-store.h
+++ b/object-store.h
@@ -258,9 +258,9 @@ static inline int write_object_file(const void *buf, unsigned long len,
 	return write_object_file_flags(buf, len, type, oid, 0);
 }
 
-int hash_object_file_literally(const void *buf, unsigned long len,
-			       const char *type, struct object_id *oid,
-			       unsigned flags);
+int write_object_file_literally(const void *buf, unsigned long len,
+				const char *type, struct object_id *oid,
+				unsigned flags);
 
 /*
  * Add an object file to the in-memory object store, without writing it

From 44439c1c5827480f68b37c3cc38f257eaeb3ed2c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:32 +0100
Subject: [PATCH 10/12] object-file API: have hash_object_file() take "enum
 object_type"
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change the hash_object_file() function to take an "enum
object_type".

Since a preceding commit all of its callers are passing either
"{commit,tree,blob,tag}_type", or the result of a call to type_name(),
the parse_object() caller that would pass NULL is now using
stream_object_signature().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 apply.c                  |  4 ++--
 builtin/fast-export.c    |  2 +-
 builtin/index-pack.c     |  4 ++--
 builtin/mktag.c          |  2 +-
 builtin/replace.c        |  2 +-
 builtin/unpack-objects.c |  2 +-
 cache-tree.c             |  6 +++---
 cache.h                  |  3 ++-
 convert.c                |  2 +-
 diffcore-rename.c        |  2 +-
 dir.c                    |  2 +-
 log-tree.c               |  2 +-
 object-file.c            | 35 +++++++++++++++++++++--------------
 object-store.h           |  2 +-
 object.c                 |  3 +--
 pack-check.c             |  2 +-
 16 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/apply.c b/apply.c
index e82a7c30f0..8513755e25 100644
--- a/apply.c
+++ b/apply.c
@@ -3157,7 +3157,7 @@ static int apply_binary(struct apply_state *state,
 		 * See if the old one matches what the patch
 		 * applies to.
 		 */
-		hash_object_file(the_hash_algo, img->buf, img->len, blob_type,
+		hash_object_file(the_hash_algo, img->buf, img->len, OBJ_BLOB,
 				 &oid);
 		if (strcmp(oid_to_hex(&oid), patch->old_oid_prefix))
 			return error(_("the patch applies to '%s' (%s), "
@@ -3203,7 +3203,7 @@ static int apply_binary(struct apply_state *state,
 				     name);
 
 		/* verify that the result matches */
-		hash_object_file(the_hash_algo, img->buf, img->len, blob_type,
+		hash_object_file(the_hash_algo, img->buf, img->len, OBJ_BLOB,
 				 &oid);
 		if (strcmp(oid_to_hex(&oid), patch->new_oid_prefix))
 			return error(_("binary patch to '%s' creates incorrect result (expecting %s, got %s)"),
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 319859db30..52aebeb521 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -300,7 +300,7 @@ static void export_blob(const struct object_id *oid)
 		if (!buf)
 			die("could not read blob %s", oid_to_hex(oid));
 		if (check_object_signature(the_repository, oid, buf, size,
-					   type_name(type)) < 0)
+					   type) < 0)
 			die("oid mismatch in blob %s", oid_to_hex(oid));
 		object = parse_object_buffer(the_repository, oid, type,
 					     size, buf, &eaten);
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index e1927205a7..d0c3e0966b 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -970,7 +970,7 @@ static struct base_data *resolve_delta(struct object_entry *delta_obj,
 	if (!result_data)
 		bad_object(delta_obj->idx.offset, _("failed to apply delta"));
 	hash_object_file(the_hash_algo, result_data, result_size,
-			 type_name(delta_obj->real_type), &delta_obj->idx.oid);
+			 delta_obj->real_type, &delta_obj->idx.oid);
 	sha1_object(result_data, NULL, result_size, delta_obj->real_type,
 		    &delta_obj->idx.oid);
 
@@ -1413,7 +1413,7 @@ static void fix_unresolved_deltas(struct hashfile *f)
 			continue;
 
 		if (check_object_signature(the_repository, &d->oid, data, size,
-					   type_name(type)) < 0)
+					   type) < 0)
 			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
 
 		/*
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 4d28eceeba..14b9fe3bc0 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -62,7 +62,7 @@ static int verify_object_in_tag(struct object_id *tagged_oid, int *tagged_type)
 
 	repl = lookup_replace_object(the_repository, tagged_oid);
 	ret = check_object_signature(the_repository, repl, buffer, size,
-				     type_name(*tagged_type));
+				     *tagged_type);
 	free(buffer);
 
 	return ret;
diff --git a/builtin/replace.c b/builtin/replace.c
index 995ca68330..53a3b24657 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -409,7 +409,7 @@ static int check_one_mergetag(struct commit *commit,
 	int i;
 
 	hash_object_file(the_hash_algo, extra->value, extra->len,
-			 type_name(OBJ_TAG), &tag_oid);
+			 OBJ_TAG, &tag_oid);
 	tag = lookup_tag(the_repository, &tag_oid);
 	if (!tag)
 		return error(_("bad mergetag in commit '%s'"), ref);
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 808041551f..dbeb0680a5 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -266,7 +266,7 @@ static void write_object(unsigned nr, enum object_type type,
 	} else {
 		struct object *obj;
 		int eaten;
-		hash_object_file(the_hash_algo, buf, size, type_name(type),
+		hash_object_file(the_hash_algo, buf, size, type,
 				 &obj_list[nr].oid);
 		added_object(nr, type, buf, size);
 		obj = parse_object_buffer(the_repository, &obj_list[nr].oid,
diff --git a/cache-tree.c b/cache-tree.c
index fdbbd191d2..6752f69d51 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -432,14 +432,14 @@ static int update_one(struct cache_tree *it,
 	if (repair) {
 		struct object_id oid;
 		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
-				 tree_type, &oid);
+				 OBJ_TREE, &oid);
 		if (has_object_file_with_flags(&oid, OBJECT_INFO_SKIP_FETCH_OBJECT))
 			oidcpy(&it->oid, &oid);
 		else
 			to_invalidate = 1;
 	} else if (dryrun) {
 		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
-				 tree_type, &it->oid);
+				 OBJ_TREE, &it->oid);
 	} else if (write_object_file_flags(buffer.buf, buffer.len, OBJ_TREE,
 					   &it->oid, flags & WRITE_TREE_SILENT
 					   ? HASH_SILENT : 0)) {
@@ -948,7 +948,7 @@ static int verify_one(struct repository *r,
 		strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
 		strbuf_add(&tree_buf, oid->hash, r->hash_algo->rawsz);
 	}
-	hash_object_file(r->hash_algo, tree_buf.buf, tree_buf.len, tree_type,
+	hash_object_file(r->hash_algo, tree_buf.buf, tree_buf.len, OBJ_TREE,
 			 &new_oid);
 	if (!oideq(&new_oid, &it->oid))
 		BUG("cache-tree for path %.*s does not match. "
diff --git a/cache.h b/cache.h
index c068f99c79..2027803c49 100644
--- a/cache.h
+++ b/cache.h
@@ -1327,7 +1327,8 @@ int parse_loose_header(const char *hdr, struct object_info *oi);
  * what we expected, but it might also indicate another error.
  */
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *buf, unsigned long size, const char *type);
+			   void *map, unsigned long size,
+			   enum object_type type);
 
 /**
  * A streaming version of check_object_signature().
diff --git a/convert.c b/convert.c
index df7186bd81..d88072fe32 100644
--- a/convert.c
+++ b/convert.c
@@ -1159,7 +1159,7 @@ static int ident_to_worktree(const char *src, size_t len,
 	/* are we "faking" in place editing ? */
 	if (src == buf->buf)
 		to_free = strbuf_detach(buf, NULL);
-	hash_object_file(the_hash_algo, src, len, "blob", &oid);
+	hash_object_file(the_hash_algo, src, len, OBJ_BLOB, &oid);
 
 	strbuf_grow(buf, len + cnt * (the_hash_algo->hexsz + 3));
 	for (;;) {
diff --git a/diffcore-rename.c b/diffcore-rename.c
index bebd4ed6a4..c0422d9e70 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -261,7 +261,7 @@ static unsigned int hash_filespec(struct repository *r,
 		if (diff_populate_filespec(r, filespec, NULL))
 			return 0;
 		hash_object_file(r->hash_algo, filespec->data, filespec->size,
-				 "blob", &filespec->oid);
+				 OBJ_BLOB, &filespec->oid);
 	}
 	return oidhash(&filespec->oid);
 }
diff --git a/dir.c b/dir.c
index d91295f2bc..5674e8a625 100644
--- a/dir.c
+++ b/dir.c
@@ -1113,7 +1113,7 @@ static int add_patterns(const char *fname, const char *base, int baselen,
 				       &istate->cache[pos]->oid);
 			else
 				hash_object_file(the_hash_algo, buf, size,
-						 "blob", &oid_stat->oid);
+						 OBJ_BLOB, &oid_stat->oid);
 			fill_stat_data(&oid_stat->stat, &st);
 			oid_stat->valid = 1;
 		}
diff --git a/log-tree.c b/log-tree.c
index d3e7a40b64..27a5b0bd61 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -561,7 +561,7 @@ static int show_one_mergetag(struct commit *commit,
 	struct strbuf signature = STRBUF_INIT;
 
 	hash_object_file(the_hash_algo, extra->value, extra->len,
-			 type_name(OBJ_TAG), &oid);
+			 OBJ_TAG, &oid);
 	tag = lookup_tag(the_repository, &oid);
 	if (!tag)
 		return -1; /* error message already given */
diff --git a/object-file.c b/object-file.c
index 9e5b849693..b1cb78c441 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1067,7 +1067,8 @@ int format_object_header(char *str, size_t size, enum object_type type,
 }
 
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *buf, unsigned long size, const char *type)
+			   void *buf, unsigned long size,
+			   enum object_type type)
 {
 	struct object_id real_oid;
 
@@ -1676,7 +1677,7 @@ int pretend_object_file(void *buf, unsigned long len, enum object_type type,
 {
 	struct cached_object *co;
 
-	hash_object_file(the_hash_algo, buf, len, type_name(type), oid);
+	hash_object_file(the_hash_algo, buf, len, type, oid);
 	if (has_object_file_with_flags(oid, OBJECT_INFO_QUICK | OBJECT_INFO_SKIP_FETCH_OBJECT) ||
 	    find_cached_object(oid))
 		return 0;
@@ -1850,15 +1851,23 @@ static int write_buffer(int fd, const void *buf, size_t len)
 	return 0;
 }
 
-void hash_object_file(const struct git_hash_algo *algo, const void *buf,
-		     unsigned long len, const char *type,
-		     struct object_id *oid)
+static void hash_object_file_literally(const struct git_hash_algo *algo,
+				       const void *buf, unsigned long len,
+				       const char *type, struct object_id *oid)
 {
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
+
 	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
 }
 
+void hash_object_file(const struct git_hash_algo *algo, const void *buf,
+		      unsigned long len, enum object_type type,
+		      struct object_id *oid)
+{
+	hash_object_file_literally(algo, buf, len, type_name(type), oid);
+}
+
 /* Finalize a file on disk, and close it. */
 static void close_loose_object(int fd)
 {
@@ -2161,9 +2170,7 @@ static int index_mem(struct index_state *istate,
 	if (write_object)
 		ret = write_object_file(buf, size, type, oid);
 	else
-		hash_object_file(the_hash_algo, buf, size, type_name(type),
-				 oid);
-
+		hash_object_file(the_hash_algo, buf, size, type, oid);
 	if (re_allocated)
 		free(buf);
 	return ret;
@@ -2189,8 +2196,8 @@ static int index_stream_convert_blob(struct index_state *istate,
 		ret = write_object_file(sbuf.buf, sbuf.len, OBJ_BLOB,
 					oid);
 	else
-		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
-				 type_name(OBJ_BLOB), oid);
+		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len, OBJ_BLOB,
+				 oid);
 	strbuf_release(&sbuf);
 	return ret;
 }
@@ -2309,7 +2316,7 @@ int index_path(struct index_state *istate, struct object_id *oid,
 			return error_errno("readlink(\"%s\")", path);
 		if (!(flags & HASH_WRITE_OBJECT))
 			hash_object_file(the_hash_algo, sb.buf, sb.len,
-					 blob_type, oid);
+					 OBJ_BLOB, oid);
 		else if (write_object_file(sb.buf, sb.len, OBJ_BLOB, oid))
 			rc = error(_("%s: failed to insert into database"), path);
 		strbuf_release(&sb);
@@ -2614,9 +2621,9 @@ int read_loose_object(const char *path,
 			git_inflate_end(&stream);
 			goto out;
 		}
-		hash_object_file(the_repository->hash_algo,
-				 *contents, *size, oi->type_name->buf,
-				 real_oid);
+		hash_object_file_literally(the_repository->hash_algo,
+					   *contents, *size,
+					   oi->type_name->buf, real_oid);
 		if (!oideq(expected_oid, real_oid))
 			goto out;
 	}
diff --git a/object-store.h b/object-store.h
index 29169d117f..bd2322ed8c 100644
--- a/object-store.h
+++ b/object-store.h
@@ -246,7 +246,7 @@ static inline void *repo_read_object_file(struct repository *r,
 int oid_object_info(struct repository *r, const struct object_id *, unsigned long *);
 
 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
-		      unsigned long len, const char *type,
+		      unsigned long len, enum object_type type,
 		      struct object_id *oid);
 
 int write_object_file_flags(const void *buf, unsigned long len,
diff --git a/object.c b/object.c
index d07678ef6d..588b8156f1 100644
--- a/object.c
+++ b/object.c
@@ -289,8 +289,7 @@ struct object *parse_object(struct repository *r, const struct object_id *oid)
 
 	buffer = repo_read_object_file(r, oid, &type, &size);
 	if (buffer) {
-		if (check_object_signature(r, repl, buffer, size,
-					   type_name(type)) < 0) {
+		if (check_object_signature(r, repl, buffer, size, type) < 0) {
 			free(buffer);
 			error(_("hash mismatch %s"), oid_to_hex(repl));
 			return NULL;
diff --git a/pack-check.c b/pack-check.c
index d8d8f91de6..bfb593ba72 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -143,7 +143,7 @@ static int verify_packfile(struct repository *r,
 				    oid_to_hex(&oid), p->pack_name,
 				    (uintmax_t)entries[i].offset);
 		else if (data && check_object_signature(r, &oid, data, size,
-							type_name(type)) < 0)
+							type) < 0)
 			err = error("packed %s from %s is corrupt",
 				    oid_to_hex(&oid), p->pack_name);
 		else if (!data && stream_object_signature(r, &oid) < 0)

From 2bbb28a3ee2f7252de02f5d0db4da79090b4f8fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:33 +0100
Subject: [PATCH 11/12] object-file.c: add a literal version of
 write_object_file_prepare()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Split off a *_literally() variant of the write_object_file_prepare()
function. To do this create a new "hash_object_body()" static helper.

We now defer the type_name() call until the very last moment in
format_object_header() for those callers that aren't "hash-object
--literally".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 object-file.c | 41 ++++++++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/object-file.c b/object-file.c
index b1cb78c441..c75c12dd0b 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1784,21 +1784,40 @@ void *read_object_with_reference(struct repository *r,
 	}
 }
 
+static void hash_object_body(const struct git_hash_algo *algo, git_hash_ctx *c,
+			     const void *buf, unsigned long len,
+			     struct object_id *oid,
+			     char *hdr, int *hdrlen)
+{
+	algo->init_fn(c);
+	algo->update_fn(c, hdr, *hdrlen);
+	algo->update_fn(c, buf, len);
+	algo->final_oid_fn(oid, c);
+}
+
 static void write_object_file_prepare(const struct git_hash_algo *algo,
+				      const void *buf, unsigned long len,
+				      enum object_type type, struct object_id *oid,
+				      char *hdr, int *hdrlen)
+{
+	git_hash_ctx c;
+
+	/* Generate the header */
+	*hdrlen = format_object_header(hdr, *hdrlen, type, len);
+
+	/* Sha1.. */
+	hash_object_body(algo, &c, buf, len, oid, hdr, hdrlen);
+}
+
+static void write_object_file_prepare_literally(const struct git_hash_algo *algo,
 				      const void *buf, unsigned long len,
 				      const char *type, struct object_id *oid,
 				      char *hdr, int *hdrlen)
 {
 	git_hash_ctx c;
 
-	/* Generate the header */
 	*hdrlen = format_object_header_literally(hdr, *hdrlen, type, len);
-
-	/* Sha1.. */
-	algo->init_fn(&c);
-	algo->update_fn(&c, hdr, *hdrlen);
-	algo->update_fn(&c, buf, len);
-	algo->final_oid_fn(oid, &c);
+	hash_object_body(algo, &c, buf, len, oid, hdr, hdrlen);
 }
 
 /*
@@ -1858,7 +1877,7 @@ static void hash_object_file_literally(const struct git_hash_algo *algo,
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
 
-	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
+	write_object_file_prepare_literally(algo, buf, len, type, oid, hdr, &hdrlen);
 }
 
 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
@@ -2029,7 +2048,7 @@ int write_object_file_flags(const void *buf, unsigned long len,
 	/* Normally if we have it in the pack then we do not bother writing
 	 * it out into .git/objects/??/?{38} file.
 	 */
-	write_object_file_prepare(the_hash_algo, buf, len, type_name(type), oid, hdr,
+	write_object_file_prepare(the_hash_algo, buf, len, type, oid, hdr,
 				  &hdrlen);
 	if (freshen_packed_object(oid) || freshen_loose_object(oid))
 		return 0;
@@ -2046,8 +2065,8 @@ int write_object_file_literally(const void *buf, unsigned long len,
 	/* type string, SP, %lu of the length plus NUL must fit this */
 	hdrlen = strlen(type) + MAX_HEADER_LEN;
 	header = xmalloc(hdrlen);
-	write_object_file_prepare(the_hash_algo, buf, len, type, oid, header,
-				  &hdrlen);
+	write_object_file_prepare_literally(the_hash_algo, buf, len, type,
+					    oid, header, &hdrlen);
 
 	if (!(flags & HASH_WRITE_OBJECT))
 		goto cleanup;

From 6aea6baeb3ece6c832dbdf1deed09f41aebf85c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?=
 <avarab@gmail.com>
Date: Sat, 5 Feb 2022 00:48:34 +0100
Subject: [PATCH 12/12] object-file API: pass an enum to
 read_object_with_reference()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change the read_object_with_reference() function to take an "enum
object_type". It was not prepared to handle an arbitrary "const
char *type", as it was itself calling type_from_string().

Let's change the only caller that passes in user data to use
type_from_string(), and convert the rest to use e.g. "OBJ_TREE"
instead of "tree_type".

The "cat-file" caller is not on the codepath that
handles"--allow-unknown", so the type_from_string() there is safe. Its
use of type_from_string() doesn't functionally differ from that of the
pre-image.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/cat-file.c     | 11 +++++++----
 builtin/fast-import.c  |  6 +++---
 builtin/grep.c         |  4 ++--
 builtin/pack-objects.c |  2 +-
 cache.h                |  2 +-
 object-file.c          |  5 ++---
 tree-walk.c            |  6 +++---
 7 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index d94050e6c1..3c5bc505e0 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -154,7 +154,10 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		break;
 
 	case 0:
-		if (type_from_string(exp_type) == OBJ_BLOB) {
+	{
+		enum object_type exp_type_id = type_from_string(exp_type);
+
+		if (exp_type_id == OBJ_BLOB) {
 			struct object_id blob_oid;
 			if (oid_object_info(the_repository, &oid, NULL) == OBJ_TAG) {
 				char *buffer = read_object_file(&oid, &type,
@@ -176,10 +179,10 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 			 * fall-back to the usual case.
 			 */
 		}
-		buf = read_object_with_reference(the_repository,
-						 &oid, exp_type, &size, NULL);
+		buf = read_object_with_reference(the_repository, &oid,
+						 exp_type_id, &size, NULL);
 		break;
-
+	}
 	default:
 		die("git cat-file: unknown option: %s", exp_type);
 	}
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index 123df7d9a5..c52e807f56 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -2483,7 +2483,7 @@ static void note_change_n(const char *p, struct branch *b, unsigned char *old_fa
 		unsigned long size;
 		char *buf = read_object_with_reference(the_repository,
 						       &commit_oid,
-						       commit_type, &size,
+						       OBJ_COMMIT, &size,
 						       &commit_oid);
 		if (!buf || size < the_hash_algo->hexsz + 6)
 			die("Not a valid commit: %s", p);
@@ -2555,7 +2555,7 @@ static void parse_from_existing(struct branch *b)
 		char *buf;
 
 		buf = read_object_with_reference(the_repository,
-						 &b->oid, commit_type, &size,
+						 &b->oid, OBJ_COMMIT, &size,
 						 &b->oid);
 		parse_from_commit(b, buf, size);
 		free(buf);
@@ -2651,7 +2651,7 @@ static struct hash_list *parse_merge(unsigned int *count)
 			unsigned long size;
 			char *buf = read_object_with_reference(the_repository,
 							       &n->oid,
-							       commit_type,
+							       OBJ_COMMIT,
 							       &size, &n->oid);
 			if (!buf || size < the_hash_algo->hexsz + 6)
 				die("Not a valid commit: %s", from);
diff --git a/builtin/grep.c b/builtin/grep.c
index 9e34a820ad..75e07b5623 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -482,7 +482,7 @@ static int grep_submodule(struct grep_opt *opt,
 		object_type = oid_object_info(subrepo, oid, NULL);
 		obj_read_unlock();
 		data = read_object_with_reference(subrepo,
-						  oid, tree_type,
+						  oid, OBJ_TREE,
 						  &size, NULL);
 		if (!data)
 			die(_("unable to read tree (%s)"), oid_to_hex(oid));
@@ -651,7 +651,7 @@ static int grep_object(struct grep_opt *opt, const struct pathspec *pathspec,
 		int hit, len;
 
 		data = read_object_with_reference(opt->repo,
-						  &obj->oid, tree_type,
+						  &obj->oid, OBJ_TREE,
 						  &size, NULL);
 		if (!data)
 			die(_("unable to read tree (%s)"), oid_to_hex(&obj->oid));
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index ba2006f221..c4df3df314 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1802,7 +1802,7 @@ static void add_preferred_base(struct object_id *oid)
 		return;
 
 	data = read_object_with_reference(the_repository, oid,
-					  tree_type, &size, &tree_oid);
+					  OBJ_TREE, &size, &tree_oid);
 	if (!data)
 		return;
 
diff --git a/cache.h b/cache.h
index 2027803c49..0e7fc8b7c2 100644
--- a/cache.h
+++ b/cache.h
@@ -1561,7 +1561,7 @@ int cache_name_stage_compare(const char *name1, int len1, int stage1, const char
 
 void *read_object_with_reference(struct repository *r,
 				 const struct object_id *oid,
-				 const char *required_type,
+				 enum object_type required_type,
 				 unsigned long *size,
 				 struct object_id *oid_ret);
 
diff --git a/object-file.c b/object-file.c
index c75c12dd0b..6cbdb836cb 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1737,16 +1737,15 @@ void *read_object_file_extended(struct repository *r,
 
 void *read_object_with_reference(struct repository *r,
 				 const struct object_id *oid,
-				 const char *required_type_name,
+				 enum object_type required_type,
 				 unsigned long *size,
 				 struct object_id *actual_oid_return)
 {
-	enum object_type type, required_type;
+	enum object_type type;
 	void *buffer;
 	unsigned long isize;
 	struct object_id actual_oid;
 
-	required_type = type_from_string(required_type_name);
 	oidcpy(&actual_oid, oid);
 	while (1) {
 		int ref_length = -1;
diff --git a/tree-walk.c b/tree-walk.c
index 3a94959d64..506234b4b8 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -89,7 +89,7 @@ void *fill_tree_descriptor(struct repository *r,
 	void *buf = NULL;
 
 	if (oid) {
-		buf = read_object_with_reference(r, oid, tree_type, &size, NULL);
+		buf = read_object_with_reference(r, oid, OBJ_TREE, &size, NULL);
 		if (!buf)
 			die("unable to read tree %s", oid_to_hex(oid));
 	}
@@ -605,7 +605,7 @@ int get_tree_entry(struct repository *r,
 	unsigned long size;
 	struct object_id root;
 
-	tree = read_object_with_reference(r, tree_oid, tree_type, &size, &root);
+	tree = read_object_with_reference(r, tree_oid, OBJ_TREE, &size, &root);
 	if (!tree)
 		return -1;
 
@@ -677,7 +677,7 @@ enum get_oid_result get_tree_entry_follow_symlinks(struct repository *r,
 			unsigned long size;
 			tree = read_object_with_reference(r,
 							  &current_tree_oid,
-							  tree_type, &size,
+							  OBJ_TREE, &size,
 							  &root);
 			if (!tree)
 				goto done;