Merge branch 'bc/object-id'

Conversion from unsigned char [40] to struct object_id continues.

* bc/object-id:
  Documentation: update and rename api-sha1-array.txt
  Rename sha1_array to oid_array
  Convert sha1_array_for_each_unique and for_each_abbrev to object_id
  Convert sha1_array_lookup to take struct object_id
  Convert remaining callers of sha1_array_lookup to object_id
  Make sha1_array_append take a struct object_id *
  sha1-array: convert internal storage for struct sha1_array to object_id
  builtin/pull: convert to struct object_id
  submodule: convert check_for_new_submodule_commits to object_id
  sha1_name: convert disambiguate_hint_fn to take object_id
  sha1_name: convert struct disambiguate_state to object_id
  test-sha1-array: convert most code to struct object_id
  parse-options-cb: convert sha1_array_append caller to struct object_id
  fsck: convert init_skiplist to struct object_id
  builtin/receive-pack: convert portions to struct object_id
  builtin/pull: convert portions to struct object_id
  builtin/diff: convert to struct object_id
  Convert GIT_SHA1_RAWSZ used for allocation to GIT_MAX_RAWSZ
  Convert GIT_SHA1_HEXSZ used for allocation to GIT_MAX_HEXSZ
  Define new hash-size constants for allocating memory

46 files changed, 459 insertions, 451 deletions

diff --git a/Documentation/technical/api-sha1-array.txt b/Documentation/technical/api-oid-array.txt
index dcc52943a5..b0c11f868d 100644
--- a/Documentation/technical/api-sha1-array.txt
+++ b/Documentation/technical/api-oid-array.txt
@@ -1,7 +1,7 @@
-sha1-array API
+oid-array API
 ==============
 
-The sha1-array API provides storage and manipulation of sets of SHA-1
+The oid-array API provides storage and manipulation of sets of object
 identifiers. The emphasis is on storage and processing efficiency,
 making them suitable for large lists. Note that the ordering of items is
 not preserved over some operations.
@@ -9,10 +9,10 @@ not preserved over some operations.
 Data Structures
 ---------------
 
-`struct sha1_array`::
+`struct oid_array`::
 
-	A single array of SHA-1 hashes. This should be initialized by
-	assignment from `SHA1_ARRAY_INIT`.  The `sha1` member contains
+	A single array of object IDs. This should be initialized by
+	assignment from `OID_ARRAY_INIT`.  The `oid` member contains
 	the actual data. The `nr` member contains the number of items in
 	the set.  The `alloc` and `sorted` members are used internally,
 	and should not be needed by API callers.
@@ -20,22 +20,22 @@ Data Structures
 Functions
 ---------
 
-`sha1_array_append`::
-	Add an item to the set. The sha1 will be placed at the end of
+`oid_array_append`::
+	Add an item to the set. The object ID will be placed at the end of
 	the array (but note that some operations below may lose this
 	ordering).
 
-`sha1_array_lookup`::
-	Perform a binary search of the array for a specific sha1.
+`oid_array_lookup`::
+	Perform a binary search of the array for a specific object ID.
 	If found, returns the offset (in number of elements) of the
-	sha1. If not found, returns a negative integer. If the array is
-	not sorted, this function has the side effect of sorting it.
+	object ID. If not found, returns a negative integer. If the array
+	is not sorted, this function has the side effect of sorting it.
 
-`sha1_array_clear`::
+`oid_array_clear`::
 	Free all memory associated with the array and return it to the
 	initial, empty state.
 
-`sha1_array_for_each_unique`::
+`oid_array_for_each_unique`::
 	Efficiently iterate over each unique element of the list,
 	executing the callback function for each one. If the array is
 	not sorted, this function has the side effect of sorting it. If
@@ -47,25 +47,25 @@ Examples
 --------
 
 -----------------------------------------
-int print_callback(const unsigned char sha1[20],
+int print_callback(const struct object_id *oid,
 		    void *data)
 {
-	printf("%s\n", sha1_to_hex(sha1));
+	printf("%s\n", oid_to_hex(oid));
 	return 0; /* always continue */
 }
 
 void some_func(void)
 {
-	struct sha1_array hashes = SHA1_ARRAY_INIT;
-	unsigned char sha1[20];
+	struct sha1_array hashes = OID_ARRAY_INIT;
+	struct object_id oid;
 
 	/* Read objects into our set */
-	while (read_object_from_stdin(sha1))
-		sha1_array_append(&hashes, sha1);
+	while (read_object_from_stdin(oid.hash))
+		oid_array_append(&hashes, &oid);
 
 	/* Check if some objects are in our set */
-	while (read_object_from_stdin(sha1)) {
-		if (sha1_array_lookup(&hashes, sha1) >= 0)
+	while (read_object_from_stdin(oid.hash)) {
+		if (oid_array_lookup(&hashes, &oid) >= 0)
 			printf("it's in there!\n");
 
 	/*
@@ -75,6 +75,6 @@ void some_func(void)
 	 * Instead, this will sort once and then skip duplicates
 	 * in linear time.
 	 */
-	sha1_array_for_each_unique(&hashes, print_callback, NULL);
+	oid_array_for_each_unique(&hashes, print_callback, NULL);
 }
 -----------------------------------------
diff --git a/bisect.c b/bisect.c
index d12583eaac..03af06c66c 100644
--- a/bisect.c
+++ b/bisect.c
@@ -12,8 +12,8 @@
 #include "sha1-array.h"
 #include "argv-array.h"
 
-static struct sha1_array good_revs;
-static struct sha1_array skipped_revs;
+static struct oid_array good_revs;
+static struct oid_array skipped_revs;
 
 static struct object_id *current_bad_oid;
 
@@ -415,9 +415,9 @@ static int register_ref(const char *refname, const struct object_id *oid,
 		current_bad_oid = xmalloc(sizeof(*current_bad_oid));
 		oidcpy(current_bad_oid, oid);
 	} else if (starts_with(refname, good_prefix.buf)) {
-		sha1_array_append(&good_revs, oid->hash);
+		oid_array_append(&good_revs, oid);
 	} else if (starts_with(refname, "skip-")) {
-		sha1_array_append(&skipped_revs, oid->hash);
+		oid_array_append(&skipped_revs, oid);
 	}
 
 	strbuf_release(&good_prefix);
@@ -453,13 +453,13 @@ static void read_bisect_paths(struct argv_array *array)
 	fclose(fp);
 }
 
-static char *join_sha1_array_hex(struct sha1_array *array, char delim)
+static char *join_sha1_array_hex(struct oid_array *array, char delim)
 {
 	struct strbuf joined_hexs = STRBUF_INIT;
 	int i;
 
 	for (i = 0; i < array->nr; i++) {
-		strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
+		strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
 		if (i + 1 < array->nr)
 			strbuf_addch(&joined_hexs, delim);
 	}
@@ -501,8 +501,7 @@ struct commit_list *filter_skipped(struct commit_list *list,
 	while (list) {
 		struct commit_list *next = list->next;
 		list->next = NULL;
-		if (0 <= sha1_array_lookup(&skipped_revs,
-					   list->item->object.oid.hash)) {
+		if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
 			if (skipped_first && !*skipped_first)
 				*skipped_first = 1;
 			/* Move current to tried list */
@@ -623,7 +622,7 @@ static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
 	argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
 	for (i = 0; i < good_revs.nr; i++)
 		argv_array_pushf(&rev_argv, good_format,
-				 sha1_to_hex(good_revs.sha1[i]));
+				 oid_to_hex(good_revs.oid + i));
 	argv_array_push(&rev_argv, "--");
 	if (read_paths)
 		read_bisect_paths(&rev_argv);
@@ -684,7 +683,7 @@ static int is_expected_rev(const struct object_id *oid)
 
 static int bisect_checkout(const unsigned char *bisect_rev, int no_checkout)
 {
-	char bisect_rev_hex[GIT_SHA1_HEXSZ + 1];
+	char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
 
 	memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
 	update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
@@ -703,11 +702,11 @@ static int bisect_checkout(const unsigned char *bisect_rev, int no_checkout)
 	return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
 }
 
-static struct commit *get_commit_reference(const unsigned char *sha1)
+static struct commit *get_commit_reference(const struct object_id *oid)
 {
-	struct commit *r = lookup_commit_reference(sha1);
+	struct commit *r = lookup_commit_reference(oid->hash);
 	if (!r)
-		die(_("Not a valid commit name %s"), sha1_to_hex(sha1));
+		die(_("Not a valid commit name %s"), oid_to_hex(oid));
 	return r;
 }
 
@@ -717,9 +716,9 @@ static struct commit **get_bad_and_good_commits(int *rev_nr)
 	int i, n = 0;
 
 	ALLOC_ARRAY(rev, 1 + good_revs.nr);
-	rev[n++] = get_commit_reference(current_bad_oid->hash);
+	rev[n++] = get_commit_reference(current_bad_oid);
 	for (i = 0; i < good_revs.nr; i++)
-		rev[n++] = get_commit_reference(good_revs.sha1[i]);
+		rev[n++] = get_commit_reference(good_revs.oid + i);
 	*rev_nr = n;
 
 	return rev;
@@ -756,9 +755,9 @@ static void handle_bad_merge_base(void)
 	exit(1);
 }
 
-static void handle_skipped_merge_base(const unsigned char *mb)
+static void handle_skipped_merge_base(const struct object_id *mb)
 {
-	char *mb_hex = sha1_to_hex(mb);
+	char *mb_hex = oid_to_hex(mb);
 	char *bad_hex = oid_to_hex(current_bad_oid);
 	char *good_hex = join_sha1_array_hex(&good_revs, ' ');
 
@@ -789,16 +788,16 @@ static void check_merge_bases(int no_checkout)
 	result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
 
 	for (; result; result = result->next) {
-		const unsigned char *mb = result->item->object.oid.hash;
-		if (!hashcmp(mb, current_bad_oid->hash)) {
+		const struct object_id *mb = &result->item->object.oid;
+		if (!oidcmp(mb, current_bad_oid)) {
 			handle_bad_merge_base();
-		} else if (0 <= sha1_array_lookup(&good_revs, mb)) {
+		} else if (0 <= oid_array_lookup(&good_revs, mb)) {
 			continue;
-		} else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
+		} else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
 			handle_skipped_merge_base(mb);
 		} else {
 			printf(_("Bisecting: a merge base must be tested\n"));
-			exit(bisect_checkout(mb, no_checkout));
+			exit(bisect_checkout(mb->hash, no_checkout));
 		}
 	}
 
diff --git a/builtin/blame.c b/builtin/blame.c
index f7aa95f4ba..07506a3e45 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1890,7 +1890,7 @@ static void emit_porcelain(struct scoreboard *sb, struct blame_entry *ent,
 	int cnt;
 	const char *cp;
 	struct origin *suspect = ent->suspect;
-	char hex[GIT_SHA1_HEXSZ + 1];
+	char hex[GIT_MAX_HEXSZ + 1];
 
 	oid_to_hex_r(hex, &suspect->commit->object.oid);
 	printf("%s %d %d %d\n",
@@ -1928,7 +1928,7 @@ static void emit_other(struct scoreboard *sb, struct blame_entry *ent, int opt)
 	const char *cp;
 	struct origin *suspect = ent->suspect;
 	struct commit_info ci;
-	char hex[GIT_SHA1_HEXSZ + 1];
+	char hex[GIT_MAX_HEXSZ + 1];
 	int show_raw_time = !!(opt & OUTPUT_RAW_TIMESTAMP);
 
 	get_commit_info(suspect->commit, &ci, 1);
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 8b85cb8cf0..1890d7a639 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -401,10 +401,10 @@ struct object_cb_data {
 	struct expand_data *expand;
 };
 
-static int batch_object_cb(const unsigned char sha1[20], void *vdata)
+static int batch_object_cb(const struct object_id *oid, void *vdata)
 {
 	struct object_cb_data *data = vdata;
-	hashcpy(data->expand->oid.hash, sha1);
+	oidcpy(&data->expand->oid, oid);
 	batch_object_write(NULL, data->opt, data->expand);
 	return 0;
 }
@@ -413,7 +413,7 @@ static int batch_loose_object(const struct object_id *oid,
 			      const char *path,
 			      void *data)
 {
-	sha1_array_append(data, oid->hash);
+	oid_array_append(data, oid);
 	return 0;
 }
 
@@ -422,7 +422,7 @@ static int batch_packed_object(const struct object_id *oid,
 			       uint32_t pos,
 			       void *data)
 {
-	sha1_array_append(data, oid->hash);
+	oid_array_append(data, oid);
 	return 0;
 }
 
@@ -462,7 +462,7 @@ static int batch_objects(struct batch_options *opt)
 		data.info.typep = &data.type;
 
 	if (opt->all_objects) {
-		struct sha1_array sa = SHA1_ARRAY_INIT;
+		struct oid_array sa = OID_ARRAY_INIT;
 		struct object_cb_data cb;
 
 		for_each_loose_object(batch_loose_object, &sa, 0);
@@ -470,9 +470,9 @@ static int batch_objects(struct batch_options *opt)
 
 		cb.opt = opt;
 		cb.expand = &data;
-		sha1_array_for_each_unique(&sa, batch_object_cb, &cb);
+		oid_array_for_each_unique(&sa, batch_object_cb, &cb);
 
-		sha1_array_clear(&sa);
+		oid_array_clear(&sa);
 		return 0;
 	}
 
diff --git a/builtin/diff.c b/builtin/diff.c
index 3d64b85337..d184aafab9 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -21,7 +21,7 @@
 #define DIFF_NO_INDEX_IMPLICIT 2
 
 struct blobinfo {
-	unsigned char sha1[20];
+	struct object_id oid;
 	const char *name;
 	unsigned mode;
 };
@@ -31,22 +31,22 @@ static const char builtin_diff_usage[] =
 
 static void stuff_change(struct diff_options *opt,
 			 unsigned old_mode, unsigned new_mode,
-			 const unsigned char *old_sha1,
-			 const unsigned char *new_sha1,
-			 int old_sha1_valid,
-			 int new_sha1_valid,
+			 const struct object_id *old_oid,
+			 const struct object_id *new_oid,
+			 int old_oid_valid,
+			 int new_oid_valid,
 			 const char *old_name,
 			 const char *new_name)
 {
 	struct diff_filespec *one, *two;
 
-	if (!is_null_sha1(old_sha1) && !is_null_sha1(new_sha1) &&
-	    !hashcmp(old_sha1, new_sha1) && (old_mode == new_mode))
+	if (!is_null_oid(old_oid) && !is_null_oid(new_oid) &&
+	    !oidcmp(old_oid, new_oid) && (old_mode == new_mode))
 		return;
 
 	if (DIFF_OPT_TST(opt, REVERSE_DIFF)) {
 		SWAP(old_mode, new_mode);
-		SWAP(old_sha1, new_sha1);
+		SWAP(old_oid, new_oid);
 		SWAP(old_name, new_name);
 	}
 
@@ -57,8 +57,8 @@ static void stuff_change(struct diff_options *opt,
 
 	one = alloc_filespec(old_name);
 	two = alloc_filespec(new_name);
-	fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
-	fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
+	fill_filespec(one, old_oid->hash, old_oid_valid, old_mode);
+	fill_filespec(two, new_oid->hash, new_oid_valid, new_mode);
 
 	diff_queue(&diff_queued_diff, one, two);
 }
@@ -89,7 +89,7 @@ static int builtin_diff_b_f(struct rev_info *revs,
 
 	stuff_change(&revs->diffopt,
 		     blob[0].mode, canon_mode(st.st_mode),
-		     blob[0].sha1, null_sha1,
+		     &blob[0].oid, &null_oid,
 		     1, 0,
 		     path, path);
 	diffcore_std(&revs->diffopt);
@@ -114,7 +114,7 @@ static int builtin_diff_blobs(struct rev_info *revs,
 
 	stuff_change(&revs->diffopt,
 		     blob[0].mode, blob[1].mode,
-		     blob[0].sha1, blob[1].sha1,
+		     &blob[0].oid, &blob[1].oid,
 		     1, 1,
 		     blob[0].name, blob[1].name);
 	diffcore_std(&revs->diffopt);
@@ -160,7 +160,7 @@ static int builtin_diff_tree(struct rev_info *revs,
 			     struct object_array_entry *ent0,
 			     struct object_array_entry *ent1)
 {
-	const unsigned char *(sha1[2]);
+	const struct object_id *(oid[2]);
 	int swap = 0;
 
 	if (argc > 1)
@@ -172,9 +172,9 @@ static int builtin_diff_tree(struct rev_info *revs,
 	 */
 	if (ent1->item->flags & UNINTERESTING)
 		swap = 1;
-	sha1[swap] = ent0->item->oid.hash;
-	sha1[1 - swap] = ent1->item->oid.hash;
-	diff_tree_sha1(sha1[0], sha1[1], "", &revs->diffopt);
+	oid[swap] = &ent0->item->oid;
+	oid[1 - swap] = &ent1->item->oid;
+	diff_tree_sha1(oid[0]->hash, oid[1]->hash, "", &revs->diffopt);
 	log_tree_diff_flush(revs);
 	return 0;
 }
@@ -184,7 +184,7 @@ static int builtin_diff_combined(struct rev_info *revs,
 				 struct object_array_entry *ent,
 				 int ents)
 {
-	struct sha1_array parents = SHA1_ARRAY_INIT;
+	struct oid_array parents = OID_ARRAY_INIT;
 	int i;
 
 	if (argc > 1)
@@ -193,10 +193,10 @@ static int builtin_diff_combined(struct rev_info *revs,
 	if (!revs->dense_combined_merges && !revs->combine_merges)
 		revs->dense_combined_merges = revs->combine_merges = 1;
 	for (i = 1; i < ents; i++)
-		sha1_array_append(&parents, ent[i].item->oid.hash);
+		oid_array_append(&parents, &ent[i].item->oid);
 	diff_tree_combined(ent[0].item->oid.hash, &parents,
 			   revs->dense_combined_merges, revs);
-	sha1_array_clear(&parents);
+	oid_array_clear(&parents);
 	return 0;
 }
 
@@ -408,7 +408,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 		} else if (obj->type == OBJ_BLOB) {
 			if (2 <= blobs)
 				die(_("more than two blobs given: '%s'"), name);
-			hashcpy(blob[blobs].sha1, obj->oid.hash);
+			hashcpy(blob[blobs].oid.hash, obj->oid.hash);
 			blob[blobs].name = name;
 			blob[blobs].mode = entry->mode;
 			blobs++;
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 2a1c1c213f..366b9d13f9 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -50,7 +50,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	char **pack_lockfile_ptr = NULL;
 	struct child_process *conn;
 	struct fetch_pack_args args;
-	struct sha1_array shallow = SHA1_ARRAY_INIT;
+	struct oid_array shallow = OID_ARRAY_INIT;
 	struct string_list deepen_not = STRING_LIST_INIT_DUP;
 
 	packet_trace_identity("fetch-pack");
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 4ef7a08afc..5f2c2ab23e 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -661,7 +661,7 @@ static int update_local_ref(struct ref *ref,
 
 		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
 		    (recurse_submodules != RECURSE_SUBMODULES_ON))
-			check_for_new_submodule_commits(ref->new_oid.hash);
+			check_for_new_submodule_commits(&ref->new_oid);
 		r = s_update_ref(msg, ref, 0);
 		format_display(display, r ? '!' : '*', what,
 			       r ? _("unable to update local ref") : NULL,
@@ -677,7 +677,7 @@ static int update_local_ref(struct ref *ref,
 		strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
 		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
 		    (recurse_submodules != RECURSE_SUBMODULES_ON))
-			check_for_new_submodule_commits(ref->new_oid.hash);
+			check_for_new_submodule_commits(&ref->new_oid);
 		r = s_update_ref("fast-forward", ref, 1);
 		format_display(display, r ? '!' : ' ', quickref.buf,
 			       r ? _("unable to update local ref") : NULL,
@@ -692,7 +692,7 @@ static int update_local_ref(struct ref *ref,
 		strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
 		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
 		    (recurse_submodules != RECURSE_SUBMODULES_ON))
-			check_for_new_submodule_commits(ref->new_oid.hash);
+			check_for_new_submodule_commits(&ref->new_oid);
 		r = s_update_ref("forced-update", ref, 1);
 		format_display(display, r ? '!' : '+', quickref.buf,
 			       r ? _("unable to update local ref") : _("forced update"),
diff --git a/builtin/merge-index.c b/builtin/merge-index.c
index 2d1b6db6bd..c99443b095 100644
--- a/builtin/merge-index.c
+++ b/builtin/merge-index.c
@@ -9,7 +9,7 @@ static int merge_entry(int pos, const char *path)
 {
 	int found;
 	const char *arguments[] = { pgm, "", "", "", path, "", "", "", NULL };
-	char hexbuf[4][GIT_SHA1_HEXSZ + 1];
+	char hexbuf[4][GIT_MAX_HEXSZ + 1];
 	char ownbuf[4][60];
 
 	if (pos >= active_nr)
diff --git a/builtin/merge.c b/builtin/merge.c
index 95572b1810..703827f006 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1255,7 +1255,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (verify_signatures) {
 		for (p = remoteheads; p; p = p->next) {
 			struct commit *commit = p->item;
-			char hex[GIT_SHA1_HEXSZ + 1];
+			char hex[GIT_MAX_HEXSZ + 1];
 			struct signature_check signature_check;
 			memset(&signature_check, 0, sizeof(signature_check));
 
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 84af7c2324..0fe35d1b5a 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2672,16 +2672,16 @@ static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
  *
  * This is filled by get_object_list.
  */
-static struct sha1_array recent_objects;
+static struct oid_array recent_objects;
 
-static int loosened_object_can_be_discarded(const unsigned char *sha1,
+static int loosened_object_can_be_discarded(const struct object_id *oid,
 					    unsigned long mtime)
 {
 	if (!unpack_unreachable_expiration)
 		return 0;
 	if (mtime > unpack_unreachable_expiration)
 		return 0;
-	if (sha1_array_lookup(&recent_objects, sha1) >= 0)
+	if (oid_array_lookup(&recent_objects, oid) >= 0)
 		return 0;
 	return 1;
 }
@@ -2690,7 +2690,7 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
 {
 	struct packed_git *p;
 	uint32_t i;
-	const unsigned char *sha1;
+	struct object_id oid;
 
 	for (p = packed_git; p; p = p->next) {
 		if (!p->pack_local || p->pack_keep)
@@ -2700,11 +2700,11 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
 			die("cannot open pack index");
 
 		for (i = 0; i < p->num_objects; i++) {
-			sha1 = nth_packed_object_sha1(p, i);
-			if (!packlist_find(&to_pack, sha1, NULL) &&
-			    !has_sha1_pack_kept_or_nonlocal(sha1) &&
-			    !loosened_object_can_be_discarded(sha1, p->mtime))
-				if (force_object_loose(sha1, p->mtime))
+			nth_packed_object_oid(&oid, p, i);
+			if (!packlist_find(&to_pack, oid.hash, NULL) &&
+			    !has_sha1_pack_kept_or_nonlocal(oid.hash) &&
+			    !loosened_object_can_be_discarded(&oid, p->mtime))
+				if (force_object_loose(oid.hash, p->mtime))
 					die("unable to force loose object");
 		}
 	}
@@ -2743,12 +2743,12 @@ static void record_recent_object(struct object *obj,
 				 const char *name,
 				 void *data)
 {
-	sha1_array_append(&recent_objects, obj->oid.hash);
+	oid_array_append(&recent_objects, &obj->oid);
 }
 
 static void record_recent_commit(struct commit *commit, void *data)
 {
-	sha1_array_append(&recent_objects, commit->object.oid.hash);
+	oid_array_append(&recent_objects, &commit->object.oid);
 }
 
 static void get_object_list(int ac, const char **av)
@@ -2816,7 +2816,7 @@ static void get_object_list(int ac, const char **av)
 	if (unpack_unreachable)
 		loosen_unused_packed_objects(&revs);
 
-	sha1_array_clear(&recent_objects);
+	oid_array_clear(&recent_objects);
 }
 
 static int option_parse_index_version(const struct option *opt,
diff --git a/builtin/patch-id.c b/builtin/patch-id.c
index a84d0003a3..81552e02e4 100644
--- a/builtin/patch-id.c
+++ b/builtin/patch-id.c
@@ -55,7 +55,7 @@ static int scan_hunk_header(const char *p, int *p_before, int *p_after)
 
 static void flush_one_hunk(struct object_id *result, git_SHA_CTX *ctx)
 {
-	unsigned char hash[GIT_SHA1_RAWSZ];
+	unsigned char hash[GIT_MAX_RAWSZ];
 	unsigned short carry = 0;
 	int i;
 
diff --git a/builtin/pull.c b/builtin/pull.c
index 3ecb881b0b..d8aa26d8ab 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -330,21 +330,21 @@ static int git_pull_config(const char *var, const char *value, void *cb)
  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
  * into merge_heads.
  */
-static void get_merge_heads(struct sha1_array *merge_heads)
+static void get_merge_heads(struct oid_array *merge_heads)
 {
 	const char *filename = git_path("FETCH_HEAD");
 	FILE *fp;
 	struct strbuf sb = STRBUF_INIT;
-	unsigned char sha1[GIT_SHA1_RAWSZ];
+	struct object_id oid;
 
 	if (!(fp = fopen(filename, "r")))
 		die_errno(_("could not open '%s' for reading"), filename);
 	while (strbuf_getline_lf(&sb, fp) != EOF) {
-		if (get_sha1_hex(sb.buf, sha1))
+		if (get_oid_hex(sb.buf, &oid))
 			continue;  /* invalid line: does not start with SHA1 */
 		if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 			continue;  /* ref is not-for-merge */
-		sha1_array_append(merge_heads, sha1);
+		oid_array_append(merge_heads, &oid);
 	}
 	fclose(fp);
 	strbuf_release(&sb);
@@ -514,8 +514,8 @@ static int run_fetch(const char *repo, const char **refspecs)
 /**
  * "Pulls into void" by branching off merge_head.
  */
-static int pull_into_void(const unsigned char *merge_head,
-		const unsigned char *curr_head)
+static int pull_into_void(const struct object_id *merge_head,
+		const struct object_id *curr_head)
 {
 	/*
 	 * Two-way merge: we treat the index as based on an empty tree,
@@ -523,10 +523,10 @@ static int pull_into_void(const unsigned char *merge_head,
 	 * index/worktree changes that the user already made on the unborn
 	 * branch.
 	 */
-	if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
+	if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head->hash, 0))
 		return 1;
 
-	if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
+	if (update_ref("initial pull", "HEAD", merge_head->hash, curr_head->hash, 0, UPDATE_REFS_DIE_ON_ERR))
 		return 1;
 
 	return 0;
@@ -647,7 +647,7 @@ static const char *get_tracking_branch(const char *remote, const char *refspec)
  * current branch forked from its remote tracking branch. Returns 0 on success,
  * -1 on failure.
  */
-static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
+static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 		const char *refspec)
 {
 	int ret;
@@ -678,7 +678,7 @@ static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
 	if (ret)
 		goto cleanup;
 
-	ret = get_sha1_hex(sb.buf, fork_point);
+	ret = get_oid_hex(sb.buf, fork_point);
 	if (ret)
 		goto cleanup;
 
@@ -691,24 +691,24 @@ cleanup:
  * Sets merge_base to the octopus merge base of curr_head, merge_head and
  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
  */
-static int get_octopus_merge_base(unsigned char *merge_base,
-		const unsigned char *curr_head,
-		const unsigned char *merge_head,
-		const unsigned char *fork_point)
+static int get_octopus_merge_base(struct object_id *merge_base,
+		const struct object_id *curr_head,
+		const struct object_id *merge_head,
+		const struct object_id *fork_point)
 {
 	struct commit_list *revs = NULL, *result;
 
-	commit_list_insert(lookup_commit_reference(curr_head), &revs);
-	commit_list_insert(lookup_commit_reference(merge_head), &revs);
-	if (!is_null_sha1(fork_point))
-		commit_list_insert(lookup_commit_reference(fork_point), &revs);
+	commit_list_insert(lookup_commit_reference(curr_head->hash), &revs);
+	commit_list_insert(lookup_commit_reference(merge_head->hash), &revs);
+	if (!is_null_oid(fork_point))
+		commit_list_insert(lookup_commit_reference(fork_point->hash), &revs);
 
 	result = reduce_heads(get_octopus_merge_bases(revs));
 	free_commit_list(revs);
 	if (!result)
 		return 1;
 
-	hashcpy(merge_base, result->item->object.oid.hash);
+	oidcpy(merge_base, &result->item->object.oid);
 	return 0;
 }
 
@@ -717,16 +717,16 @@ static int get_octopus_merge_base(unsigned char *merge_base,
  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
  * appropriate arguments and returns its exit status.
  */
-static int run_rebase(const unsigned char *curr_head,
-		const unsigned char *merge_head,
-		const unsigned char *fork_point)
+static int run_rebase(const struct object_id *curr_head,
+		const struct object_id *merge_head,
+		const struct object_id *fork_point)
 {
 	int ret;
-	unsigned char oct_merge_base[GIT_SHA1_RAWSZ];
+	struct object_id oct_merge_base;
 	struct argv_array args = ARGV_ARRAY_INIT;
 
-	if (!get_octopus_merge_base(oct_merge_base, curr_head, merge_head, fork_point))
-		if (!is_null_sha1(fork_point) && !hashcmp(oct_merge_base, fork_point))
+	if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
+		if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 			fork_point = NULL;
 
 	argv_array_push(&args, "rebase");
@@ -754,12 +754,12 @@ static int run_rebase(const unsigned char *curr_head,
 		warning(_("ignoring --verify-signatures for rebase"));
 
 	argv_array_push(&args, "--onto");
-	argv_array_push(&args, sha1_to_hex(merge_head));
+	argv_array_push(&args, oid_to_hex(merge_head));
 
-	if (fork_point && !is_null_sha1(fork_point))
-		argv_array_push(&args, sha1_to_hex(fork_point));
+	if (fork_point && !is_null_oid(fork_point))
+		argv_array_push(&args, oid_to_hex(fork_point));
 	else
-		argv_array_push(&args, sha1_to_hex(merge_head));
+		argv_array_push(&args, oid_to_hex(merge_head));
 
 	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 	argv_array_clear(&args);
@@ -769,9 +769,9 @@ static int run_rebase(const unsigned char *curr_head,
 int cmd_pull(int argc, const char **argv, const char *prefix)
 {
 	const char *repo, **refspecs;
-	struct sha1_array merge_heads = SHA1_ARRAY_INIT;
-	unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
-	unsigned char rebase_fork_point[GIT_SHA1_RAWSZ];
+	struct oid_array merge_heads = OID_ARRAY_INIT;
+	struct object_id orig_head, curr_head;
+	struct object_id rebase_fork_point;
 
 	if (!getenv("GIT_REFLOG_ACTION"))
 		set_reflog_message(argc, argv);
@@ -794,8 +794,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (file_exists(git_path("MERGE_HEAD")))
 		die_conclude_merge();
 
-	if (get_sha1("HEAD", orig_head))
-		hashclr(orig_head);
+	if (get_oid("HEAD", &orig_head))
+		oidclr(&orig_head);
 
 	if (!opt_rebase && opt_autostash != -1)
 		die(_("--[no-]autostash option is only valid with --rebase."));
@@ -805,15 +805,15 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		if (opt_autostash != -1)
 			autostash = opt_autostash;
 
-		if (is_null_sha1(orig_head) && !is_cache_unborn())
+		if (is_null_oid(&orig_head) && !is_cache_unborn())
 			die(_("Updating an unborn branch with changes added to the index."));
 
 		if (!autostash)
 			require_clean_work_tree(N_("pull with rebase"),
 				_("please commit or stash them."), 1, 0);
 
-		if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
-			hashclr(rebase_fork_point);
+		if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
+			oidclr(&rebase_fork_point);
 	}
 
 	if (run_fetch(repo, refspecs))
@@ -822,11 +822,11 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (opt_dry_run)
 		return 0;
 
-	if (get_sha1("HEAD", curr_head))
-		hashclr(curr_head);
+	if (get_oid("HEAD", &curr_head))
+		oidclr(&curr_head);
 
-	if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
-			hashcmp(orig_head, curr_head)) {
+	if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
+			oidcmp(&orig_head, &curr_head)) {
 		/*
 		 * The fetch involved updating the current branch.
 		 *
@@ -837,15 +837,15 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 
 		warning(_("fetch updated the current branch head.\n"
 			"fast-forwarding your working tree from\n"
-			"commit %s."), sha1_to_hex(orig_head));
+			"commit %s."), oid_to_hex(&orig_head));
 
-		if (checkout_fast_forward(orig_head, curr_head, 0))
+		if (checkout_fast_forward(orig_head.hash, curr_head.hash, 0))
 			die(_("Cannot fast-forward your working tree.\n"
 				"After making sure that you saved anything precious from\n"
 				"$ git diff %s\n"
 				"output, run\n"
 				"$ git reset --hard\n"
-				"to recover."), sha1_to_hex(orig_head));
+				"to recover."), oid_to_hex(&orig_head));
 	}
 
 	get_merge_heads(&merge_heads);
@@ -853,10 +853,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!merge_heads.nr)
 		die_no_merge_candidates(repo, refspecs);
 
-	if (is_null_sha1(orig_head)) {
+	if (is_null_oid(&orig_head)) {
 		if (merge_heads.nr > 1)
 			die(_("Cannot merge multiple branches into empty head."));
-		return pull_into_void(*merge_heads.sha1, curr_head);
+		return pull_into_void(merge_heads.oid, &curr_head);
 	}
 	if (opt_rebase && merge_heads.nr > 1)
 		die(_("Cannot rebase onto multiple branches."));
@@ -865,15 +865,15 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		struct commit_list *list = NULL;
 		struct commit *merge_head, *head;
 
-		head = lookup_commit_reference(orig_head);
+		head = lookup_commit_reference(orig_head.hash);
 		commit_list_insert(head, &list);
-		merge_head = lookup_commit_reference(merge_heads.sha1[0]);
+		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
 		if (is_descendant_of(merge_head, list)) {
 			/* we can fast-forward this without invoking rebase */
 			opt_ff = "--ff-only";
 			return run_merge();
 		}
-		return run_rebase(curr_head, *merge_heads.sha1, rebase_fork_point);
+		return run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 	} else {
 		return run_merge();
 	}
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 7020278081..3cba3fd278 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -225,10 +225,10 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
 	return git_default_config(var, value, cb);
 }
 
-static void show_ref(const char *path, const unsigned char *sha1)
+static void show_ref(const char *path, const struct object_id *oid)
 {
 	if (sent_capabilities) {
-		packet_write_fmt(1, "%s %s\n", sha1_to_hex(sha1), path);
+		packet_write_fmt(1, "%s %s\n", oid_to_hex(oid), path);
 	} else {
 		struct strbuf cap = STRBUF_INIT;
 
@@ -244,7 +244,7 @@ static void show_ref(const char *path, const unsigned char *sha1)
 			strbuf_addstr(&cap, " push-options");
 		strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
 		packet_write_fmt(1, "%s %s%c%s\n",
-			     sha1_to_hex(sha1), path, 0, cap.buf);
+			     oid_to_hex(oid), path, 0, cap.buf);
 		strbuf_release(&cap);
 		sent_capabilities = 1;
 	}
@@ -271,7 +271,7 @@ static int show_ref_cb(const char *path_full, const struct object_id *oid,
 	} else {
 		oidset_insert(seen, oid);
 	}
-	show_ref(path, oid->hash);
+	show_ref(path, oid);
 	return 0;
 }
 
@@ -284,7 +284,7 @@ static void show_one_alternate_ref(const char *refname,
 	if (oidset_insert(seen, oid))
 		return;
 
-	show_ref(".have", oid->hash);
+	show_ref(".have", oid);
 }
 
 static void write_head_info(void)
@@ -295,7 +295,7 @@ static void write_head_info(void)
 	for_each_alternate_ref(show_one_alternate_ref, &seen);
 	oidset_clear(&seen);
 	if (!sent_capabilities)
-		show_ref("capabilities^{}", null_sha1);
+		show_ref("capabilities^{}", &null_oid);
 
 	advertise_shallow_grafts(1);
 
@@ -309,8 +309,8 @@ struct command {
 	unsigned int skip_update:1,
 		     did_not_exist:1;
 	int index;
-	unsigned char old_sha1[20];
-	unsigned char new_sha1[20];
+	struct object_id old_oid;
+	struct object_id new_oid;
 	char ref_name[FLEX_ARRAY]; /* more */
 };
 
@@ -723,7 +723,7 @@ static int feed_receive_hook(void *state_, const char **bufp, size_t *sizep)
 		return -1; /* EOF */
 	strbuf_reset(&state->buf);
 	strbuf_addf(&state->buf, "%s %s %s\n",
-		    sha1_to_hex(cmd->old_sha1), sha1_to_hex(cmd->new_sha1),
+		    oid_to_hex(&cmd->old_oid), oid_to_hex(&cmd->new_oid),
 		    cmd->ref_name);
 	state->cmd = cmd->next;
 	if (bufp) {
@@ -764,8 +764,8 @@ static int run_update_hook(struct command *cmd)
 		return 0;
 
 	argv[1] = cmd->ref_name;
-	argv[2] = sha1_to_hex(cmd->old_sha1);
-	argv[3] = sha1_to_hex(cmd->new_sha1);
+	argv[2] = oid_to_hex(&cmd->old_oid);
+	argv[3] = oid_to_hex(&cmd->new_oid);
 	argv[4] = NULL;
 
 	proc.no_stdin = 1;
@@ -831,7 +831,7 @@ static int command_singleton_iterator(void *cb_data, unsigned char sha1[20]);
 static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 {
 	static struct lock_file shallow_lock;
-	struct sha1_array extra = SHA1_ARRAY_INIT;
+	struct oid_array extra = OID_ARRAY_INIT;
 	struct check_connected_options opt = CHECK_CONNECTED_INIT;
 	uint32_t mask = 1 << (cmd->index % 32);
 	int i;
@@ -842,13 +842,13 @@ static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 		if (si->used_shallow[i] &&
 		    (si->used_shallow[i][cmd->index / 32] & mask) &&
 		    !delayed_reachability_test(si, i))
-			sha1_array_append(&extra, si->shallow->sha1[i]);
+			oid_array_append(&extra, &si->shallow->oid[i]);
 
 	opt.env = tmp_objdir_env(tmp_objdir);
 	setup_alternate_shallow(&shallow_lock, &opt.shallow_file, &extra);
 	if (check_connected(command_singleton_iterator, cmd, &opt)) {
 		rollback_lock_file(&shallow_lock);
-		sha1_array_clear(&extra);
+		oid_array_clear(&extra);
 		return -1;
 	}
 
@@ -859,10 +859,10 @@ static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 	 * not lose these new roots..
 	 */
 	for (i = 0; i < extra.nr; i++)
-		register_shallow(extra.sha1[i]);
+		register_shallow(extra.oid[i].hash);
 
 	si->shallow_ref[cmd->index] = 0;
-	sha1_array_clear(&extra);
+	oid_array_clear(&extra);
 	return 0;
 }
 
@@ -988,8 +988,8 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 	const char *name = cmd->ref_name;
 	struct strbuf namespaced_name_buf = STRBUF_INIT;
 	const char *namespaced_name, *ret;
-	unsigned char *old_sha1 = cmd->old_sha1;
-	unsigned char *new_sha1 = cmd->new_sha1;
+	struct object_id *old_oid = &cmd->old_oid;
+	struct object_id *new_oid = &cmd->new_oid;
 
 	/* only refs/... are allowed */
 	if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
@@ -1014,20 +1014,20 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 				refuse_unconfigured_deny();
 			return "branch is currently checked out";
 		case DENY_UPDATE_INSTEAD:
-			ret = update_worktree(new_sha1);
+			ret = update_worktree(new_oid->hash);
 			if (ret)
 				return ret;
 			break;
 		}
 	}
 
-	if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
+	if (!is_null_oid(new_oid) && !has_object_file(new_oid)) {
 		error("unpack should have generated %s, "
-		      "but I can't find it!", sha1_to_hex(new_sha1));
+		      "but I can't find it!", oid_to_hex(new_oid));
 		return "bad pack";
 	}
 
-	if (!is_null_sha1(old_sha1) && is_null_sha1(new_sha1)) {
+	if (!is_null_oid(old_oid) && is_null_oid(new_oid)) {
 		if (deny_deletes && starts_with(name, "refs/heads/")) {
 			rp_error("denying ref deletion for %s", name);
 			return "deletion prohibited";
@@ -1053,14 +1053,14 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		}
 	}
 
-	if (deny_non_fast_forwards && !is_null_sha1(new_sha1) &&
-	    !is_null_sha1(old_sha1) &&
+	if (deny_non_fast_forwards && !is_null_oid(new_oid) &&
+	    !is_null_oid(old_oid) &&
 	    starts_with(name, "refs/heads/")) {
 		struct object *old_object, *new_object;
 		struct commit *old_commit, *new_commit;
 
-		old_object = parse_object(old_sha1);
-		new_object = parse_object(new_sha1);
+		old_object = parse_object(old_oid->hash);
+		new_object = parse_object(new_oid->hash);
 
 		if (!old_object || !new_object ||
 		    old_object->type != OBJ_COMMIT ||
@@ -1081,10 +1081,10 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		return "hook declined";
 	}
 
-	if (is_null_sha1(new_sha1)) {
+	if (is_null_oid(new_oid)) {
 		struct strbuf err = STRBUF_INIT;
-		if (!parse_object(old_sha1)) {
-			old_sha1 = NULL;
+		if (!parse_object(old_oid->hash)) {
+			old_oid = NULL;
 			if (ref_exists(name)) {
 				rp_warning("Allowing deletion of corrupt ref.");
 			} else {
@@ -1094,7 +1094,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		}
 		if (ref_transaction_delete(transaction,
 					   namespaced_name,
-					   old_sha1,
+					   old_oid->hash,
 					   0, "push", &err)) {
 			rp_error("%s", err.buf);
 			strbuf_release(&err);
@@ -1111,7 +1111,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 
 		if (ref_transaction_update(transaction,
 					   namespaced_name,
-					   new_sha1, old_sha1,
+					   new_oid->hash, old_oid->hash,
 					   0, "push",
 					   &err)) {
 			rp_error("%s", err.buf);
@@ -1162,7 +1162,7 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 	const char *dst_name;
 	struct string_list_item *item;
 	struct command *dst_cmd;
-	unsigned char sha1[GIT_SHA1_RAWSZ];
+	unsigned char sha1[GIT_MAX_RAWSZ];
 	int flag;
 
 	strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
@@ -1187,8 +1187,8 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 
 	dst_cmd = (struct command *) item->util;
 
-	if (!hashcmp(cmd->old_sha1, dst_cmd->old_sha1) &&
-	    !hashcmp(cmd->new_sha1, dst_cmd->new_sha1))
+	if (!oidcmp(&cmd->old_oid, &dst_cmd->old_oid) &&
+	    !oidcmp(&cmd->new_oid, &dst_cmd->new_oid))
 		return;
 
 	dst_cmd->skip_update = 1;
@@ -1196,11 +1196,11 @@ 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_sha1, DEFAULT_ABBREV),
-		 find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV),
+		 find_unique_abbrev(cmd->old_oid.hash, DEFAULT_ABBREV),
+		 find_unique_abbrev(cmd->new_oid.hash, DEFAULT_ABBREV),
 		 dst_cmd->ref_name,
-		 find_unique_abbrev(dst_cmd->old_sha1, DEFAULT_ABBREV),
-		 find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
+		 find_unique_abbrev(dst_cmd->old_oid.hash, DEFAULT_ABBREV),
+		 find_unique_abbrev(dst_cmd->new_oid.hash, DEFAULT_ABBREV));
 
 	cmd->error_string = dst_cmd->error_string =
 		"inconsistent aliased update";
@@ -1231,10 +1231,10 @@ static int command_singleton_iterator(void *cb_data, unsigned char sha1[20])
 	struct command **cmd_list = cb_data;
 	struct command *cmd = *cmd_list;
 
-	if (!cmd || is_null_sha1(cmd->new_sha1))
+	if (!cmd || is_null_oid(&cmd->new_oid))
 		return -1; /* end of list */
 	*cmd_list = NULL; /* this returns only one */
-	hashcpy(sha1, cmd->new_sha1);
+	hashcpy(sha1, cmd->new_oid.hash);
 	return 0;
 }
 
@@ -1275,8 +1275,8 @@ static int iterate_receive_command_list(void *cb_data, unsigned char sha1[20])
 		if (shallow_update && data->si->shallow_ref[cmd->index])
 			/* to be checked in update_shallow_ref() */
 			continue;
-		if (!is_null_sha1(cmd->new_sha1) && !cmd->skip_update) {
-			hashcpy(sha1, cmd->new_sha1);
+		if (!is_null_oid(&cmd->new_oid) && !cmd->skip_update) {
+			hashcpy(sha1, cmd->new_oid.hash);
 			*cmd_list = cmd->next;
 			return 0;
 		}
@@ -1303,7 +1303,7 @@ static void reject_updates_to_hidden(struct command *commands)
 
 		if (!ref_is_hidden(cmd->ref_name, refname_full.buf))
 			continue;
-		if (is_null_sha1(cmd->new_sha1))
+		if (is_null_oid(&cmd->new_oid))
 			cmd->error_string = "deny deleting a hidden ref";
 		else
 			cmd->error_string = "deny updating a hidden ref";
@@ -1486,23 +1486,23 @@ static struct command **queue_command(struct command **tail,
 				      const char *line,
 				      int linelen)
 {
-	unsigned char old_sha1[20], new_sha1[20];
+	struct object_id old_oid, new_oid;
 	struct command *cmd;
 	const char *refname;
 	int reflen;
+	const char *p;
 
-	if (linelen < 83 ||
-	    line[40] != ' ' ||
-	    line[81] != ' ' ||
-	    get_sha1_hex(line, old_sha1) ||
-	    get_sha1_hex(line + 41, new_sha1))
+	if (parse_oid_hex(line, &old_oid, &p) ||
+	    *p++ != ' ' ||
+	    parse_oid_hex(p, &new_oid, &p) ||
+	    *p++ != ' ')
 		die("protocol error: expected old/new/ref, got '%s'", line);
 
-	refname = line + 82;
-	reflen = linelen - 82;
+	refname = p;
+	reflen = linelen - (p - line);
 	FLEX_ALLOC_MEM(cmd, ref_name, refname, reflen);
-	hashcpy(cmd->old_sha1, old_sha1);
-	hashcpy(cmd->new_sha1, new_sha1);
+	oidcpy(&cmd->old_oid, &old_oid);
+	oidcpy(&cmd->new_oid, &new_oid);
 	*tail = cmd;
 	return &cmd->next;
 }
@@ -1529,7 +1529,7 @@ static void queue_commands_from_cert(struct command **tail,
 	}
 }
 
-static struct command *read_head_info(struct sha1_array *shallow)
+static struct command *read_head_info(struct oid_array *shallow)
 {
 	struct command *commands = NULL;
 	struct command **p = &commands;
@@ -1541,12 +1541,12 @@ static struct command *read_head_info(struct sha1_array *shallow)
 		if (!line)
 			break;
 
-		if (len == 48 && starts_with(line, "shallow ")) {
-			unsigned char sha1[20];
-			if (get_sha1_hex(line + 8, sha1))
+		if (len > 8 && starts_with(line, "shallow ")) {
+			struct object_id oid;
+			if (get_oid_hex(line + 8, &oid))
 				die("protocol error: expected shallow sha, got '%s'",
 				    line + 8);
-			sha1_array_append(shallow, sha1);
+			oid_array_append(shallow, &oid);
 			continue;
 		}
 
@@ -1807,7 +1807,7 @@ static void prepare_shallow_update(struct command *commands,
 
 static void update_shallow_info(struct command *commands,
 				struct shallow_info *si,
-				struct sha1_array *ref)
+				struct oid_array *ref)
 {
 	struct command *cmd;
 	int *ref_status;
@@ -1818,9 +1818,9 @@ static void update_shallow_info(struct command *commands,
 	}
 
 	for (cmd = commands; cmd; cmd = cmd->next) {
-		if (is_null_sha1(cmd->new_sha1))
+		if (is_null_oid(&cmd->new_oid))
 			continue;
-		sha1_array_append(ref, cmd->new_sha1);
+		oid_array_append(ref, &cmd->new_oid);
 		cmd->index = ref->nr - 1;
 	}
 	si->ref = ref;
@@ -1833,7 +1833,7 @@ static void update_shallow_info(struct command *commands,
 	ALLOC_ARRAY(ref_status, ref->nr);
 	assign_shallow_commits_to_refs(si, NULL, ref_status);
 	for (cmd = commands; cmd; cmd = cmd->next) {
-		if (is_null_sha1(cmd->new_sha1))
+		if (is_null_oid(&cmd->new_oid))
 			continue;
 		if (ref_status[cmd->index]) {
 			cmd->error_string = "shallow update not allowed";
@@ -1871,7 +1871,7 @@ static int delete_only(struct command *commands)
 {
 	struct command *cmd;
 	for (cmd = commands; cmd; cmd = cmd->next) {
-		if (!is_null_sha1(cmd->new_sha1))
+		if (!is_null_oid(&cmd->new_oid))
 			return 0;
 	}
 	return 1;
@@ -1881,8 +1881,8 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 {
 	int advertise_refs = 0;
 	struct command *commands;
-	struct sha1_array shallow = SHA1_ARRAY_INIT;
-	struct sha1_array ref = SHA1_ARRAY_INIT;
+	struct oid_array shallow = OID_ARRAY_INIT;
+	struct oid_array ref = OID_ARRAY_INIT;
 	struct shallow_info si;
 
 	struct option options[] = {
@@ -1974,8 +1974,8 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 	}
 	if (use_sideband)
 		packet_flush(1);
-	sha1_array_clear(&shallow);
-	sha1_array_clear(&ref);
+	oid_array_clear(&shallow);
+	oid_array_clear(&ref);
 	free((void *)push_cert_nonce);
 	return 0;
 }
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 0aa93d5891..bcf77f0b8a 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -212,7 +212,7 @@ static void print_var_int(const char *var, int val)
 static int show_bisect_vars(struct rev_list_info *info, int reaches, int all)
 {
 	int cnt, flags = info->flags;
-	char hex[GIT_SHA1_HEXSZ + 1] = "";
+	char hex[GIT_MAX_HEXSZ + 1] = "";
 	struct commit_list *tried;
 	struct rev_info *revs = info->revs;
 
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index f54d7b5028..0513330910 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -205,9 +205,9 @@ static int anti_reference(const char *refname, const struct object_id *oid, int
 	return 0;
 }
 
-static int show_abbrev(const unsigned char *sha1, void *cb_data)
+static int show_abbrev(const struct object_id *oid, void *cb_data)
 {
-	show_rev(NORMAL, sha1, NULL);
+	show_rev(NORMAL, oid->hash, NULL);
 	return 0;
 }
 
diff --git a/builtin/send-pack.c b/builtin/send-pack.c
index 832fd7ed0a..b8e2e74fe0 100644
--- a/builtin/send-pack.c
+++ b/builtin/send-pack.c
@@ -131,8 +131,8 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 	const char *dest = NULL;
 	int fd[2];
 	struct child_process *conn;
-	struct sha1_array extra_have = SHA1_ARRAY_INIT;
-	struct sha1_array shallow = SHA1_ARRAY_INIT;
+	struct oid_array extra_have = OID_ARRAY_INIT;
+	struct oid_array shallow = OID_ARRAY_INIT;
 	struct ref *remote_refs, *local_refs;
 	int ret;
 	int helper_status = 0;
diff --git a/cache.h b/cache.h
index 556468c25b..ba27595d54 100644
--- a/cache.h
+++ b/cache.h
@@ -66,8 +66,12 @@ unsigned long git_deflate_bound(git_zstream *, unsigned long);
 #define GIT_SHA1_RAWSZ 20
 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
 
+/* The length in byte and in hex digits of the largest possible hash value. */
+#define GIT_MAX_RAWSZ GIT_SHA1_RAWSZ
+#define GIT_MAX_HEXSZ GIT_SHA1_HEXSZ
+
 struct object_id {
-	unsigned char hash[GIT_SHA1_RAWSZ];
+	unsigned char hash[GIT_MAX_RAWSZ];
 };
 
 #if defined(DT_UNKNOWN) && !defined(NO_D_TYPE_IN_DIRENT)
@@ -978,7 +982,7 @@ extern char *sha1_pack_index_name(const unsigned char *sha1);
 extern const char *find_unique_abbrev(const unsigned char *sha1, int len);
 extern int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len);
 
-extern const unsigned char null_sha1[GIT_SHA1_RAWSZ];
+extern const unsigned char null_sha1[GIT_MAX_RAWSZ];
 extern const struct object_id null_oid;
 
 static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
@@ -1360,7 +1364,7 @@ extern int get_sha1_with_context(const char *str, unsigned flags, unsigned char
 
 extern int get_oid(const char *str, struct object_id *oid);
 
-typedef int each_abbrev_fn(const unsigned char *sha1, void *);
+typedef int each_abbrev_fn(const struct object_id *oid, void *);
 extern int for_each_abbrev(const char *prefix, each_abbrev_fn, void *);
 
 extern int set_disambiguate_hint_config(const char *var, const char *value);
diff --git a/combine-diff.c b/combine-diff.c
index d3560573ac..2848034fe9 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -1312,7 +1312,7 @@ static const char *path_path(void *obj)
 
 /* find set of paths that every parent touches */
 static struct combine_diff_path *find_paths_generic(const unsigned char *sha1,
-	const struct sha1_array *parents, struct diff_options *opt)
+	const struct oid_array *parents, struct diff_options *opt)
 {
 	struct combine_diff_path *paths = NULL;
 	int i, num_parent = parents->nr;
@@ -1336,7 +1336,7 @@ static struct combine_diff_path *find_paths_generic(const unsigned char *sha1,
 			opt->output_format = stat_opt;
 		else
 			opt->output_format = DIFF_FORMAT_NO_OUTPUT;
-		diff_tree_sha1(parents->sha1[i], sha1, "", opt);
+		diff_tree_sha1(parents->oid[i].hash, sha1, "", opt);
 		diffcore_std(opt);
 		paths = intersect_paths(paths, i, num_parent);
 
@@ -1360,7 +1360,7 @@ static struct combine_diff_path *find_paths_generic(const unsigned char *sha1,
  * rename/copy detection, etc, comparing all trees simultaneously (= faster).
  */
 static struct combine_diff_path *find_paths_multitree(
-	const unsigned char *sha1, const struct sha1_array *parents,
+	const unsigned char *sha1, const struct oid_array *parents,
 	struct diff_options *opt)
 {
 	int i, nparent = parents->nr;
@@ -1370,7 +1370,7 @@ static struct combine_diff_path *find_paths_multitree(
 
 	ALLOC_ARRAY(parents_sha1, nparent);
 	for (i = 0; i < nparent; i++)
-		parents_sha1[i] = parents->sha1[i];
+		parents_sha1[i] = parents->oid[i].hash;
 
 	/* fake list head, so worker can assume it is non-NULL */
 	paths_head.next = NULL;
@@ -1385,7 +1385,7 @@ static struct combine_diff_path *find_paths_multitree(
 
 
 void diff_tree_combined(const unsigned char *sha1,
-			const struct sha1_array *parents,
+			const struct oid_array *parents,
 			int dense,
 			struct rev_info *rev)
 {
@@ -1463,7 +1463,7 @@ void diff_tree_combined(const unsigned char *sha1,
 		if (stat_opt) {
 			diffopts.output_format = stat_opt;
 
-			diff_tree_sha1(parents->sha1[0], sha1, "", &diffopts);
+			diff_tree_sha1(parents->oid[0].hash, sha1, "", &diffopts);
 			diffcore_std(&diffopts);
 			if (opt->orderfile)
 				diffcore_order(opt->orderfile);
@@ -1533,12 +1533,12 @@ void diff_tree_combined_merge(const struct commit *commit, int dense,
 			      struct rev_info *rev)
 {
 	struct commit_list *parent = get_saved_parents(rev, commit);
-	struct sha1_array parents = SHA1_ARRAY_INIT;
+	struct oid_array parents = OID_ARRAY_INIT;
 
 	while (parent) {
-		sha1_array_append(&parents, parent->item->object.oid.hash);
+		oid_array_append(&parents, &parent->item->object.oid);
 		parent = parent->next;
 	}
 	diff_tree_combined(commit->object.oid.hash, &parents, dense, rev);
-	sha1_array_clear(&parents);
+	oid_array_clear(&parents);
 }
diff --git a/commit.h b/commit.h
index 528272ac9b..7b1986d5c8 100644
--- a/commit.h
+++ b/commit.h
@@ -261,7 +261,7 @@ extern struct commit_list *get_merge_bases_many_dirty(struct commit *one, int n,
 /* largest positive number a signed 32-bit integer can contain */
 #define INFINITE_DEPTH 0x7fffffff
 
-struct sha1_array;
+struct oid_array;
 struct ref;
 extern int register_shallow(const unsigned char *sha1);
 extern int unregister_shallow(const unsigned char *sha1);
@@ -273,18 +273,18 @@ extern struct commit_list *get_shallow_commits_by_rev_list(
 		int ac, const char **av, int shallow_flag, int not_shallow_flag);
 extern void set_alternate_shallow_file(const char *path, int override);
 extern int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
-				 const struct sha1_array *extra);
+				 const struct oid_array *extra);
 extern void setup_alternate_shallow(struct lock_file *shallow_lock,
 				    const char **alternate_shallow_file,
-				    const struct sha1_array *extra);
-extern const char *setup_temporary_shallow(const struct sha1_array *extra);
+				    const struct oid_array *extra);
+extern const char *setup_temporary_shallow(const struct oid_array *extra);
 extern void advertise_shallow_grafts(int);
 
 struct shallow_info {
-	struct sha1_array *shallow;
+	struct oid_array *shallow;
 	int *ours, nr_ours;
 	int *theirs, nr_theirs;
-	struct sha1_array *ref;
+	struct oid_array *ref;
 
 	/* for receive-pack */
 	uint32_t **used_shallow;
@@ -295,7 +295,7 @@ struct shallow_info {
 	int nr_commits;
 };
 
-extern void prepare_shallow_info(struct shallow_info *, struct sha1_array *);
+extern void prepare_shallow_info(struct shallow_info *, struct oid_array *);
 extern void clear_shallow_info(struct shallow_info *);
 extern void remove_nonexistent_theirs_shallow(struct shallow_info *);
 extern void assign_shallow_commits_to_refs(struct shallow_info *info,
diff --git a/connect.c b/connect.c
index 7d65c1c736..6afde189a3 100644
--- a/connect.c
+++ b/connect.c
@@ -111,8 +111,8 @@ static void annotate_refs_with_symref_info(struct ref *ref)
  */
 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 			      struct ref **list, unsigned int flags,
-			      struct sha1_array *extra_have,
-			      struct sha1_array *shallow_points)
+			      struct oid_array *extra_have,
+			      struct oid_array *shallow_points)
 {
 	struct ref **orig_list = list;
 
@@ -153,7 +153,7 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 				die("protocol error: expected shallow sha-1, got '%s'", arg);
 			if (!shallow_points)
 				die("repository on the other end cannot be shallow");
-			sha1_array_append(shallow_points, old_oid.hash);
+			oid_array_append(shallow_points, &old_oid);
 			continue;
 		}
 
@@ -169,7 +169,7 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 		}
 
 		if (extra_have && !strcmp(name, ".have")) {
-			sha1_array_append(extra_have, old_oid.hash);
+			oid_array_append(extra_have, &old_oid);
 			continue;
 		}
 
diff --git a/diff.c b/diff.c
index 92d78e4596..11eef1c85d 100644
--- a/diff.c
+++ b/diff.c
@@ -398,7 +398,7 @@ static struct diff_tempfile {
 	 */
 	const char *name;
 
-	char hex[GIT_SHA1_HEXSZ + 1];
+	char hex[GIT_MAX_HEXSZ + 1];
 	char mode[10];
 
 	/*
@@ -4219,7 +4219,7 @@ const char *diff_aligned_abbrev(const struct object_id *oid, int len)
 	 * uniqueness across all objects (statistically speaking).
 	 */
 	if (abblen < GIT_SHA1_HEXSZ - 3) {
-		static char hex[GIT_SHA1_HEXSZ + 1];
+		static char hex[GIT_MAX_HEXSZ + 1];
 		if (len < abblen && abblen <= len + 2)
 			xsnprintf(hex, sizeof(hex), "%s%.*s", abbrev, len+3-abblen, "..");
 		else
diff --git a/diff.h b/diff.h
index e9ccb38c26..5be1ee77a7 100644
--- a/diff.h
+++ b/diff.h
@@ -14,7 +14,7 @@ struct diff_queue_struct;
 struct strbuf;
 struct diff_filespec;
 struct userdiff_driver;
-struct sha1_array;
+struct oid_array;
 struct commit;
 struct combine_diff_path;
 
@@ -236,7 +236,7 @@ struct combine_diff_path {
 extern void show_combined_diff(struct combine_diff_path *elem, int num_parent,
 			      int dense, struct rev_info *);
 
-extern void diff_tree_combined(const unsigned char *sha1, const struct sha1_array *parents, int dense, struct rev_info *rev);
+extern void diff_tree_combined(const unsigned char *sha1, const struct oid_array *parents, int dense, struct rev_info *rev);
 
 extern void diff_tree_combined_merge(const struct commit *commit, int dense, struct rev_info *rev);
 
diff --git a/fetch-pack.c b/fetch-pack.c
index d07d85ce30..42969353d6 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1015,7 +1015,7 @@ static void update_shallow(struct fetch_pack_args *args,
 			   struct ref **sought, int nr_sought,
 			   struct shallow_info *si)
 {
-	struct sha1_array ref = SHA1_ARRAY_INIT;
+	struct oid_array ref = OID_ARRAY_INIT;
 	int *status;
 	int i;
 
@@ -1038,18 +1038,18 @@ static void update_shallow(struct fetch_pack_args *args,
 		 * shallow points that exist in the pack (iow in repo
 		 * after get_pack() and reprepare_packed_git())
 		 */
-		struct sha1_array extra = SHA1_ARRAY_INIT;
-		unsigned char (*sha1)[20] = si->shallow->sha1;
+		struct oid_array extra = OID_ARRAY_INIT;
+		struct object_id *oid = si->shallow->oid;
 		for (i = 0; i < si->shallow->nr; i++)
-			if (has_sha1_file(sha1[i]))
-				sha1_array_append(&extra, sha1[i]);
+			if (has_object_file(&oid[i]))
+				oid_array_append(&extra, &oid[i]);
 		if (extra.nr) {
 			setup_alternate_shallow(&shallow_lock,
 						&alternate_shallow_file,
 						&extra);
 			commit_lock_file(&shallow_lock);
 		}
-		sha1_array_clear(&extra);
+		oid_array_clear(&extra);
 		return;
 	}
 
@@ -1060,7 +1060,7 @@ static void update_shallow(struct fetch_pack_args *args,
 	if (!si->nr_ours && !si->nr_theirs)
 		return;
 	for (i = 0; i < nr_sought; i++)
-		sha1_array_append(&ref, sought[i]->old_oid.hash);
+		oid_array_append(&ref, &sought[i]->old_oid);
 	si->ref = &ref;
 
 	if (args->update_shallow) {
@@ -1070,23 +1070,23 @@ static void update_shallow(struct fetch_pack_args *args,
 		 * shallow roots that are actually reachable from new
 		 * refs.
 		 */
-		struct sha1_array extra = SHA1_ARRAY_INIT;
-		unsigned char (*sha1)[20] = si->shallow->sha1;
+		struct oid_array extra = OID_ARRAY_INIT;
+		struct object_id *oid = si->shallow->oid;
 		assign_shallow_commits_to_refs(si, NULL, NULL);
 		if (!si->nr_ours && !si->nr_theirs) {
-			sha1_array_clear(&ref);
+			oid_array_clear(&ref);
 			return;
 		}
 		for (i = 0; i < si->nr_ours; i++)
-			sha1_array_append(&extra, sha1[si->ours[i]]);
+			oid_array_append(&extra, &oid[si->ours[i]]);
 		for (i = 0; i < si->nr_theirs; i++)
-			sha1_array_append(&extra, sha1[si->theirs[i]]);
+			oid_array_append(&extra, &oid[si->theirs[i]]);
 		setup_alternate_shallow(&shallow_lock,
 					&alternate_shallow_file,
 					&extra);
 		commit_lock_file(&shallow_lock);
-		sha1_array_clear(&extra);
-		sha1_array_clear(&ref);
+		oid_array_clear(&extra);
+		oid_array_clear(&ref);
 		return;
 	}
 
@@ -1102,7 +1102,7 @@ static void update_shallow(struct fetch_pack_args *args,
 				sought[i]->status = REF_STATUS_REJECT_SHALLOW;
 	}
 	free(status);
-	sha1_array_clear(&ref);
+	oid_array_clear(&ref);
 }
 
 struct ref *fetch_pack(struct fetch_pack_args *args,
@@ -1110,7 +1110,7 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
 		       const struct ref *ref,
 		       const char *dest,
 		       struct ref **sought, int nr_sought,
-		       struct sha1_array *shallow,
+		       struct oid_array *shallow,
 		       char **pack_lockfile)
 {
 	struct ref *ref_cpy;
diff --git a/fetch-pack.h b/fetch-pack.h
index a2d46e6e75..b6aeb43a8e 100644
--- a/fetch-pack.h
+++ b/fetch-pack.h
@@ -4,7 +4,7 @@
 #include "string-list.h"
 #include "run-command.h"
 
-struct sha1_array;
+struct oid_array;
 
 struct fetch_pack_args {
 	const char *uploadpack;
@@ -42,7 +42,7 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
 		       const char *dest,
 		       struct ref **sought,
 		       int nr_sought,
-		       struct sha1_array *shallow,
+		       struct oid_array *shallow,
 		       char **pack_lockfile);
 
 /*
diff --git a/fsck.c b/fsck.c
index 939792752b..e6152e4e6d 100644
--- a/fsck.c
+++ b/fsck.c
@@ -132,10 +132,10 @@ static int fsck_msg_type(enum fsck_msg_id msg_id,
 
 static void init_skiplist(struct fsck_options *options, const char *path)
 {
-	static struct sha1_array skiplist = SHA1_ARRAY_INIT;
+	static struct oid_array skiplist = OID_ARRAY_INIT;
 	int sorted, fd;
-	char buffer[41];
-	unsigned char sha1[20];
+	char buffer[GIT_MAX_HEXSZ + 1];
+	struct object_id oid;
 
 	if (options->skiplist)
 		sorted = options->skiplist->sorted;
@@ -148,17 +148,18 @@ static void init_skiplist(struct fsck_options *options, const char *path)
 	if (fd < 0)
 		die("Could not open skip list: %s", path);
 	for (;;) {
+		const char *p;
 		int result = read_in_full(fd, buffer, sizeof(buffer));
 		if (result < 0)
 			die_errno("Could not read '%s'", path);
 		if (!result)
 			break;
-		if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
+		if (parse_oid_hex(buffer, &oid, &p) || *p != '\n')
 			die("Invalid SHA-1: %s", buffer);
-		sha1_array_append(&skiplist, sha1);
+		oid_array_append(&skiplist, &oid);
 		if (sorted && skiplist.nr > 1 &&
-				hashcmp(skiplist.sha1[skiplist.nr - 2],
-					sha1) > 0)
+				oidcmp(&skiplist.oid[skiplist.nr - 2],
+				       &oid) > 0)
 			sorted = 0;
 	}
 	close(fd);
@@ -279,7 +280,7 @@ static int report(struct fsck_options *options, struct object *object,
 		return 0;
 
 	if (options->skiplist && object &&
-			sha1_array_lookup(options->skiplist, object->oid.hash) >= 0)
+			oid_array_lookup(options->skiplist, &object->oid) >= 0)
 		return 0;
 
 	if (msg_type == FSCK_FATAL)
diff --git a/fsck.h b/fsck.h
index 1891c1863b..4525510d99 100644
--- a/fsck.h
+++ b/fsck.h
@@ -34,7 +34,7 @@ struct fsck_options {
 	fsck_error error_func;
 	unsigned strict:1;
 	int *msg_type;
-	struct sha1_array *skiplist;
+	struct oid_array *skiplist;
 	struct decoration *object_names;
 };
 
diff --git a/hex.c b/hex.c
index eab7b626ee..28b44118cb 100644
--- a/hex.c
+++ b/hex.c
@@ -85,7 +85,7 @@ char *oid_to_hex_r(char *buffer, const struct object_id *oid)
 char *sha1_to_hex(const unsigned char *sha1)
 {
 	static int bufno;
-	static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
+	static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 	bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 	return sha1_to_hex_r(hexbuffer[bufno], sha1);
 }
diff --git a/parse-options-cb.c b/parse-options-cb.c
index b7d8f7dcb2..7419780a9b 100644
--- a/parse-options-cb.c
+++ b/parse-options-cb.c
@@ -96,17 +96,17 @@ int parse_opt_commits(const struct option *opt, const char *arg, int unset)
 
 int parse_opt_object_name(const struct option *opt, const char *arg, int unset)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 
 	if (unset) {
-		sha1_array_clear(opt->value);
+		oid_array_clear(opt->value);
 		return 0;
 	}
 	if (!arg)
 		return -1;
-	if (get_sha1(arg, sha1))
+	if (get_oid(arg, &oid))
 		return error(_("malformed object name '%s'"), arg);
-	sha1_array_append(opt->value, sha1);
+	oid_array_append(opt->value, &oid);
 	return 0;
 }
 
diff --git a/patch-ids.c b/patch-ids.c
index ce285c2e0c..fa8f11de82 100644
--- a/patch-ids.c
+++ b/patch-ids.c
@@ -71,7 +71,7 @@ static int init_patch_id_entry(struct patch_id *patch,
 			       struct commit *commit,
 			       struct patch_ids *ids)
 {
-	unsigned char header_only_patch_id[GIT_SHA1_RAWSZ];
+	unsigned char header_only_patch_id[GIT_MAX_RAWSZ];
 
 	patch->commit = commit;
 	if (commit_patch_id(commit, &ids->diffopts, header_only_patch_id, 1))
diff --git a/patch-ids.h b/patch-ids.h
index 0f34ea11ea..b9e5751f8e 100644
--- a/patch-ids.h
+++ b/patch-ids.h
@@ -3,7 +3,7 @@
 
 struct patch_id {
 	struct hashmap_entry ent;
-	unsigned char patch_id[GIT_SHA1_RAWSZ];
+	unsigned char patch_id[GIT_MAX_RAWSZ];
 	struct commit *commit;
 };
 
diff --git a/ref-filter.c b/ref-filter.c
index 1e39273005..3a640448fd 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1678,22 +1678,22 @@ static int filter_pattern_match(struct ref_filter *filter, const char *refname)
  * the need to parse the object via parse_object(). peel_ref() might be a
  * more efficient alternative to obtain the pointee.
  */
-static const unsigned char *match_points_at(struct sha1_array *points_at,
-					    const unsigned char *sha1,
-					    const char *refname)
+static const struct object_id *match_points_at(struct oid_array *points_at,
+					       const struct object_id *oid,
+					       const char *refname)
 {
-	const unsigned char *tagged_sha1 = NULL;
+	const struct object_id *tagged_oid = NULL;
 	struct object *obj;
 
-	if (sha1_array_lookup(points_at, sha1) >= 0)
-		return sha1;
-	obj = parse_object(sha1);
+	if (oid_array_lookup(points_at, oid) >= 0)
+		return oid;
+	obj = parse_object(oid->hash);
 	if (!obj)
 		die(_("malformed object at '%s'"), refname);
 	if (obj->type == OBJ_TAG)
-		tagged_sha1 = ((struct tag *)obj)->tagged->oid.hash;
-	if (tagged_sha1 && sha1_array_lookup(points_at, tagged_sha1) >= 0)
-		return tagged_sha1;
+		tagged_oid = &((struct tag *)obj)->tagged->oid;
+	if (tagged_oid && oid_array_lookup(points_at, tagged_oid) >= 0)
+		return tagged_oid;
 	return NULL;
 }
 
@@ -1773,7 +1773,7 @@ static int ref_filter_handler(const char *refname, const struct object_id *oid,
 	if (!filter_pattern_match(filter, refname))
 		return 0;
 
-	if (filter->points_at.nr && !match_points_at(&filter->points_at, oid->hash, refname))
+	if (filter->points_at.nr && !match_points_at(&filter->points_at, oid, refname))
 		return 0;
 
 	/*
diff --git a/ref-filter.h b/ref-filter.h
index dde40f6849..c20167aa3c 100644
--- a/ref-filter.h
+++ b/ref-filter.h
@@ -51,7 +51,7 @@ struct ref_array {
 
 struct ref_filter {
 	const char **name_patterns;
-	struct sha1_array points_at;
+	struct oid_array points_at;
 	struct commit_list *with_commit;
 	struct commit_list *no_commit;
 
diff --git a/remote-curl.c b/remote-curl.c
index e953d06f66..d41fe16ff3 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -167,7 +167,7 @@ struct discovery {
 	char *buf;
 	size_t len;
 	struct ref *refs;
-	struct sha1_array shallow;
+	struct oid_array shallow;
 	unsigned proto_git : 1;
 };
 static struct discovery *last_discovery;
@@ -234,7 +234,7 @@ static void free_discovery(struct discovery *d)
 	if (d) {
 		if (d == last_discovery)
 			last_discovery = NULL;
-		free(d->shallow.sha1);
+		free(d->shallow.oid);
 		free(d->buf_alloc);
 		free_refs(d->refs);
 		free(d);
diff --git a/remote.h b/remote.h
index d7992c4ef1..949badc4ee 100644
--- a/remote.h
+++ b/remote.h
@@ -149,11 +149,11 @@ int check_ref_type(const struct ref *ref, int flags);
  */
 void free_refs(struct ref *ref);
 
-struct sha1_array;
+struct oid_array;
 extern struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 				     struct ref **list, unsigned int flags,
-				     struct sha1_array *extra_have,
-				     struct sha1_array *shallow);
+				     struct oid_array *extra_have,
+				     struct oid_array *shallow);
 
 int resolve_remote_symref(struct ref *ref, struct ref *list);
 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid);
diff --git a/send-pack.c b/send-pack.c
index 66e652f7ef..78bb34ebec 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -50,7 +50,7 @@ static void feed_object(const unsigned char *sha1, FILE *fh, int negative)
 /*
  * Make a pack stream and spit it out into file descriptor fd
  */
-static int pack_objects(int fd, struct ref *refs, struct sha1_array *extra, struct send_pack_args *args)
+static int pack_objects(int fd, struct ref *refs, struct oid_array *extra, struct send_pack_args *args)
 {
 	/*
 	 * The child becomes pack-objects --revs; we feed
@@ -98,7 +98,7 @@ static int pack_objects(int fd, struct ref *refs, struct sha1_array *extra, stru
 	 */
 	po_in = xfdopen(po.in, "w");
 	for (i = 0; i < extra->nr; i++)
-		feed_object(extra->sha1[i], po_in, 1);
+		feed_object(extra->oid[i].hash, po_in, 1);
 
 	while (refs) {
 		if (!is_null_oid(&refs->old_oid))
@@ -376,7 +376,7 @@ static void reject_invalid_nonce(const char *nonce, int len)
 int send_pack(struct send_pack_args *args,
 	      int fd[], struct child_process *conn,
 	      struct ref *remote_refs,
-	      struct sha1_array *extra_have)
+	      struct oid_array *extra_have)
 {
 	int in = fd[0];
 	int out = fd[1];
diff --git a/send-pack.h b/send-pack.h
index 67fc40f4ec..6af71f7008 100644
--- a/send-pack.h
+++ b/send-pack.h
@@ -32,6 +32,6 @@ int option_parse_push_signed(const struct option *opt,
 
 int send_pack(struct send_pack_args *args,
 	      int fd[], struct child_process *conn,
-	      struct ref *remote_refs, struct sha1_array *extra_have);
+	      struct ref *remote_refs, struct oid_array *extra_have);
 
 #endif
diff --git a/sha1-array.c b/sha1-array.c
index c1cc25cd95..7d646ab5b8 100644
--- a/sha1-array.c
+++ b/sha1-array.c
@@ -2,60 +2,60 @@
 #include "sha1-array.h"
 #include "sha1-lookup.h"
 
-void sha1_array_append(struct sha1_array *array, const unsigned char *sha1)
+void oid_array_append(struct oid_array *array, const struct object_id *oid)
 {
-	ALLOC_GROW(array->sha1, array->nr + 1, array->alloc);
-	hashcpy(array->sha1[array->nr++], sha1);
+	ALLOC_GROW(array->oid, array->nr + 1, array->alloc);
+	oidcpy(&array->oid[array->nr++], oid);
 	array->sorted = 0;
 }
 
 static int void_hashcmp(const void *a, const void *b)
 {
-	return hashcmp(a, b);
+	return oidcmp(a, b);
 }
 
-static void sha1_array_sort(struct sha1_array *array)
+static void oid_array_sort(struct oid_array *array)
 {
-	QSORT(array->sha1, array->nr, void_hashcmp);
+	QSORT(array->oid, array->nr, void_hashcmp);
 	array->sorted = 1;
 }
 
 static const unsigned char *sha1_access(size_t index, void *table)
 {
-	unsigned char (*array)[20] = table;
-	return array[index];
+	struct object_id *array = table;
+	return array[index].hash;
 }
 
-int sha1_array_lookup(struct sha1_array *array, const unsigned char *sha1)
+int oid_array_lookup(struct oid_array *array, const struct object_id *oid)
 {
 	if (!array->sorted)
-		sha1_array_sort(array);
-	return sha1_pos(sha1, array->sha1, array->nr, sha1_access);
+		oid_array_sort(array);
+	return sha1_pos(oid->hash, array->oid, array->nr, sha1_access);
 }
 
-void sha1_array_clear(struct sha1_array *array)
+void oid_array_clear(struct oid_array *array)
 {
-	free(array->sha1);
-	array->sha1 = NULL;
+	free(array->oid);
+	array->oid = NULL;
 	array->nr = 0;
 	array->alloc = 0;
 	array->sorted = 0;
 }
 
-int sha1_array_for_each_unique(struct sha1_array *array,
-				for_each_sha1_fn fn,
+int oid_array_for_each_unique(struct oid_array *array,
+				for_each_oid_fn fn,
 				void *data)
 {
 	int i;
 
 	if (!array->sorted)
-		sha1_array_sort(array);
+		oid_array_sort(array);
 
 	for (i = 0; i < array->nr; i++) {
 		int ret;
-		if (i > 0 && !hashcmp(array->sha1[i], array->sha1[i-1]))
+		if (i > 0 && !oidcmp(array->oid + i, array->oid + i - 1))
 			continue;
-		ret = fn(array->sha1[i], data);
+		ret = fn(array->oid + i, data);
 		if (ret)
 			return ret;
 	}
diff --git a/sha1-array.h b/sha1-array.h
index b3230be0dd..04b0756334 100644
--- a/sha1-array.h
+++ b/sha1-array.h
@@ -1,23 +1,23 @@
 #ifndef SHA1_ARRAY_H
 #define SHA1_ARRAY_H
 
-struct sha1_array {
-	unsigned char (*sha1)[20];
+struct oid_array {
+	struct object_id *oid;
 	int nr;
 	int alloc;
 	int sorted;
 };
 
-#define SHA1_ARRAY_INIT { NULL, 0, 0, 0 }
+#define OID_ARRAY_INIT { NULL, 0, 0, 0 }
 
-void sha1_array_append(struct sha1_array *array, const unsigned char *sha1);
-int sha1_array_lookup(struct sha1_array *array, const unsigned char *sha1);
-void sha1_array_clear(struct sha1_array *array);
+void oid_array_append(struct oid_array *array, const struct object_id *oid);
+int oid_array_lookup(struct oid_array *array, const struct object_id *oid);
+void oid_array_clear(struct oid_array *array);
 
-typedef int (*for_each_sha1_fn)(const unsigned char sha1[20],
-				void *data);
-int sha1_array_for_each_unique(struct sha1_array *array,
-			       for_each_sha1_fn fn,
+typedef int (*for_each_oid_fn)(const struct object_id *oid,
+			       void *data);
+int oid_array_for_each_unique(struct oid_array *array,
+			       for_each_oid_fn fn,
 			       void *data);
 
 #endif /* SHA1_ARRAY_H */
diff --git a/sha1_file.c b/sha1_file.c
index 7369f7495a..2270f36a2b 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1606,7 +1606,7 @@ static void mark_bad_packed_object(struct packed_git *p,
 		if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
 			return;
 	p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
-				      st_mult(GIT_SHA1_RAWSZ,
+				      st_mult(GIT_MAX_RAWSZ,
 					      st_add(p->num_bad_objects, 1)));
 	hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
 	p->num_bad_objects++;
@@ -3759,7 +3759,7 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
 		strbuf_addf(path, "/%s", de->d_name);
 
 		if (strlen(de->d_name) == GIT_SHA1_HEXSZ - 2)  {
-			char hex[GIT_SHA1_HEXSZ+1];
+			char hex[GIT_MAX_HEXSZ+1];
 			struct object_id oid;
 
 			xsnprintf(hex, sizeof(hex), "%02x%s",
@@ -3913,7 +3913,7 @@ static int check_stream_sha1(git_zstream *stream,
 			     const unsigned char *expected_sha1)
 {
 	git_SHA_CTX c;
-	unsigned char real_sha1[GIT_SHA1_RAWSZ];
+	unsigned char real_sha1[GIT_MAX_RAWSZ];
 	unsigned char buf[4096];
 	unsigned long total_read;
 	int status = Z_OK;
diff --git a/sha1_name.c b/sha1_name.c
index d9d1b2fce8..8eec9f7c1b 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -11,16 +11,16 @@
 
 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
 
-typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
+typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
 
 struct disambiguate_state {
 	int len; /* length of prefix in hex chars */
-	char hex_pfx[GIT_SHA1_HEXSZ + 1];
-	unsigned char bin_pfx[GIT_SHA1_RAWSZ];
+	char hex_pfx[GIT_MAX_HEXSZ + 1];
+	struct object_id bin_pfx;
 
 	disambiguate_hint_fn fn;
 	void *cb_data;
-	unsigned char candidate[GIT_SHA1_RAWSZ];
+	struct object_id candidate;
 	unsigned candidate_exists:1;
 	unsigned candidate_checked:1;
 	unsigned candidate_ok:1;
@@ -29,7 +29,7 @@ struct disambiguate_state {
 	unsigned always_call_fn:1;
 };
 
-static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
+static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
 {
 	if (ds->always_call_fn) {
 		ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
@@ -37,10 +37,10 @@ static void update_candidates(struct disambiguate_state *ds, const unsigned char
 	}
 	if (!ds->candidate_exists) {
 		/* this is the first candidate */
-		hashcpy(ds->candidate, current);
+		oidcpy(&ds->candidate, current);
 		ds->candidate_exists = 1;
 		return;
-	} else if (!hashcmp(ds->candidate, current)) {
+	} else if (!oidcmp(&ds->candidate, current)) {
 		/* the same as what we already have seen */
 		return;
 	}
@@ -52,14 +52,14 @@ static void update_candidates(struct disambiguate_state *ds, const unsigned char
 	}
 
 	if (!ds->candidate_checked) {
-		ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
+		ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
 		ds->disambiguate_fn_used = 1;
 		ds->candidate_checked = 1;
 	}
 
 	if (!ds->candidate_ok) {
 		/* discard the candidate; we know it does not satisfy fn */
-		hashcpy(ds->candidate, current);
+		oidcpy(&ds->candidate, current);
 		ds->candidate_checked = 0;
 		return;
 	}
@@ -80,7 +80,7 @@ static void update_candidates(struct disambiguate_state *ds, const unsigned char
 static void find_short_object_filename(struct disambiguate_state *ds)
 {
 	struct alternate_object_database *alt;
-	char hex[GIT_SHA1_HEXSZ];
+	char hex[GIT_MAX_HEXSZ];
 	static struct alternate_object_database *fakeent;
 
 	if (!fakeent) {
@@ -107,15 +107,15 @@ static void find_short_object_filename(struct disambiguate_state *ds)
 			continue;
 
 		while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
-			unsigned char sha1[20];
+			struct object_id oid;
 
-			if (strlen(de->d_name) != 38)
+			if (strlen(de->d_name) != GIT_SHA1_HEXSZ - 2)
 				continue;
 			if (memcmp(de->d_name, ds->hex_pfx + 2, ds->len - 2))
 				continue;
-			memcpy(hex + 2, de->d_name, 38);
-			if (!get_sha1_hex(hex, sha1))
-				update_candidates(ds, sha1);
+			memcpy(hex + 2, de->d_name, GIT_SHA1_HEXSZ - 2);
+			if (!get_oid_hex(hex, &oid))
+				update_candidates(ds, &oid);
 		}
 		closedir(dir);
 	}
@@ -140,7 +140,7 @@ static void unique_in_pack(struct packed_git *p,
 			   struct disambiguate_state *ds)
 {
 	uint32_t num, last, i, first = 0;
-	const unsigned char *current = NULL;
+	const struct object_id *current = NULL;
 
 	open_pack_index(p);
 	num = p->num_objects;
@@ -151,7 +151,7 @@ static void unique_in_pack(struct packed_git *p,
 		int cmp;
 
 		current = nth_packed_object_sha1(p, mid);
-		cmp = hashcmp(ds->bin_pfx, current);
+		cmp = hashcmp(ds->bin_pfx.hash, current);
 		if (!cmp) {
 			first = mid;
 			break;
@@ -169,8 +169,9 @@ static void unique_in_pack(struct packed_git *p,
 	 * 0, 1 or more objects that actually match(es).
 	 */
 	for (i = first; i < num && !ds->ambiguous; i++) {
-		current = nth_packed_object_sha1(p, i);
-		if (!match_sha(ds->len, ds->bin_pfx, current))
+		struct object_id oid;
+		current = nth_packed_object_oid(&oid, p, i);
+		if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 			break;
 		update_candidates(ds, current);
 	}
@@ -213,66 +214,66 @@ static int finish_object_disambiguation(struct disambiguate_state *ds,
 		 * same repository!
 		 */
 		ds->candidate_ok = (!ds->disambiguate_fn_used ||
-				    ds->fn(ds->candidate, ds->cb_data));
+				    ds->fn(&ds->candidate, ds->cb_data));
 
 	if (!ds->candidate_ok)
 		return SHORT_NAME_AMBIGUOUS;
 
-	hashcpy(sha1, ds->candidate);
+	hashcpy(sha1, ds->candidate.hash);
 	return 0;
 }
 
-static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
+static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(sha1, NULL);
+	int kind = sha1_object_info(oid->hash, NULL);
 	return kind == OBJ_COMMIT;
 }
 
-static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
+static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 {
 	struct object *obj;
 	int kind;
 
-	kind = sha1_object_info(sha1, NULL);
+	kind = sha1_object_info(oid->hash, NULL);
 	if (kind == OBJ_COMMIT)
 		return 1;
 	if (kind != OBJ_TAG)
 		return 0;
 
 	/* We need to do this the hard way... */
-	obj = deref_tag(parse_object(sha1), NULL, 0);
+	obj = deref_tag(parse_object(oid->hash), NULL, 0);
 	if (obj && obj->type == OBJ_COMMIT)
 		return 1;
 	return 0;
 }
 
-static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
+static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(sha1, NULL);
+	int kind = sha1_object_info(oid->hash, NULL);
 	return kind == OBJ_TREE;
 }
 
-static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
+static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 {
 	struct object *obj;
 	int kind;
 
-	kind = sha1_object_info(sha1, NULL);
+	kind = sha1_object_info(oid->hash, NULL);
 	if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 		return 1;
 	if (kind != OBJ_TAG)
 		return 0;
 
 	/* We need to do this the hard way... */
-	obj = deref_tag(parse_object(sha1), NULL, 0);
+	obj = deref_tag(parse_object(oid->hash), NULL, 0);
 	if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 		return 1;
 	return 0;
 }
 
-static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
+static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 {
-	int kind = sha1_object_info(sha1, NULL);
+	int kind = sha1_object_info(oid->hash, NULL);
 	return kind == OBJ_BLOB;
 }
 
@@ -332,7 +333,7 @@ static int init_object_disambiguation(const char *name, int len,
 		ds->hex_pfx[i] = c;
 		if (!(i & 1))
 			val <<= 4;
-		ds->bin_pfx[i >> 1] |= val;
+		ds->bin_pfx.hash[i >> 1] |= val;
 	}
 
 	ds->len = len;
@@ -341,31 +342,32 @@ static int init_object_disambiguation(const char *name, int len,
 	return 0;
 }
 
-static int show_ambiguous_object(const unsigned char *sha1, void *data)
+static int show_ambiguous_object(const struct object_id *oid, void *data)
 {
 	const struct disambiguate_state *ds = data;
 	struct strbuf desc = STRBUF_INIT;
 	int type;
 
-	if (ds->fn && !ds->fn(sha1, ds->cb_data))
+
+	if (ds->fn && !ds->fn(oid, ds->cb_data))
 		return 0;
 
-	type = sha1_object_info(sha1, NULL);
+	type = sha1_object_info(oid->hash, NULL);
 	if (type == OBJ_COMMIT) {
-		struct commit *commit = lookup_commit(sha1);
+		struct commit *commit = lookup_commit(oid->hash);
 		if (commit) {
 			struct pretty_print_context pp = {0};
 			pp.date_mode.type = DATE_SHORT;
 			format_commit_message(commit, " %ad - %s", &desc, &pp);
 		}
 	} else if (type == OBJ_TAG) {
-		struct tag *tag = lookup_tag(sha1);
+		struct tag *tag = lookup_tag(oid->hash);
 		if (!parse_tag(tag) && tag->tag)
 			strbuf_addf(&desc, " %s", tag->tag);
 	}
 
 	advise("  %s %s%s",
-	       find_unique_abbrev(sha1, DEFAULT_ABBREV),
+	       find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
 	       typename(type) ? typename(type) : "unknown type",
 	       desc.buf);
 
@@ -422,15 +424,15 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 	return status;
 }
 
-static int collect_ambiguous(const unsigned char *sha1, void *data)
+static int collect_ambiguous(const struct object_id *oid, void *data)
 {
-	sha1_array_append(data, sha1);
+	oid_array_append(data, oid);
 	return 0;
 }
 
 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 {
-	struct sha1_array collect = SHA1_ARRAY_INIT;
+	struct oid_array collect = OID_ARRAY_INIT;
 	struct disambiguate_state ds;
 	int ret;
 
@@ -443,8 +445,8 @@ int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 	find_short_object_filename(&ds);
 	find_short_packed_object(&ds);
 
-	ret = sha1_array_for_each_unique(&collect, fn, cb_data);
-	sha1_array_clear(&collect);
+	ret = oid_array_for_each_unique(&collect, fn, cb_data);
+	oid_array_clear(&collect);
 	return ret;
 }
 
@@ -509,7 +511,7 @@ int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 {
 	static int bufno;
-	static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
+	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);
diff --git a/shallow.c b/shallow.c
index 11f7dde9d9..25b6db989b 100644
--- a/shallow.c
+++ b/shallow.c
@@ -260,7 +260,7 @@ static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
 }
 
 static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
-				   const struct sha1_array *extra,
+				   const struct oid_array *extra,
 				   unsigned flags)
 {
 	struct write_shallow_data data;
@@ -273,7 +273,7 @@ static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
 	if (!extra)
 		return data.count;
 	for (i = 0; i < extra->nr; i++) {
-		strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
+		strbuf_addstr(out, oid_to_hex(extra->oid + i));
 		strbuf_addch(out, '\n');
 		data.count++;
 	}
@@ -281,14 +281,14 @@ static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
 }
 
 int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
-			  const struct sha1_array *extra)
+			  const struct oid_array *extra)
 {
 	return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
 }
 
 static struct tempfile temporary_shallow;
 
-const char *setup_temporary_shallow(const struct sha1_array *extra)
+const char *setup_temporary_shallow(const struct oid_array *extra)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int fd;
@@ -312,7 +312,7 @@ const char *setup_temporary_shallow(const struct sha1_array *extra)
 
 void setup_alternate_shallow(struct lock_file *shallow_lock,
 			     const char **alternate_shallow_file,
-			     const struct sha1_array *extra)
+			     const struct oid_array *extra)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int fd;
@@ -385,7 +385,7 @@ struct trace_key trace_shallow = TRACE_KEY_INIT(SHALLOW);
  * Step 1, split sender shallow commits into "ours" and "theirs"
  * Step 2, clean "ours" based on .git/shallow
  */
-void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
+void prepare_shallow_info(struct shallow_info *info, struct oid_array *sa)
 {
 	int i;
 	trace_printf_key(&trace_shallow, "shallow: prepare_shallow_info\n");
@@ -396,9 +396,9 @@ void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
 	ALLOC_ARRAY(info->ours, sa->nr);
 	ALLOC_ARRAY(info->theirs, sa->nr);
 	for (i = 0; i < sa->nr; i++) {
-		if (has_sha1_file(sa->sha1[i])) {
+		if (has_object_file(sa->oid + i)) {
 			struct commit_graft *graft;
-			graft = lookup_commit_graft(sa->sha1[i]);
+			graft = lookup_commit_graft(sa->oid[i].hash);
 			if (graft && graft->nr_parent < 0)
 				continue;
 			info->ours[info->nr_ours++] = i;
@@ -417,13 +417,13 @@ void clear_shallow_info(struct shallow_info *info)
 
 void remove_nonexistent_theirs_shallow(struct shallow_info *info)
 {
-	unsigned char (*sha1)[20] = info->shallow->sha1;
+	struct object_id *oid = info->shallow->oid;
 	int i, dst;
 	trace_printf_key(&trace_shallow, "shallow: remove_nonexistent_theirs_shallow\n");
 	for (i = dst = 0; i < info->nr_theirs; i++) {
 		if (i != dst)
 			info->theirs[dst] = info->theirs[i];
-		if (has_sha1_file(sha1[info->theirs[i]]))
+		if (has_object_file(oid + info->theirs[i]))
 			dst++;
 	}
 	info->nr_theirs = dst;
@@ -559,8 +559,8 @@ static void post_assign_shallow(struct shallow_info *info,
 void assign_shallow_commits_to_refs(struct shallow_info *info,
 				    uint32_t **used, int *ref_status)
 {
-	unsigned char (*sha1)[20] = info->shallow->sha1;
-	struct sha1_array *ref = info->ref;
+	struct object_id *oid = info->shallow->oid;
+	struct oid_array *ref = info->ref;
 	unsigned int i, nr;
 	int *shallow, nr_shallow = 0;
 	struct paint_info pi;
@@ -599,18 +599,18 @@ void assign_shallow_commits_to_refs(struct shallow_info *info,
 
 	/* Mark potential bottoms so we won't go out of bound */
 	for (i = 0; i < nr_shallow; i++) {
-		struct commit *c = lookup_commit(sha1[shallow[i]]);
+		struct commit *c = lookup_commit(oid[shallow[i]].hash);
 		c->object.flags |= BOTTOM;
 	}
 
 	for (i = 0; i < ref->nr; i++)
-		paint_down(&pi, ref->sha1[i], i);
+		paint_down(&pi, ref->oid[i].hash, i);
 
 	if (used) {
 		int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
 		memset(used, 0, sizeof(*used) * info->shallow->nr);
 		for (i = 0; i < nr_shallow; i++) {
-			const struct commit *c = lookup_commit(sha1[shallow[i]]);
+			const struct commit *c = lookup_commit(oid[shallow[i]].hash);
 			uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
 			if (*map)
 				used[shallow[i]] = xmemdupz(*map, bitmap_size);
@@ -664,7 +664,7 @@ static void post_assign_shallow(struct shallow_info *info,
 				struct ref_bitmap *ref_bitmap,
 				int *ref_status)
 {
-	unsigned char (*sha1)[20] = info->shallow->sha1;
+	struct object_id *oid = info->shallow->oid;
 	struct commit *c;
 	uint32_t **bitmap;
 	int dst, i, j;
@@ -679,7 +679,7 @@ static void post_assign_shallow(struct shallow_info *info,
 	for (i = dst = 0; i < info->nr_theirs; i++) {
 		if (i != dst)
 			info->theirs[dst] = info->theirs[i];
-		c = lookup_commit(sha1[info->theirs[i]]);
+		c = lookup_commit(oid[info->theirs[i]].hash);
 		bitmap = ref_bitmap_at(ref_bitmap, c);
 		if (!*bitmap)
 			continue;
@@ -700,7 +700,7 @@ static void post_assign_shallow(struct shallow_info *info,
 	for (i = dst = 0; i < info->nr_ours; i++) {
 		if (i != dst)
 			info->ours[dst] = info->ours[i];
-		c = lookup_commit(sha1[info->ours[i]]);
+		c = lookup_commit(oid[info->ours[i]].hash);
 		bitmap = ref_bitmap_at(ref_bitmap, c);
 		if (!*bitmap)
 			continue;
@@ -722,7 +722,7 @@ static void post_assign_shallow(struct shallow_info *info,
 int delayed_reachability_test(struct shallow_info *si, int c)
 {
 	if (si->need_reachability_test[c]) {
-		struct commit *commit = lookup_commit(si->shallow->sha1[c]);
+		struct commit *commit = lookup_commit(si->shallow->oid[c].hash);
 
 		if (!si->commits) {
 			struct commit_array ca;
diff --git a/submodule.c b/submodule.c
index 2ee9705729..6368d5fa6a 100644
--- a/submodule.c
+++ b/submodule.c
@@ -21,8 +21,8 @@ static int config_update_recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
 static int parallel_jobs = 1;
 static struct string_list changed_submodule_paths = STRING_LIST_INIT_NODUP;
 static int initialized_fetch_ref_tips;
-static struct sha1_array ref_tips_before_fetch;
-static struct sha1_array ref_tips_after_fetch;
+static struct oid_array ref_tips_before_fetch;
+static struct oid_array ref_tips_after_fetch;
 
 /*
  * The following flag is set if the .gitmodules file is unmerged. We then
@@ -622,35 +622,35 @@ static int has_remote(const char *refname, const struct object_id *oid,
 	return 1;
 }
 
-static int append_sha1_to_argv(const unsigned char sha1[20], void *data)
+static int append_oid_to_argv(const struct object_id *oid, void *data)
 {
 	struct argv_array *argv = data;
-	argv_array_push(argv, sha1_to_hex(sha1));
+	argv_array_push(argv, oid_to_hex(oid));
 	return 0;
 }
 
-static int check_has_commit(const unsigned char sha1[20], void *data)
+static int check_has_commit(const struct object_id *oid, void *data)
 {
 	int *has_commit = data;
 
-	if (!lookup_commit_reference(sha1))
+	if (!lookup_commit_reference(oid->hash))
 		*has_commit = 0;
 
 	return 0;
 }
 
-static int submodule_has_commits(const char *path, struct sha1_array *commits)
+static int submodule_has_commits(const char *path, struct oid_array *commits)
 {
 	int has_commit = 1;
 
 	if (add_submodule_odb(path))
 		return 0;
 
-	sha1_array_for_each_unique(commits, check_has_commit, &has_commit);
+	oid_array_for_each_unique(commits, check_has_commit, &has_commit);
 	return has_commit;
 }
 
-static int submodule_needs_pushing(const char *path, struct sha1_array *commits)
+static int submodule_needs_pushing(const char *path, struct oid_array *commits)
 {
 	if (!submodule_has_commits(path, commits))
 		/*
@@ -672,7 +672,7 @@ static int submodule_needs_pushing(const char *path, struct sha1_array *commits)
 		int needs_pushing = 0;
 
 		argv_array_push(&cp.args, "rev-list");
-		sha1_array_for_each_unique(commits, append_sha1_to_argv, &cp.args);
+		oid_array_for_each_unique(commits, append_oid_to_argv, &cp.args);
 		argv_array_pushl(&cp.args, "--not", "--remotes", "-n", "1" , NULL);
 
 		prepare_submodule_repo_env(&cp.env_array);
@@ -694,18 +694,18 @@ static int submodule_needs_pushing(const char *path, struct sha1_array *commits)
 	return 0;
 }
 
-static struct sha1_array *submodule_commits(struct string_list *submodules,
+static struct oid_array *submodule_commits(struct string_list *submodules,
 					    const char *path)
 {
 	struct string_list_item *item;
 
 	item = string_list_insert(submodules, path);
 	if (item->util)
-		return (struct sha1_array *) item->util;
+		return (struct oid_array *) item->util;
 
-	/* NEEDSWORK: should we have sha1_array_init()? */
-	item->util = xcalloc(1, sizeof(struct sha1_array));
-	return (struct sha1_array *) item->util;
+	/* NEEDSWORK: should we have oid_array_init()? */
+	item->util = xcalloc(1, sizeof(struct oid_array));
+	return (struct oid_array *) item->util;
 }
 
 static void collect_submodules_from_diff(struct diff_queue_struct *q,
@@ -717,11 +717,11 @@ static void collect_submodules_from_diff(struct diff_queue_struct *q,
 
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
-		struct sha1_array *commits;
+		struct oid_array *commits;
 		if (!S_ISGITLINK(p->two->mode))
 			continue;
 		commits = submodule_commits(submodules, p->two->path);
-		sha1_array_append(commits, p->two->oid.hash);
+		oid_array_append(commits, &p->two->oid);
 	}
 }
 
@@ -741,11 +741,11 @@ static void free_submodules_sha1s(struct string_list *submodules)
 {
 	struct string_list_item *item;
 	for_each_string_list_item(item, submodules)
-		sha1_array_clear((struct sha1_array *) item->util);
+		oid_array_clear((struct oid_array *) item->util);
 	string_list_clear(submodules, 1);
 }
 
-int find_unpushed_submodules(struct sha1_array *commits,
+int find_unpushed_submodules(struct oid_array *commits,
 		const char *remotes_name, struct string_list *needs_pushing)
 {
 	struct rev_info rev;
@@ -758,7 +758,7 @@ int find_unpushed_submodules(struct sha1_array *commits,
 
 	/* argv.argv[0] will be ignored by setup_revisions */
 	argv_array_push(&argv, "find_unpushed_submodules");
-	sha1_array_for_each_unique(commits, append_sha1_to_argv, &argv);
+	oid_array_for_each_unique(commits, append_oid_to_argv, &argv);
 	argv_array_push(&argv, "--not");
 	argv_array_pushf(&argv, "--remotes=%s", remotes_name);
 
@@ -773,7 +773,7 @@ int find_unpushed_submodules(struct sha1_array *commits,
 	argv_array_clear(&argv);
 
 	for_each_string_list_item(submodule, &submodules) {
-		struct sha1_array *commits = (struct sha1_array *) submodule->util;
+		struct oid_array *commits = (struct oid_array *) submodule->util;
 
 		if (submodule_needs_pushing(submodule->string, commits))
 			string_list_insert(needs_pushing, submodule->string);
@@ -806,7 +806,7 @@ static int push_submodule(const char *path, int dry_run)
 	return 1;
 }
 
-int push_unpushed_submodules(struct sha1_array *commits,
+int push_unpushed_submodules(struct oid_array *commits,
 			     const char *remotes_name,
 			     int dry_run)
 {
@@ -888,23 +888,23 @@ static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 static int add_sha1_to_array(const char *ref, const struct object_id *oid,
 			     int flags, void *data)
 {
-	sha1_array_append(data, oid->hash);
+	oid_array_append(data, oid);
 	return 0;
 }
 
-void check_for_new_submodule_commits(unsigned char new_sha1[20])
+void check_for_new_submodule_commits(struct object_id *oid)
 {
 	if (!initialized_fetch_ref_tips) {
 		for_each_ref(add_sha1_to_array, &ref_tips_before_fetch);
 		initialized_fetch_ref_tips = 1;
 	}
 
-	sha1_array_append(&ref_tips_after_fetch, new_sha1);
+	oid_array_append(&ref_tips_after_fetch, oid);
 }
 
-static int add_sha1_to_argv(const unsigned char sha1[20], void *data)
+static int add_oid_to_argv(const struct object_id *oid, void *data)
 {
-	argv_array_push(data, sha1_to_hex(sha1));
+	argv_array_push(data, oid_to_hex(oid));
 	return 0;
 }
 
@@ -920,11 +920,11 @@ static void calculate_changed_submodule_paths(void)
 
 	init_revisions(&rev, NULL);
 	argv_array_push(&argv, "--"); /* argv[0] program name */
-	sha1_array_for_each_unique(&ref_tips_after_fetch,
-				   add_sha1_to_argv, &argv);
+	oid_array_for_each_unique(&ref_tips_after_fetch,
+				   add_oid_to_argv, &argv);
 	argv_array_push(&argv, "--not");
-	sha1_array_for_each_unique(&ref_tips_before_fetch,
-				   add_sha1_to_argv, &argv);
+	oid_array_for_each_unique(&ref_tips_before_fetch,
+				   add_oid_to_argv, &argv);
 	setup_revisions(argv.argc, argv.argv, &rev, NULL);
 	if (prepare_revision_walk(&rev))
 		die("revision walk setup failed");
@@ -950,8 +950,8 @@ static void calculate_changed_submodule_paths(void)
 	}
 
 	argv_array_clear(&argv);
-	sha1_array_clear(&ref_tips_before_fetch);
-	sha1_array_clear(&ref_tips_after_fetch);
+	oid_array_clear(&ref_tips_before_fetch);
+	oid_array_clear(&ref_tips_after_fetch);
 	initialized_fetch_ref_tips = 0;
 }
 
diff --git a/submodule.h b/submodule.h
index 8a8bc49dc9..a86f757a06 100644
--- a/submodule.h
+++ b/submodule.h
@@ -3,7 +3,7 @@
 
 struct diff_options;
 struct argv_array;
-struct sha1_array;
+struct oid_array;
 
 enum {
 	RECURSE_SUBMODULES_ONLY = -5,
@@ -72,7 +72,7 @@ extern int should_update_submodules(void);
  * and it should be updated. Returns NULL otherwise.
  */
 extern const struct submodule *submodule_from_ce(const struct cache_entry *ce);
-extern void check_for_new_submodule_commits(unsigned char new_sha1[20]);
+extern void check_for_new_submodule_commits(struct object_id *oid);
 extern int fetch_populated_submodules(const struct argv_array *options,
 			       const char *prefix, int command_line_option,
 			       int quiet, int max_parallel_jobs);
@@ -87,10 +87,10 @@ extern int merge_submodule(unsigned char result[20], const char *path,
 			   const unsigned char base[20],
 			   const unsigned char a[20],
 			   const unsigned char b[20], int search);
-extern int find_unpushed_submodules(struct sha1_array *commits,
+extern int find_unpushed_submodules(struct oid_array *commits,
 				    const char *remotes_name,
 				    struct string_list *needs_pushing);
-extern int push_unpushed_submodules(struct sha1_array *commits,
+extern int push_unpushed_submodules(struct oid_array *commits,
 				    const char *remotes_name,
 				    int dry_run);
 extern void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir);
diff --git a/t/helper/test-sha1-array.c b/t/helper/test-sha1-array.c
index f7a53c4ad6..edfd52d82a 100644
--- a/t/helper/test-sha1-array.c
+++ b/t/helper/test-sha1-array.c
@@ -1,33 +1,33 @@
 #include "cache.h"
 #include "sha1-array.h"
 
-static int print_sha1(const unsigned char sha1[20], void *data)
+static int print_oid(const struct object_id *oid, void *data)
 {
-	puts(sha1_to_hex(sha1));
+	puts(oid_to_hex(oid));
 	return 0;
 }
 
 int cmd_main(int argc, const char **argv)
 {
-	struct sha1_array array = SHA1_ARRAY_INIT;
+	struct oid_array array = OID_ARRAY_INIT;
 	struct strbuf line = STRBUF_INIT;
 
 	while (strbuf_getline(&line, stdin) != EOF) {
 		const char *arg;
-		unsigned char sha1[20];
+		struct object_id oid;
 
 		if (skip_prefix(line.buf, "append ", &arg)) {
-			if (get_sha1_hex(arg, sha1))
+			if (get_oid_hex(arg, &oid))
 				die("not a hexadecimal SHA1: %s", arg);
-			sha1_array_append(&array, sha1);
+			oid_array_append(&array, &oid);
 		} else if (skip_prefix(line.buf, "lookup ", &arg)) {
-			if (get_sha1_hex(arg, sha1))
+			if (get_oid_hex(arg, &oid))
 				die("not a hexadecimal SHA1: %s", arg);
-			printf("%d\n", sha1_array_lookup(&array, sha1));
+			printf("%d\n", oid_array_lookup(&array, &oid));
 		} else if (!strcmp(line.buf, "clear"))
-			sha1_array_clear(&array);
+			oid_array_clear(&array);
 		else if (!strcmp(line.buf, "for_each_unique"))
-			sha1_array_for_each_unique(&array, print_sha1, NULL);
+			oid_array_for_each_unique(&array, print_oid, NULL);
 		else
 			die("unknown command: %s", line.buf);
 	}
diff --git a/transport.c b/transport.c
index 417ed7f19f..c83f3b71be 100644
--- a/transport.c
+++ b/transport.c
@@ -116,8 +116,8 @@ struct git_transport_data {
 	struct child_process *conn;
 	int fd[2];
 	unsigned got_remote_heads : 1;
-	struct sha1_array extra_have;
-	struct sha1_array shallow;
+	struct oid_array extra_have;
+	struct oid_array shallow;
 };
 
 static int set_git_option(struct git_transport_options *opts,
@@ -447,7 +447,7 @@ static int print_one_push_status(struct ref *ref, const char *dest, int count,
 
 static int measure_abbrev(const struct object_id *oid, int sofar)
 {
-	char hex[GIT_SHA1_HEXSZ + 1];
+	char hex[GIT_MAX_HEXSZ + 1];
 	int w = find_unique_abbrev_r(hex, oid->hash, DEFAULT_ABBREV);
 
 	return (w < sofar) ? sofar : w;
@@ -1023,19 +1023,20 @@ int transport_push(struct transport *transport,
 			      TRANSPORT_RECURSE_SUBMODULES_ONLY)) &&
 		    !is_bare_repository()) {
 			struct ref *ref = remote_refs;
-			struct sha1_array commits = SHA1_ARRAY_INIT;
+			struct oid_array commits = OID_ARRAY_INIT;
 
 			for (; ref; ref = ref->next)
 				if (!is_null_oid(&ref->new_oid))
-					sha1_array_append(&commits, ref->new_oid.hash);
+					oid_array_append(&commits,
+							  &ref->new_oid);
 
 			if (!push_unpushed_submodules(&commits,
 						      transport->remote->name,
 						      pretend)) {
-				sha1_array_clear(&commits);
+				oid_array_clear(&commits);
 				die("Failed to push all needed submodules!");
 			}
-			sha1_array_clear(&commits);
+			oid_array_clear(&commits);
 		}
 
 		if (((flags & TRANSPORT_RECURSE_SUBMODULES_CHECK) ||
@@ -1044,19 +1045,20 @@ int transport_push(struct transport *transport,
 		      !pretend)) && !is_bare_repository()) {
 			struct ref *ref = remote_refs;
 			struct string_list needs_pushing = STRING_LIST_INIT_DUP;
-			struct sha1_array commits = SHA1_ARRAY_INIT;
+			struct oid_array commits = OID_ARRAY_INIT;
 
 			for (; ref; ref = ref->next)
 				if (!is_null_oid(&ref->new_oid))
-					sha1_array_append(&commits, ref->new_oid.hash);
+					oid_array_append(&commits,
+							  &ref->new_oid);
 
 			if (find_unpushed_submodules(&commits, transport->remote->name,
 						&needs_pushing)) {
-				sha1_array_clear(&commits);
+				oid_array_clear(&commits);
 				die_with_unpushed_submodules(&needs_pushing);
 			}
 			string_list_clear(&needs_pushing, 0);
-			sha1_array_clear(&commits);
+			oid_array_clear(&commits);
 		}
 
 		if (!(flags & TRANSPORT_RECURSE_SUBMODULES_ONLY))
diff --git a/wt-status.h b/wt-status.h
index 54fec77032..6018c627b1 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -80,7 +80,7 @@ struct wt_status {
 	int hints;
 
 	enum wt_status_format status_format;
-	unsigned char sha1_commit[GIT_SHA1_RAWSZ]; /* when not Initial */
+	unsigned char sha1_commit[GIT_MAX_RAWSZ]; /* when not Initial */
 
 	/* These are computed during processing of the individual sections */
 	int commitable;