Merge branch 'bc/object-id'

Conversion from uchar[20] to struct object_id continues.

* bc/object-id: (36 commits)
  convert: convert to struct object_id
  sha1_file: introduce a constant for max header length
  Convert lookup_replace_object to struct object_id
  sha1_file: convert read_sha1_file to struct object_id
  sha1_file: convert read_object_with_reference to object_id
  tree-walk: convert tree entry functions to object_id
  streaming: convert istream internals to struct object_id
  tree-walk: convert get_tree_entry_follow_symlinks internals to object_id
  builtin/notes: convert static functions to object_id
  builtin/fmt-merge-msg: convert remaining code to object_id
  sha1_file: convert sha1_object_info* to object_id
  Convert remaining callers of sha1_object_info_extended to object_id
  packfile: convert unpack_entry to struct object_id
  sha1_file: convert retry_bad_packed_offset to struct object_id
  sha1_file: convert assert_sha1_type to object_id
  builtin/mktree: convert to struct object_id
  streaming: convert open_istream to use struct object_id
  sha1_file: convert check_sha1_signature to struct object_id
  sha1_file: convert read_loose_object to use struct object_id
  builtin/index-pack: convert struct ref_delta_entry to object_id
  ...

apply.c

@@ -3180,7 +3180,7 @@ static int apply_binary(struct apply_state *state,
 		unsigned long size;
 		char *result;
 
-		result = read_sha1_file(oid.hash, &type, &size);
+		result = read_object_file(&oid, &type, &size);
 		if (!result)
 			return error(_("the necessary postimage %s for "
 				       "'%s' cannot be read"),
@@ -3242,7 +3242,7 @@ static int read_blob_object(struct strbuf *buf, const struct object_id *oid, uns
 		unsigned long sz;
 		char *result;
 
-		result = read_sha1_file(oid->hash, &type, &sz);
+		result = read_object_file(oid, &type, &sz);
 		if (!result)
 			return -1;
 		/* XXX read_sha1_file NUL-terminates */

archive-tar.c

@@ -111,7 +111,7 @@ static void write_trailer(void)
  * queues up writes, so that all our write(2) calls write exactly one
  * full block; pads writes to RECORDSIZE
  */
-static int stream_blocked(const unsigned char *sha1)
+static int stream_blocked(const struct object_id *oid)
 {
 	struct git_istream *st;
 	enum object_type type;
@@ -119,9 +119,9 @@ static int stream_blocked(const unsigned char *sha1)
 	char buf[BLOCKSIZE];
 	ssize_t readlen;
 
-	st = open_istream(sha1, &type, &sz, NULL);
+	st = open_istream(oid, &type, &sz, NULL);
 	if (!st)
-		return error("cannot stream blob %s", sha1_to_hex(sha1));
+		return error("cannot stream blob %s", oid_to_hex(oid));
 	for (;;) {
 		readlen = read_istream(st, buf, sizeof(buf));
 		if (readlen <= 0)
@@ -218,7 +218,7 @@ static void prepare_header(struct archiver_args *args,
 }
 
 static void write_extended_header(struct archiver_args *args,
-				  const unsigned char *sha1,
+				  const struct object_id *oid,
 				  const void *buffer, unsigned long size)
 {
 	struct ustar_header header;
@@ -226,14 +226,14 @@ static void write_extended_header(struct archiver_args *args,
 	memset(&header, 0, sizeof(header));
 	*header.typeflag = TYPEFLAG_EXT_HEADER;
 	mode = 0100666;
-	xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
+	xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
 	prepare_header(args, &header, mode, size);
 	write_blocked(&header, sizeof(header));
 	write_blocked(buffer, size);
 }
 
 static int write_tar_entry(struct archiver_args *args,
-			   const unsigned char *sha1,
+			   const struct object_id *oid,
 			   const char *path, size_t pathlen,
 			   unsigned int mode)
 {
@@ -257,7 +257,7 @@ static int write_tar_entry(struct archiver_args *args,
 		mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 	} else {
 		return error("unsupported file mode: 0%o (SHA1: %s)",
-			     mode, sha1_to_hex(sha1));
+			     mode, oid_to_hex(oid));
 	}
 	if (pathlen > sizeof(header.name)) {
 		size_t plen = get_path_prefix(path, pathlen,
@@ -268,7 +268,7 @@ static int write_tar_entry(struct archiver_args *args,
 			memcpy(header.name, path + plen + 1, rest);
 		} else {
 			xsnprintf(header.name, sizeof(header.name), "%s.data",
-				  sha1_to_hex(sha1));
+				  oid_to_hex(oid));
 			strbuf_append_ext_header(&ext_header, "path",
 						 path, pathlen);
 		}
@@ -276,14 +276,14 @@ static int write_tar_entry(struct archiver_args *args,
 		memcpy(header.name, path, pathlen);
 
 	if (S_ISREG(mode) && !args->convert &&
-	    sha1_object_info(sha1, &size) == OBJ_BLOB &&
+	    oid_object_info(oid, &size) == OBJ_BLOB &&
 	    size > big_file_threshold)
 		buffer = NULL;
 	else if (S_ISLNK(mode) || S_ISREG(mode)) {
 		enum object_type type;
-		buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
+		buffer = object_file_to_archive(args, path, oid, old_mode, &type, &size);
 		if (!buffer)
-			return error("cannot read %s", sha1_to_hex(sha1));
+			return error("cannot read %s", oid_to_hex(oid));
 	} else {
 		buffer = NULL;
 		size = 0;
@@ -292,7 +292,7 @@ static int write_tar_entry(struct archiver_args *args,
 	if (S_ISLNK(mode)) {
 		if (size > sizeof(header.linkname)) {
 			xsnprintf(header.linkname, sizeof(header.linkname),
-				  "see %s.paxheader", sha1_to_hex(sha1));
+				  "see %s.paxheader", oid_to_hex(oid));
 			strbuf_append_ext_header(&ext_header, "linkpath",
 			                         buffer, size);
 		} else
@@ -308,7 +308,7 @@ static int write_tar_entry(struct archiver_args *args,
 	prepare_header(args, &header, mode, size_in_header);
 
 	if (ext_header.len > 0) {
-		write_extended_header(args, sha1, ext_header.buf,
+		write_extended_header(args, oid, ext_header.buf,
 				      ext_header.len);
 	}
 	strbuf_release(&ext_header);
@@ -317,7 +317,7 @@ static int write_tar_entry(struct archiver_args *args,
 		if (buffer)
 			write_blocked(buffer, size);
 		else
-			err = stream_blocked(sha1);
+			err = stream_blocked(oid);
 	}
 	free(buffer);
 	return err;

archive-zip.c

@@ -276,7 +276,7 @@ static int entry_is_binary(const char *path, const void *buffer, size_t size)
 #define STREAM_BUFFER_SIZE (1024 * 16)
 
 static int write_zip_entry(struct archiver_args *args,
-			   const unsigned char *sha1,
+			   const struct object_id *oid,
 			   const char *path, size_t pathlen,
 			   unsigned int mode)
 {
@@ -314,7 +314,7 @@ static int write_zip_entry(struct archiver_args *args,
 
 	if (pathlen > 0xffff) {
 		return error("path too long (%d chars, SHA1: %s): %s",
-				(int)pathlen, sha1_to_hex(sha1), path);
+				(int)pathlen, oid_to_hex(oid), path);
 	}
 
 	if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
@@ -325,7 +325,7 @@ static int write_zip_entry(struct archiver_args *args,
 		compressed_size = 0;
 		buffer = NULL;
 	} else if (S_ISREG(mode) || S_ISLNK(mode)) {
-		enum object_type type = sha1_object_info(sha1, &size);
+		enum object_type type = oid_object_info(oid, &size);
 
 		method = 0;
 		attr2 = S_ISLNK(mode) ? ((mode | 0777) << 16) :
@@ -337,18 +337,18 @@ static int write_zip_entry(struct archiver_args *args,
 
 		if (S_ISREG(mode) && type == OBJ_BLOB && !args->convert &&
 		    size > big_file_threshold) {
-			stream = open_istream(sha1, &type, &size, NULL);
+			stream = open_istream(oid, &type, &size, NULL);
 			if (!stream)
 				return error("cannot stream blob %s",
-					     sha1_to_hex(sha1));
+					     oid_to_hex(oid));
 			flags |= ZIP_STREAM;
 			out = buffer = NULL;
 		} else {
-			buffer = sha1_file_to_archive(args, path, sha1, mode,
+			buffer = object_file_to_archive(args, path, oid, mode,
 							&type, &size);
 			if (!buffer)
 				return error("cannot read %s",
-					     sha1_to_hex(sha1));
+					     oid_to_hex(oid));
 			crc = crc32(crc, buffer, size);
 			is_binary = entry_is_binary(path_without_prefix,
 						    buffer, size);
@@ -357,7 +357,7 @@ static int write_zip_entry(struct archiver_args *args,
 		compressed_size = (method == 0) ? size : 0;
 	} else {
 		return error("unsupported file mode: 0%o (SHA1: %s)", mode,
-				sha1_to_hex(sha1));
+				oid_to_hex(oid));
 	}
 
 	if (creator_version > max_creator_version)

archive.c

@@ -63,8 +63,8 @@ static void format_subst(const struct commit *commit,
 	free(to_free);
 }
 
-void *sha1_file_to_archive(const struct archiver_args *args,
+void *object_file_to_archive(const struct archiver_args *args,
-			   const char *path, const unsigned char *sha1,
+			     const char *path, const struct object_id *oid,
 			     unsigned int mode, enum object_type *type,
 			     unsigned long *sizep)
 {
@@ -72,7 +72,7 @@ void *sha1_file_to_archive(const struct archiver_args *args,
 	const struct commit *commit = args->convert ? args->commit : NULL;
 
 	path += args->baselen;
-	buffer = read_sha1_file(sha1, type, sizep);
+	buffer = read_object_file(oid, type, sizep);
 	if (buffer && S_ISREG(mode)) {
 		struct strbuf buf = STRBUF_INIT;
 		size_t size = 0;
@@ -121,7 +121,7 @@ static int check_attr_export_subst(const struct attr_check *check)
 	return check && ATTR_TRUE(check->items[1].value);
 }
 
-static int write_archive_entry(const unsigned char *sha1, const char *base,
+static int write_archive_entry(const struct object_id *oid, const char *base,
 		int baselen, const char *filename, unsigned mode, int stage,
 		void *context)
 {
@@ -153,7 +153,7 @@ static int write_archive_entry(const unsigned char *sha1, const char *base,
 	if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 		if (args->verbose)
 			fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
-		err = write_entry(args, sha1, path.buf, path.len, mode);
+		err = write_entry(args, oid, path.buf, path.len, mode);
 		if (err)
 			return err;
 		return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
@@ -161,7 +161,7 @@ static int write_archive_entry(const unsigned char *sha1, const char *base,
 
 	if (args->verbose)
 		fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
-	return write_entry(args, sha1, path.buf, path.len, mode);
+	return write_entry(args, oid, path.buf, path.len, mode);
 }
 
 static void queue_directory(const unsigned char *sha1,
@@ -191,14 +191,14 @@ static int write_directory(struct archiver_context *c)
 	d->path[d->len - 1] = '\0'; /* no trailing slash */
 	ret =
 		write_directory(c) ||
-		write_archive_entry(d->oid.hash, d->path, d->baselen,
+		write_archive_entry(&d->oid, d->path, d->baselen,
 				    d->path + d->baselen, d->mode,
 				    d->stage, c) != READ_TREE_RECURSIVE;
 	free(d);
 	return ret ? -1 : 0;
 }
 
-static int queue_or_write_archive_entry(const unsigned char *sha1,
+static int queue_or_write_archive_entry(const struct object_id *oid,
 		struct strbuf *base, const char *filename,
 		unsigned mode, int stage, void *context)
 {
@@ -224,14 +224,14 @@ static int queue_or_write_archive_entry(const unsigned char *sha1,
 
 		if (check_attr_export_ignore(check))
 			return 0;
-		queue_directory(sha1, base, filename,
+		queue_directory(oid->hash, base, filename,
 				mode, stage, c);
 		return READ_TREE_RECURSIVE;
 	}
 
 	if (write_directory(c))
 		return -1;
-	return write_archive_entry(sha1, base->buf, base->len, filename, mode,
+	return write_archive_entry(oid, base->buf, base->len, filename, mode,
 				   stage, context);
 }
 
@@ -250,7 +250,7 @@ int write_archive_entries(struct archiver_args *args,
 			len--;
 		if (args->verbose)
 			fprintf(stderr, "%.*s\n", (int)len, args->base);
-		err = write_entry(args, args->tree->object.oid.hash, args->base,
+		err = write_entry(args, &args->tree->object.oid, args->base,
 				  len, 040777);
 		if (err)
 			return err;
@@ -303,7 +303,7 @@ static const struct archiver *lookup_archiver(const char *name)
 	return NULL;
 }
 
-static int reject_entry(const unsigned char *sha1, struct strbuf *base,
+static int reject_entry(const struct object_id *oid, struct strbuf *base,
 			const char *filename, unsigned mode,
 			int stage, void *context)
 {
@@ -397,8 +397,8 @@ static void parse_treeish_arg(const char **argv,
 		unsigned int mode;
 		int err;
 
-		err = get_tree_entry(tree->object.oid.hash, prefix,
+		err = get_tree_entry(&tree->object.oid, prefix, &tree_oid,
-				     tree_oid.hash, &mode);
+				     &mode);
 		if (err || !S_ISDIR(mode))
 			die("current working directory is untracked");
 

archive.h

@@ -31,7 +31,7 @@ extern void init_tar_archiver(void);
 extern void init_zip_archiver(void);
 
 typedef int (*write_archive_entry_fn_t)(struct archiver_args *args,
-					const unsigned char *sha1,
+					const struct object_id *oid,
 					const char *path, size_t pathlen,
 					unsigned int mode);
 
@@ -39,8 +39,8 @@ extern int write_archive_entries(struct archiver_args *args, write_archive_entry
 extern int write_archive(int argc, const char **argv, const char *prefix, const char *name_hint, int remote);
 
 const char *archive_format_from_filename(const char *filename);
-extern void *sha1_file_to_archive(const struct archiver_args *args,
+extern void *object_file_to_archive(const struct archiver_args *args,
-				  const char *path, const unsigned char *sha1,
+				    const char *path, const struct object_id *oid,
 				    unsigned int mode, enum object_type *type,
 				    unsigned long *sizep);
 

bisect.c

@@ -132,7 +132,8 @@ static void show_list(const char *debug, int counted, int nr,
 		unsigned flags = commit->object.flags;
 		enum object_type type;
 		unsigned long size;
-		char *buf = read_sha1_file(commit->object.oid.hash, &type, &size);
+		char *buf = read_object_file(&commit->object.oid, &type,
+					     &size);
 		const char *subject_start;
 		int subject_len;
 

blame.c

@@ -80,8 +80,8 @@ static void verify_working_tree_path(struct commit *work_tree, const char *path)
 		struct object_id blob_oid;
 		unsigned mode;
 
-		if (!get_tree_entry(commit_oid->hash, path, blob_oid.hash, &mode) &&
+		if (!get_tree_entry(commit_oid, path, &blob_oid, &mode) &&
-		    sha1_object_info(blob_oid.hash, NULL) == OBJ_BLOB)
+		    oid_object_info(&blob_oid, NULL) == OBJ_BLOB)
 			return;
 	}
 
@@ -297,7 +297,7 @@ static void fill_origin_blob(struct diff_options *opt,
 		    textconv_object(o->path, o->mode, &o->blob_oid, 1, &file->ptr, &file_size))
 			;
 		else
-			file->ptr = read_sha1_file(o->blob_oid.hash, &type,
+			file->ptr = read_object_file(&o->blob_oid, &type,
 						     &file_size);
 		file->size = file_size;
 
@@ -502,11 +502,9 @@ static int fill_blob_sha1_and_mode(struct blame_origin *origin)
 {
 	if (!is_null_oid(&origin->blob_oid))
 		return 0;
-	if (get_tree_entry(origin->commit->object.oid.hash,
+	if (get_tree_entry(&origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode))
-			   origin->path,
-			   origin->blob_oid.hash, &origin->mode))
 		goto error_out;
-	if (sha1_object_info(origin->blob_oid.hash, NULL) != OBJ_BLOB)
+	if (oid_object_info(&origin->blob_oid, NULL) != OBJ_BLOB)
 		goto error_out;
 	return 0;
  error_out:
@@ -1831,7 +1829,7 @@ void setup_scoreboard(struct blame_scoreboard *sb, const char *path, struct blam
 				    &sb->final_buf_size))
 			;
 		else
-			sb->final_buf = read_sha1_file(o->blob_oid.hash, &type,
+			sb->final_buf = read_object_file(&o->blob_oid, &type,
 							 &sb->final_buf_size);
 
 		if (!sb->final_buf)

builtin/am.c

@@ -1550,7 +1550,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	discard_cache();
 	read_cache_from(index_path);
 
-	if (write_index_as_tree(orig_tree.hash, &the_index, index_path, 0, NULL))
+	if (write_index_as_tree(&orig_tree, &the_index, index_path, 0, NULL))
 		return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
 
 	say(state, stdout, _("Using index info to reconstruct a base tree..."));
@@ -1575,7 +1575,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 		return error(_("Did you hand edit your patch?\n"
 				"It does not apply to blobs recorded in its index."));
 
-	if (write_index_as_tree(their_tree.hash, &the_index, index_path, 0, NULL))
+	if (write_index_as_tree(&their_tree, &the_index, index_path, 0, NULL))
 		return error("could not write tree");
 
 	say(state, stdout, _("Falling back to patching base and 3-way merge..."));
@@ -1626,7 +1626,7 @@ static void do_commit(const struct am_state *state)
 	if (run_hook_le(NULL, "pre-applypatch", NULL))
 		exit(1);
 
-	if (write_cache_as_tree(tree.hash, 0, NULL))
+	if (write_cache_as_tree(&tree, 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 
 	if (!get_oid_commit("HEAD", &parent)) {
@@ -2004,7 +2004,7 @@ static int clean_index(const struct object_id *head, const struct object_id *rem
 	if (fast_forward_to(head_tree, head_tree, 1))
 		return -1;
 
-	if (write_cache_as_tree(index.hash, 0, NULL))
+	if (write_cache_as_tree(&index, 0, NULL))
 		return -1;
 
 	index_tree = parse_tree_indirect(&index);

builtin/blame.c

@@ -499,7 +499,7 @@ static int read_ancestry(const char *graft_file)
 
 static int update_auto_abbrev(int auto_abbrev, struct blame_origin *suspect)
 {
-	const char *uniq = find_unique_abbrev(suspect->commit->object.oid.hash,
+	const char *uniq = find_unique_abbrev(&suspect->commit->object.oid,
 					      auto_abbrev);
 	int len = strlen(uniq);
 	if (auto_abbrev < len)
@@ -655,7 +655,7 @@ static int is_a_rev(const char *name)
 
 	if (get_oid(name, &oid))
 		return 0;
-	return OBJ_NONE < sha1_object_info(oid.hash, NULL);
+	return OBJ_NONE < oid_object_info(&oid, NULL);
 }
 
 int cmd_blame(int argc, const char **argv, const char *prefix)

builtin/branch.c

@@ -273,7 +273,7 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
 			       bname.buf,
 			       (flags & REF_ISBROKEN) ? "broken"
 			       : (flags & REF_ISSYMREF) ? target
-			       : find_unique_abbrev(oid.hash, DEFAULT_ABBREV));
+			       : find_unique_abbrev(&oid, DEFAULT_ABBREV));
 		}
 		delete_branch_config(bname.buf);
 

builtin/cat-file.c

@@ -32,7 +32,7 @@ static int filter_object(const char *path, unsigned mode,
 {
 	enum object_type type;
 
-	*buf = read_sha1_file(oid->hash, &type, size);
+	*buf = read_object_file(oid, &type, size);
 	if (!*buf)
 		return error(_("cannot read object %s '%s'"),
 			     oid_to_hex(oid), path);
@@ -77,7 +77,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	switch (opt) {
 	case 't':
 		oi.type_name = &sb;
-		if (sha1_object_info_extended(oid.hash, &oi, flags) < 0)
+		if (oid_object_info_extended(&oid, &oi, flags) < 0)
 			die("git cat-file: could not get object info");
 		if (sb.len) {
 			printf("%s\n", sb.buf);
@@ -88,7 +88,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 
 	case 's':
 		oi.sizep = &size;
-		if (sha1_object_info_extended(oid.hash, &oi, flags) < 0)
+		if (oid_object_info_extended(&oid, &oi, flags) < 0)
 			die("git cat-file: could not get object info");
 		printf("%lu\n", size);
 		return 0;
@@ -116,7 +116,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		/* else fallthrough */
 
 	case 'p':
-		type = sha1_object_info(oid.hash, NULL);
+		type = oid_object_info(&oid, NULL);
 		if (type < 0)
 			die("Not a valid object name %s", obj_name);
 
@@ -130,7 +130,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 
 		if (type == OBJ_BLOB)
 			return stream_blob_to_fd(1, &oid, NULL, 0);
-		buf = read_sha1_file(oid.hash, &type, &size);
+		buf = read_object_file(&oid, &type, &size);
 		if (!buf)
 			die("Cannot read object %s", obj_name);
 
@@ -140,8 +140,9 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	case 0:
 		if (type_from_string(exp_type) == OBJ_BLOB) {
 			struct object_id blob_oid;
-			if (sha1_object_info(oid.hash, NULL) == OBJ_TAG) {
+			if (oid_object_info(&oid, NULL) == OBJ_TAG) {
-				char *buffer = read_sha1_file(oid.hash, &type, &size);
+				char *buffer = read_object_file(&oid, &type,
+								&size);
 				const char *target;
 				if (!skip_prefix(buffer, "object ", &target) ||
 				    get_oid_hex(target, &blob_oid))
@@ -150,7 +151,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 			} else
 				oidcpy(&blob_oid, &oid);
 
-			if (sha1_object_info(blob_oid.hash, NULL) == OBJ_BLOB)
+			if (oid_object_info(&blob_oid, NULL) == OBJ_BLOB)
 				return stream_blob_to_fd(1, &blob_oid, NULL, 0);
 			/*
 			 * we attempted to dereference a tag to a blob
@@ -159,7 +160,7 @@ 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(oid.hash, exp_type, &size, NULL);
+		buf = read_object_with_reference(&oid, exp_type, &size, NULL);
 		break;
 
 	default:
@@ -304,7 +305,8 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 				enum object_type type;
 				if (!textconv_object(data->rest, 0100644, oid,
 						     1, &contents, &size))
-					contents = read_sha1_file(oid->hash, &type,
+					contents = read_object_file(oid,
+								    &type,
 								    &size);
 				if (!contents)
 					die("could not convert '%s' %s",
@@ -321,7 +323,7 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 		unsigned long size;
 		void *contents;
 
-		contents = read_sha1_file(oid->hash, &type, &size);
+		contents = read_object_file(oid, &type, &size);
 		if (!contents)
 			die("object %s disappeared", oid_to_hex(oid));
 		if (type != data->type)
@@ -340,7 +342,7 @@ static void batch_object_write(const char *obj_name, struct batch_options *opt,
 	struct strbuf buf = STRBUF_INIT;
 
 	if (!data->skip_object_info &&
-	    sha1_object_info_extended(data->oid.hash, &data->info,
+	    oid_object_info_extended(&data->oid, &data->info,
 				     OBJECT_INFO_LOOKUP_REPLACE) < 0) {
 		printf("%s missing\n",
 		       obj_name ? obj_name : oid_to_hex(&data->oid));

builtin/checkout.c

@@ -66,7 +66,7 @@ static int post_checkout_hook(struct commit *old_commit, struct commit *new_comm
 
 }
 
-static int update_some(const unsigned char *sha1, struct strbuf *base,
+static int update_some(const struct object_id *oid, struct strbuf *base,
 		const char *pathname, unsigned mode, int stage, void *context)
 {
 	int len;
@@ -78,7 +78,7 @@ static int update_some(const unsigned char *sha1, struct strbuf *base,
 
 	len = base->len + strlen(pathname);
 	ce = xcalloc(1, cache_entry_size(len));
-	hashcpy(ce->oid.hash, sha1);
+	oidcpy(&ce->oid, oid);
 	memcpy(ce->name, base->buf, base->len);
 	memcpy(ce->name + base->len, pathname, len - base->len);
 	ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
@@ -405,10 +405,10 @@ static void describe_detached_head(const char *msg, struct commit *commit)
 		pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 	if (print_sha1_ellipsis()) {
 		fprintf(stderr, "%s %s... %s\n", msg,
-			find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
+			find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 	} else {
 		fprintf(stderr, "%s %s %s\n", msg,
-			find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
+			find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 	}
 	strbuf_release(&sb);
 }
@@ -720,7 +720,7 @@ static int add_pending_uninteresting_ref(const char *refname,
 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 {
 	strbuf_addstr(sb, "  ");
-	strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
+	strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 	strbuf_addch(sb, ' ');
 	if (!parse_commit(commit))
 		pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
@@ -778,7 +778,7 @@ static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 			" git branch <new-branch-name> %s\n\n",
 			/* Give ngettext() the count */
 			lost),
-			find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
+			find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 }
 
 /*

builtin/commit-tree.c

@@ -58,7 +58,7 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 				usage(commit_tree_usage);
 			if (get_oid_commit(argv[i], &oid))
 				die("Not a valid object name %s", argv[i]);
-			assert_sha1_type(oid.hash, OBJ_COMMIT);
+			assert_oid_type(&oid, OBJ_COMMIT);
 			new_parent(lookup_commit(&oid), &parents);
 			continue;
 		}

builtin/describe.c

@@ -285,7 +285,7 @@ static void append_name(struct commit_name *n, struct strbuf *dst)
 
 static void append_suffix(int depth, const struct object_id *oid, struct strbuf *dst)
 {
-	strbuf_addf(dst, "-%d-g%s", depth, find_unique_abbrev(oid->hash, abbrev));
+	strbuf_addf(dst, "-%d-g%s", depth, find_unique_abbrev(oid, abbrev));
 }
 
 static void describe_commit(struct object_id *oid, struct strbuf *dst)
@@ -383,7 +383,7 @@ static void describe_commit(struct object_id *oid, struct strbuf *dst)
 	if (!match_cnt) {
 		struct object_id *cmit_oid = &cmit->object.oid;
 		if (always) {
-			strbuf_add_unique_abbrev(dst, cmit_oid->hash, abbrev);
+			strbuf_add_unique_abbrev(dst, cmit_oid, abbrev);
 			if (suffix)
 				strbuf_addstr(dst, suffix);
 			return;
@@ -502,7 +502,7 @@ static void describe(const char *arg, int last_one)
 
 	if (cmit)
 		describe_commit(&oid, &sb);
-	else if (sha1_object_info(oid.hash, NULL) == OBJ_BLOB)
+	else if (oid_object_info(&oid, NULL) == OBJ_BLOB)
 		describe_blob(oid, &sb);
 	else
 		die(_("%s is neither a commit nor blob"), arg);

builtin/difftool.c

@@ -306,7 +306,7 @@ static char *get_symlink(const struct object_id *oid, const char *path)
 	} else {
 		enum object_type type;
 		unsigned long size;
-		data = read_sha1_file(oid->hash, &type, &size);
+		data = read_object_file(oid, &type, &size);
 		if (!data)
 			die(_("could not read object %s for symlink %s"),
 				oid_to_hex(oid), path);

builtin/fast-export.c

@@ -237,10 +237,10 @@ static void export_blob(const struct object_id *oid)
 		object = (struct object *)lookup_blob(oid);
 		eaten = 0;
 	} else {
-		buf = read_sha1_file(oid->hash, &type, &size);
+		buf = read_object_file(oid, &type, &size);
 		if (!buf)
 			die ("Could not read blob %s", oid_to_hex(oid));
-		if (check_sha1_signature(oid->hash, buf, size, type_name(type)) < 0)
+		if (check_object_signature(oid, buf, size, type_name(type)) < 0)
 			die("sha1 mismatch in blob %s", oid_to_hex(oid));
 		object = parse_object_buffer(oid, type, size, buf, &eaten);
 	}
@@ -682,7 +682,7 @@ static void handle_tag(const char *name, struct tag *tag)
 		return;
 	}
 
-	buf = read_sha1_file(tag->object.oid.hash, &type, &size);
+	buf = read_object_file(&tag->object.oid, &type, &size);
 	if (!buf)
 		die ("Could not read tag %s", oid_to_hex(&tag->object.oid));
 	message = memmem(buf, size, "\n\n", 2);
@@ -947,7 +947,7 @@ static void import_marks(char *input_file)
 		if (last_idnum < mark)
 			last_idnum = mark;
 
-		type = sha1_object_info(oid.hash, NULL);
+		type = oid_object_info(&oid, NULL);
 		if (type < 0)
 			die("object not found: %s", oid_to_hex(&oid));
 

builtin/fetch.c

@@ -637,7 +637,7 @@ static int update_local_ref(struct ref *ref,
 	struct branch *current_branch = branch_get(NULL);
 	const char *pretty_ref = prettify_refname(ref->name);
 
-	type = sha1_object_info(ref->new_oid.hash, NULL);
+	type = oid_object_info(&ref->new_oid, NULL);
 	if (type < 0)
 		die(_("object %s not found"), oid_to_hex(&ref->new_oid));
 
@@ -708,9 +708,9 @@ static int update_local_ref(struct ref *ref,
 	if (in_merge_bases(current, updated)) {
 		struct strbuf quickref = STRBUF_INIT;
 		int r;
-		strbuf_add_unique_abbrev(&quickref, current->object.oid.hash, DEFAULT_ABBREV);
+		strbuf_add_unique_abbrev(&quickref, &current->object.oid, DEFAULT_ABBREV);
 		strbuf_addstr(&quickref, "..");
-		strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
+		strbuf_add_unique_abbrev(&quickref, &ref->new_oid, DEFAULT_ABBREV);
 		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
 		    (recurse_submodules != RECURSE_SUBMODULES_ON))
 			check_for_new_submodule_commits(&ref->new_oid);
@@ -723,9 +723,9 @@ static int update_local_ref(struct ref *ref,
 	} else if (force || ref->force) {
 		struct strbuf quickref = STRBUF_INIT;
 		int r;
-		strbuf_add_unique_abbrev(&quickref, current->object.oid.hash, DEFAULT_ABBREV);
+		strbuf_add_unique_abbrev(&quickref, &current->object.oid, DEFAULT_ABBREV);
 		strbuf_addstr(&quickref, "...");
-		strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
+		strbuf_add_unique_abbrev(&quickref, &ref->new_oid, DEFAULT_ABBREV);
 		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
 		    (recurse_submodules != RECURSE_SUBMODULES_ON))
 			check_for_new_submodule_commits(&ref->new_oid);

builtin/fmt-merge-msg.c

@@ -485,10 +485,10 @@ static void fmt_merge_msg_sigs(struct strbuf *out)
 	struct strbuf tagbuf = STRBUF_INIT;
 
 	for (i = 0; i < origins.nr; i++) {
-		unsigned char *sha1 = origins.items[i].util;
+		struct object_id *oid = origins.items[i].util;
 		enum object_type type;
 		unsigned long size, len;
-		char *buf = read_sha1_file(sha1, &type, &size);
+		char *buf = read_object_file(oid, &type, &size);
 		struct strbuf sig = STRBUF_INIT;
 
 		if (!buf || type != OBJ_TAG)

builtin/fsck.c

@@ -65,7 +65,7 @@ static const char *printable_type(struct object *obj)
 	const char *ret;
 
 	if (obj->type == OBJ_NONE) {
-		enum object_type type = sha1_object_info(obj->oid.hash, NULL);
+		enum object_type type = oid_object_info(&obj->oid, NULL);
 		if (type > 0)
 			object_as_type(obj, type, 0);
 	}
@@ -513,7 +513,7 @@ static struct object *parse_loose_object(const struct object_id *oid,
 	unsigned long size;
 	int eaten;
 
-	if (read_loose_object(path, oid->hash, &type, &size, &contents) < 0)
+	if (read_loose_object(path, oid, &type, &size, &contents) < 0)
 		return NULL;
 
 	if (!contents && type != OBJ_BLOB)

builtin/grep.c

@@ -306,7 +306,7 @@ static void *lock_and_read_oid_file(const struct object_id *oid, enum object_typ
 	void *data;
 
 	grep_read_lock();
-	data = read_sha1_file(oid->hash, type, size);
+	data = read_object_file(oid, type, size);
 	grep_read_unlock();
 	return data;
 }
@@ -452,7 +452,7 @@ static int grep_submodule(struct grep_opt *opt, struct repository *superproject,
 		object = parse_object_or_die(oid, oid_to_hex(oid));
 
 		grep_read_lock();
-		data = read_object_with_reference(object->oid.hash, tree_type,
+		data = read_object_with_reference(&object->oid, tree_type,
 						  &size, NULL);
 		grep_read_unlock();
 
@@ -614,7 +614,7 @@ static int grep_object(struct grep_opt *opt, const struct pathspec *pathspec,
 		int hit, len;
 
 		grep_read_lock();
-		data = read_object_with_reference(obj->oid.hash, tree_type,
+		data = read_object_with_reference(&obj->oid, tree_type,
 						  &size, NULL);
 		grep_read_unlock();
 

builtin/index-pack.c

@@ -59,7 +59,7 @@ struct ofs_delta_entry {
 };
 
 struct ref_delta_entry {
-	unsigned char sha1[20];
+	struct object_id oid;
 	int obj_no;
 };
 
@@ -222,7 +222,7 @@ static unsigned check_object(struct object *obj)
 
 	if (!(obj->flags & FLAG_CHECKED)) {
 		unsigned long size;
-		int type = sha1_object_info(obj->oid.hash, &size);
+		int type = oid_object_info(&obj->oid, &size);
 		if (type <= 0)
 			die(_("did not receive expected object %s"),
 			      oid_to_hex(&obj->oid));
@@ -672,18 +672,18 @@ static void find_ofs_delta_children(off_t offset,
 	*last_index = last;
 }
 
-static int compare_ref_delta_bases(const unsigned char *sha1,
+static int compare_ref_delta_bases(const struct object_id *oid1,
-				   const unsigned char *sha2,
+				   const struct object_id *oid2,
 				   enum object_type type1,
 				   enum object_type type2)
 {
 	int cmp = type1 - type2;
 	if (cmp)
 		return cmp;
-	return hashcmp(sha1, sha2);
+	return oidcmp(oid1, oid2);
 }
 
-static int find_ref_delta(const unsigned char *sha1, enum object_type type)
+static int find_ref_delta(const struct object_id *oid, enum object_type type)
 {
 	int first = 0, last = nr_ref_deltas;
 
@@ -692,7 +692,7 @@ static int find_ref_delta(const unsigned char *sha1, enum object_type type)
 		struct ref_delta_entry *delta = &ref_deltas[next];
 		int cmp;
 
-		cmp = compare_ref_delta_bases(sha1, delta->sha1,
+		cmp = compare_ref_delta_bases(oid, &delta->oid,
 					      type, objects[delta->obj_no].type);
 		if (!cmp)
 			return next;
@@ -705,11 +705,11 @@ static int find_ref_delta(const unsigned char *sha1, enum object_type type)
 	return -first-1;
 }
 
-static void find_ref_delta_children(const unsigned char *sha1,
+static void find_ref_delta_children(const struct object_id *oid,
 				    int *first_index, int *last_index,
 				    enum object_type type)
 {
-	int first = find_ref_delta(sha1, type);
+	int first = find_ref_delta(oid, type);
 	int last = first;
 	int end = nr_ref_deltas - 1;
 
@@ -718,9 +718,9 @@ static void find_ref_delta_children(const unsigned char *sha1,
 		*last_index = -1;
 		return;
 	}
-	while (first > 0 && !hashcmp(ref_deltas[first - 1].sha1, sha1))
+	while (first > 0 && !oidcmp(&ref_deltas[first - 1].oid, oid))
 		--first;
-	while (last < end && !hashcmp(ref_deltas[last + 1].sha1, sha1))
+	while (last < end && !oidcmp(&ref_deltas[last + 1].oid, oid))
 		++last;
 	*first_index = first;
 	*last_index = last;
@@ -772,7 +772,7 @@ static int check_collison(struct object_entry *entry)
 
 	memset(&data, 0, sizeof(data));
 	data.entry = entry;
-	data.st = open_istream(entry->idx.oid.hash, &type, &size, NULL);
+	data.st = open_istream(&entry->idx.oid, &type, &size, NULL);
 	if (!data.st)
 		return -1;
 	if (size != entry->size || type != entry->type)
@@ -811,12 +811,12 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 		enum object_type has_type;
 		unsigned long has_size;
 		read_lock();
-		has_type = sha1_object_info(oid->hash, &has_size);
+		has_type = oid_object_info(oid, &has_size);
 		if (has_type < 0)
 			die(_("cannot read existing object info %s"), oid_to_hex(oid));
 		if (has_type != type || has_size != size)
 			die(_("SHA1 COLLISION FOUND WITH %s !"), oid_to_hex(oid));
-		has_data = read_sha1_file(oid->hash, &has_type, &has_size);
+		has_data = read_object_file(oid, &has_type, &has_size);
 		read_unlock();
 		if (!data)
 			data = new_data = get_data_from_pack(obj_entry);
@@ -992,7 +992,7 @@ static struct base_data *find_unresolved_deltas_1(struct base_data *base,
 						  struct base_data *prev_base)
 {
 	if (base->ref_last == -1 && base->ofs_last == -1) {
-		find_ref_delta_children(base->obj->idx.oid.hash,
+		find_ref_delta_children(&base->obj->idx.oid,
 					&base->ref_first, &base->ref_last,
 					OBJ_REF_DELTA);
 
@@ -1076,7 +1076,7 @@ static int compare_ref_delta_entry(const void *a, const void *b)
 	const struct ref_delta_entry *delta_a = a;
 	const struct ref_delta_entry *delta_b = b;
 
-	return hashcmp(delta_a->sha1, delta_b->sha1);
+	return oidcmp(&delta_a->oid, &delta_b->oid);
 }
 
 static void resolve_base(struct object_entry *obj)
@@ -1142,7 +1142,7 @@ static void parse_pack_objects(unsigned char *hash)
 			ofs_delta++;
 		} else if (obj->type == OBJ_REF_DELTA) {
 			ALLOC_GROW(ref_deltas, nr_ref_deltas + 1, ref_deltas_alloc);
-			hashcpy(ref_deltas[nr_ref_deltas].sha1, ref_delta_oid.hash);
+			oidcpy(&ref_deltas[nr_ref_deltas].oid, &ref_delta_oid);
 			ref_deltas[nr_ref_deltas].obj_no = i;
 			nr_ref_deltas++;
 		} else if (!data) {
@@ -1374,14 +1374,15 @@ static void fix_unresolved_deltas(struct hashfile *f)
 
 		if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
 			continue;
-		base_obj->data = read_sha1_file(d->sha1, &type, &base_obj->size);
+		base_obj->data = read_object_file(&d->oid, &type,
+						  &base_obj->size);
 		if (!base_obj->data)
 			continue;
 
-		if (check_sha1_signature(d->sha1, base_obj->data,
+		if (check_object_signature(&d->oid, base_obj->data,
 				base_obj->size, type_name(type)))
-			die(_("local object %s is corrupt"), sha1_to_hex(d->sha1));
+			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
-		base_obj->obj = append_obj_to_pack(f, d->sha1,
+		base_obj->obj = append_obj_to_pack(f, d->oid.hash,
 					base_obj->data, base_obj->size, type);
 		find_unresolved_deltas(base_obj);
 		display_progress(progress, nr_resolved_deltas);

builtin/log.c

@@ -518,7 +518,7 @@ static int show_tag_object(const struct object_id *oid, struct rev_info *rev)
 {
 	unsigned long size;
 	enum object_type type;
-	char *buf = read_sha1_file(oid->hash, &type, &size);
+	char *buf = read_object_file(oid, &type, &size);
 	int offset = 0;
 
 	if (!buf)
@@ -541,7 +541,7 @@ static int show_tag_object(const struct object_id *oid, struct rev_info *rev)
 	return 0;
 }
 
-static int show_tree_object(const unsigned char *sha1,
+static int show_tree_object(const struct object_id *oid,
 		struct strbuf *base,
 		const char *pathname, unsigned mode, int stage, void *context)
 {
@@ -1873,12 +1873,12 @@ static void print_commit(char sign, struct commit *commit, int verbose,
 {
 	if (!verbose) {
 		fprintf(file, "%c %s\n", sign,
-		       find_unique_abbrev(commit->object.oid.hash, abbrev));
+		       find_unique_abbrev(&commit->object.oid, abbrev));
 	} else {
 		struct strbuf buf = STRBUF_INIT;
 		pp_commit_easy(CMIT_FMT_ONELINE, commit, &buf);
 		fprintf(file, "%c %s %s\n", sign,
-		       find_unique_abbrev(commit->object.oid.hash, abbrev),
+		       find_unique_abbrev(&commit->object.oid, abbrev),
 		       buf.buf);
 		strbuf_release(&buf);
 	}

builtin/ls-files.c

@@ -240,7 +240,7 @@ static void show_ce(struct repository *repo, struct dir_struct *dir,
 			printf("%s%06o %s %d\t",
 			       tag,
 			       ce->ce_mode,
-			       find_unique_abbrev(ce->oid.hash, abbrev),
+			       find_unique_abbrev(&ce->oid, abbrev),
 			       ce_stage(ce));
 		}
 		write_eolinfo(repo->index, ce, fullname);
@@ -271,7 +271,7 @@ static void show_ru_info(const struct index_state *istate)
 			if (!ui->mode[i])
 				continue;
 			printf("%s%06o %s %d\t", tag_resolve_undo, ui->mode[i],
-			       find_unique_abbrev(ui->sha1[i], abbrev),
+			       find_unique_abbrev(&ui->oid[i], abbrev),
 			       i + 1);
 			write_name(path);
 		}

builtin/ls-tree.c

@@ -60,7 +60,7 @@ static int show_recursive(const char *base, int baselen, const char *pathname)
 	return 0;
 }
 
-static int show_tree(const unsigned char *sha1, struct strbuf *base,
+static int show_tree(const struct object_id *oid, struct strbuf *base,
 		const char *pathname, unsigned mode, int stage, void *context)
 {
 	int retval = 0;
@@ -94,7 +94,7 @@ static int show_tree(const unsigned char *sha1, struct strbuf *base,
 			char size_text[24];
 			if (!strcmp(type, blob_type)) {
 				unsigned long size;
-				if (sha1_object_info(sha1, &size) == OBJ_BAD)
+				if (oid_object_info(oid, &size) == OBJ_BAD)
 					xsnprintf(size_text, sizeof(size_text),
 						  "BAD");
 				else
@@ -103,11 +103,11 @@ static int show_tree(const unsigned char *sha1, struct strbuf *base,
 			} else
 				xsnprintf(size_text, sizeof(size_text), "-");
 			printf("%06o %s %s %7s\t", mode, type,
-			       find_unique_abbrev(sha1, abbrev),
+			       find_unique_abbrev(oid, abbrev),
 			       size_text);
 		} else
 			printf("%06o %s %s\t", mode, type,
-			       find_unique_abbrev(sha1, abbrev));
+			       find_unique_abbrev(oid, abbrev));
 	}
 	baselen = base->len;
 	strbuf_addstr(base, pathname);

builtin/merge-tree.c

@@ -60,7 +60,7 @@ static void *result(struct merge_list *entry, unsigned long *size)
 	const char *path = entry->path;
 
 	if (!entry->stage)
-		return read_sha1_file(entry->blob->object.oid.hash, &type, size);
+		return read_object_file(&entry->blob->object.oid, &type, size);
 	base = NULL;
 	if (entry->stage == 1) {
 		base = entry->blob;
@@ -82,7 +82,8 @@ static void *origin(struct merge_list *entry, unsigned long *size)
 	enum object_type type;
 	while (entry) {
 		if (entry->stage == 2)
-			return read_sha1_file(entry->blob->object.oid.hash, &type, size);
+			return read_object_file(&entry->blob->object.oid,
+						&type, size);
 		entry = entry->link;
 	}
 	return NULL;

builtin/merge.c

@@ -639,7 +639,7 @@ static int read_tree_trivial(struct object_id *common, struct object_id *head,
 
 static void write_tree_trivial(struct object_id *oid)
 {
-	if (write_cache_as_tree(oid->hash, 0, NULL))
+	if (write_cache_as_tree(oid, 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 }
 
@@ -1324,7 +1324,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
 			check_commit_signature(commit, &signature_check);
 
-			find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
+			find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
 			switch (signature_check.result) {
 			case 'G':
 				break;
@@ -1417,9 +1417,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
 		if (verbosity >= 0) {
 			printf(_("Updating %s..%s\n"),
-			       find_unique_abbrev(head_commit->object.oid.hash,
+			       find_unique_abbrev(&head_commit->object.oid,
 						  DEFAULT_ABBREV),
-			       find_unique_abbrev(remoteheads->item->object.oid.hash,
+			       find_unique_abbrev(&remoteheads->item->object.oid,
 						  DEFAULT_ABBREV));
 		}
 		strbuf_addstr(&msg, "Fast-forward");

builtin/mktag.c

@@ -18,17 +18,17 @@
 /*
  * We refuse to tag something we can't verify. Just because.
  */
-static int verify_object(const unsigned char *sha1, const char *expected_type)
+static int verify_object(const struct object_id *oid, const char *expected_type)
 {
 	int ret = -1;
 	enum object_type type;
 	unsigned long size;
-	void *buffer = read_sha1_file(sha1, &type, &size);
+	void *buffer = read_object_file(oid, &type, &size);
-	const unsigned char *repl = lookup_replace_object(sha1);
+	const struct object_id *repl = lookup_replace_object(oid);
 
 	if (buffer) {
 		if (type == type_from_string(expected_type))
-			ret = check_sha1_signature(repl, buffer, size, expected_type);
+			ret = check_object_signature(repl, buffer, size, expected_type);
 		free(buffer);
 	}
 	return ret;
@@ -38,8 +38,8 @@ static int verify_tag(char *buffer, unsigned long size)
 {
 	int typelen;
 	char type[20];
-	unsigned char sha1[20];
+	struct object_id oid;
-	const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
+	const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb, *p;
 	size_t len;
 
 	if (size < 84)
@@ -52,11 +52,11 @@ static int verify_tag(char *buffer, unsigned long size)
 	if (memcmp(object, "object ", 7))
 		return error("char%d: does not start with \"object \"", 0);
 
-	if (get_sha1_hex(object + 7, sha1))
+	if (parse_oid_hex(object + 7, &oid, &p))
 		return error("char%d: could not get SHA1 hash", 7);
 
 	/* Verify type line */
-	type_line = object + 48;
+	type_line = p + 1;
 	if (memcmp(type_line - 1, "\ntype ", 6))
 		return error("char%d: could not find \"\\ntype \"", 47);
 
@@ -80,8 +80,8 @@ static int verify_tag(char *buffer, unsigned long size)
 	type[typelen] = 0;
 
 	/* Verify that the object matches */
-	if (verify_object(sha1, type))
+	if (verify_object(&oid, type))
-		return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
+		return error("char%d: could not verify object %s", 7, oid_to_hex(&oid));
 
 	/* Verify the tag-name: we don't allow control characters or spaces in it */
 	tag_line += 4;

builtin/mktree.c

@@ -10,13 +10,13 @@
 
 static struct treeent {
 	unsigned mode;
-	unsigned char sha1[20];
+	struct object_id oid;
 	int len;
 	char name[FLEX_ARRAY];
 } **entries;
 static int alloc, used;
 
-static void append_to_tree(unsigned mode, unsigned char *sha1, char *path)
+static void append_to_tree(unsigned mode, struct object_id *oid, char *path)
 {
 	struct treeent *ent;
 	size_t len = strlen(path);
@@ -26,7 +26,7 @@ static void append_to_tree(unsigned mode, unsigned char *sha1, char *path)
 	FLEX_ALLOC_MEM(ent, name, path, len);
 	ent->mode = mode;
 	ent->len = len;
-	hashcpy(ent->sha1, sha1);
+	oidcpy(&ent->oid, oid);
 
 	ALLOC_GROW(entries, used + 1, alloc);
 	entries[used++] = ent;
@@ -54,7 +54,7 @@ static void write_tree(struct object_id *oid)
 	for (i = 0; i < used; i++) {
 		struct treeent *ent = entries[i];
 		strbuf_addf(&buf, "%o %s%c", ent->mode, ent->name, '\0');
-		strbuf_add(&buf, ent->sha1, 20);
+		strbuf_add(&buf, ent->oid.hash, the_hash_algo->rawsz);
 	}
 
 	write_object_file(buf.buf, buf.len, tree_type, oid);
@@ -69,11 +69,12 @@ static const char *mktree_usage[] = {
 static void mktree_line(char *buf, size_t len, int nul_term_line, int allow_missing)
 {
 	char *ptr, *ntr;
+	const char *p;
 	unsigned mode;
 	enum object_type mode_type; /* object type derived from mode */
 	enum object_type obj_type; /* object type derived from sha */
 	char *path, *to_free = NULL;
-	unsigned char sha1[20];
+	struct object_id oid;
 
 	ptr = buf;
 	/*
@@ -85,9 +86,8 @@ static void mktree_line(char *buf, size_t len, int nul_term_line, int allow_miss
 		die("input format error: %s", buf);
 	ptr = ntr + 1; /* type */
 	ntr = strchr(ptr, ' ');
-	if (!ntr || buf + len <= ntr + 40 ||
+	if (!ntr || parse_oid_hex(ntr + 1, &oid, &p) ||
-	    ntr[41] != '\t' ||
+	    *p != '\t')
-	    get_sha1_hex(ntr + 1, sha1))
 		die("input format error: %s", buf);
 
 	/* It is perfectly normal if we do not have a commit from a submodule */
@@ -116,12 +116,12 @@ static void mktree_line(char *buf, size_t len, int nul_term_line, int allow_miss
 	}
 
 	/* Check the type of object identified by sha1 */
-	obj_type = sha1_object_info(sha1, NULL);
+	obj_type = oid_object_info(&oid, NULL);
 	if (obj_type < 0) {
 		if (allow_missing) {
 			; /* no problem - missing objects are presumed to be of the right type */
 		} else {
-			die("entry '%s' object %s is unavailable", path, sha1_to_hex(sha1));
+			die("entry '%s' object %s is unavailable", path, oid_to_hex(&oid));
 		}
 	} else {
 		if (obj_type != mode_type) {
@@ -131,11 +131,11 @@ static void mktree_line(char *buf, size_t len, int nul_term_line, int allow_miss
 			 * because the new tree entry will never be correct.
 			 */
 			die("entry '%s' object %s is a %s but specified type was (%s)",
-				path, sha1_to_hex(sha1), type_name(obj_type), type_name(mode_type));
+				path, oid_to_hex(&oid), type_name(obj_type), type_name(mode_type));
 		}
 	}
 
-	append_to_tree(mode, sha1, path);
+	append_to_tree(mode, &oid, path);
 	free(to_free);
 }
 

builtin/name-rev.c

@@ -328,7 +328,7 @@ static void show_name(const struct object *obj,
 	else if (allow_undefined)
 		printf("undefined\n");
 	else if (always)
-		printf("%s\n", find_unique_abbrev(oid->hash, DEFAULT_ABBREV));
+		printf("%s\n", find_unique_abbrev(oid, DEFAULT_ABBREV));
 	else
 		die("cannot describe '%s'", oid_to_hex(oid));
 	strbuf_release(&buf);

builtin/notes.c

@@ -118,11 +118,11 @@ static int list_each_note(const struct object_id *object_oid,
 	return 0;
 }
 
-static void copy_obj_to_fd(int fd, const unsigned char *sha1)
+static void copy_obj_to_fd(int fd, const struct object_id *oid)
 {
 	unsigned long size;
 	enum object_type type;
-	char *buf = read_sha1_file(sha1, &type, &size);
+	char *buf = read_object_file(oid, &type, &size);
 	if (buf) {
 		if (size)
 			write_or_die(fd, buf, size);
@@ -162,7 +162,7 @@ static void write_commented_object(int fd, const struct object_id *object)
 }
 
 static void prepare_note_data(const struct object_id *object, struct note_data *d,
-		const unsigned char *old_note)
+		const struct object_id *old_note)
 {
 	if (d->use_editor || !d->given) {
 		int fd;
@@ -253,7 +253,7 @@ static int parse_reuse_arg(const struct option *opt, const char *arg, int unset)
 
 	if (get_oid(arg, &object))
 		die(_("failed to resolve '%s' as a valid ref."), arg);
-	if (!(buf = read_sha1_file(object.hash, &type, &len))) {
+	if (!(buf = read_object_file(&object, &type, &len))) {
 		free(buf);
 		die(_("failed to read object '%s'."), arg);
 	}
@@ -457,7 +457,7 @@ static int add(int argc, const char **argv, const char *prefix)
 			oid_to_hex(&object));
 	}
 
-	prepare_note_data(&object, &d, note ? note->hash : NULL);
+	prepare_note_data(&object, &d, note);
 	if (d.buf.len || allow_empty) {
 		write_note_data(&d, &new_note);
 		if (add_note(t, &object, &new_note, combine_notes_overwrite))
@@ -602,13 +602,13 @@ static int append_edit(int argc, const char **argv, const char *prefix)
 	t = init_notes_check(argv[0], NOTES_INIT_WRITABLE);
 	note = get_note(t, &object);
 
-	prepare_note_data(&object, &d, edit && note ? note->hash : NULL);
+	prepare_note_data(&object, &d, edit && note ? note : NULL);
 
 	if (note && !edit) {
 		/* Append buf to previous note contents */
 		unsigned long size;
 		enum object_type type;
-		char *prev_buf = read_sha1_file(note->hash, &type, &size);
+		char *prev_buf = read_object_file(note, &type, &size);
 
 		strbuf_grow(&d.buf, size + 1);
 		if (d.buf.len && prev_buf && size)

builtin/pack-objects.c

@@ -122,11 +122,10 @@ static void *get_delta(struct object_entry *entry)
 	void *buf, *base_buf, *delta_buf;
 	enum object_type type;
 
-	buf = read_sha1_file(entry->idx.oid.hash, &type, &size);
+	buf = read_object_file(&entry->idx.oid, &type, &size);
 	if (!buf)
 		die("unable to read %s", oid_to_hex(&entry->idx.oid));
-	base_buf = read_sha1_file(entry->delta->idx.oid.hash, &type,
+	base_buf = read_object_file(&entry->delta->idx.oid, &type, &base_size);
-				  &base_size);
 	if (!base_buf)
 		die("unable to read %s",
 		    oid_to_hex(&entry->delta->idx.oid));
@@ -267,11 +266,10 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 	if (!usable_delta) {
 		if (entry->type == OBJ_BLOB &&
 		    entry->size > big_file_threshold &&
-		    (st = open_istream(entry->idx.oid.hash, &type, &size, NULL)) != NULL)
+		    (st = open_istream(&entry->idx.oid, &type, &size, NULL)) != NULL)
 			buf = NULL;
 		else {
-			buf = read_sha1_file(entry->idx.oid.hash, &type,
+			buf = read_object_file(&entry->idx.oid, &type, &size);
-					     &size);
 			if (!buf)
 				die(_("unable to read %s"),
 				    oid_to_hex(&entry->idx.oid));
@@ -1190,7 +1188,7 @@ static struct pbase_tree_cache *pbase_tree_get(const struct object_id *oid)
 	/* Did not find one.  Either we got a bogus request or
 	 * we need to read and perhaps cache.
 	 */
-	data = read_sha1_file(oid->hash, &type, &size);
+	data = read_object_file(oid, &type, &size);
 	if (!data)
 		return NULL;
 	if (type != OBJ_TREE) {
@@ -1351,7 +1349,7 @@ static void add_preferred_base(struct object_id *oid)
 	if (window <= num_preferred_base++)
 		return;
 
-	data = read_object_with_reference(oid->hash, tree_type, &size, tree_oid.hash);
+	data = read_object_with_reference(oid, tree_type, &size, &tree_oid);
 	if (!data)
 		return;
 
@@ -1516,7 +1514,7 @@ static void check_object(struct object_entry *entry)
 		unuse_pack(&w_curs);
 	}
 
-	entry->type = sha1_object_info(entry->idx.oid.hash, &entry->size);
+	entry->type = oid_object_info(&entry->idx.oid, &entry->size);
 	/*
 	 * The error condition is checked in prepare_pack().  This is
 	 * to permit a missing preferred base object to be ignored
@@ -1578,8 +1576,7 @@ static void drop_reused_delta(struct object_entry *entry)
 		 * And if that fails, the error will be recorded in entry->type
 		 * and dealt with in prepare_pack().
 		 */
-		entry->type = sha1_object_info(entry->idx.oid.hash,
+		entry->type = oid_object_info(&entry->idx.oid, &entry->size);
-					       &entry->size);
 	}
 }
 
@@ -1871,8 +1868,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 	/* Load data if not already done */
 	if (!trg->data) {
 		read_lock();
-		trg->data = read_sha1_file(trg_entry->idx.oid.hash, &type,
+		trg->data = read_object_file(&trg_entry->idx.oid, &type, &sz);
-					   &sz);
 		read_unlock();
 		if (!trg->data)
 			die("object %s cannot be read",
@@ -1885,8 +1881,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 	}
 	if (!src->data) {
 		read_lock();
-		src->data = read_sha1_file(src_entry->idx.oid.hash, &type,
+		src->data = read_object_file(&src_entry->idx.oid, &type, &sz);
-					   &sz);
 		read_unlock();
 		if (!src->data) {
 			if (src_entry->preferred_base) {
@@ -2709,7 +2704,7 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 static int add_loose_object(const struct object_id *oid, const char *path,
 			    void *data)
 {
-	enum object_type type = sha1_object_info(oid->hash, NULL);
+	enum object_type type = oid_object_info(oid, NULL);
 
 	if (type < 0) {
 		warning("loose object at %s could not be examined", path);

builtin/prune.c

@@ -50,7 +50,7 @@ static int prune_object(const struct object_id *oid, const char *fullpath,
 	if (st.st_mtime > expire)
 		return 0;
 	if (show_only || verbose) {
-		enum object_type type = sha1_object_info(oid->hash, NULL);
+		enum object_type type = oid_object_info(oid, NULL);
 		printf("%s %s\n", oid_to_hex(oid),
 		       (type > 0) ? type_name(type) : "unknown");
 	}

builtin/receive-pack.c

@@ -1242,11 +1242,11 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 	rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
 		 " its target '%s' (%s..%s)",
 		 cmd->ref_name,
-		 find_unique_abbrev(cmd->old_oid.hash, DEFAULT_ABBREV),
+		 find_unique_abbrev(&cmd->old_oid, DEFAULT_ABBREV),
-		 find_unique_abbrev(cmd->new_oid.hash, DEFAULT_ABBREV),
+		 find_unique_abbrev(&cmd->new_oid, DEFAULT_ABBREV),
 		 dst_cmd->ref_name,
-		 find_unique_abbrev(dst_cmd->old_oid.hash, DEFAULT_ABBREV),
+		 find_unique_abbrev(&dst_cmd->old_oid, DEFAULT_ABBREV),
-		 find_unique_abbrev(dst_cmd->new_oid.hash, DEFAULT_ABBREV));
+		 find_unique_abbrev(&dst_cmd->new_oid, DEFAULT_ABBREV));
 
 	cmd->error_string = dst_cmd->error_string =
 		"inconsistent aliased update";

builtin/reflog.c

@@ -75,7 +75,7 @@ static int tree_is_complete(const struct object_id *oid)
 	if (!tree->buffer) {
 		enum object_type type;
 		unsigned long size;
-		void *data = read_sha1_file(oid->hash, &type, &size);
+		void *data = read_object_file(oid, &type, &size);
 		if (!data) {
 			tree->object.flags |= INCOMPLETE;
 			return 0;

builtin/replace.c

@@ -53,8 +53,8 @@ static int show_reference(const char *refname, const struct object_id *oid,
 			if (get_oid(refname, &object))
 				return error("Failed to resolve '%s' as a valid ref.", refname);
 
-			obj_type = sha1_object_info(object.hash, NULL);
+			obj_type = oid_object_info(&object, NULL);
-			repl_type = sha1_object_info(oid->hash, NULL);
+			repl_type = oid_object_info(oid, NULL);
 
 			printf("%s (%s) -> %s (%s)\n", refname, type_name(obj_type),
 			       oid_to_hex(oid), type_name(repl_type));
@@ -162,8 +162,8 @@ static int replace_object_oid(const char *object_ref,
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
 
-	obj_type = sha1_object_info(object->hash, NULL);
+	obj_type = oid_object_info(object, NULL);
-	repl_type = sha1_object_info(repl->hash, NULL);
+	repl_type = oid_object_info(repl, NULL);
 	if (!force && obj_type != repl_type)
 		die("Objects must be of the same type.\n"
 		    "'%s' points to a replaced object of type '%s'\n"
@@ -290,7 +290,7 @@ static int edit_and_replace(const char *object_ref, int force, int raw)
 	if (get_oid(object_ref, &old_oid) < 0)
 		die("Not a valid object name: '%s'", object_ref);
 
-	type = sha1_object_info(old_oid.hash, NULL);
+	type = oid_object_info(&old_oid, NULL);
 	if (type < 0)
 		die("unable to get object type for %s", oid_to_hex(&old_oid));
 

builtin/reset.c

@@ -109,7 +109,7 @@ static void print_new_head_line(struct commit *commit)
 	struct strbuf buf = STRBUF_INIT;
 
 	printf(_("HEAD is now at %s"),
-		find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
+		find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 
 	pp_commit_easy(CMIT_FMT_ONELINE, commit, &buf);
 	if (buf.len > 0)

builtin/rev-list.c

@@ -108,7 +108,7 @@ static void show_commit(struct commit *commit, void *data)
 	if (!revs->graph)
 		fputs(get_revision_mark(revs, commit), stdout);
 	if (revs->abbrev_commit && revs->abbrev)
-		fputs(find_unique_abbrev(commit->object.oid.hash, revs->abbrev),
+		fputs(find_unique_abbrev(&commit->object.oid, revs->abbrev),
 		      stdout);
 	else
 		fputs(oid_to_hex(&commit->object.oid), stdout);

builtin/rev-parse.c

@@ -159,7 +159,7 @@ static void show_rev(int type, const struct object_id *oid, const char *name)
 		}
 	}
 	else if (abbrev)
-		show_with_type(type, find_unique_abbrev(oid->hash, abbrev));
+		show_with_type(type, find_unique_abbrev(oid, abbrev));
 	else
 		show_with_type(type, oid_to_hex(oid));
 }

builtin/rm.c

@@ -178,7 +178,7 @@ static int check_local_mod(struct object_id *head, int index_only)
 		 * way as changed from the HEAD.
 		 */
 		if (no_head
-		     || get_tree_entry(head->hash, name, oid.hash, &mode)
+		     || get_tree_entry(head, name, &oid, &mode)
 		     || ce->ce_mode != create_ce_mode(mode)
 		     || oidcmp(&ce->oid, &oid))
 			staged_changes = 1;

builtin/show-branch.c

@@ -292,7 +292,7 @@ static void show_one_commit(struct commit *commit, int no_name)
 		}
 		else
 			printf("[%s] ",
-			       find_unique_abbrev(commit->object.oid.hash,
+			       find_unique_abbrev(&commit->object.oid,
 						  DEFAULT_ABBREV));
 	}
 	puts(pretty_str);

builtin/show-ref.c

@@ -29,7 +29,7 @@ static void show_one(const char *refname, const struct object_id *oid)
 	if (quiet)
 		return;
 
-	hex = find_unique_abbrev(oid->hash, abbrev);
+	hex = find_unique_abbrev(oid, abbrev);
 	if (hash_only)
 		printf("%s\n", hex);
 	else
@@ -39,7 +39,7 @@ static void show_one(const char *refname, const struct object_id *oid)
 		return;
 
 	if (!peel_ref(refname, &peeled)) {
-		hex = find_unique_abbrev(peeled.hash, abbrev);
+		hex = find_unique_abbrev(&peeled, abbrev);
 		printf("%s %s^{}\n", hex, refname);
 	}
 }

builtin/tag.c

@@ -99,7 +99,8 @@ static int delete_tag(const char *name, const char *ref,
 {
 	if (delete_ref(NULL, ref, oid, 0))
 		return 1;
-	printf(_("Deleted tag '%s' (was %s)\n"), name, find_unique_abbrev(oid->hash, DEFAULT_ABBREV));
+	printf(_("Deleted tag '%s' (was %s)\n"), name,
+	       find_unique_abbrev(oid, DEFAULT_ABBREV));
 	return 0;
 }
 
@@ -167,7 +168,7 @@ static void write_tag_body(int fd, const struct object_id *oid)
 	enum object_type type;
 	char *buf, *sp;
 
-	buf = read_sha1_file(oid->hash, &type, &size);
+	buf = read_object_file(oid, &type, &size);
 	if (!buf)
 		return;
 	/* skip header */
@@ -211,7 +212,7 @@ static void create_tag(const struct object_id *object, const char *tag,
 	struct strbuf header = STRBUF_INIT;
 	char *path = NULL;
 
-	type = sha1_object_info(object->hash, NULL);
+	type = oid_object_info(object, NULL);
 	if (type <= OBJ_NONE)
 	    die(_("bad object type."));
 
@@ -293,17 +294,17 @@ static void create_reflog_msg(const struct object_id *oid, struct strbuf *sb)
 		strbuf_addstr(sb, rla);
 	} else {
 		strbuf_addstr(sb, "tag: tagging ");
-		strbuf_add_unique_abbrev(sb, oid->hash, DEFAULT_ABBREV);
+		strbuf_add_unique_abbrev(sb, oid, DEFAULT_ABBREV);
 	}
 
 	strbuf_addstr(sb, " (");
-	type = sha1_object_info(oid->hash, NULL);
+	type = oid_object_info(oid, NULL);
 	switch (type) {
 	default:
 		strbuf_addstr(sb, "object of unknown type");
 		break;
 	case OBJ_COMMIT:
-		if ((buf = read_sha1_file(oid->hash, &type, &size)) != NULL) {
+		if ((buf = read_object_file(oid, &type, &size)) != NULL) {
 			subject_len = find_commit_subject(buf, &subject_start);
 			strbuf_insert(sb, sb->len, subject_start, subject_len);
 		} else {
@@ -558,7 +559,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		die("%s", err.buf);
 	ref_transaction_free(transaction);
 	if (force && !is_null_oid(&prev) && oidcmp(&prev, &object))
-		printf(_("Updated tag '%s' (was %s)\n"), tag, find_unique_abbrev(prev.hash, DEFAULT_ABBREV));
+		printf(_("Updated tag '%s' (was %s)\n"), tag,
+		       find_unique_abbrev(&prev, DEFAULT_ABBREV));
 
 	UNLEAK(buf);
 	UNLEAK(ref);

builtin/unpack-file.c

@@ -9,7 +9,7 @@ static char *create_temp_file(struct object_id *oid)
 	unsigned long size;
 	int fd;
 
-	buf = read_sha1_file(oid->hash, &type, &size);
+	buf = read_object_file(oid, &type, &size);
 	if (!buf || type != OBJ_BLOB)
 		die("unable to read blob object %s", oid_to_hex(oid));
 

builtin/unpack-objects.c

@@ -199,7 +199,7 @@ static int check_object(struct object *obj, int type, void *data, struct fsck_op
 
 	if (!(obj->flags & FLAG_OPEN)) {
 		unsigned long size;
-		int type = sha1_object_info(obj->oid.hash, &size);
+		int type = oid_object_info(&obj->oid, &size);
 		if (type != obj->type || type <= 0)
 			die("object of unexpected type");
 		obj->flags |= FLAG_WRITTEN;
@@ -423,7 +423,7 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 	if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 		return;
 
-	base = read_sha1_file(base_oid.hash, &type, &base_size);
+	base = read_object_file(&base_oid, &type, &base_size);
 	if (!base) {
 		error("failed to read delta-pack base object %s",
 		      oid_to_hex(&base_oid));

builtin/update-index.c

@@ -592,7 +592,7 @@ static struct cache_entry *read_one_ent(const char *which,
 	int size;
 	struct cache_entry *ce;
 
-	if (get_tree_entry(ent->hash, path, oid.hash, &mode)) {
+	if (get_tree_entry(ent, path, &oid, &mode)) {
 		if (which)
 			error("%s: not in %s branch.", path, which);
 		return NULL;

builtin/verify-commit.c

@@ -44,7 +44,7 @@ static int verify_commit(const char *name, unsigned flags)
 	if (get_oid(name, &oid))
 		return error("commit '%s' not found.", name);
 
-	buf = read_sha1_file(oid.hash, &type, &size);
+	buf = read_object_file(&oid, &type, &size);
 	if (!buf)
 		return error("%s: unable to read file.", name);
 	if (type != OBJ_COMMIT)

builtin/worktree.c

@@ -502,7 +502,7 @@ static void show_worktree(struct worktree *wt, int path_maxlen, int abbrev_len)
 		strbuf_addstr(&sb, "(bare)");
 	else {
 		strbuf_addf(&sb, "%-*s ", abbrev_len,
-				find_unique_abbrev(wt->head_oid.hash, DEFAULT_ABBREV));
+				find_unique_abbrev(&wt->head_oid, DEFAULT_ABBREV));
 		if (wt->is_detached)
 			strbuf_addstr(&sb, "(detached HEAD)");
 		else if (wt->head_ref) {
@@ -527,7 +527,7 @@ static void measure_widths(struct worktree **wt, int *abbrev, int *maxlen)
 
 		if (path_len > *maxlen)
 			*maxlen = path_len;
-		sha1_len = strlen(find_unique_abbrev(wt[i]->head_oid.hash, *abbrev));
+		sha1_len = strlen(find_unique_abbrev(&wt[i]->head_oid, *abbrev));
 		if (sha1_len > *abbrev)
 			*abbrev = sha1_len;
 	}

builtin/write-tree.c

@@ -19,7 +19,7 @@ int cmd_write_tree(int argc, const char **argv, const char *unused_prefix)
 {
 	int flags = 0, ret;
 	const char *prefix = NULL;
-	unsigned char sha1[20];
+	struct object_id oid;
 	const char *me = "git-write-tree";
 	struct option write_tree_options[] = {
 		OPT_BIT(0, "missing-ok", &flags, N_("allow missing objects"),
@@ -38,10 +38,10 @@ int cmd_write_tree(int argc, const char **argv, const char *unused_prefix)
 	argc = parse_options(argc, argv, unused_prefix, write_tree_options,
 			     write_tree_usage, 0);
 
-	ret = write_cache_as_tree(sha1, flags, prefix);
+	ret = write_cache_as_tree(&oid, flags, prefix);
 	switch (ret) {
 	case 0:
-		printf("%s\n", sha1_to_hex(sha1));
+		printf("%s\n", oid_to_hex(&oid));
 		break;
 	case WRITE_TREE_UNREADABLE_INDEX:
 		die("%s: error reading the index", me);

bulk-checkin.c

@@ -60,17 +60,17 @@ clear_exit:
 	reprepare_packed_git();
 }
 
-static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
+static int already_written(struct bulk_checkin_state *state, struct object_id *oid)
 {
 	int i;
 
 	/* The object may already exist in the repository */
-	if (has_sha1_file(sha1))
+	if (has_sha1_file(oid->hash))
 		return 1;
 
 	/* Might want to keep the list sorted */
 	for (i = 0; i < state->nr_written; i++)
-		if (!hashcmp(state->written[i]->oid.hash, sha1))
+		if (!oidcmp(&state->written[i]->oid, oid))
 			return 1;
 
 	/* This is a new object we need to keep */
@@ -186,7 +186,7 @@ static void prepare_to_stream(struct bulk_checkin_state *state,
 }
 
 static int deflate_to_pack(struct bulk_checkin_state *state,
-			   unsigned char result_sha1[],
+			   struct object_id *result_oid,
 			   int fd, size_t size,
 			   enum object_type type, const char *path,
 			   unsigned flags)
@@ -236,17 +236,17 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
 		if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 			return error("cannot seek back");
 	}
-	the_hash_algo->final_fn(result_sha1, &ctx);
+	the_hash_algo->final_fn(result_oid->hash, &ctx);
 	if (!idx)
 		return 0;
 
 	idx->crc32 = crc32_end(state->f);
-	if (already_written(state, result_sha1)) {
+	if (already_written(state, result_oid)) {
 		hashfile_truncate(state->f, &checkpoint);
 		state->offset = checkpoint.offset;
 		free(idx);
 	} else {
-		hashcpy(idx->oid.hash, result_sha1);
+		oidcpy(&idx->oid, result_oid);
 		ALLOC_GROW(state->written,
 			   state->nr_written + 1,
 			   state->alloc_written);
@@ -255,11 +255,11 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
 	return 0;
 }
 
-int index_bulk_checkin(unsigned char *sha1,
+int index_bulk_checkin(struct object_id *oid,
 		       int fd, size_t size, enum object_type type,
 		       const char *path, unsigned flags)
 {
-	int status = deflate_to_pack(&state, sha1, fd, size, type,
+	int status = deflate_to_pack(&state, oid, fd, size, type,
 				     path, flags);
 	if (!state.plugged)
 		finish_bulk_checkin(&state);

bulk-checkin.h

@@ -4,7 +4,7 @@
 #ifndef BULK_CHECKIN_H
 #define BULK_CHECKIN_H
 
-extern int index_bulk_checkin(unsigned char sha1[],
+extern int index_bulk_checkin(struct object_id *oid,
 			      int fd, size_t size, enum object_type type,
 			      const char *path, unsigned flags);
 

bundle.c

@@ -222,7 +222,7 @@ static int is_tag_in_date_range(struct object *tag, struct rev_info *revs)
 	if (revs->max_age == -1 && revs->min_age == -1)
 		goto out;
 
-	buf = read_sha1_file(tag->oid.hash, &type, &size);
+	buf = read_object_file(&tag->oid, &type, &size);
 	if (!buf)
 		goto out;
 	line = memmem(buf, size, "\ntagger ", 8);

cache-tree.c

@@ -320,7 +320,7 @@ static int update_one(struct cache_tree *it,
 		struct cache_tree_sub *sub = NULL;
 		const char *path, *slash;
 		int pathlen, entlen;
-		const unsigned char *sha1;
+		const struct object_id *oid;
 		unsigned mode;
 		int expected_missing = 0;
 		int contains_ita = 0;
@@ -338,7 +338,7 @@ static int update_one(struct cache_tree *it,
 				die("cache-tree.c: '%.*s' in '%s' not found",
 				    entlen, path + baselen, path);
 			i += sub->count;
-			sha1 = sub->cache_tree->oid.hash;
+			oid = &sub->cache_tree->oid;
 			mode = S_IFDIR;
 			contains_ita = sub->cache_tree->entry_count < 0;
 			if (contains_ita) {
@@ -347,19 +347,19 @@ static int update_one(struct cache_tree *it,
 			}
 		}
 		else {
-			sha1 = ce->oid.hash;
+			oid = &ce->oid;
 			mode = ce->ce_mode;
 			entlen = pathlen - baselen;
 			i++;
 		}
 
-		if (is_null_sha1(sha1) ||
+		if (is_null_oid(oid) ||
-		    (mode != S_IFGITLINK && !missing_ok && !has_sha1_file(sha1))) {
+		    (mode != S_IFGITLINK && !missing_ok && !has_object_file(oid))) {
 			strbuf_release(&buffer);
 			if (expected_missing)
 				return -1;
 			return error("invalid object %06o %s for '%.*s'",
-				mode, sha1_to_hex(sha1), entlen+baselen, path);
+				mode, oid_to_hex(oid), entlen+baselen, path);
 		}
 
 		/*
@@ -385,12 +385,12 @@ static int update_one(struct cache_tree *it,
 		/*
 		 * "sub" can be an empty tree if all subentries are i-t-a.
 		 */
-		if (contains_ita && !hashcmp(sha1, EMPTY_TREE_SHA1_BIN))
+		if (contains_ita && !oidcmp(oid, &empty_tree_oid))
 			continue;
 
 		strbuf_grow(&buffer, entlen + 100);
 		strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
-		strbuf_add(&buffer, sha1, 20);
+		strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);
 
 #if DEBUG
 		fprintf(stderr, "cache-tree update-one %o %.*s\n",
@@ -401,7 +401,7 @@ static int update_one(struct cache_tree *it,
 	if (repair) {
 		struct object_id oid;
 		hash_object_file(buffer.buf, buffer.len, tree_type, &oid);
-		if (has_sha1_file(oid.hash))
+		if (has_object_file(&oid))
 			oidcpy(&it->oid, &oid);
 		else
 			to_invalidate = 1;
@@ -465,7 +465,7 @@ static void write_one(struct strbuf *buffer, struct cache_tree *it,
 #endif
 
 	if (0 <= it->entry_count) {
-		strbuf_add(buffer, it->oid.hash, 20);
+		strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);
 	}
 	for (i = 0; i < it->subtree_nr; i++) {
 		struct cache_tree_sub *down = it->down[i];
@@ -492,6 +492,7 @@ static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
 	char *ep;
 	struct cache_tree *it;
 	int i, subtree_nr;
+	const unsigned rawsz = the_hash_algo->rawsz;
 
 	it = NULL;
 	/* skip name, but make sure name exists */
@@ -520,11 +521,11 @@ static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
 		goto free_return;
 	buf++; size--;
 	if (0 <= it->entry_count) {
-		if (size < 20)
+		if (size < rawsz)
 			goto free_return;
-		hashcpy(it->oid.hash, (const unsigned char*)buf);
+		memcpy(it->oid.hash, (const unsigned char*)buf, rawsz);
-		buf += 20;
+		buf += rawsz;
-		size -= 20;
+		size -= rawsz;
 	}
 
 #if DEBUG
@@ -599,7 +600,7 @@ static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *pat
 	return it;
 }
 
-int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
+int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
 {
 	int entries, was_valid;
 	struct lock_file lock_file = LOCK_INIT;
@@ -640,19 +641,19 @@ int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, co
 			ret = WRITE_TREE_PREFIX_ERROR;
 			goto out;
 		}
-		hashcpy(sha1, subtree->oid.hash);
+		oidcpy(oid, &subtree->oid);
 	}
 	else
-		hashcpy(sha1, index_state->cache_tree->oid.hash);
+		oidcpy(oid, &index_state->cache_tree->oid);
 
 out:
 	rollback_lock_file(&lock_file);
 	return ret;
 }
 
-int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
+int write_cache_as_tree(struct object_id *oid, int flags, const char *prefix)
 {
-	return write_index_as_tree(sha1, &the_index, get_index_file(), flags, prefix);
+	return write_index_as_tree(oid, &the_index, get_index_file(), flags, prefix);
 }
 
 static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)

cache-tree.h

@@ -47,8 +47,8 @@ int update_main_cache_tree(int);
 #define WRITE_TREE_UNMERGED_INDEX (-2)
 #define WRITE_TREE_PREFIX_ERROR (-3)
 
-int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, const char *index_path, int flags, const char *prefix);
+int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix);
-int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix);
+int write_cache_as_tree(struct object_id *oid, int flags, const char *prefix);
 void prime_cache_tree(struct index_state *, struct tree *);
 
 extern int cache_tree_matches_traversal(struct cache_tree *, struct name_entry *ent, struct traverse_info *info);

cache.h

@@ -955,14 +955,14 @@ extern void sha1_file_name(struct strbuf *buf, const unsigned char *sha1);
  * more calls to find_unique_abbrev are made.
  *
  * The `_r` variant writes to a buffer supplied by the caller, which must be at
- * least `GIT_SHA1_HEXSZ + 1` bytes. The return value is the number of bytes
+ * least `GIT_MAX_HEXSZ + 1` bytes. The return value is the number of bytes
  * written (excluding the NUL terminator).
  *
  * Note that while this version avoids the static buffer, it is not fully
  * reentrant, as it calls into other non-reentrant git code.
  */
-extern const char *find_unique_abbrev(const unsigned char *sha1, int len);
+extern const char *find_unique_abbrev(const struct object_id *oid, int len);
-extern int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len);
+extern int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len);
 
 extern const unsigned char null_sha1[GIT_MAX_RAWSZ];
 extern const struct object_id null_oid;
@@ -1189,19 +1189,19 @@ extern char *xdg_config_home(const char *filename);
  */
 extern char *xdg_cache_home(const char *filename);
 
-extern void *read_sha1_file_extended(const unsigned char *sha1,
+extern void *read_object_file_extended(const struct object_id *oid,
 				       enum object_type *type,
 				       unsigned long *size, int lookup_replace);
-static inline void *read_sha1_file(const unsigned char *sha1, enum object_type *type, unsigned long *size)
+static inline void *read_object_file(const struct object_id *oid, enum object_type *type, unsigned long *size)
 {
-	return read_sha1_file_extended(sha1, type, size, 1);
+	return read_object_file_extended(oid, type, size, 1);
 }
 
 /*
  * This internal function is only declared here for the benefit of
  * lookup_replace_object().  Please do not call it directly.
  */
-extern const unsigned char *do_lookup_replace_object(const unsigned char *sha1);
+extern const struct object_id *do_lookup_replace_object(const struct object_id *oid);
 
 /*
  * If object sha1 should be replaced, return the replacement object's
@@ -1209,15 +1209,15 @@ extern const unsigned char *do_lookup_replace_object(const unsigned char *sha1);
  * either sha1 or a pointer to a permanently-allocated value.  When
  * object replacement is suppressed, always return sha1.
  */
-static inline const unsigned char *lookup_replace_object(const unsigned char *sha1)
+static inline const struct object_id *lookup_replace_object(const struct object_id *oid)
 {
 	if (!check_replace_refs)
-		return sha1;
+		return oid;
-	return do_lookup_replace_object(sha1);
+	return do_lookup_replace_object(oid);
 }
 
-/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
+/* Read and unpack an object file into memory, write memory to an object file */
-extern int sha1_object_info(const unsigned char *, unsigned long *);
+extern int oid_object_info(const struct object_id *, unsigned long *);
 
 extern int hash_object_file(const void *buf, unsigned long len,
 			    const char *type, struct object_id *oid);
@@ -1240,19 +1240,19 @@ extern void *map_sha1_file(const unsigned char *sha1, unsigned long *size);
 extern int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz);
 extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
 
-extern int check_sha1_signature(const unsigned char *sha1, void *buf, unsigned long size, const char *type);
+extern int check_object_signature(const struct object_id *oid, void *buf, unsigned long size, const char *type);
 
 extern int finalize_object_file(const char *tmpfile, const char *filename);
 
 /*
- * Open the loose object at path, check its sha1, and return the contents,
+ * Open the loose object at path, check its hash, and return the contents,
  * type, and size. If the object is a blob, then "contents" may return NULL,
  * to allow streaming of large blobs.
  *
  * Returns 0 on success, negative on error (details may be written to stderr).
  */
 int read_loose_object(const char *path,
-		      const unsigned char *expected_sha1,
+		      const struct object_id *expected_oid,
 		      enum object_type *type,
 		      unsigned long *size,
 		      void **contents);
@@ -1279,7 +1279,7 @@ extern int has_object_file_with_flags(const struct object_id *oid, int flags);
  */
 extern int has_loose_object_nonlocal(const unsigned char *sha1);
 
-extern void assert_sha1_type(const unsigned char *sha1, enum object_type expect);
+extern void assert_oid_type(const struct object_id *oid, enum object_type expect);
 
 /* Helper to check and "touch" a file */
 extern int check_and_freshen_file(const char *fn, int freshen);
@@ -1435,10 +1435,10 @@ extern int df_name_compare(const char *name1, int len1, int mode1, const char *n
 extern int name_compare(const char *name1, size_t len1, const char *name2, size_t len2);
 extern int cache_name_stage_compare(const char *name1, int len1, int stage1, const char *name2, int len2, int stage2);
 
-extern void *read_object_with_reference(const unsigned char *sha1,
+extern void *read_object_with_reference(const struct object_id *oid,
 					const char *required_type,
 					unsigned long *size,
-					unsigned char *sha1_ret);
+					struct object_id *oid_ret);
 
 extern struct object *peel_to_type(const char *name, int namelen,
 				   struct object *o, enum object_type);
@@ -1779,7 +1779,7 @@ struct object_info {
 #define OBJECT_INFO_QUICK 8
 /* Do not check loose object */
 #define OBJECT_INFO_IGNORE_LOOSE 16
-extern int sha1_object_info_extended(const unsigned char *, struct object_info *, unsigned flags);
+extern int oid_object_info_extended(const struct object_id *, struct object_info *, unsigned flags);
 
 /*
  * Set this to 0 to prevent sha1_object_info_extended() from fetching missing

combine-diff.c

@@ -306,7 +306,7 @@ static char *grab_blob(const struct object_id *oid, unsigned int mode,
 		*size = fill_textconv(textconv, df, &blob);
 		free_filespec(df);
 	} else {
-		blob = read_sha1_file(oid->hash, &type, size);
+		blob = read_object_file(oid, &type, size);
 		if (type != OBJ_BLOB)
 			die("object '%s' is not a blob!", oid_to_hex(oid));
 	}
@@ -915,11 +915,11 @@ static void show_combined_header(struct combine_diff_path *elem,
 			 "", elem->path, line_prefix, c_meta, c_reset);
 	printf("%s%sindex ", line_prefix, c_meta);
 	for (i = 0; i < num_parent; i++) {
-		abb = find_unique_abbrev(elem->parent[i].oid.hash,
+		abb = find_unique_abbrev(&elem->parent[i].oid,
 					 abbrev);
 		printf("%s%s", i ? "," : "", abb);
 	}
-	abb = find_unique_abbrev(elem->oid.hash, abbrev);
+	abb = find_unique_abbrev(&elem->oid, abbrev);
 	printf("..%s%s\n", abb, c_reset);
 
 	if (mode_differs) {

commit.c

@@ -266,7 +266,7 @@ const void *get_commit_buffer(const struct commit *commit, unsigned long *sizep)
 	if (!ret) {
 		enum object_type type;
 		unsigned long size;
-		ret = read_sha1_file(commit->object.oid.hash, &type, &size);
+		ret = read_object_file(&commit->object.oid, &type, &size);
 		if (!ret)
 			die("cannot read commit object %s",
 			    oid_to_hex(&commit->object.oid));
@@ -383,7 +383,7 @@ int parse_commit_gently(struct commit *item, int quiet_on_missing)
 		return -1;
 	if (item->object.parsed)
 		return 0;
-	buffer = read_sha1_file(item->object.oid.hash, &type, &size);
+	buffer = read_object_file(&item->object.oid, &type, &size);
 	if (!buffer)
 		return quiet_on_missing ? -1 :
 			error("Could not read %s",
@@ -1206,7 +1206,7 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
 	desc = merge_remote_util(parent);
 	if (!desc || !desc->obj)
 		return;
-	buf = read_sha1_file(desc->obj->oid.hash, &type, &size);
+	buf = read_object_file(&desc->obj->oid, &type, &size);
 	if (!buf || type != OBJ_TAG)
 		goto free_return;
 	len = parse_signature(buf, size);
@@ -1517,7 +1517,7 @@ int commit_tree_extended(const char *msg, size_t msg_len,
 	int encoding_is_utf8;
 	struct strbuf buffer;
 
-	assert_sha1_type(tree->hash, OBJ_TREE);
+	assert_oid_type(tree, OBJ_TREE);
 
 	if (memchr(msg, '\0', msg_len))
 		return error("a NUL byte in commit log message not allowed.");

config.c

@@ -1488,7 +1488,7 @@ int git_config_from_blob_oid(config_fn_t fn,
 	unsigned long size;
 	int ret;
 
-	buf = read_sha1_file(oid->hash, &type, &size);
+	buf = read_object_file(oid, &type, &size);
 	if (!buf)
 		return error("unable to load config blob object '%s'", name);
 	if (type != OBJ_BLOB) {

convert.c

@@ -914,7 +914,7 @@ static int ident_to_worktree(const char *path, const char *src, size_t len,
 		to_free = strbuf_detach(buf, NULL);
 	hash_object_file(src, len, "blob", &oid);
 
-	strbuf_grow(buf, len + cnt * 43);
+	strbuf_grow(buf, len + cnt * (the_hash_algo->hexsz + 3));
 	for (;;) {
 		/* step 1: run to the next '$' */
 		dollar = memchr(src, '$', len);
@@ -1510,7 +1510,7 @@ struct ident_filter {
 	struct stream_filter filter;
 	struct strbuf left;
 	int state;
-	char ident[45]; /* ": x40 $" */
+	char ident[GIT_MAX_HEXSZ + 5]; /* ": x40 $" */
 };
 
 static int is_foreign_ident(const char *str)
@@ -1635,12 +1635,12 @@ static struct stream_filter_vtbl ident_vtbl = {
 	ident_free_fn,
 };
 
-static struct stream_filter *ident_filter(const unsigned char *sha1)
+static struct stream_filter *ident_filter(const struct object_id *oid)
 {
 	struct ident_filter *ident = xmalloc(sizeof(*ident));
 
 	xsnprintf(ident->ident, sizeof(ident->ident),
-		  ": %s $", sha1_to_hex(sha1));
+		  ": %s $", oid_to_hex(oid));
 	strbuf_init(&ident->left, 0);
 	ident->filter.vtbl = &ident_vtbl;
 	ident->state = 0;
@@ -1655,7 +1655,7 @@ static struct stream_filter *ident_filter(const unsigned char *sha1)
  * Note that you would be crazy to set CRLF, smuge/clean or ident to a
  * large binary blob you would want us not to slurp into the memory!
  */
-struct stream_filter *get_stream_filter(const char *path, const unsigned char *sha1)
+struct stream_filter *get_stream_filter(const char *path, const struct object_id *oid)
 {
 	struct conv_attrs ca;
 	struct stream_filter *filter = NULL;
@@ -1668,7 +1668,7 @@ struct stream_filter *get_stream_filter(const char *path, const unsigned char *s
 		return NULL;
 
 	if (ca.ident)
-		filter = ident_filter(sha1);
+		filter = ident_filter(oid);
 
 	if (output_eol(ca.crlf_action) == EOL_CRLF)
 		filter = cascade_filter(filter, lf_to_crlf_filter());

convert.h

@@ -93,7 +93,7 @@ extern int would_convert_to_git_filter_fd(const char *path);
 
 struct stream_filter; /* opaque */
 
-extern struct stream_filter *get_stream_filter(const char *path, const unsigned char *);
+extern struct stream_filter *get_stream_filter(const char *path, const struct object_id *);
 extern void free_stream_filter(struct stream_filter *);
 extern int is_null_stream_filter(struct stream_filter *);
 

diff.c

@@ -3638,7 +3638,7 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 	else {
 		enum object_type type;
 		if (size_only || (flags & CHECK_BINARY)) {
-			type = sha1_object_info(s->oid.hash, &s->size);
+			type = oid_object_info(&s->oid, &s->size);
 			if (type < 0)
 				die("unable to read %s",
 				    oid_to_hex(&s->oid));
@@ -3649,7 +3649,7 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 				return 0;
 			}
 		}
-		s->data = read_sha1_file(s->oid.hash, &type, &s->size);
+		s->data = read_object_file(&s->oid, &type, &s->size);
 		if (!s->data)
 			die("unable to read %s", oid_to_hex(&s->oid));
 		s->should_free = 1;
@@ -3834,7 +3834,7 @@ static int similarity_index(struct diff_filepair *p)
 static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
 {
 	if (startup_info->have_repository)
-		return find_unique_abbrev(oid->hash, abbrev);
+		return find_unique_abbrev(oid, abbrev);
 	else {
 		char *hex = oid_to_hex(oid);
 		if (abbrev < 0)

dir.c

@@ -243,7 +243,7 @@ static int do_read_blob(const struct object_id *oid, struct oid_stat *oid_stat,
 	*size_out = 0;
 	*data_out = NULL;
 
-	data = read_sha1_file(oid->hash, &type, &sz);
+	data = read_object_file(oid, &type, &sz);
 	if (!data || type != OBJ_BLOB) {
 		free(data);
 		return -1;

entry.c

@@ -85,7 +85,7 @@ static int create_file(const char *path, unsigned int mode)
 static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
 {
 	enum object_type type;
-	void *blob_data = read_sha1_file(ce->oid.hash, &type, size);
+	void *blob_data = read_object_file(&ce->oid, &type, size);
 
 	if (blob_data) {
 		if (type == OBJ_BLOB)
@@ -266,7 +266,7 @@ static int write_entry(struct cache_entry *ce,
 
 	if (ce_mode_s_ifmt == S_IFREG) {
 		struct stream_filter *filter = get_stream_filter(ce->name,
-								 ce->oid.hash);
+								 &ce->oid);
 		if (filter &&
 		    !streaming_write_entry(ce, path, filter,
 					   state, to_tempfile,

fast-import.c

@@ -1412,7 +1412,7 @@ static void load_tree(struct tree_entry *root)
 			die("Can't load tree %s", oid_to_hex(oid));
 	} else {
 		enum object_type type;
-		buf = read_sha1_file(oid->hash, &type, &size);
+		buf = read_object_file(oid, &type, &size);
 		if (!buf || type != OBJ_TREE)
 			die("Can't load tree %s", oid_to_hex(oid));
 	}
@@ -1913,7 +1913,7 @@ static void read_marks(void)
 			die("corrupt mark line: %s", line);
 		e = find_object(&oid);
 		if (!e) {
-			enum object_type type = sha1_object_info(oid.hash, NULL);
+			enum object_type type = oid_object_info(&oid, NULL);
 			if (type < 0)
 				die("object not found: %s", oid_to_hex(&oid));
 			e = insert_object(&oid);
@@ -2443,7 +2443,7 @@ static void file_change_m(const char *p, struct branch *b)
 		enum object_type expected = S_ISDIR(mode) ?
 						OBJ_TREE: OBJ_BLOB;
 		enum object_type type = oe ? oe->type :
-					sha1_object_info(oid.hash, NULL);
+					oid_object_info(&oid, NULL);
 		if (type < 0)
 			die("%s not found: %s",
 					S_ISDIR(mode) ?  "Tree" : "Blob",
@@ -2583,8 +2583,9 @@ static void note_change_n(const char *p, struct branch *b, unsigned char *old_fa
 		oidcpy(&commit_oid, &commit_oe->idx.oid);
 	} else if (!get_oid(p, &commit_oid)) {
 		unsigned long size;
-		char *buf = read_object_with_reference(commit_oid.hash,
+		char *buf = read_object_with_reference(&commit_oid,
-			commit_type, &size, commit_oid.hash);
+						       commit_type, &size,
+						       &commit_oid);
 		if (!buf || size < 46)
 			die("Not a valid commit: %s", p);
 		free(buf);
@@ -2603,7 +2604,7 @@ static void note_change_n(const char *p, struct branch *b, unsigned char *old_fa
 			die("Not a blob (actually a %s): %s",
 				type_name(oe->type), command_buf.buf);
 	} else if (!is_null_oid(&oid)) {
-		enum object_type type = sha1_object_info(oid.hash, NULL);
+		enum object_type type = oid_object_info(&oid, NULL);
 		if (type < 0)
 			die("Blob not found: %s", command_buf.buf);
 		if (type != OBJ_BLOB)
@@ -2653,9 +2654,8 @@ static void parse_from_existing(struct branch *b)
 		unsigned long size;
 		char *buf;
 
-		buf = read_object_with_reference(b->oid.hash,
+		buf = read_object_with_reference(&b->oid, commit_type, &size,
-						 commit_type, &size,
+						 &b->oid);
-						 b->oid.hash);
 		parse_from_commit(b, buf, size);
 		free(buf);
 	}
@@ -2732,8 +2732,9 @@ static struct hash_list *parse_merge(unsigned int *count)
 			oidcpy(&n->oid, &oe->idx.oid);
 		} else if (!get_oid(from, &n->oid)) {
 			unsigned long size;
-			char *buf = read_object_with_reference(n->oid.hash,
+			char *buf = read_object_with_reference(&n->oid,
-				commit_type, &size, n->oid.hash);
+							       commit_type,
+							       &size, &n->oid);
 			if (!buf || size < 46)
 				die("Not a valid commit: %s", from);
 			free(buf);
@@ -2890,7 +2891,7 @@ static void parse_new_tag(const char *arg)
 	} else if (!get_oid(from, &oid)) {
 		struct object_entry *oe = find_object(&oid);
 		if (!oe) {
-			type = sha1_object_info(oid.hash, NULL);
+			type = oid_object_info(&oid, NULL);
 			if (type < 0)
 				die("Not a valid object: %s", from);
 		} else
@@ -2966,7 +2967,7 @@ static void cat_blob(struct object_entry *oe, struct object_id *oid)
 	char *buf;
 
 	if (!oe || oe->pack_id == MAX_PACK_ID) {
-		buf = read_sha1_file(oid->hash, &type, &size);
+		buf = read_object_file(oid, &type, &size);
 	} else {
 		type = oe->type;
 		buf = gfi_unpack_entry(oe, &size);
@@ -3048,7 +3049,7 @@ static struct object_entry *dereference(struct object_entry *oe,
 	unsigned long size;
 	char *buf = NULL;
 	if (!oe) {
-		enum object_type type = sha1_object_info(oid->hash, NULL);
+		enum object_type type = oid_object_info(oid, NULL);
 		if (type < 0)
 			die("object not found: %s", oid_to_hex(oid));
 		/* cache it! */
@@ -3071,7 +3072,7 @@ static struct object_entry *dereference(struct object_entry *oe,
 		buf = gfi_unpack_entry(oe, &size);
 	} else {
 		enum object_type unused;
-		buf = read_sha1_file(oid->hash, &unused, &size);
+		buf = read_object_file(oid, &unused, &size);
 	}
 	if (!buf)
 		die("Can't load object %s", oid_to_hex(oid));

fsck.c

@@ -811,7 +811,7 @@ static int fsck_tag_buffer(struct tag *tag, const char *data,
 		enum object_type type;
 
 		buffer = to_free =
-			read_sha1_file(tag->object.oid.hash, &type, &size);
+			read_object_file(&tag->object.oid, &type, &size);
 		if (!buffer)
 			return report(options, &tag->object,
 				FSCK_MSG_MISSING_TAG_OBJECT,

grep.c

@@ -2015,7 +2015,7 @@ static int grep_source_load_oid(struct grep_source *gs)
 	enum object_type type;
 
 	grep_read_lock();
-	gs->buf = read_sha1_file(gs->identifier, &type, &gs->size);
+	gs->buf = read_object_file(gs->identifier, &type, &gs->size);
 	grep_read_unlock();
 
 	if (!gs->buf)

http-push.c

@@ -361,7 +361,7 @@ static void start_put(struct transfer_request *request)
 	ssize_t size;
 	git_zstream stream;
 
-	unpacked = read_sha1_file(request->obj->oid.hash, &type, &len);
+	unpacked = read_object_file(&request->obj->oid, &type, &len);
 	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(type), len) + 1;
 
 	/* Set it up */

http-walker.c

@@ -22,7 +22,7 @@ enum object_request_state {
 
 struct object_request {
 	struct walker *walker;
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct alt_base *repo;
 	enum object_request_state state;
 	struct http_object_request *req;
@@ -56,7 +56,7 @@ static void start_object_request(struct walker *walker,
 	struct active_request_slot *slot;
 	struct http_object_request *req;
 
-	req = new_http_object_request(obj_req->repo->base, obj_req->sha1);
+	req = new_http_object_request(obj_req->repo->base, obj_req->oid.hash);
 	if (req == NULL) {
 		obj_req->state = ABORTED;
 		return;
@@ -82,7 +82,7 @@ static void finish_object_request(struct object_request *obj_req)
 		return;
 
 	if (obj_req->req->rename == 0)
-		walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
+		walker_say(obj_req->walker, "got %s\n", oid_to_hex(&obj_req->oid));
 }
 
 static void process_object_response(void *callback_data)
@@ -129,7 +129,7 @@ static int fill_active_slot(struct walker *walker)
 	list_for_each_safe(pos, tmp, head) {
 		obj_req = list_entry(pos, struct object_request, node);
 		if (obj_req->state == WAITING) {
-			if (has_sha1_file(obj_req->sha1))
+			if (has_sha1_file(obj_req->oid.hash))
 				obj_req->state = COMPLETE;
 			else {
 				start_object_request(walker, obj_req);
@@ -148,7 +148,7 @@ static void prefetch(struct walker *walker, unsigned char *sha1)
 
 	newreq = xmalloc(sizeof(*newreq));
 	newreq->walker = walker;
-	hashcpy(newreq->sha1, sha1);
+	hashcpy(newreq->oid.hash, sha1);
 	newreq->repo = data->alt;
 	newreq->state = WAITING;
 	newreq->req = NULL;
@@ -481,13 +481,13 @@ static int fetch_object(struct walker *walker, unsigned char *sha1)
 
 	list_for_each(pos, head) {
 		obj_req = list_entry(pos, struct object_request, node);
-		if (!hashcmp(obj_req->sha1, sha1))
+		if (!hashcmp(obj_req->oid.hash, sha1))
 			break;
 	}
 	if (obj_req == NULL)
 		return error("Couldn't find request for %s in the queue", hex);
 
-	if (has_sha1_file(obj_req->sha1)) {
+	if (has_sha1_file(obj_req->oid.hash)) {
 		if (obj_req->req != NULL)
 			abort_http_object_request(obj_req->req);
 		abort_object_request(obj_req);
@@ -541,7 +541,7 @@ static int fetch_object(struct walker *walker, unsigned char *sha1)
 	} else if (req->zret != Z_STREAM_END) {
 		walker->corrupt_object_found++;
 		ret = error("File %s (%s) corrupt", hex, req->url);
-	} else if (hashcmp(obj_req->sha1, req->real_sha1)) {
+	} else if (hashcmp(obj_req->oid.hash, req->real_sha1)) {
 		ret = error("File %s has bad hash", hex);
 	} else if (req->rename < 0) {
 		struct strbuf buf = STRBUF_INIT;

line-log.c

@@ -501,8 +501,7 @@ static void fill_blob_sha1(struct commit *commit, struct diff_filespec *spec)
 	unsigned mode;
 	struct object_id oid;
 
-	if (get_tree_entry(commit->object.oid.hash, spec->path,
+	if (get_tree_entry(&commit->object.oid, spec->path, &oid, &mode))
-			   oid.hash, &mode))
 		die("There is no path %s in the commit", spec->path);
 	fill_filespec(spec, &oid, 1, mode);
 

list-objects-filter.c

@@ -117,7 +117,7 @@ static enum list_objects_filter_result filter_blobs_limit(
 		assert(obj->type == OBJ_BLOB);
 		assert((obj->flags & SEEN) == 0);
 
-		t = sha1_object_info(obj->oid.hash, &object_length);
+		t = oid_object_info(&obj->oid, &object_length);
 		if (t != OBJ_BLOB) { /* probably OBJ_NONE */
 			/*
 			 * We DO NOT have the blob locally, so we cannot

log-tree.c

@@ -177,7 +177,7 @@ static void show_parents(struct commit *commit, int abbrev, FILE *file)
 	struct commit_list *p;
 	for (p = commit->parents; p ; p = p->next) {
 		struct commit *parent = p->item;
-		fprintf(file, " %s", find_unique_abbrev(parent->object.oid.hash, abbrev));
+		fprintf(file, " %s", find_unique_abbrev(&parent->object.oid, abbrev));
 	}
 }
 
@@ -185,7 +185,7 @@ static void show_children(struct rev_info *opt, struct commit *commit, int abbre
 {
 	struct commit_list *p = lookup_decoration(&opt->children, &commit->object);
 	for ( ; p; p = p->next) {
-		fprintf(opt->diffopt.file, " %s", find_unique_abbrev(p->item->object.oid.hash, abbrev));
+		fprintf(opt->diffopt.file, " %s", find_unique_abbrev(&p->item->object.oid, abbrev));
 	}
 }
 
@@ -558,7 +558,7 @@ void show_log(struct rev_info *opt)
 
 		if (!opt->graph)
 			put_revision_mark(opt, commit);
-		fputs(find_unique_abbrev(commit->object.oid.hash, abbrev_commit), opt->diffopt.file);
+		fputs(find_unique_abbrev(&commit->object.oid, abbrev_commit), opt->diffopt.file);
 		if (opt->print_parents)
 			show_parents(commit, abbrev_commit, opt->diffopt.file);
 		if (opt->children.name)
@@ -620,7 +620,8 @@ void show_log(struct rev_info *opt)
 
 		if (!opt->graph)
 			put_revision_mark(opt, commit);
-		fputs(find_unique_abbrev(commit->object.oid.hash, abbrev_commit),
+		fputs(find_unique_abbrev(&commit->object.oid,
+					 abbrev_commit),
 		      opt->diffopt.file);
 		if (opt->print_parents)
 			show_parents(commit, abbrev_commit, opt->diffopt.file);
@@ -628,8 +629,7 @@ void show_log(struct rev_info *opt)
 			show_children(opt, commit, abbrev_commit);
 		if (parent)
 			fprintf(opt->diffopt.file, " (from %s)",
-			       find_unique_abbrev(parent->object.oid.hash,
+			       find_unique_abbrev(&parent->object.oid, abbrev_commit));
-						  abbrev_commit));
 		fputs(diff_get_color_opt(&opt->diffopt, DIFF_RESET), opt->diffopt.file);
 		show_decorations(opt, commit);
 		if (opt->commit_format == CMIT_FMT_ONELINE) {

mailmap.c

@@ -224,7 +224,7 @@ static int read_mailmap_blob(struct string_list *map,
 	if (get_oid(name, &oid) < 0)
 		return 0;
 
-	buf = read_sha1_file(oid.hash, &type, &size);
+	buf = read_object_file(&oid, &type, &size);
 	if (!buf)
 		return error("unable to read mailmap object at %s", name);
 	if (type != OBJ_BLOB)

match-trees.c

@@ -54,7 +54,7 @@ static void *fill_tree_desc_strict(struct tree_desc *desc,
 	enum object_type type;
 	unsigned long size;
 
-	buffer = read_sha1_file(hash->hash, &type, &size);
+	buffer = read_object_file(hash, &type, &size);
 	if (!buffer)
 		die("unable to read tree (%s)", oid_to_hex(hash));
 	if (type != OBJ_TREE)
@@ -180,7 +180,7 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,
 	if (*subpath)
 		subpath++;
 
-	buf = read_sha1_file(oid1->hash, &type, &sz);
+	buf = read_object_file(oid1, &type, &sz);
 	if (!buf)
 		die("cannot read tree %s", oid_to_hex(oid1));
 	init_tree_desc(&desc, buf, sz);
@@ -269,7 +269,7 @@ void shift_tree(const struct object_id *hash1,
 		if (!*del_prefix)
 			return;
 
-		if (get_tree_entry(hash2->hash, del_prefix, shifted->hash, &mode))
+		if (get_tree_entry(hash2, del_prefix, shifted, &mode))
 			die("cannot find path %s in tree %s",
 			    del_prefix, oid_to_hex(hash2));
 		return;
@@ -296,12 +296,12 @@ void shift_tree_by(const struct object_id *hash1,
 	unsigned candidate = 0;
 
 	/* Can hash2 be a tree at shift_prefix in tree hash1? */
-	if (!get_tree_entry(hash1->hash, shift_prefix, sub1.hash, &mode1) &&
+	if (!get_tree_entry(hash1, shift_prefix, &sub1, &mode1) &&
 	    S_ISDIR(mode1))
 		candidate |= 1;
 
 	/* Can hash1 be a tree at shift_prefix in tree hash2? */
-	if (!get_tree_entry(hash2->hash, shift_prefix, sub2.hash, &mode2) &&
+	if (!get_tree_entry(hash2, shift_prefix, &sub2, &mode2) &&
 	    S_ISDIR(mode2))
 		candidate |= 2;
 

merge-blobs.c

@@ -11,7 +11,7 @@ static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
 	unsigned long size;
 	enum object_type type;
 
-	buf = read_sha1_file(obj->object.oid.hash, &type, &size);
+	buf = read_object_file(&obj->object.oid, &type, &size);
 	if (!buf)
 		return -1;
 	if (type != OBJ_BLOB) {
@@ -66,7 +66,7 @@ void *merge_blobs(const char *path, struct blob *base, struct blob *our, struct
 			return NULL;
 		if (!our)
 			our = their;
-		return read_sha1_file(our->object.oid.hash, &type, size);
+		return read_object_file(&our->object.oid, &type, size);
 	}
 
 	if (fill_mmfile_blob(&f1, our) < 0)

merge-recursive.c

@@ -290,7 +290,7 @@ static void output_commit_title(struct merge_options *o, struct commit *commit)
 		strbuf_addf(&o->obuf, "virtual %s\n",
 			merge_remote_util(commit)->name);
 	else {
-		strbuf_add_unique_abbrev(&o->obuf, commit->object.oid.hash,
+		strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
 					 DEFAULT_ABBREV);
 		strbuf_addch(&o->obuf, ' ');
 		if (parse_commit(commit) != 0)
@@ -402,7 +402,7 @@ struct tree *write_tree_from_memory(struct merge_options *o)
 	return result;
 }
 
-static int save_files_dirs(const unsigned char *sha1,
+static int save_files_dirs(const struct object_id *oid,
 		struct strbuf *base, const char *path,
 		unsigned int mode, int stage, void *context)
 {
@@ -427,16 +427,16 @@ static void get_files_dirs(struct merge_options *o, struct tree *tree)
 	read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
 }
 
-static int get_tree_entry_if_blob(const unsigned char *tree,
+static int get_tree_entry_if_blob(struct tree *tree,
 				  const char *path,
-				  unsigned char *hashy,
+				  struct object_id *hashy,
 				  unsigned int *mode_o)
 {
 	int ret;
 
-	ret = get_tree_entry(tree, path, hashy, mode_o);
+	ret = get_tree_entry(&tree->object.oid, path, hashy, mode_o);
 	if (S_ISDIR(*mode_o)) {
-		hashcpy(hashy, null_sha1);
+		oidcpy(hashy, &null_oid);
 		*mode_o = 0;
 	}
 	return ret;
@@ -452,12 +452,12 @@ static struct stage_data *insert_stage_data(const char *path,
 {
 	struct string_list_item *item;
 	struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
-	get_tree_entry_if_blob(o->object.oid.hash, path,
+	get_tree_entry_if_blob(o, path,
-			       e->stages[1].oid.hash, &e->stages[1].mode);
+			       &e->stages[1].oid, &e->stages[1].mode);
-	get_tree_entry_if_blob(a->object.oid.hash, path,
+	get_tree_entry_if_blob(a, path,
-			       e->stages[2].oid.hash, &e->stages[2].mode);
+			       &e->stages[2].oid, &e->stages[2].mode);
-	get_tree_entry_if_blob(b->object.oid.hash, path,
+	get_tree_entry_if_blob(b, path,
-			       e->stages[3].oid.hash, &e->stages[3].mode);
+			       &e->stages[3].oid, &e->stages[3].mode);
 	item = string_list_insert(entries, path);
 	item->util = e;
 	return e;
@@ -891,7 +891,7 @@ static int update_file_flags(struct merge_options *o,
 			goto update_index;
 		}
 
-		buf = read_sha1_file(oid->hash, &type, &size);
+		buf = read_object_file(oid, &type, &size);
 		if (!buf)
 			return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
 		if (type != OBJ_BLOB) {
@@ -1559,11 +1559,11 @@ static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 
 static int tree_has_path(struct tree *tree, const char *path)
 {
-	unsigned char hashy[GIT_MAX_RAWSZ];
+	struct object_id hashy;
 	unsigned int mode_o;
 
-	return !get_tree_entry(tree->object.oid.hash, path,
+	return !get_tree_entry(&tree->object.oid, path,
-			       hashy, &mode_o);
+			       &hashy, &mode_o);
 }
 
 /*
@@ -2159,9 +2159,9 @@ static void apply_directory_rename_modifications(struct merge_options *o,
 	 * the various conflict_rename_*() functions update the index
 	 * explicitly rather than relying on unpack_trees() to have done it.
 	 */
-	get_tree_entry(tree->object.oid.hash,
+	get_tree_entry(&tree->object.oid,
 		       pair->two->path,
-		       re->dst_entry->stages[stage].oid.hash,
+		       &re->dst_entry->stages[stage].oid,
 		       &re->dst_entry->stages[stage].mode);
 
 	/* Update pair status */
@@ -2646,7 +2646,7 @@ static int read_oid_strbuf(struct merge_options *o,
 	void *buf;
 	enum object_type type;
 	unsigned long size;
-	buf = read_sha1_file(oid->hash, &type, &size);
+	buf = read_object_file(oid, &type, &size);
 	if (!buf)
 		return err(o, _("cannot read object %s"), oid_to_hex(oid));
 	if (type != OBJ_BLOB) {

notes-cache.c

@@ -77,7 +77,7 @@ char *notes_cache_get(struct notes_cache *c, struct object_id *key_oid,
 	value_oid = get_note(&c->tree, key_oid);
 	if (!value_oid)
 		return NULL;
-	value = read_sha1_file(value_oid->hash, &type, &size);
+	value = read_object_file(value_oid, &type, &size);
 
 	*outsize = size;
 	return value;

notes-merge.c

@@ -322,7 +322,7 @@ static void write_note_to_worktree(const struct object_id *obj,
 {
 	enum object_type type;
 	unsigned long size;
-	void *buf = read_sha1_file(note->hash, &type, &size);
+	void *buf = read_object_file(note, &type, &size);
 
 	if (!buf)
 		die("cannot read note %s for object %s",

notes.c

@@ -796,13 +796,13 @@ int combine_notes_concatenate(struct object_id *cur_oid,
 
 	/* read in both note blob objects */
 	if (!is_null_oid(new_oid))
-		new_msg = read_sha1_file(new_oid->hash, &new_type, &new_len);
+		new_msg = read_object_file(new_oid, &new_type, &new_len);
 	if (!new_msg || !new_len || new_type != OBJ_BLOB) {
 		free(new_msg);
 		return 0;
 	}
 	if (!is_null_oid(cur_oid))
-		cur_msg = read_sha1_file(cur_oid->hash, &cur_type, &cur_len);
+		cur_msg = read_object_file(cur_oid, &cur_type, &cur_len);
 	if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
 		free(cur_msg);
 		free(new_msg);
@@ -858,7 +858,7 @@ static int string_list_add_note_lines(struct string_list *list,
 		return 0;
 
 	/* read_sha1_file NUL-terminates */
-	data = read_sha1_file(oid->hash, &t, &len);
+	data = read_object_file(oid, &t, &len);
 	if (t != OBJ_BLOB || !data || !len) {
 		free(data);
 		return t != OBJ_BLOB || !data;
@@ -1012,7 +1012,7 @@ void init_notes(struct notes_tree *t, const char *notes_ref,
 		return;
 	if (flags & NOTES_INIT_WRITABLE && read_ref(notes_ref, &object_oid))
 		die("Cannot use notes ref %s", notes_ref);
-	if (get_tree_entry(object_oid.hash, "", oid.hash, &mode))
+	if (get_tree_entry(&object_oid, "", &oid, &mode))
 		die("Failed to read notes tree referenced by %s (%s)",
 		    notes_ref, oid_to_hex(&object_oid));
 
@@ -1217,7 +1217,7 @@ static void format_note(struct notes_tree *t, const struct object_id *object_oid
 	if (!oid)
 		return;
 
-	if (!(msg = read_sha1_file(oid->hash, &type, &msglen)) || type != OBJ_BLOB) {
+	if (!(msg = read_object_file(oid, &type, &msglen)) || type != OBJ_BLOB) {
 		free(msg);
 		return;
 	}

object.c

@@ -244,7 +244,7 @@ struct object *parse_object(const struct object_id *oid)
 	unsigned long size;
 	enum object_type type;
 	int eaten;
-	const unsigned char *repl = lookup_replace_object(oid->hash);
+	const struct object_id *repl = lookup_replace_object(oid);
 	void *buffer;
 	struct object *obj;
 
@@ -254,8 +254,8 @@ struct object *parse_object(const struct object_id *oid)
 
 	if ((obj && obj->type == OBJ_BLOB && has_object_file(oid)) ||
 	    (!obj && has_object_file(oid) &&
-	     sha1_object_info(oid->hash, NULL) == OBJ_BLOB)) {
+	     oid_object_info(oid, NULL) == OBJ_BLOB)) {
-		if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
+		if (check_object_signature(repl, NULL, 0, NULL) < 0) {
 			error("sha1 mismatch %s", oid_to_hex(oid));
 			return NULL;
 		}
@@ -263,11 +263,11 @@ struct object *parse_object(const struct object_id *oid)
 		return lookup_object(oid->hash);
 	}
 
-	buffer = read_sha1_file(oid->hash, &type, &size);
+	buffer = read_object_file(oid, &type, &size);
 	if (buffer) {
-		if (check_sha1_signature(repl, buffer, size, type_name(type)) < 0) {
+		if (check_object_signature(repl, buffer, size, type_name(type)) < 0) {
 			free(buffer);
-			error("sha1 mismatch %s", sha1_to_hex(repl));
+			error("sha1 mismatch %s", oid_to_hex(repl));
 			return NULL;
 		}
 

pack-bitmap-write.c

@@ -73,8 +73,7 @@ void bitmap_writer_build_type_index(struct pack_idx_entry **index,
 			break;
 
 		default:
-			real_type = sha1_object_info(entry->idx.oid.hash,
+			real_type = oid_object_info(&entry->idx.oid, NULL);
-						     NULL);
 			break;
 		}
 

pack-check.c

@@ -126,7 +126,7 @@ static int verify_packfile(struct packed_git *p,
 
 		if (type == OBJ_BLOB && big_file_threshold <= size) {
 			/*
-			 * Let check_sha1_signature() check it with
+			 * Let check_object_signature() check it with
 			 * the streaming interface; no point slurping
 			 * the data in-core only to discard.
 			 */
@@ -141,7 +141,7 @@ static int verify_packfile(struct packed_git *p,
 			err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 				    oid_to_hex(entries[i].oid.oid), p->pack_name,
 				    (uintmax_t)entries[i].offset);
-		else if (check_sha1_signature(entries[i].oid.hash, data, size, type_name(type)))
+		else if (check_object_signature(entries[i].oid.oid, data, size, type_name(type)))
 			err = error("packed %s from %s is corrupt",
 				    oid_to_hex(entries[i].oid.oid), p->pack_name);
 		else if (fn) {

packfile.c

@@ -1095,13 +1095,13 @@ static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
 {
 	int type;
 	struct revindex_entry *revidx;
-	const unsigned char *sha1;
+	struct object_id oid;
 	revidx = find_pack_revindex(p, obj_offset);
 	if (!revidx)
 		return OBJ_BAD;
-	sha1 = nth_packed_object_sha1(p, revidx->nr);
+	nth_packed_object_oid(&oid, p, revidx->nr);
-	mark_bad_packed_object(p, sha1);
+	mark_bad_packed_object(p, oid.hash);
-	type = sha1_object_info(sha1, NULL);
+	type = oid_object_info(&oid, NULL);
 	if (type <= OBJ_NONE)
 		return OBJ_BAD;
 	return type;
@@ -1452,7 +1452,7 @@ struct unpack_entry_stack_ent {
 	unsigned long size;
 };
 
-static void *read_object(const unsigned char *sha1, enum object_type *type,
+static void *read_object(const struct object_id *oid, enum object_type *type,
 			 unsigned long *size)
 {
 	struct object_info oi = OBJECT_INFO_INIT;
@@ -1461,7 +1461,7 @@ static void *read_object(const unsigned char *sha1, enum object_type *type,
 	oi.sizep = size;
 	oi.contentp = &content;
 
-	if (sha1_object_info_extended(sha1, &oi, 0) < 0)
+	if (oid_object_info_extended(oid, &oi, 0) < 0)
 		return NULL;
 	return content;
 }
@@ -1501,11 +1501,11 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 			struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
 			off_t len = revidx[1].offset - obj_offset;
 			if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
-				const unsigned char *sha1 =
+				struct object_id oid;
-					nth_packed_object_sha1(p, revidx->nr);
+				nth_packed_object_oid(&oid, p, revidx->nr);
 				error("bad packed object CRC for %s",
-				      sha1_to_hex(sha1));
+				      oid_to_hex(&oid));
-				mark_bad_packed_object(p, sha1);
+				mark_bad_packed_object(p, oid.hash);
 				data = NULL;
 				goto out;
 			}
@@ -1588,16 +1588,16 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 			 * of a corrupted pack, and is better than failing outright.
 			 */
 			struct revindex_entry *revidx;
-			const unsigned char *base_sha1;
+			struct object_id base_oid;
 			revidx = find_pack_revindex(p, obj_offset);
 			if (revidx) {
-				base_sha1 = nth_packed_object_sha1(p, revidx->nr);
+				nth_packed_object_oid(&base_oid, p, revidx->nr);
 				error("failed to read delta base object %s"
 				      " at offset %"PRIuMAX" from %s",
-				      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
+				      oid_to_hex(&base_oid), (uintmax_t)obj_offset,
 				      p->pack_name);
-				mark_bad_packed_object(p, base_sha1);
+				mark_bad_packed_object(p, base_oid.hash);
-				base = read_object(base_sha1, &type, &base_size);
+				base = read_object(&base_oid, &type, &base_size);
 				external_base = base;
 			}
 		}

pretty.c

@@ -549,7 +549,7 @@ static void add_merge_info(const struct pretty_print_context *pp,
 		struct object_id *oidp = &parent->item->object.oid;
 		strbuf_addch(sb, ' ');
 		if (pp->abbrev)
-			strbuf_add_unique_abbrev(sb, oidp->hash, pp->abbrev);
+			strbuf_add_unique_abbrev(sb, oidp, pp->abbrev);
 		else
 			strbuf_addstr(sb, oid_to_hex(oidp));
 		parent = parent->next;
@@ -1156,7 +1156,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		return 1;
 	case 'h':		/* abbreviated commit hash */
 		strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_COMMIT));
-		strbuf_add_unique_abbrev(sb, commit->object.oid.hash,
+		strbuf_add_unique_abbrev(sb, &commit->object.oid,
 					 c->pretty_ctx->abbrev);
 		strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_RESET));
 		return 1;
@@ -1164,7 +1164,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		strbuf_addstr(sb, oid_to_hex(&commit->tree->object.oid));
 		return 1;
 	case 't':		/* abbreviated tree hash */
-		strbuf_add_unique_abbrev(sb, commit->tree->object.oid.hash,
+		strbuf_add_unique_abbrev(sb, &commit->tree->object.oid,
 					 c->pretty_ctx->abbrev);
 		return 1;
 	case 'P':		/* parent hashes */
@@ -1178,7 +1178,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		for (p = commit->parents; p; p = p->next) {
 			if (p != commit->parents)
 				strbuf_addch(sb, ' ');
-			strbuf_add_unique_abbrev(sb, p->item->object.oid.hash,
+			strbuf_add_unique_abbrev(sb, &p->item->object.oid,
 						 c->pretty_ctx->abbrev);
 		}
 		return 1;

reachable.c

@@ -77,7 +77,7 @@ static void add_recent_object(const struct object_id *oid,
 	 * later processing, and the revision machinery expects
 	 * commits and tags to have been parsed.
 	 */
-	type = sha1_object_info(oid->hash, NULL);
+	type = oid_object_info(oid, NULL);
 	if (type < 0)
 		die("unable to get object info for %s", oid_to_hex(oid));
 

read-cache.c

@@ -185,7 +185,7 @@ static int ce_compare_link(const struct cache_entry *ce, size_t expected_size)
 	if (strbuf_readlink(&sb, ce->name, expected_size))
 		return -1;
 
-	buffer = read_sha1_file(ce->oid.hash, &type, &size);
+	buffer = read_object_file(&ce->oid, &type, &size);
 	if (buffer) {
 		if (size == sb.len)
 			match = memcmp(buffer, sb.buf, size);
@@ -2693,7 +2693,7 @@ void *read_blob_data_from_index(const struct index_state *istate,
 	}
 	if (pos < 0)
 		return NULL;
-	data = read_sha1_file(istate->cache[pos]->oid.hash, &type, &sz);
+	data = read_object_file(&istate->cache[pos]->oid, &type, &sz);
 	if (!data || type != OBJ_BLOB) {
 		free(data);
 		return NULL;

ref-filter.c

@@ -728,7 +728,7 @@ int verify_ref_format(struct ref_format *format)
 static void *get_obj(const struct object_id *oid, struct object **obj, unsigned long *sz, int *eaten)
 {
 	enum object_type type;
-	void *buf = read_sha1_file(oid->hash, &type, sz);
+	void *buf = read_object_file(oid, &type, sz);
 
 	if (buf)
 		*obj = parse_object_buffer(oid, type, *sz, buf, eaten);
@@ -737,18 +737,18 @@ static void *get_obj(const struct object_id *oid, struct object **obj, unsigned
 	return buf;
 }
 
-static int grab_objectname(const char *name, const unsigned char *sha1,
+static int grab_objectname(const char *name, const struct object_id *oid,
 			   struct atom_value *v, struct used_atom *atom)
 {
 	if (starts_with(name, "objectname")) {
 		if (atom->u.objectname.option == O_SHORT) {
-			v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
+			v->s = xstrdup(find_unique_abbrev(oid, DEFAULT_ABBREV));
 			return 1;
 		} else if (atom->u.objectname.option == O_FULL) {
-			v->s = xstrdup(sha1_to_hex(sha1));
+			v->s = xstrdup(oid_to_hex(oid));
 			return 1;
 		} else if (atom->u.objectname.option == O_LENGTH) {
-			v->s = xstrdup(find_unique_abbrev(sha1, atom->u.objectname.length));
+			v->s = xstrdup(find_unique_abbrev(oid, atom->u.objectname.length));
 			return 1;
 		} else
 			die("BUG: unknown %%(objectname) option");
@@ -775,7 +775,7 @@ static void grab_common_values(struct atom_value *val, int deref, struct object
 			v->s = xstrfmt("%lu", sz);
 		}
 		else if (deref)
-			grab_objectname(name, obj->oid.hash, v, &used_atom[i]);
+			grab_objectname(name, &obj->oid, v, &used_atom[i]);
 	}
 }
 
@@ -1455,7 +1455,7 @@ static void populate_value(struct ref_array_item *ref)
 				v->s = xstrdup(buf + 1);
 			}
 			continue;
-		} else if (!deref && grab_objectname(name, ref->objectname.hash, v, atom)) {
+		} else if (!deref && grab_objectname(name, &ref->objectname, v, atom)) {
 			continue;
 		} else if (!strcmp(name, "HEAD")) {
 			if (atom->u.head && !strcmp(ref->refname, atom->u.head))

refs.c

@@ -301,7 +301,7 @@ enum peel_status peel_object(const struct object_id *name, struct object_id *oid
 	struct object *o = lookup_unknown_object(name->hash);
 
 	if (o->type == OBJ_NONE) {
-		int type = sha1_object_info(name->hash, NULL);
+		int type = oid_object_info(name, NULL);
 		if (type < 0 || !object_as_type(o, type, 0))
 			return PEEL_INVALID;
 	}

remote-testsvn.c

@@ -61,7 +61,7 @@ static char *read_ref_note(const struct object_id *oid)
 	init_notes(NULL, notes_ref, NULL, 0);
 	if (!(note_oid = get_note(NULL, oid)))
 		return NULL;	/* note tree not found */
-	if (!(msg = read_sha1_file(note_oid->hash, &type, &msglen)))
+	if (!(msg = read_object_file(note_oid, &type, &msglen)))
 		error("Empty notes tree. %s", notes_ref);
 	else if (!msglen || type != OBJ_BLOB) {
 		error("Note contains unusable content. "
@@ -108,7 +108,7 @@ static int note2mark_cb(const struct object_id *object_oid,
 	enum object_type type;
 	struct rev_note note;
 
-	if (!(msg = read_sha1_file(note_oid->hash, &type, &msglen)) ||
+	if (!(msg = read_object_file(note_oid, &type, &msglen)) ||
 			!msglen || type != OBJ_BLOB) {
 		free(msg);
 		return 1;

remote.c

@@ -1376,7 +1376,7 @@ static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***ds
 			continue; /* not a tag */
 		if (string_list_has_string(&dst_tag, ref->name))
 			continue; /* they already have it */
-		if (sha1_object_info(ref->new_oid.hash, NULL) != OBJ_TAG)
+		if (oid_object_info(&ref->new_oid, NULL) != OBJ_TAG)
 			continue; /* be conservative */
 		item = string_list_append(&src_tag, ref->name);
 		item->util = ref;

replace_object.c

@@ -8,8 +8,8 @@
  * sha1.
  */
 static struct replace_object {
-	unsigned char original[20];
+	struct object_id original;
-	unsigned char replacement[20];
+	struct object_id replacement;
 } **replace_object;
 
 static int replace_object_alloc, replace_object_nr;
@@ -17,7 +17,7 @@ static int replace_object_alloc, replace_object_nr;
 static const unsigned char *replace_sha1_access(size_t index, void *table)
 {
 	struct replace_object **replace = table;
-	return replace[index]->original;
+	return replace[index]->original.hash;
 }
 
 static int replace_object_pos(const unsigned char *sha1)
@@ -29,7 +29,7 @@ static int replace_object_pos(const unsigned char *sha1)
 static int register_replace_object(struct replace_object *replace,
 				   int ignore_dups)
 {
-	int pos = replace_object_pos(replace->original);
+	int pos = replace_object_pos(replace->original.hash);
 
 	if (0 <= pos) {
 		if (ignore_dups)
@@ -59,14 +59,14 @@ static int register_replace_ref(const char *refname,
 	const char *hash = slash ? slash + 1 : refname;
 	struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
 
-	if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->original)) {
+	if (get_oid_hex(hash, &repl_obj->original)) {
 		free(repl_obj);
 		warning("bad replace ref name: %s", refname);
 		return 0;
 	}
 
 	/* Copy sha1 from the read ref */
-	hashcpy(repl_obj->replacement, oid->hash);
+	oidcpy(&repl_obj->replacement, oid);
 
 	/* Register new object */
 	if (register_replace_object(repl_obj, 1))
@@ -92,16 +92,16 @@ static void prepare_replace_object(void)
 #define MAXREPLACEDEPTH 5
 
 /*
- * If a replacement for object sha1 has been set up, return the
+ * If a replacement for object oid has been set up, return the
  * replacement object's name (replaced recursively, if necessary).
- * The return value is either sha1 or a pointer to a
+ * The return value is either oid or a pointer to a
  * permanently-allocated value.  This function always respects replace
  * references, regardless of the value of check_replace_refs.
  */
-const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
+const struct object_id *do_lookup_replace_object(const struct object_id *oid)
 {
 	int pos, depth = MAXREPLACEDEPTH;
-	const unsigned char *cur = sha1;
+	const struct object_id *cur = oid;
 
 	prepare_replace_object();
 
@@ -109,11 +109,11 @@ const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
 	do {
 		if (--depth < 0)
 			die("replace depth too high for object %s",
-			    sha1_to_hex(sha1));
+			    oid_to_hex(oid));
 
-		pos = replace_object_pos(cur);
+		pos = replace_object_pos(cur->hash);
 		if (0 <= pos)
-			cur = replace_object[pos]->replacement;
+			cur = &replace_object[pos]->replacement;
 	} while (0 <= pos);
 
 	return cur;

rerere.c

@@ -979,7 +979,7 @@ static int handle_cache(const char *path, unsigned char *sha1, const char *outpu
 			break;
 		i = ce_stage(ce) - 1;
 		if (!mmfile[i].ptr) {
-			mmfile[i].ptr = read_sha1_file(ce->oid.hash, &type,
+			mmfile[i].ptr = read_object_file(&ce->oid, &type,
 							 &size);
 			mmfile[i].size = size;
 		}

resolve-undo.c

@@ -24,7 +24,7 @@ void record_resolve_undo(struct index_state *istate, struct cache_entry *ce)
 	if (!lost->util)
 		lost->util = xcalloc(1, sizeof(*ui));
 	ui = lost->util;
-	hashcpy(ui->sha1[stage - 1], ce->oid.hash);
+	oidcpy(&ui->oid[stage - 1], &ce->oid);
 	ui->mode[stage - 1] = ce->ce_mode;
 }
 
@@ -44,7 +44,7 @@ void resolve_undo_write(struct strbuf *sb, struct string_list *resolve_undo)
 		for (i = 0; i < 3; i++) {
 			if (!ui->mode[i])
 				continue;
-			strbuf_add(sb, ui->sha1[i], 20);
+			strbuf_add(sb, ui->oid[i].hash, the_hash_algo->rawsz);
 		}
 	}
 }
@@ -55,6 +55,7 @@ struct string_list *resolve_undo_read(const char *data, unsigned long size)
 	size_t len;
 	char *endptr;
 	int i;
+	const unsigned rawsz = the_hash_algo->rawsz;
 
 	resolve_undo = xcalloc(1, sizeof(*resolve_undo));
 	resolve_undo->strdup_strings = 1;
@@ -87,11 +88,11 @@ struct string_list *resolve_undo_read(const char *data, unsigned long size)
 		for (i = 0; i < 3; i++) {
 			if (!ui->mode[i])
 				continue;
-			if (size < 20)
+			if (size < rawsz)
 				goto error;
-			hashcpy(ui->sha1[i], (const unsigned char *)data);
+			memcpy(ui->oid[i].hash, (const unsigned char *)data, rawsz);
-			size -= 20;
+			size -= rawsz;
-			data += 20;
+			data += rawsz;
 		}
 	}
 	return resolve_undo;
@@ -145,7 +146,7 @@ int unmerge_index_entry_at(struct index_state *istate, int pos)
 		struct cache_entry *nce;
 		if (!ru->mode[i])
 			continue;
-		nce = make_cache_entry(ru->mode[i], ru->sha1[i],
+		nce = make_cache_entry(ru->mode[i], ru->oid[i].hash,
 				       name, i + 1, 0);
 		if (matched)
 			nce->ce_flags |= CE_MATCHED;

resolve-undo.h

@@ -3,7 +3,7 @@
 
 struct resolve_undo_info {
 	unsigned int mode[3];
-	unsigned char sha1[3][20];
+	struct object_id oid[3];
 };
 
 extern void record_resolve_undo(struct index_state *, struct cache_entry *);

send-pack.c

@@ -37,14 +37,14 @@ int option_parse_push_signed(const struct option *opt,
 	die("bad %s argument: %s", opt->long_name, arg);
 }
 
-static void feed_object(const unsigned char *sha1, FILE *fh, int negative)
+static void feed_object(const struct object_id *oid, FILE *fh, int negative)
 {
-	if (negative && !has_sha1_file(sha1))
+	if (negative && !has_sha1_file(oid->hash))
 		return;
 
 	if (negative)
 		putc('^', fh);
-	fputs(sha1_to_hex(sha1), fh);
+	fputs(oid_to_hex(oid), fh);
 	putc('\n', fh);
 }
 
@@ -89,13 +89,13 @@ static int pack_objects(int fd, struct ref *refs, struct oid_array *extra, struc
 	 */
 	po_in = xfdopen(po.in, "w");
 	for (i = 0; i < extra->nr; i++)
-		feed_object(extra->oid[i].hash, po_in, 1);
+		feed_object(&extra->oid[i], po_in, 1);
 
 	while (refs) {
 		if (!is_null_oid(&refs->old_oid))
-			feed_object(refs->old_oid.hash, po_in, 1);
+			feed_object(&refs->old_oid, po_in, 1);
 		if (!is_null_oid(&refs->new_oid))
-			feed_object(refs->new_oid.hash, po_in, 0);
+			feed_object(&refs->new_oid, po_in, 0);
 		refs = refs->next;
 	}
 

sequencer.c

@@ -282,7 +282,7 @@ struct commit_message {
 
 static const char *short_commit_name(struct commit *commit)
 {
-	return find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV);
+	return find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV);
 }
 
 static int get_message(struct commit *commit, struct commit_message *out)
@@ -1112,7 +1112,7 @@ static int try_to_commit(struct strbuf *msg, const char *author,
 		commit_list_insert(current_head, &parents);
 	}
 
-	if (write_cache_as_tree(tree.hash, 0, NULL)) {
+	if (write_cache_as_tree(&tree, 0, NULL)) {
 		res = error(_("git write-tree failed to write a tree"));
 		goto out;
 	}
@@ -1474,7 +1474,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 		 * that represents the "current" state for merge-recursive
 		 * to work on.
 		 */
-		if (write_cache_as_tree(head.hash, 0, NULL))
+		if (write_cache_as_tree(&head, 0, NULL))
 			return error(_("your index file is unmerged."));
 	} else {
 		unborn = get_oid("HEAD", &head);
@@ -2876,7 +2876,8 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 
 		if (!get_oid(name, &oid)) {
 			if (!lookup_commit_reference_gently(&oid, 1)) {
-				enum object_type type = sha1_object_info(oid.hash, NULL);
+				enum object_type type = oid_object_info(&oid,
+									NULL);
 				return error(_("%s: can't cherry-pick a %s"),
 					name, type_name(type));
 			}

sha1_file.c

@@ -30,6 +30,9 @@
 #include "packfile.h"
 #include "fetch-object.h"
 
+/* The maximum size for an object header. */
+#define MAX_HEADER_LEN 32
+
 const unsigned char null_sha1[GIT_MAX_RAWSZ];
 const struct object_id null_oid;
 const struct object_id empty_tree_oid = {
@@ -784,22 +787,22 @@ void *xmmap(void *start, size_t length,
  * With "map" == NULL, try reading the object named with "sha1" using
  * the streaming interface and rehash it to do the same.
  */
-int check_sha1_signature(const unsigned char *sha1, void *map,
+int check_object_signature(const struct object_id *oid, void *map,
 			   unsigned long size, const char *type)
 {
 	struct object_id real_oid;
 	enum object_type obj_type;
 	struct git_istream *st;
 	git_hash_ctx c;
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 	int hdrlen;
 
 	if (map) {
 		hash_object_file(map, size, type, &real_oid);
-		return hashcmp(sha1, real_oid.hash) ? -1 : 0;
+		return oidcmp(oid, &real_oid) ? -1 : 0;
 	}
 
-	st = open_istream(sha1, &obj_type, &size, NULL);
+	st = open_istream(oid, &obj_type, &size, NULL);
 	if (!st)
 		return -1;
 
@@ -823,7 +826,7 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
 	}
 	the_hash_algo->final_fn(real_oid.hash, &c);
 	close_istream(st);
-	return hashcmp(sha1, real_oid.hash) ? -1 : 0;
+	return oidcmp(oid, &real_oid) ? -1 : 0;
 }
 
 int git_open_cloexec(const char *name, int flags)
@@ -1150,7 +1153,7 @@ static int sha1_loose_object_info(const unsigned char *sha1,
 	unsigned long mapsize;
 	void *map;
 	git_zstream stream;
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 	struct strbuf hdrbuf = STRBUF_INIT;
 	unsigned long size_scratch;
 
@@ -1222,24 +1225,25 @@ static int sha1_loose_object_info(const unsigned char *sha1,
 
 int fetch_if_missing = 1;
 
-int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
+int oid_object_info_extended(const struct object_id *oid, struct object_info *oi, unsigned flags)
 {
 	static struct object_info blank_oi = OBJECT_INFO_INIT;
 	struct pack_entry e;
 	int rtype;
-	const unsigned char *real = (flags & OBJECT_INFO_LOOKUP_REPLACE) ?
+	const struct object_id *real = oid;
-				    lookup_replace_object(sha1) :
-				    sha1;
 	int already_retried = 0;
 
-	if (is_null_sha1(real))
+	if (flags & OBJECT_INFO_LOOKUP_REPLACE)
+		real = lookup_replace_object(oid);
+
+	if (is_null_oid(real))
 		return -1;
 
 	if (!oi)
 		oi = &blank_oi;
 
 	if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
-		struct cached_object *co = find_cached_object(real);
+		struct cached_object *co = find_cached_object(real->hash);
 		if (co) {
 			if (oi->typep)
 				*(oi->typep) = co->type;
@@ -1259,20 +1263,20 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 	}
 
 	while (1) {
-		if (find_pack_entry(real, &e))
+		if (find_pack_entry(real->hash, &e))
 			break;
 
 		if (flags & OBJECT_INFO_IGNORE_LOOSE)
 			return -1;
 
 		/* Most likely it's a loose object. */
-		if (!sha1_loose_object_info(real, oi, flags))
+		if (!sha1_loose_object_info(real->hash, oi, flags))
 			return 0;
 
 		/* Not a loose object; someone else may have just packed it. */
 		if (!(flags & OBJECT_INFO_QUICK)) {
 			reprepare_packed_git();
-			if (find_pack_entry(real, &e))
+			if (find_pack_entry(real->hash, &e))
 				break;
 		}
 
@@ -1283,7 +1287,7 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 			 * TODO Investigate haveing fetch_object() return
 			 * TODO error/success and stopping the music here.
 			 */
-			fetch_object(repository_format_partial_clone, real);
+			fetch_object(repository_format_partial_clone, real->hash);
 			already_retried = 1;
 			continue;
 		}
@@ -1299,8 +1303,8 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 		return 0;
 	rtype = packed_object_info(e.p, e.offset, oi);
 	if (rtype < 0) {
-		mark_bad_packed_object(e.p, real);
+		mark_bad_packed_object(e.p, real->hash);
-		return sha1_object_info_extended(real, oi, 0);
+		return oid_object_info_extended(real, oi, 0);
 	} else if (oi->whence == OI_PACKED) {
 		oi->u.packed.offset = e.offset;
 		oi->u.packed.pack = e.p;
@@ -1312,14 +1316,14 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 }
 
 /* returns enum object_type or negative */
-int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
+int oid_object_info(const struct object_id *oid, unsigned long *sizep)
 {
 	enum object_type type;
 	struct object_info oi = OBJECT_INFO_INIT;
 
 	oi.typep = &type;
 	oi.sizep = sizep;
-	if (sha1_object_info_extended(sha1, &oi,
+	if (oid_object_info_extended(oid, &oi,
 				     OBJECT_INFO_LOOKUP_REPLACE) < 0)
 		return -1;
 	return type;
@@ -1328,13 +1332,16 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 static void *read_object(const unsigned char *sha1, enum object_type *type,
 			 unsigned long *size)
 {
+	struct object_id oid;
 	struct object_info oi = OBJECT_INFO_INIT;
 	void *content;
 	oi.typep = type;
 	oi.sizep = size;
 	oi.contentp = &content;
 
-	if (sha1_object_info_extended(sha1, &oi, 0) < 0)
+	hashcpy(oid.hash, sha1);
+
+	if (oid_object_info_extended(&oid, &oi, 0) < 0)
 		return NULL;
 	return content;
 }
@@ -1362,7 +1369,7 @@ int pretend_object_file(void *buf, unsigned long len, enum object_type type,
  * deal with them should arrange to call read_object() and give error
  * messages themselves.
  */
-void *read_sha1_file_extended(const unsigned char *sha1,
+void *read_object_file_extended(const struct object_id *oid,
 				enum object_type *type,
 				unsigned long *size,
 				int lookup_replace)
@@ -1371,56 +1378,56 @@ void *read_sha1_file_extended(const unsigned char *sha1,
 	const struct packed_git *p;
 	const char *path;
 	struct stat st;
-	const unsigned char *repl = lookup_replace ? lookup_replace_object(sha1)
+	const struct object_id *repl = lookup_replace ? lookup_replace_object(oid)
-						   : sha1;
+						      : oid;
 
 	errno = 0;
-	data = read_object(repl, type, size);
+	data = read_object(repl->hash, type, size);
 	if (data)
 		return data;
 
 	if (errno && errno != ENOENT)
-		die_errno("failed to read object %s", sha1_to_hex(sha1));
+		die_errno("failed to read object %s", oid_to_hex(oid));
 
 	/* die if we replaced an object with one that does not exist */
-	if (repl != sha1)
+	if (repl != oid)
 		die("replacement %s not found for %s",
-		    sha1_to_hex(repl), sha1_to_hex(sha1));
+		    oid_to_hex(repl), oid_to_hex(oid));
 
-	if (!stat_sha1_file(repl, &st, &path))
+	if (!stat_sha1_file(repl->hash, &st, &path))
 		die("loose object %s (stored in %s) is corrupt",
-		    sha1_to_hex(repl), path);
+		    oid_to_hex(repl), path);
 
-	if ((p = has_packed_and_bad(repl)) != NULL)
+	if ((p = has_packed_and_bad(repl->hash)) != NULL)
 		die("packed object %s (stored in %s) is corrupt",
-		    sha1_to_hex(repl), p->pack_name);
+		    oid_to_hex(repl), p->pack_name);
 
 	return NULL;
 }
 
-void *read_object_with_reference(const unsigned char *sha1,
+void *read_object_with_reference(const struct object_id *oid,
 				 const char *required_type_name,
 				 unsigned long *size,
-				 unsigned char *actual_sha1_return)
+				 struct object_id *actual_oid_return)
 {
 	enum object_type type, required_type;
 	void *buffer;
 	unsigned long isize;
-	unsigned char actual_sha1[20];
+	struct object_id actual_oid;
 
 	required_type = type_from_string(required_type_name);
-	hashcpy(actual_sha1, sha1);
+	oidcpy(&actual_oid, oid);
 	while (1) {
 		int ref_length = -1;
 		const char *ref_type = NULL;
 
-		buffer = read_sha1_file(actual_sha1, &type, &isize);
+		buffer = read_object_file(&actual_oid, &type, &isize);
 		if (!buffer)
 			return NULL;
 		if (type == required_type) {
 			*size = isize;
-			if (actual_sha1_return)
+			if (actual_oid_return)
-				hashcpy(actual_sha1_return, actual_sha1);
+				oidcpy(actual_oid_return, &actual_oid);
 			return buffer;
 		}
 		/* Handle references */
@@ -1434,15 +1441,15 @@ void *read_object_with_reference(const unsigned char *sha1,
 		}
 		ref_length = strlen(ref_type);
 
-		if (ref_length + 40 > isize ||
+		if (ref_length + GIT_SHA1_HEXSZ > isize ||
 		    memcmp(buffer, ref_type, ref_length) ||
-		    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
+		    get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
 			free(buffer);
 			return NULL;
 		}
 		free(buffer);
 		/* Now we have the ID of the referred-to object in
-		 * actual_sha1.  Check again. */
+		 * actual_oid.  Check again. */
 	}
 }
 
@@ -1515,7 +1522,7 @@ static int write_buffer(int fd, const void *buf, size_t len)
 int hash_object_file(const void *buf, unsigned long len, const char *type,
 		     struct object_id *oid)
 {
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
 	write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
 	return 0;
@@ -1670,7 +1677,7 @@ static int freshen_packed_object(const unsigned char *sha1)
 int write_object_file(const void *buf, unsigned long len, const char *type,
 		      struct object_id *oid)
 {
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
 
 	/* Normally if we have it in the pack then we do not bother writing
@@ -1690,7 +1697,7 @@ int hash_object_file_literally(const void *buf, unsigned long len,
 	int hdrlen, status = 0;
 
 	/* type string, SP, %lu of the length plus NUL must fit this */
-	hdrlen = strlen(type) + 32;
+	hdrlen = strlen(type) + MAX_HEADER_LEN;
 	header = xmalloc(hdrlen);
 	write_object_file_prepare(buf, len, type, oid, header, &hdrlen);
 
@@ -1710,7 +1717,7 @@ int force_object_loose(const struct object_id *oid, time_t mtime)
 	void *buf;
 	unsigned long len;
 	enum object_type type;
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 	int hdrlen;
 	int ret;
 
@@ -1728,9 +1735,11 @@ int force_object_loose(const struct object_id *oid, time_t mtime)
 
 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
 {
+	struct object_id oid;
 	if (!startup_info->have_repository)
 		return 0;
-	return sha1_object_info_extended(sha1, NULL,
+	hashcpy(oid.hash, sha1);
+	return oid_object_info_extended(&oid, NULL,
 					flags | OBJECT_INFO_SKIP_CACHED) >= 0;
 }
 
@@ -1897,7 +1906,7 @@ static int index_stream(struct object_id *oid, int fd, size_t size,
 			enum object_type type, const char *path,
 			unsigned flags)
 {
-	return index_bulk_checkin(oid->hash, fd, size, type, path, flags);
+	return index_bulk_checkin(oid, fd, size, type, path, flags);
 }
 
 int index_fd(struct object_id *oid, int fd, struct stat *st,
@@ -1971,13 +1980,13 @@ int read_pack_header(int fd, struct pack_header *header)
 	return 0;
 }
 
-void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
+void assert_oid_type(const struct object_id *oid, enum object_type expect)
 {
-	enum object_type type = sha1_object_info(sha1, NULL);
+	enum object_type type = oid_object_info(oid, NULL);
 	if (type < 0)
-		die("%s is not a valid object", sha1_to_hex(sha1));
+		die("%s is not a valid object", oid_to_hex(oid));
 	if (type != expect)
-		die("%s is not a valid '%s' object", sha1_to_hex(sha1),
+		die("%s is not a valid '%s' object", oid_to_hex(oid),
 		    type_name(expect));
 }
 
@@ -2181,7 +2190,7 @@ static int check_stream_sha1(git_zstream *stream,
 }
 
 int read_loose_object(const char *path,
-		      const unsigned char *expected_sha1,
+		      const struct object_id *expected_oid,
 		      enum object_type *type,
 		      unsigned long *size,
 		      void **contents)
@@ -2190,7 +2199,7 @@ int read_loose_object(const char *path,
 	void *map = NULL;
 	unsigned long mapsize;
 	git_zstream stream;
-	char hdr[32];
+	char hdr[MAX_HEADER_LEN];
 
 	*contents = NULL;
 
@@ -2213,19 +2222,19 @@ int read_loose_object(const char *path,
 	}
 
 	if (*type == OBJ_BLOB) {
-		if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
+		if (check_stream_sha1(&stream, hdr, *size, path, expected_oid->hash) < 0)
 			goto out;
 	} else {
-		*contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
+		*contents = unpack_sha1_rest(&stream, hdr, *size, expected_oid->hash);
 		if (!*contents) {
 			error("unable to unpack contents of %s", path);
 			git_inflate_end(&stream);
 			goto out;
 		}
-		if (check_sha1_signature(expected_sha1, *contents,
+		if (check_object_signature(expected_oid, *contents,
 					 *size, type_name(*type))) {
 			error("sha1 mismatch for %s (expected %s)", path,
-			      sha1_to_hex(expected_sha1));
+			      oid_to_hex(expected_oid));
 			free(*contents);
 			goto out;
 		}

sha1_name.c

@@ -238,7 +238,7 @@ static int finish_object_disambiguation(struct disambiguate_state *ds,
 
 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(oid->hash, NULL);
+	int kind = oid_object_info(oid, NULL);
 	return kind == OBJ_COMMIT;
 }
 
@@ -247,7 +247,7 @@ static int disambiguate_committish_only(const struct object_id *oid, void *cb_da
 	struct object *obj;
 	int kind;
 
-	kind = sha1_object_info(oid->hash, NULL);
+	kind = oid_object_info(oid, NULL);
 	if (kind == OBJ_COMMIT)
 		return 1;
 	if (kind != OBJ_TAG)
@@ -262,7 +262,7 @@ static int disambiguate_committish_only(const struct object_id *oid, void *cb_da
 
 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(oid->hash, NULL);
+	int kind = oid_object_info(oid, NULL);
 	return kind == OBJ_TREE;
 }
 
@@ -271,7 +271,7 @@ static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_
 	struct object *obj;
 	int kind;
 
-	kind = sha1_object_info(oid->hash, NULL);
+	kind = oid_object_info(oid, NULL);
 	if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 		return 1;
 	if (kind != OBJ_TAG)
@@ -286,7 +286,7 @@ static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_
 
 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(oid->hash, NULL);
+	int kind = oid_object_info(oid, NULL);
 	return kind == OBJ_BLOB;
 }
 
@@ -365,7 +365,7 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 	if (ds->fn && !ds->fn(oid, ds->cb_data))
 		return 0;
 
-	type = sha1_object_info(oid->hash, NULL);
+	type = oid_object_info(oid, NULL);
 	if (type == OBJ_COMMIT) {
 		struct commit *commit = lookup_commit(oid);
 		if (commit) {
@@ -380,7 +380,7 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 	}
 
 	advise("  %s %s%s",
-	       find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
+	       find_unique_abbrev(oid, DEFAULT_ABBREV),
 	       type_name(type) ? type_name(type) : "unknown type",
 	       desc.buf);
 
@@ -569,7 +569,7 @@ static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 		find_abbrev_len_for_pack(p, mad);
 }
 
-int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
+int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 {
 	struct disambiguate_state ds;
 	struct min_abbrev_data mad;
@@ -596,14 +596,14 @@ int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 			len = FALLBACK_DEFAULT_ABBREV;
 	}
 
-	sha1_to_hex_r(hex, sha1);
+	oid_to_hex_r(hex, oid);
 	if (len == GIT_SHA1_HEXSZ || !len)
 		return GIT_SHA1_HEXSZ;
 
 	mad.init_len = len;
 	mad.cur_len = len;
 	mad.hex = hex;
-	mad.hash = sha1;
+	mad.hash = oid->hash;
 
 	find_abbrev_len_packed(&mad);
 
@@ -621,13 +621,13 @@ int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 	return mad.cur_len;
 }
 
-const char *find_unique_abbrev(const unsigned char *sha1, int len)
+const char *find_unique_abbrev(const struct object_id *oid, int len)
 {
 	static int bufno;
 	static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 	char *hex = hexbuffer[bufno];
 	bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
-	find_unique_abbrev_r(hex, sha1, len);
+	find_unique_abbrev_r(hex, oid, len);
 	return hex;
 }
 
@@ -1529,8 +1529,7 @@ static void diagnose_invalid_oid_path(const char *prefix,
 	if (is_missing_file_error(errno)) {
 		char *fullname = xstrfmt("%s%s", prefix, filename);
 
-		if (!get_tree_entry(tree_oid->hash, fullname,
+		if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
-				    oid.hash, &mode)) {
 			die("Path '%s' exists, but not '%s'.\n"
 			    "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
 			    fullname,
@@ -1722,8 +1721,8 @@ static int get_oid_with_context_1(const char *name,
 					filename, oid->hash, &oc->symlink_path,
 					&oc->mode);
 			} else {
-				ret = get_tree_entry(tree_oid.hash, filename,
+				ret = get_tree_entry(&tree_oid, filename, oid,
-						     oid->hash, &oc->mode);
+						     &oc->mode);
 				if (ret && only_to_die) {
 					diagnose_invalid_oid_path(prefix,
 								   filename,

strbuf.c

@@ -897,12 +897,12 @@ void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
 	strbuf_setlen(sb, sb->len + len);
 }
 
-void strbuf_add_unique_abbrev(struct strbuf *sb, const unsigned char *sha1,
+void strbuf_add_unique_abbrev(struct strbuf *sb, const struct object_id *oid,
 			      int abbrev_len)
 {
 	int r;
 	strbuf_grow(sb, GIT_SHA1_HEXSZ + 1);
-	r = find_unique_abbrev_r(sb->buf + sb->len, sha1, abbrev_len);
+	r = find_unique_abbrev_r(sb->buf + sb->len, oid, abbrev_len);
 	strbuf_setlen(sb, sb->len + r);
 }
 

strbuf.h

@@ -72,6 +72,12 @@ struct strbuf {
 extern char strbuf_slopbuf[];
 #define STRBUF_INIT  { .alloc = 0, .len = 0, .buf = strbuf_slopbuf }
 
+/*
+ * Predeclare this here, since cache.h includes this file before it defines the
+ * struct.
+ */
+struct object_id;
+
 /**
  * Life Cycle Functions
  * --------------------
@@ -558,7 +564,7 @@ extern void strbuf_list_free(struct strbuf **);
  * the strbuf `sb`.
  */
 extern void strbuf_add_unique_abbrev(struct strbuf *sb,
-				     const unsigned char *sha1,
+				     const struct object_id *oid,
 				     int abbrev_len);
 
 /**

streaming.c

@@ -14,7 +14,7 @@ enum input_source {
 
 typedef int (*open_istream_fn)(struct git_istream *,
 			       struct object_info *,
-			       const unsigned char *,
+			       const struct object_id *,
 			       enum object_type *);
 typedef int (*close_istream_fn)(struct git_istream *);
 typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
@@ -27,7 +27,7 @@ struct stream_vtbl {
 #define open_method_decl(name) \
 	int open_istream_ ##name \
 	(struct git_istream *st, struct object_info *oi, \
-	 const unsigned char *sha1, \
+	 const struct object_id *oid, \
 	 enum object_type *type)
 
 #define close_method_decl(name) \
@@ -105,7 +105,7 @@ ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
 	return st->vtbl->read(st, buf, sz);
 }
 
-static enum input_source istream_source(const unsigned char *sha1,
+static enum input_source istream_source(const struct object_id *oid,
 					enum object_type *type,
 					struct object_info *oi)
 {
@@ -114,7 +114,7 @@ static enum input_source istream_source(const unsigned char *sha1,
 
 	oi->typep = type;
 	oi->sizep = &size;
-	status = sha1_object_info_extended(sha1, oi, 0);
+	status = oid_object_info_extended(oid, oi, 0);
 	if (status < 0)
 		return stream_error;
 
@@ -130,14 +130,14 @@ static enum input_source istream_source(const unsigned char *sha1,
 	}
 }
 
-struct git_istream *open_istream(const unsigned char *sha1,
+struct git_istream *open_istream(const struct object_id *oid,
 				 enum object_type *type,
 				 unsigned long *size,
 				 struct stream_filter *filter)
 {
 	struct git_istream *st;
 	struct object_info oi = OBJECT_INFO_INIT;
-	const unsigned char *real = lookup_replace_object(sha1);
+	const struct object_id *real = lookup_replace_object(oid);
 	enum input_source src = istream_source(real, type, &oi);
 
 	if (src < 0)
@@ -335,7 +335,7 @@ static struct stream_vtbl loose_vtbl = {
 
 static open_method_decl(loose)
 {
-	st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
+	st->u.loose.mapped = map_sha1_file(oid->hash, &st->u.loose.mapsize);
 	if (!st->u.loose.mapped)
 		return -1;
 	if ((unpack_sha1_header(&st->z,
@@ -486,7 +486,7 @@ static struct stream_vtbl incore_vtbl = {
 
 static open_method_decl(incore)
 {
-	st->u.incore.buf = read_sha1_file_extended(sha1, type, &st->size, 0);
+	st->u.incore.buf = read_object_file_extended(oid, type, &st->size, 0);
 	st->u.incore.read_ptr = 0;
 	st->vtbl = &incore_vtbl;
 
@@ -507,7 +507,7 @@ int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter
 	ssize_t kept = 0;
 	int result = -1;
 
-	st = open_istream(oid->hash, &type, &sz, filter);
+	st = open_istream(oid, &type, &sz, filter);
 	if (!st) {
 		if (filter)
 			free_stream_filter(filter);

streaming.h

@@ -8,7 +8,7 @@
 /* opaque */
 struct git_istream;
 
-extern struct git_istream *open_istream(const unsigned char *, enum object_type *, unsigned long *, struct stream_filter *);
+extern struct git_istream *open_istream(const struct object_id *, enum object_type *, unsigned long *, struct stream_filter *);
 extern int close_istream(struct git_istream *);
 extern ssize_t read_istream(struct git_istream *, void *, size_t);