Merge branch 'ab/object-file-api-updates'

Object-file API shuffling.

* ab/object-file-api-updates:
  object-file API: pass an enum to read_object_with_reference()
  object-file.c: add a literal version of write_object_file_prepare()
  object-file API: have hash_object_file() take "enum object_type"
  object API: rename hash_object_file_literally() to write_*()
  object-file API: split up and simplify check_object_signature()
  object API users + docs: check <0, not !0 with check_object_signature()
  object API docs: move check_object_signature() docs to cache.h
  object API: correct "buf" v.s. "map" mismatch in *.c and *.h
  object-file API: have write_object_file() take "enum object_type"
  object-file API: add a format_object_header() function
  object-file API: return "void", not "int" from hash_object_file()
  object-file.c: split up declaration of unrelated variables

apply.c

@@ -3164,7 +3164,7 @@ 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), "
@@ -3210,7 +3210,7 @@ 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)"),
@@ -3599,7 +3599,7 @@ 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."));
@@ -3615,7 +3615,7 @@ 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 */
@@ -3628,7 +3628,7 @@ 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 */
@@ -4328,7 +4328,7 @@ 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);

builtin/cat-file.c

@@ -156,7 +156,10 @@ 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,
@@ -178,10 +181,10 @@ 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,
+		buf = read_object_with_reference(the_repository, &oid,
-						 &oid, exp_type, &size, NULL);
+						 exp_type_id, &size, NULL);
 		break;
-
+	}
 	default:
 		die("git cat-file: unknown option: %s", exp_type);
 	}

builtin/checkout.c

@@ -303,7 +303,7 @@ 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);

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) < 0)
 			die("oid mismatch in blob %s", oid_to_hex(oid));
 		object = parse_object_buffer(the_repository, oid, type,
 					     size, buf, &eaten);

builtin/fast-import.c

@@ -944,8 +944,8 @@ static int store_object(
 	git_hash_ctx c;
 	git_zstream s;
 
-	hdrlen = xsnprintf((char *)hdr, sizeof(hdr), "%s %lu",
+	hdrlen = format_object_header((char *)hdr, sizeof(hdr), type,
-			   type_name(type), (unsigned long)dat->len) + 1;
+				      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);
@@ -1098,7 +1098,7 @@ 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);
@@ -2490,7 +2490,7 @@ 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);
@@ -2562,7 +2562,7 @@ 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);
@@ -2658,7 +2658,7 @@ 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);

builtin/grep.c

@@ -484,7 +484,7 @@ 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));
@@ -653,7 +653,7 @@ 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));

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;

builtin/index-pack.c

@@ -453,8 +453,7 @@ 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,
+		hdrlen = format_object_header(hdr, sizeof(hdr), type, size);
-				   type_name(type),(uintmax_t)size) + 1;
 		the_hash_algo->init_fn(&c);
 		the_hash_algo->update_fn(&c, hdr, hdrlen);
 	} else
@@ -975,7 +974,7 @@ 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);
 
@@ -1419,9 +1418,8 @@ static void fix_unresolved_deltas(struct hashfile *f)
 		if (!data)
 			continue;
 
-		if (check_object_signature(the_repository, &d->oid,
+		if (check_object_signature(the_repository, &d->oid, data, size,
-					   data, size,
+					   type) < 0)
-					   type_name(type), NULL))
 			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
 
 		/*

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,
+	ret = check_object_signature(the_repository, repl, buffer, size,
-				     buffer, size, type_name(*tagged_type),
+				     *tagged_type);
-				     NULL);
 	free(buffer);
 
 	return ret;
@@ -97,10 +96,10 @@ 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, 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);

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);
 }
 

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)

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;
 

builtin/receive-pack.c

@@ -749,7 +749,7 @@ 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);
 

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);
@@ -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);

builtin/tag.c

@@ -239,7 +239,7 @@ 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;
 }

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);
@@ -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,

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,
+	header_len = format_object_header((char *)obuf, sizeof(obuf),
-			       type_name(type), (uintmax_t)size) + 1;
+					  type, size);
 	the_hash_algo->init_fn(&ctx);
 	the_hash_algo->update_fn(&ctx, obuf, header_len);
 

cache-tree.c

@@ -432,15 +432,15 @@ 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, 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);
@@ -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. "

cache.h

@@ -1320,9 +1320,23 @@ 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.
+ *
+ * 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,
+			   void *map, unsigned long size,
-			   struct object_id *real_oidp);
+			   enum object_type 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);
 
@@ -1549,7 +1563,7 @@ 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);
 

commit.c

@@ -1568,7 +1568,7 @@ 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;

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 (;;) {

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);
 }

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;
 		}

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);

log-tree.c

@@ -565,7 +565,7 @@ 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 */

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;
 }

merge-ort.c

@@ -1938,7 +1938,7 @@ 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);
 
@@ -3392,7 +3392,7 @@ 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);
 }
 

merge-recursive.c

@@ -1376,7 +1376,7 @@ 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);
 

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);
 }

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;
 }

object-file.c

@@ -1049,35 +1049,50 @@ void *xmmap(void *start, size_t length,
 	return ret;
 }
 
-/*
+static int format_object_header_literally(char *str, size_t size,
- * With an in-core object data in "map", rehash it to make sure the
+					  const char *type, size_t objsize)
- * object name actually matches "oid" to detect object corruption.
- * With "map" == 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,
-			   struct object_id *real_oidp)
 {
-	struct object_id tmp;
+	return xsnprintf(str, size, "%s %"PRIuMAX, type, (uintmax_t)objsize) + 1;
-	struct object_id *real_oid = real_oidp ? real_oidp : &tmp;
+}
+
+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);
+}
+
+int check_object_signature(struct repository *r, const struct object_id *oid,
+			   void *buf, unsigned long size,
+			   enum object_type type)
+{
+	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 (map) {
-		hash_object_file(r->hash_algo, map, size, type, real_oid);
-		return !oideq(oid, real_oid) ? -1 : 0;
-	}
-
 	st = open_istream(r, oid, &obj_type, &size, NULL);
 	if (!st)
 		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);
@@ -1094,9 +1109,9 @@ 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)
@@ -1662,7 +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;
@@ -1722,16 +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;
@@ -1769,21 +1783,40 @@ 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);
-	*hdrlen = xsnprintf(hdr, *hdrlen, "%s %"PRIuMAX , type, (uintmax_t)len)+1;
+	hash_object_body(algo, &c, buf, len, oid, hdr, hdrlen);
-
-	/* Sha1.. */
-	algo->init_fn(&c);
-	algo->update_fn(&c, hdr, *hdrlen);
-	algo->update_fn(&c, buf, len);
-	algo->final_oid_fn(oid, &c);
 }
 
 /*
@@ -1836,14 +1869,21 @@ 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,
+static void hash_object_file_literally(const struct git_hash_algo *algo,
-		     unsigned long len, const char *type,
+				       const void *buf, unsigned long len,
-		     struct object_id *oid)
+				       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;
+	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,
+		      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. */
@@ -1998,7 +2038,7 @@ 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];
@@ -2014,9 +2054,9 @@ 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,
+int write_object_file_literally(const void *buf, unsigned long len,
-			       const char *type, struct object_id *oid,
+				const char *type, struct object_id *oid,
-			       unsigned flags)
+				unsigned flags)
 {
 	char *header;
 	int hdrlen, status = 0;
@@ -2024,8 +2064,8 @@ int hash_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,
+	write_object_file_prepare_literally(the_hash_algo, buf, len, type,
-				  &hdrlen);
+					    oid, header, &hdrlen);
 
 	if (!(flags & HASH_WRITE_OBJECT))
 		goto cleanup;
@@ -2052,7 +2092,7 @@ 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);
 
@@ -2118,7 +2158,8 @@ static int index_mem(struct index_state *istate,
 		     enum object_type type,
 		     const char *path, unsigned flags)
 {
-	int ret, re_allocated = 0;
+	int ret = 0;
+	int re_allocated = 0;
 	int write_object = flags & HASH_WRITE_OBJECT;
 
 	if (!type)
@@ -2145,10 +2186,9 @@ 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
-		ret = hash_object_file(the_hash_algo, buf, size,
+		hash_object_file(the_hash_algo, buf, size, type, oid);
-				       type_name(type), oid);
 	if (re_allocated)
 		free(buf);
 	return ret;
@@ -2160,7 +2200,7 @@ 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;
 
@@ -2171,11 +2211,11 @@ 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
-		ret = hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
+		hash_object_file(the_hash_algo, sbuf.buf, sbuf.len, OBJ_BLOB,
-				       type_name(OBJ_BLOB), oid);
+				 oid);
 	strbuf_release(&sbuf);
 	return ret;
 }
@@ -2294,8 +2334,8 @@ 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, 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;
@@ -2599,9 +2639,10 @@ int read_loose_object(const char *path,
 			git_inflate_end(&stream);
 			goto out;
 		}
-		if (check_object_signature(the_repository, expected_oid,
+		hash_object_file_literally(the_repository->hash_algo,
 					   *contents, *size,
-					   oi->type_name->buf, real_oid))
+					   oi->type_name->buf, real_oid);
+		if (!oideq(expected_oid, real_oid))
 			goto out;
 	}
 

object-store.h

@@ -245,22 +245,22 @@ 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,
+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);
+		      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);
 }
 
-int hash_object_file_literally(const void *buf, unsigned long len,
+int write_object_file_literally(const void *buf, unsigned long len,
-			       const char *type, struct object_id *oid,
+				const char *type, struct object_id *oid,
-			       unsigned flags);
+				unsigned flags);
 
 /*
  * Add an object file to the in-memory object store, without writing it
@@ -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);
 
 /*

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;
 		}
@@ -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,
+		if (check_object_signature(r, repl, buffer, size, type) < 0) {
-					   type_name(type), NULL) < 0) {
 			free(buffer);
 			error(_("hash mismatch %s"), oid_to_hex(repl));
 			return NULL;

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,
+		else if (data && check_object_signature(r, &oid, data, size,
-						type_name(type), NULL))
+							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) {

read-cache.c

@@ -736,7 +736,7 @@ 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);
 }

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;