Merge branch 'bc/object-id'

Conversion from uchar[20] to struct object_id continues.

* bc/object-id: (25 commits)
  refs/files-backend: convert static functions to object_id
  refs: convert read_raw_ref backends to struct object_id
  refs: convert peel_object to struct object_id
  refs: convert resolve_ref_unsafe to struct object_id
  worktree: convert struct worktree to object_id
  refs: convert resolve_gitlink_ref to struct object_id
  Convert remaining callers of resolve_gitlink_ref to object_id
  sha1_file: convert index_path and index_fd to struct object_id
  refs: convert reflog_expire parameter to struct object_id
  refs: convert read_ref_at to struct object_id
  refs: convert peel_ref to struct object_id
  builtin/pack-objects: convert to struct object_id
  pack-bitmap: convert traverse_bitmap_commit_list to object_id
  refs: convert dwim_log to struct object_id
  builtin/reflog: convert remaining unsigned char uses to object_id
  refs: convert dwim_ref and expand_ref to struct object_id
  refs: convert read_ref and read_ref_full to object_id
  refs: convert resolve_refdup and refs_resolve_refdup to struct object_id
  Convert check_connected to use struct object_id
  refs: update ref transactions to use struct object_id
  ...

30 files changed, 179 insertions, 179 deletions

diff --git a/builtin/am.c b/builtin/am.c
index 40968428d..4b6f1534f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1068,8 +1068,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	if (!get_oid("HEAD", &curr_head)) {
 		write_state_text(state, "abort-safety", oid_to_hex(&curr_head));
 		if (!state->rebasing)
-			update_ref_oid("am", "ORIG_HEAD", &curr_head, NULL, 0,
-					UPDATE_REFS_DIE_ON_ERR);
+			update_ref("am", "ORIG_HEAD", &curr_head, NULL, 0,
+				   UPDATE_REFS_DIE_ON_ERR);
 	} else {
 		write_state_text(state, "abort-safety", "");
 		if (!state->rebasing)
@@ -1685,8 +1685,8 @@ static void do_commit(const struct am_state *state)
 	strbuf_addf(&sb, "%s: %.*s", reflog_msg, linelen(state->msg),
 			state->msg);
 
-	update_ref_oid(sb.buf, "HEAD", &commit, old_oid, 0,
-			UPDATE_REFS_DIE_ON_ERR);
+	update_ref(sb.buf, "HEAD", &commit, old_oid, 0,
+		   UPDATE_REFS_DIE_ON_ERR);
 
 	if (state->rebasing) {
 		FILE *fp = xfopen(am_path(state, "rewritten"), "a");
@@ -2132,7 +2132,7 @@ static void am_abort(struct am_state *state)
 
 	am_rerere_clear();
 
-	curr_branch = resolve_refdup("HEAD", 0, curr_head.hash, NULL);
+	curr_branch = resolve_refdup("HEAD", 0, &curr_head, NULL);
 	has_curr_head = curr_branch && !is_null_oid(&curr_head);
 	if (!has_curr_head)
 		hashcpy(curr_head.hash, EMPTY_TREE_SHA1_BIN);
@@ -2144,9 +2144,9 @@ static void am_abort(struct am_state *state)
 	clean_index(&curr_head, &orig_head);
 
 	if (has_orig_head)
-		update_ref_oid("am --abort", "HEAD", &orig_head,
-				has_curr_head ? &curr_head : NULL, 0,
-				UPDATE_REFS_DIE_ON_ERR);
+		update_ref("am --abort", "HEAD", &orig_head,
+			   has_curr_head ? &curr_head : NULL, 0,
+			   UPDATE_REFS_DIE_ON_ERR);
 	else if (curr_branch)
 		delete_ref(NULL, curr_branch, NULL, REF_NODEREF);
 
diff --git a/builtin/branch.c b/builtin/branch.c
index 79dc9181f..b1ed64930 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -125,7 +125,7 @@ static int branch_merged(int kind, const char *name,
 		if (upstream &&
 		    (reference_name = reference_name_to_free =
 		     resolve_refdup(upstream, RESOLVE_REF_READING,
-				    oid.hash, NULL)) != NULL)
+				    &oid, NULL)) != NULL)
 			reference_rev = lookup_commit_reference(&oid);
 	}
 	if (!reference_rev)
@@ -241,7 +241,7 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
 					RESOLVE_REF_READING
 					| RESOLVE_REF_NO_RECURSE
 					| RESOLVE_REF_ALLOW_BAD_NAME,
-					oid.hash, &flags);
+					&oid, &flags);
 		if (!target) {
 			error(remote_branch
 			      ? _("remote-tracking branch '%s' not found.")
@@ -257,7 +257,7 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
 			goto next;
 		}
 
-		if (delete_ref(NULL, name, is_null_oid(&oid) ? NULL : oid.hash,
+		if (delete_ref(NULL, name, is_null_oid(&oid) ? NULL : &oid,
 			       REF_NODEREF)) {
 			error(remote_branch
 			      ? _("Error deleting remote-tracking branch '%s'")
@@ -636,7 +636,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 
 	track = git_branch_track;
 
-	head = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
+	head = resolve_refdup("HEAD", 0, &head_oid, NULL);
 	if (!head)
 		die(_("Failed to resolve HEAD as a valid ref."));
 	if (!strcmp(head, "HEAD"))
diff --git a/builtin/checkout.c b/builtin/checkout.c
index fcff0de19..6c2b4cd41 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -377,7 +377,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
-	read_ref_full("HEAD", 0, rev.hash, NULL);
+	read_ref_full("HEAD", 0, &rev, NULL);
 	head = lookup_commit_reference_gently(&rev, 1);
 
 	errs |= post_checkout_hook(head, head, 0);
@@ -662,7 +662,7 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 	if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 		/* Nothing to do. */
 	} else if (opts->force_detach || !new->path) {	/* No longer on any branch. */
-		update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
+		update_ref(msg.buf, "HEAD", &new->commit->object.oid, NULL,
 			   REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 		if (!opts->quiet) {
 			if (old->path &&
@@ -825,7 +825,7 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	memset(&old, 0, sizeof(old));
-	old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
+	old.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 	if (old.path)
 		old.commit = lookup_commit_reference_gently(&rev, 1);
 	if (!(flag & REF_ISSYMREF))
@@ -1036,7 +1036,7 @@ static int parse_branchname_arg(int argc, const char **argv,
 	setup_branch_path(new);
 
 	if (!check_refname_format(new->path, 0) &&
-	    !read_ref(new->path, branch_rev.hash))
+	    !read_ref(new->path, &branch_rev))
 		oidcpy(rev, &branch_rev);
 	else
 		new->path = NULL; /* not an existing branch */
@@ -1134,7 +1134,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		struct object_id rev;
 		int flag;
 
-		if (!read_ref_full("HEAD", 0, rev.hash, &flag) &&
+		if (!read_ref_full("HEAD", 0, &rev, &flag) &&
 		    (flag & REF_ISSYMREF) && is_null_oid(&rev))
 			return switch_unborn_to_new_branch(opts);
 	}
diff --git a/builtin/clone.c b/builtin/clone.c
index 96a3aaaa1..cf6eddc9c 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -588,7 +588,7 @@ static void write_remote_refs(const struct ref *local_refs)
 	for (r = local_refs; r; r = r->next) {
 		if (!r->peer_ref)
 			continue;
-		if (ref_transaction_create(t, r->peer_ref->name, r->old_oid.hash,
+		if (ref_transaction_create(t, r->peer_ref->name, &r->old_oid,
 					   0, NULL, &err))
 			die("%s", err.buf);
 	}
@@ -610,12 +610,12 @@ static void write_followtags(const struct ref *refs, const char *msg)
 			continue;
 		if (!has_object_file(&ref->old_oid))
 			continue;
-		update_ref(msg, ref->name, ref->old_oid.hash,
-			   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+		update_ref(msg, ref->name, &ref->old_oid, NULL, 0,
+			   UPDATE_REFS_DIE_ON_ERR);
 	}
 }
 
-static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
+static int iterate_ref_map(void *cb_data, struct object_id *oid)
 {
 	struct ref **rm = cb_data;
 	struct ref *ref = *rm;
@@ -630,7 +630,7 @@ static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
 	if (!ref)
 		return -1;
 
-	hashcpy(sha1, ref->old_oid.hash);
+	oidcpy(oid, &ref->old_oid);
 	*rm = ref->next;
 	return 0;
 }
@@ -682,23 +682,23 @@ static void update_head(const struct ref *our, const struct ref *remote,
 		if (create_symref("HEAD", our->name, NULL) < 0)
 			die(_("unable to update HEAD"));
 		if (!option_bare) {
-			update_ref(msg, "HEAD", our->old_oid.hash, NULL, 0,
+			update_ref(msg, "HEAD", &our->old_oid, NULL, 0,
 				   UPDATE_REFS_DIE_ON_ERR);
 			install_branch_config(0, head, option_origin, our->name);
 		}
 	} else if (our) {
 		struct commit *c = lookup_commit_reference(&our->old_oid);
 		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
-		update_ref(msg, "HEAD", c->object.oid.hash,
-			   NULL, REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
+		update_ref(msg, "HEAD", &c->object.oid, NULL, REF_NODEREF,
+			   UPDATE_REFS_DIE_ON_ERR);
 	} else if (remote) {
 		/*
 		 * We know remote HEAD points to a non-branch, or
 		 * HEAD points to a branch but we don't know which one.
 		 * Detach HEAD in all these cases.
 		 */
-		update_ref(msg, "HEAD", remote->old_oid.hash,
-			   NULL, REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
+		update_ref(msg, "HEAD", &remote->old_oid, NULL, REF_NODEREF,
+			   UPDATE_REFS_DIE_ON_ERR);
 	}
 }
 
@@ -715,7 +715,7 @@ static int checkout(int submodule_progress)
 	if (option_no_checkout)
 		return 0;
 
-	head = resolve_refdup("HEAD", RESOLVE_REF_READING, oid.hash, NULL);
+	head = resolve_refdup("HEAD", RESOLVE_REF_READING, &oid, NULL);
 	if (!head) {
 		warning(_("remote HEAD refers to nonexistent ref, "
 			  "unable to checkout.\n"));
diff --git a/builtin/commit.c b/builtin/commit.c
index 1a4ad725b..c38542ee4 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1790,9 +1790,9 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	transaction = ref_transaction_begin(&err);
 	if (!transaction ||
-	    ref_transaction_update(transaction, "HEAD", oid.hash,
+	    ref_transaction_update(transaction, "HEAD", &oid,
 				   current_head
-				   ? current_head->object.oid.hash : null_sha1,
+				   ? &current_head->object.oid : &null_oid,
 				   0, sb.buf, &err) ||
 	    ref_transaction_commit(transaction, &err)) {
 		rollback_index_files();
diff --git a/builtin/describe.c b/builtin/describe.c
index 979556d9f..e14e162ef 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -181,7 +181,7 @@ static int get_name(const char *path, const struct object_id *oid, int flag, voi
 	}
 
 	/* Is it annotated? */
-	if (!peel_ref(path, peeled.hash)) {
+	if (!peel_ref(path, &peeled)) {
 		is_annotated = !!oidcmp(oid, &peeled);
 	} else {
 		oidcpy(&peeled, oid);
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 2fb60d6d4..d74c73f77 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -823,7 +823,7 @@ static void get_tags_and_duplicates(struct rev_cmdline_info *info)
 		if (e->flags & UNINTERESTING)
 			continue;
 
-		if (dwim_ref(e->name, strlen(e->name), oid.hash, &full_name) != 1)
+		if (dwim_ref(e->name, strlen(e->name), &oid, &full_name) != 1)
 			continue;
 
 		if (refspecs) {
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 225c73492..e705237fa 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -457,8 +457,8 @@ static int s_update_ref(const char *action,
 	transaction = ref_transaction_begin(&err);
 	if (!transaction ||
 	    ref_transaction_update(transaction, ref->name,
-				   ref->new_oid.hash,
-				   check_old ? ref->old_oid.hash : NULL,
+				   &ref->new_oid,
+				   check_old ? &ref->old_oid : NULL,
 				   0, msg, &err))
 		goto fail;
 
@@ -727,7 +727,7 @@ static int update_local_ref(struct ref *ref,
 	}
 }
 
-static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
+static int iterate_ref_map(void *cb_data, struct object_id *oid)
 {
 	struct ref **rm = cb_data;
 	struct ref *ref = *rm;
@@ -737,7 +737,7 @@ static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
 	if (!ref)
 		return -1; /* end of the list */
 	*rm = ref->next;
-	hashcpy(sha1, ref->old_oid.hash);
+	oidcpy(oid, &ref->old_oid);
 	return 0;
 }
 
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index e99b5ddbf..b69f7d3be 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -603,7 +603,7 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
 
 	/* get current branch */
 	current_branch = current_branch_to_free =
-		resolve_refdup("HEAD", RESOLVE_REF_READING, head_oid.hash, NULL);
+		resolve_refdup("HEAD", RESOLVE_REF_READING, &head_oid, NULL);
 	if (!current_branch)
 		die("No current branch");
 	if (starts_with(current_branch, "refs/heads/"))
diff --git a/builtin/fsck.c b/builtin/fsck.c
index 56afe405b..5f91116d7 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -555,7 +555,7 @@ static int fsck_head_link(void)
 	if (verbose)
 		fprintf(stderr, "Checking HEAD link\n");
 
-	head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, NULL);
+	head_points_at = resolve_ref_unsafe("HEAD", 0, &head_oid, NULL);
 	if (!head_points_at) {
 		errors_found |= ERROR_REFS;
 		return error("Invalid HEAD");
diff --git a/builtin/log.c b/builtin/log.c
index d81a09051..ba9d4cd78 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -975,7 +975,7 @@ static char *find_branch_name(struct rev_info *rev)
 		return NULL;
 	ref = rev->cmdline.rev[positive].name;
 	tip_oid = &rev->cmdline.rev[positive].item->oid;
-	if (dwim_ref(ref, strlen(ref), branch_oid.hash, &full_ref) &&
+	if (dwim_ref(ref, strlen(ref), &branch_oid, &full_ref) &&
 	    skip_prefix(full_ref, "refs/heads/", &v) &&
 	    !oidcmp(tip_oid, &branch_oid))
 		branch = xstrdup(v);
diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index 6dbd167d3..e99f5405c 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -156,7 +156,7 @@ static int handle_fork_point(int argc, const char **argv)
 	struct commit_list *bases;
 	int i, ret = 0;
 
-	switch (dwim_ref(argv[0], strlen(argv[0]), oid.hash, &refname)) {
+	switch (dwim_ref(argv[0], strlen(argv[0]), &oid, &refname)) {
 	case 0:
 		die("No such ref: '%s'", argv[0]);
 	case 1:
diff --git a/builtin/merge.c b/builtin/merge.c
index ab5ffe85e..6071dbfe3 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -405,9 +405,8 @@ static void finish(struct commit *head_commit,
 			printf(_("No merge message -- not updating HEAD\n"));
 		else {
 			const char *argv_gc_auto[] = { "gc", "--auto", NULL };
-			update_ref(reflog_message.buf, "HEAD",
-				new_head->hash, head->hash, 0,
-				UPDATE_REFS_DIE_ON_ERR);
+			update_ref(reflog_message.buf, "HEAD", new_head, head,
+				   0, UPDATE_REFS_DIE_ON_ERR);
 			/*
 			 * We ignore errors in 'gc --auto', since the
 			 * user should see them.
@@ -455,7 +454,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
 	if (!remote_head)
 		die(_("'%s' does not point to a commit"), remote);
 
-	if (dwim_ref(remote, strlen(remote), branch_head.hash, &found_ref) > 0) {
+	if (dwim_ref(remote, strlen(remote), &branch_head, &found_ref) > 0) {
 		if (starts_with(found_ref, "refs/heads/")) {
 			strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 				    oid_to_hex(&branch_head), remote);
@@ -1143,7 +1142,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	 * Check if we are _not_ on a detached HEAD, i.e. if there is a
 	 * current branch.
 	 */
-	branch = branch_to_free = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
+	branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
 	if (branch)
 		skip_prefix(branch, "refs/heads/", &branch);
 	if (!branch || is_null_oid(&head_oid))
@@ -1261,8 +1260,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			die(_("Can merge only exactly one commit into empty head"));
 		remote_head_oid = &remoteheads->item->object.oid;
 		read_empty(remote_head_oid->hash, 0);
-		update_ref("initial pull", "HEAD", remote_head_oid->hash,
-			   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+		update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
+			   UPDATE_REFS_DIE_ON_ERR);
 		goto done;
 	}
 
@@ -1357,8 +1356,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		free(list);
 	}
 
-	update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.oid.hash,
-		   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+	update_ref("updating ORIG_HEAD", "ORIG_HEAD",
+		   &head_commit->object.oid, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
 
 	if (remoteheads && !common) {
 		/* No common ancestors found. */
diff --git a/builtin/notes.c b/builtin/notes.c
index 8e54f2d14..12afdf190 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -724,7 +724,7 @@ static int merge_commit(struct notes_merge_options *o)
 	init_notes(t, "NOTES_MERGE_PARTIAL", combine_notes_overwrite, 0);
 
 	o->local_ref = local_ref_to_free =
-		resolve_refdup("NOTES_MERGE_REF", 0, oid.hash, NULL);
+		resolve_refdup("NOTES_MERGE_REF", 0, &oid, NULL);
 	if (!o->local_ref)
 		die(_("failed to resolve NOTES_MERGE_REF"));
 
@@ -736,8 +736,8 @@ static int merge_commit(struct notes_merge_options *o)
 	format_commit_message(partial, "%s", &msg, &pretty_ctx);
 	strbuf_trim(&msg);
 	strbuf_insert(&msg, 0, "notes: ", 7);
-	update_ref(msg.buf, o->local_ref, oid.hash,
-		   is_null_oid(&parent_oid) ? NULL : parent_oid.hash,
+	update_ref(msg.buf, o->local_ref, &oid,
+		   is_null_oid(&parent_oid) ? NULL : &parent_oid,
 		   0, UPDATE_REFS_DIE_ON_ERR);
 
 	free_notes(t);
@@ -850,12 +850,12 @@ static int merge(int argc, const char **argv, const char *prefix)
 
 	if (result >= 0) /* Merge resulted (trivially) in result_oid */
 		/* Update default notes ref with new commit */
-		update_ref(msg.buf, default_notes_ref(), result_oid.hash, NULL,
-			   0, UPDATE_REFS_DIE_ON_ERR);
+		update_ref(msg.buf, default_notes_ref(), &result_oid, NULL, 0,
+			   UPDATE_REFS_DIE_ON_ERR);
 	else { /* Merge has unresolved conflicts */
 		const struct worktree *wt;
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
-		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_oid.hash, NULL,
+		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", &result_oid, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
 		wt = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6e77dfd44..631de2876 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -151,7 +151,7 @@ static unsigned long do_compress(void **pptr, unsigned long size)
 }
 
 static unsigned long write_large_blob_data(struct git_istream *st, struct sha1file *f,
-					   const unsigned char *sha1)
+					   const struct object_id *oid)
 {
 	git_zstream stream;
 	unsigned char ibuf[1024 * 16];
@@ -165,7 +165,7 @@ static unsigned long write_large_blob_data(struct git_istream *st, struct sha1fi
 		int zret = Z_OK;
 		readlen = read_istream(st, ibuf, sizeof(ibuf));
 		if (readlen == -1)
-			die(_("unable to read %s"), sha1_to_hex(sha1));
+			die(_("unable to read %s"), oid_to_hex(oid));
 
 		stream.next_in = ibuf;
 		stream.avail_in = readlen;
@@ -339,7 +339,7 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
 		sha1write(f, header, hdrlen);
 	}
 	if (st) {
-		datalen = write_large_blob_data(st, f, entry->idx.oid.hash);
+		datalen = write_large_blob_data(st, f, &entry->idx.oid);
 		close_istream(st);
 	} else {
 		sha1write(f, buf, datalen);
@@ -557,13 +557,13 @@ static enum write_one_status write_one(struct sha1file *f,
 static int mark_tagged(const char *path, const struct object_id *oid, int flag,
 		       void *cb_data)
 {
-	unsigned char peeled[20];
+	struct object_id peeled;
 	struct object_entry *entry = packlist_find(&to_pack, oid->hash, NULL);
 
 	if (entry)
 		entry->tagged = 1;
-	if (!peel_ref(path, peeled)) {
-		entry = packlist_find(&to_pack, peeled, NULL);
+	if (!peel_ref(path, &peeled)) {
+		entry = packlist_find(&to_pack, peeled.hash, NULL);
 		if (entry)
 			entry->tagged = 1;
 	}
@@ -792,7 +792,7 @@ static void write_pack_file(void)
 	write_order = compute_write_order();
 
 	do {
-		unsigned char sha1[20];
+		struct object_id oid;
 		char *pack_tmp_name = NULL;
 
 		if (pack_to_stdout)
@@ -823,13 +823,13 @@ static void write_pack_file(void)
 		 * If so, rewrite it like in fast-import
 		 */
 		if (pack_to_stdout) {
-			sha1close(f, sha1, CSUM_CLOSE);
+			sha1close(f, oid.hash, CSUM_CLOSE);
 		} else if (nr_written == nr_remaining) {
-			sha1close(f, sha1, CSUM_FSYNC);
+			sha1close(f, oid.hash, CSUM_FSYNC);
 		} else {
-			int fd = sha1close(f, sha1, 0);
-			fixup_pack_header_footer(fd, sha1, pack_tmp_name,
-						 nr_written, sha1, offset);
+			int fd = sha1close(f, oid.hash, 0);
+			fixup_pack_header_footer(fd, oid.hash, pack_tmp_name,
+						 nr_written, oid.hash, offset);
 			close(fd);
 			if (write_bitmap_index) {
 				warning(_(no_split_warning));
@@ -863,16 +863,16 @@ static void write_pack_file(void)
 			strbuf_addf(&tmpname, "%s-", base_name);
 
 			if (write_bitmap_index) {
-				bitmap_writer_set_checksum(sha1);
+				bitmap_writer_set_checksum(oid.hash);
 				bitmap_writer_build_type_index(written_list, nr_written);
 			}
 
 			finish_tmp_packfile(&tmpname, pack_tmp_name,
 					    written_list, nr_written,
-					    &pack_idx_opts, sha1);
+					    &pack_idx_opts, oid.hash);
 
 			if (write_bitmap_index) {
-				strbuf_addf(&tmpname, "%s.bitmap", sha1_to_hex(sha1));
+				strbuf_addf(&tmpname, "%s.bitmap", oid_to_hex(&oid));
 
 				stop_progress(&progress_state);
 
@@ -887,7 +887,7 @@ static void write_pack_file(void)
 
 			strbuf_release(&tmpname);
 			free(pack_tmp_name);
-			puts(sha1_to_hex(sha1));
+			puts(oid_to_hex(&oid));
 		}
 
 		/* mark written objects as written to previous pack */
@@ -928,13 +928,13 @@ static int no_try_delta(const char *path)
  * found the item, since that saves us from having to look it up again a
  * few lines later when we want to add the new entry.
  */
-static int have_duplicate_entry(const unsigned char *sha1,
+static int have_duplicate_entry(const struct object_id *oid,
 				int exclude,
 				uint32_t *index_pos)
 {
 	struct object_entry *entry;
 
-	entry = packlist_find(&to_pack, sha1, index_pos);
+	entry = packlist_find(&to_pack, oid->hash, index_pos);
 	if (!entry)
 		return 0;
 
@@ -990,7 +990,7 @@ static int want_found_object(int exclude, struct packed_git *p)
  * function finds if there is any pack that has the object and returns the pack
  * and its offset in these variables.
  */
-static int want_object_in_pack(const unsigned char *sha1,
+static int want_object_in_pack(const struct object_id *oid,
 			       int exclude,
 			       struct packed_git **found_pack,
 			       off_t *found_offset)
@@ -998,7 +998,7 @@ static int want_object_in_pack(const unsigned char *sha1,
 	struct mru_entry *entry;
 	int want;
 
-	if (!exclude && local && has_loose_object_nonlocal(sha1))
+	if (!exclude && local && has_loose_object_nonlocal(oid->hash))
 		return 0;
 
 	/*
@@ -1019,7 +1019,7 @@ static int want_object_in_pack(const unsigned char *sha1,
 		if (p == *found_pack)
 			offset = *found_offset;
 		else
-			offset = find_pack_entry_one(sha1, p);
+			offset = find_pack_entry_one(oid->hash, p);
 
 		if (offset) {
 			if (!*found_pack) {
@@ -1039,7 +1039,7 @@ static int want_object_in_pack(const unsigned char *sha1,
 	return 1;
 }
 
-static void create_object_entry(const unsigned char *sha1,
+static void create_object_entry(const struct object_id *oid,
 				enum object_type type,
 				uint32_t hash,
 				int exclude,
@@ -1050,7 +1050,7 @@ static void create_object_entry(const unsigned char *sha1,
 {
 	struct object_entry *entry;
 
-	entry = packlist_alloc(&to_pack, sha1, index_pos);
+	entry = packlist_alloc(&to_pack, oid->hash, index_pos);
 	entry->hash = hash;
 	if (type)
 		entry->type = type;
@@ -1070,17 +1070,17 @@ static const char no_closure_warning[] = N_(
 "disabling bitmap writing, as some objects are not being packed"
 );
 
-static int add_object_entry(const unsigned char *sha1, enum object_type type,
+static int add_object_entry(const struct object_id *oid, enum object_type type,
 			    const char *name, int exclude)
 {
 	struct packed_git *found_pack = NULL;
 	off_t found_offset = 0;
 	uint32_t index_pos;
 
-	if (have_duplicate_entry(sha1, exclude, &index_pos))
+	if (have_duplicate_entry(oid, exclude, &index_pos))
 		return 0;
 
-	if (!want_object_in_pack(sha1, exclude, &found_pack, &found_offset)) {
+	if (!want_object_in_pack(oid, exclude, &found_pack, &found_offset)) {
 		/* The pack is missing an object, so it will not have closure */
 		if (write_bitmap_index) {
 			warning(_(no_closure_warning));
@@ -1089,7 +1089,7 @@ static int add_object_entry(const unsigned char *sha1, enum object_type type,
 		return 0;
 	}
 
-	create_object_entry(sha1, type, pack_name_hash(name),
+	create_object_entry(oid, type, pack_name_hash(name),
 			    exclude, name && no_try_delta(name),
 			    index_pos, found_pack, found_offset);
 
@@ -1097,27 +1097,27 @@ static int add_object_entry(const unsigned char *sha1, enum object_type type,
 	return 1;
 }
 
-static int add_object_entry_from_bitmap(const unsigned char *sha1,
+static int add_object_entry_from_bitmap(const struct object_id *oid,
 					enum object_type type,
 					int flags, uint32_t name_hash,
 					struct packed_git *pack, off_t offset)
 {
 	uint32_t index_pos;
 
-	if (have_duplicate_entry(sha1, 0, &index_pos))
+	if (have_duplicate_entry(oid, 0, &index_pos))
 		return 0;
 
-	if (!want_object_in_pack(sha1, 0, &pack, &offset))
+	if (!want_object_in_pack(oid, 0, &pack, &offset))
 		return 0;
 
-	create_object_entry(sha1, type, name_hash, 0, 0, index_pos, pack, offset);
+	create_object_entry(oid, type, name_hash, 0, 0, index_pos, pack, offset);
 
 	display_progress(progress_state, nr_result);
 	return 1;
 }
 
 struct pbase_tree_cache {
-	unsigned char sha1[20];
+	struct object_id oid;
 	int ref;
 	int temporary;
 	void *tree_data;
@@ -1125,9 +1125,9 @@ struct pbase_tree_cache {
 };
 
 static struct pbase_tree_cache *(pbase_tree_cache[256]);
-static int pbase_tree_cache_ix(const unsigned char *sha1)
+static int pbase_tree_cache_ix(const struct object_id *oid)
 {
-	return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
+	return oid->hash[0] % ARRAY_SIZE(pbase_tree_cache);
 }
 static int pbase_tree_cache_ix_incr(int ix)
 {
@@ -1144,14 +1144,14 @@ static struct pbase_tree {
 	struct pbase_tree_cache pcache;
 } *pbase_tree;
 
-static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
+static struct pbase_tree_cache *pbase_tree_get(const struct object_id *oid)
 {
 	struct pbase_tree_cache *ent, *nent;
 	void *data;
 	unsigned long size;
 	enum object_type type;
 	int neigh;
-	int my_ix = pbase_tree_cache_ix(sha1);
+	int my_ix = pbase_tree_cache_ix(oid);
 	int available_ix = -1;
 
 	/* pbase-tree-cache acts as a limited hashtable.
@@ -1160,7 +1160,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 	 */
 	for (neigh = 0; neigh < 8; neigh++) {
 		ent = pbase_tree_cache[my_ix];
-		if (ent && !hashcmp(ent->sha1, sha1)) {
+		if (ent && !oidcmp(&ent->oid, oid)) {
 			ent->ref++;
 			return ent;
 		}
@@ -1176,7 +1176,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 	/* Did not find one.  Either we got a bogus request or
 	 * we need to read and perhaps cache.
 	 */
-	data = read_sha1_file(sha1, &type, &size);
+	data = read_sha1_file(oid->hash, &type, &size);
 	if (!data)
 		return NULL;
 	if (type != OBJ_TREE) {
@@ -1202,7 +1202,7 @@ static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 		free(ent->tree_data);
 		nent = ent;
 	}
-	hashcpy(nent->sha1, sha1);
+	oidcpy(&nent->oid, oid);
 	nent->tree_data = data;
 	nent->tree_size = size;
 	nent->ref = 1;
@@ -1247,7 +1247,7 @@ static void add_pbase_object(struct tree_desc *tree,
 		if (cmp < 0)
 			return;
 		if (name[cmplen] != '/') {
-			add_object_entry(entry.oid->hash,
+			add_object_entry(entry.oid,
 					 object_type(entry.mode),
 					 fullname, 1);
 			return;
@@ -1258,7 +1258,7 @@ static void add_pbase_object(struct tree_desc *tree,
 			const char *down = name+cmplen+1;
 			int downlen = name_cmp_len(down);
 
-			tree = pbase_tree_get(entry.oid->hash);
+			tree = pbase_tree_get(entry.oid);
 			if (!tree)
 				return;
 			init_tree_desc(&sub, tree->tree_data, tree->tree_size);
@@ -1317,7 +1317,7 @@ static void add_preferred_base_object(const char *name)
 	cmplen = name_cmp_len(name);
 	for (it = pbase_tree; it; it = it->next) {
 		if (cmplen == 0) {
-			add_object_entry(it->pcache.sha1, OBJ_TREE, NULL, 1);
+			add_object_entry(&it->pcache.oid, OBJ_TREE, NULL, 1);
 		}
 		else {
 			struct tree_desc tree;
@@ -1327,22 +1327,22 @@ static void add_preferred_base_object(const char *name)
 	}
 }
 
-static void add_preferred_base(unsigned char *sha1)
+static void add_preferred_base(struct object_id *oid)
 {
 	struct pbase_tree *it;
 	void *data;
 	unsigned long size;
-	unsigned char tree_sha1[20];
+	struct object_id tree_oid;
 
 	if (window <= num_preferred_base++)
 		return;
 
-	data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
+	data = read_object_with_reference(oid->hash, tree_type, &size, tree_oid.hash);
 	if (!data)
 		return;
 
 	for (it = pbase_tree; it; it = it->next) {
-		if (!hashcmp(it->pcache.sha1, tree_sha1)) {
+		if (!oidcmp(&it->pcache.oid, &tree_oid)) {
 			free(data);
 			return;
 		}
@@ -1352,7 +1352,7 @@ static void add_preferred_base(unsigned char *sha1)
 	it->next = pbase_tree;
 	pbase_tree = it;
 
-	hashcpy(it->pcache.sha1, tree_sha1);
+	oidcpy(&it->pcache.oid, &tree_oid);
 	it->pcache.tree_data = data;
 	it->pcache.tree_size = size;
 }
@@ -2357,7 +2357,7 @@ static void add_tag_chain(const struct object_id *oid)
 			die("unable to pack objects reachable from tag %s",
 			    oid_to_hex(oid));
 
-		add_object_entry(tag->object.oid.hash, OBJ_TAG, NULL, 0);
+		add_object_entry(&tag->object.oid, OBJ_TAG, NULL, 0);
 
 		if (tag->tagged->type != OBJ_TAG)
 			return;
@@ -2371,7 +2371,7 @@ static int add_ref_tag(const char *path, const struct object_id *oid, int flag,
 	struct object_id peeled;
 
 	if (starts_with(path, "refs/tags/") && /* is a tag? */
-	    !peel_ref(path, peeled.hash)    && /* peelable? */
+	    !peel_ref(path, &peeled)    && /* peelable? */
 	    packlist_find(&to_pack, peeled.hash, NULL))      /* object packed? */
 		add_tag_chain(oid);
 	return 0;
@@ -2505,8 +2505,9 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 
 static void read_object_list_from_stdin(void)
 {
-	char line[40 + 1 + PATH_MAX + 2];
-	unsigned char sha1[20];
+	char line[GIT_MAX_HEXSZ + 1 + PATH_MAX + 2];
+	struct object_id oid;
+	const char *p;
 
 	for (;;) {
 		if (!fgets(line, sizeof(line), stdin)) {
@@ -2520,17 +2521,17 @@ static void read_object_list_from_stdin(void)
 			continue;
 		}
 		if (line[0] == '-') {
-			if (get_sha1_hex(line+1, sha1))
-				die("expected edge sha1, got garbage:\n %s",
+			if (get_oid_hex(line+1, &oid))
+				die("expected edge object ID, got garbage:\n %s",
 				    line);
-			add_preferred_base(sha1);
+			add_preferred_base(&oid);
 			continue;
 		}
-		if (get_sha1_hex(line, sha1))
-			die("expected sha1, got garbage:\n %s", line);
+		if (parse_oid_hex(line, &oid, &p))
+			die("expected object ID, got garbage:\n %s", line);
 
-		add_preferred_base_object(line+41);
-		add_object_entry(sha1, 0, line+41, 0);
+		add_preferred_base_object(p + 1);
+		add_object_entry(&oid, 0, p + 1, 0);
 	}
 }
 
@@ -2538,7 +2539,7 @@ static void read_object_list_from_stdin(void)
 
 static void show_commit(struct commit *commit, void *data)
 {
-	add_object_entry(commit->object.oid.hash, OBJ_COMMIT, NULL, 0);
+	add_object_entry(&commit->object.oid, OBJ_COMMIT, NULL, 0);
 	commit->object.flags |= OBJECT_ADDED;
 
 	if (write_bitmap_index)
@@ -2548,13 +2549,13 @@ static void show_commit(struct commit *commit, void *data)
 static void show_object(struct object *obj, const char *name, void *data)
 {
 	add_preferred_base_object(name);
-	add_object_entry(obj->oid.hash, obj->type, name, 0);
+	add_object_entry(&obj->oid, obj->type, name, 0);
 	obj->flags |= OBJECT_ADDED;
 }
 
 static void show_edge(struct commit *commit)
 {
-	add_preferred_base(commit->object.oid.hash);
+	add_preferred_base(&commit->object.oid);
 }
 
 struct in_pack_object {
@@ -2601,7 +2602,7 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 	memset(&in_pack, 0, sizeof(in_pack));
 
 	for (p = packed_git; p; p = p->next) {
-		const unsigned char *sha1;
+		struct object_id oid;
 		struct object *o;
 
 		if (!p->pack_local || p->pack_keep)
@@ -2614,8 +2615,8 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 			   in_pack.alloc);
 
 		for (i = 0; i < p->num_objects; i++) {
-			sha1 = nth_packed_object_sha1(p, i);
-			o = lookup_unknown_object(sha1);
+			nth_packed_object_oid(&oid, p, i);
+			o = lookup_unknown_object(oid.hash);
 			if (!(o->flags & OBJECT_ADDED))
 				mark_in_pack_object(o, p, &in_pack);
 			o->flags |= OBJECT_ADDED;
@@ -2626,7 +2627,7 @@ static void add_objects_in_unpacked_packs(struct rev_info *revs)
 		QSORT(in_pack.array, in_pack.nr, ofscmp);
 		for (i = 0; i < in_pack.nr; i++) {
 			struct object *o = in_pack.array[i].object;
-			add_object_entry(o->oid.hash, o->type, "", 0);
+			add_object_entry(&o->oid, o->type, "", 0);
 		}
 	}
 	free(in_pack.array);
@@ -2642,7 +2643,7 @@ static int add_loose_object(const struct object_id *oid, const char *path,
 		return 0;
 	}
 
-	add_object_entry(oid->hash, type, "", 0);
+	add_object_entry(oid, type, "", 0);
 	return 0;
 }
 
@@ -2658,7 +2659,7 @@ static void add_unreachable_loose_objects(void)
 				      NULL, NULL, NULL);
 }
 
-static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
+static int has_sha1_pack_kept_or_nonlocal(const struct object_id *oid)
 {
 	static struct packed_git *last_found = (void *)1;
 	struct packed_git *p;
@@ -2667,7 +2668,7 @@ static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
 
 	while (p) {
 		if ((!p->pack_local || p->pack_keep) &&
-			find_pack_entry_one(sha1, p)) {
+			find_pack_entry_one(oid->hash, p)) {
 			last_found = p;
 			return 1;
 		}
@@ -2718,7 +2719,7 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
 		for (i = 0; i < p->num_objects; i++) {
 			nth_packed_object_oid(&oid, p, i);
 			if (!packlist_find(&to_pack, oid.hash, NULL) &&
-			    !has_sha1_pack_kept_or_nonlocal(oid.hash) &&
+			    !has_sha1_pack_kept_or_nonlocal(&oid) &&
 			    !loosened_object_can_be_discarded(&oid, p->mtime))
 				if (force_object_loose(oid.hash, p->mtime))
 					die("unable to force loose object");
diff --git a/builtin/pull.c b/builtin/pull.c
index 0413c78a3..a28f0ffad 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -548,7 +548,7 @@ static int pull_into_void(const struct object_id *merge_head,
 	if (checkout_fast_forward(&empty_tree_oid, merge_head, 0))
 		return 1;
 
-	if (update_ref("initial pull", "HEAD", merge_head->hash, curr_head->hash, 0, UPDATE_REFS_DIE_ON_ERR))
+	if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 		return 1;
 
 	return 0;
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index cc4876740..4d37a160d 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -870,7 +870,7 @@ static void refuse_unconfigured_deny_delete_current(void)
 	rp_error("%s", _(refuse_unconfigured_deny_delete_current_msg));
 }
 
-static int command_singleton_iterator(void *cb_data, unsigned char sha1[20]);
+static int command_singleton_iterator(void *cb_data, struct object_id *oid);
 static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 {
 	static struct lock_file shallow_lock;
@@ -1139,7 +1139,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		}
 		if (ref_transaction_delete(transaction,
 					   namespaced_name,
-					   old_oid ? old_oid->hash : NULL,
+					   old_oid,
 					   0, "push", &err)) {
 			rp_error("%s", err.buf);
 			strbuf_release(&err);
@@ -1156,7 +1156,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 
 		if (ref_transaction_update(transaction,
 					   namespaced_name,
-					   new_oid->hash, old_oid->hash,
+					   new_oid, old_oid,
 					   0, "push",
 					   &err)) {
 			rp_error("%s", err.buf);
@@ -1270,7 +1270,7 @@ static void check_aliased_updates(struct command *commands)
 	string_list_clear(&ref_list, 0);
 }
 
-static int command_singleton_iterator(void *cb_data, unsigned char sha1[20])
+static int command_singleton_iterator(void *cb_data, struct object_id *oid)
 {
 	struct command **cmd_list = cb_data;
 	struct command *cmd = *cmd_list;
@@ -1278,7 +1278,7 @@ static int command_singleton_iterator(void *cb_data, unsigned char sha1[20])
 	if (!cmd || is_null_oid(&cmd->new_oid))
 		return -1; /* end of list */
 	*cmd_list = NULL; /* this returns only one */
-	hashcpy(sha1, cmd->new_oid.hash);
+	oidcpy(oid, &cmd->new_oid);
 	return 0;
 }
 
@@ -1309,7 +1309,7 @@ struct iterate_data {
 	struct shallow_info *si;
 };
 
-static int iterate_receive_command_list(void *cb_data, unsigned char sha1[20])
+static int iterate_receive_command_list(void *cb_data, struct object_id *oid)
 {
 	struct iterate_data *data = cb_data;
 	struct command **cmd_list = &data->cmds;
@@ -1320,7 +1320,7 @@ static int iterate_receive_command_list(void *cb_data, unsigned char sha1[20])
 			/* to be checked in update_shallow_ref() */
 			continue;
 		if (!is_null_oid(&cmd->new_oid) && !cmd->skip_update) {
-			hashcpy(sha1, cmd->new_oid.hash);
+			oidcpy(oid, &cmd->new_oid);
 			*cmd_list = cmd->next;
 			return 0;
 		}
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 2067cca5b..ab31a3b6a 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -42,7 +42,7 @@ struct expire_reflog_policy_cb {
 };
 
 struct collected_reflog {
-	unsigned char sha1[20];
+	struct object_id oid;
 	char reflog[FLEX_ARRAY];
 };
 
@@ -385,7 +385,7 @@ static int collect_reflog(const char *ref, const struct object_id *oid, int unus
 	struct collect_reflog_cb *cb = cb_data;
 
 	FLEX_ALLOC_STR(e, reflog, ref);
-	hashcpy(e->sha1, oid->hash);
+	oidcpy(&e->oid, oid);
 	ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
 	cb->e[cb->nr++] = e;
 	return 0;
@@ -589,7 +589,7 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 		for (i = 0; i < collected.nr; i++) {
 			struct collected_reflog *e = collected.e[i];
 			set_reflog_expiry_param(&cb.cmd, explicit_expiry, e->reflog);
-			status |= reflog_expire(e->reflog, e->sha1, flags,
+			status |= reflog_expire(e->reflog, &e->oid, flags,
 						reflog_expiry_prepare,
 						should_expire_reflog_ent,
 						reflog_expiry_cleanup,
@@ -601,13 +601,13 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 
 	for (; i < argc; i++) {
 		char *ref;
-		unsigned char sha1[20];
-		if (!dwim_log(argv[i], strlen(argv[i]), sha1, &ref)) {
+		struct object_id oid;
+		if (!dwim_log(argv[i], strlen(argv[i]), &oid, &ref)) {
 			status |= error("%s points nowhere!", argv[i]);
 			continue;
 		}
 		set_reflog_expiry_param(&cb.cmd, explicit_expiry, ref);
-		status |= reflog_expire(ref, sha1, flags,
+		status |= reflog_expire(ref, &oid, flags,
 					reflog_expiry_prepare,
 					should_expire_reflog_ent,
 					reflog_expiry_cleanup,
@@ -659,7 +659,7 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
 
 	for ( ; i < argc; i++) {
 		const char *spec = strstr(argv[i], "@{");
-		unsigned char sha1[20];
+		struct object_id oid;
 		char *ep, *ref;
 		int recno;
 
@@ -668,7 +668,7 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (!dwim_log(argv[i], spec - argv[i], sha1, &ref)) {
+		if (!dwim_log(argv[i], spec - argv[i], &oid, &ref)) {
 			status |= error("no reflog for '%s'", argv[i]);
 			continue;
 		}
@@ -683,7 +683,7 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
 			cb.cmd.expire_total = 0;
 		}
 
-		status |= reflog_expire(ref, sha1, flags,
+		status |= reflog_expire(ref, &oid, flags,
 					reflog_expiry_prepare,
 					should_expire_reflog_ent,
 					reflog_expiry_cleanup,
diff --git a/builtin/remote.c b/builtin/remote.c
index bc8962369..a04ea50e4 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -690,7 +690,7 @@ static int mv(int argc, const char **argv)
 		int flag = 0;
 		struct object_id oid;
 
-		read_ref_full(item->string, RESOLVE_REF_READING, oid.hash, &flag);
+		read_ref_full(item->string, RESOLVE_REF_READING, &oid, &flag);
 		if (!(flag & REF_ISSYMREF))
 			continue;
 		if (delete_ref(NULL, item->string, NULL, REF_NODEREF))
diff --git a/builtin/replace.c b/builtin/replace.c
index 3e71a7715..10078ae37 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -113,7 +113,7 @@ static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
 		strbuf_addstr(&ref, oid_to_hex(&oid));
 		full_hex = ref.buf + base_len;
 
-		if (read_ref(ref.buf, oid.hash)) {
+		if (read_ref(ref.buf, &oid)) {
 			error("replace ref '%s' not found.", full_hex);
 			had_error = 1;
 			continue;
@@ -128,7 +128,7 @@ static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
 static int delete_replace_ref(const char *name, const char *ref,
 			      const struct object_id *oid)
 {
-	if (delete_ref(NULL, ref, oid->hash, 0))
+	if (delete_ref(NULL, ref, oid, 0))
 		return 1;
 	printf("Deleted replace ref '%s'\n", name);
 	return 0;
@@ -144,7 +144,7 @@ static void check_ref_valid(struct object_id *object,
 	if (check_refname_format(ref->buf, 0))
 		die("'%s' is not a valid ref name.", ref->buf);
 
-	if (read_ref(ref->buf, prev->hash))
+	if (read_ref(ref->buf, prev))
 		oidclr(prev);
 	else if (!force)
 		die("replace ref '%s' already exists", ref->buf);
@@ -175,7 +175,7 @@ static int replace_object_oid(const char *object_ref,
 
 	transaction = ref_transaction_begin(&err);
 	if (!transaction ||
-	    ref_transaction_update(transaction, ref.buf, repl->hash, prev.hash,
+	    ref_transaction_update(transaction, ref.buf, repl, &prev,
 				   0, NULL, &err) ||
 	    ref_transaction_commit(transaction, &err))
 		die("%s", err.buf);
diff --git a/builtin/reset.c b/builtin/reset.c
index 9cd89b230..d4003f76a 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -266,12 +266,12 @@ static int reset_refs(const char *rev, const struct object_id *oid)
 	if (!get_oid("HEAD", &oid_orig)) {
 		orig = &oid_orig;
 		set_reflog_message(&msg, "updating ORIG_HEAD", NULL);
-		update_ref_oid(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
+		update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
 			   UPDATE_REFS_MSG_ON_ERR);
 	} else if (old_orig)
-		delete_ref(NULL, "ORIG_HEAD", old_orig->hash, 0);
+		delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 	set_reflog_message(&msg, "updating HEAD", rev);
-	update_ref_status = update_ref_oid(msg.buf, "HEAD", oid, orig, 0,
+	update_ref_status = update_ref(msg.buf, "HEAD", oid, orig, 0,
 				       UPDATE_REFS_MSG_ON_ERR);
 	strbuf_release(&msg);
 	return update_ref_status;
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index c1c74d4a7..9bf8d5991 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -258,14 +258,14 @@ static int show_bisect_vars(struct rev_list_info *info, int reaches, int all)
 }
 
 static int show_object_fast(
-	const unsigned char *sha1,
+	const struct object_id *oid,
 	enum object_type type,
 	int exclude,
 	uint32_t name_hash,
 	struct packed_git *found_pack,
 	off_t found_offset)
 {
-	fprintf(stdout, "%s\n", sha1_to_hex(sha1));
+	fprintf(stdout, "%s\n", oid_to_hex(oid));
 	return 1;
 }
 
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index a8d7e6f7a..74aa644cb 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -133,7 +133,7 @@ static void show_rev(int type, const struct object_id *oid, const char *name)
 			struct object_id discard;
 			char *full;
 
-			switch (dwim_ref(name, strlen(name), discard.hash, &full)) {
+			switch (dwim_ref(name, strlen(name), &discard, &full)) {
 			case 0:
 				/*
 				 * Not found -- not a ref.  We could
diff --git a/builtin/show-branch.c b/builtin/show-branch.c
index 6fa1f62a8..2e24b5c33 100644
--- a/builtin/show-branch.c
+++ b/builtin/show-branch.c
@@ -705,8 +705,8 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			static const char *fake_av[2];
 
 			fake_av[0] = resolve_refdup("HEAD",
-						    RESOLVE_REF_READING,
-						    oid.hash, NULL);
+						    RESOLVE_REF_READING, &oid,
+						    NULL);
 			fake_av[1] = NULL;
 			av = fake_av;
 			ac = 1;
@@ -720,7 +720,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			die(Q_("only %d entry can be shown at one time.",
 			       "only %d entries can be shown at one time.",
 			       MAX_REVS), MAX_REVS);
-		if (!dwim_ref(*av, strlen(*av), oid.hash, &ref))
+		if (!dwim_ref(*av, strlen(*av), &oid, &ref))
 			die(_("no such ref %s"), *av);
 
 		/* Has the base been specified? */
@@ -731,7 +731,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 				/* Ah, that is a date spec... */
 				timestamp_t at;
 				at = approxidate(reflog_base);
-				read_ref_at(ref, flags, at, -1, oid.hash, NULL,
+				read_ref_at(ref, flags, at, -1, &oid, NULL,
 					    NULL, NULL, &base);
 			}
 		}
@@ -743,7 +743,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			timestamp_t timestamp;
 			int tz;
 
-			if (read_ref_at(ref, flags, 0, base+i, oid.hash, &logmsg,
+			if (read_ref_at(ref, flags, 0, base + i, &oid, &logmsg,
 					&timestamp, &tz, NULL)) {
 				reflog = i;
 				break;
@@ -775,7 +775,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 	}
 
 	head = resolve_refdup("HEAD", RESOLVE_REF_READING,
-			      head_oid.hash, NULL);
+			      &head_oid, NULL);
 
 	if (with_current_branch && head) {
 		int has_head = 0;
diff --git a/builtin/show-ref.c b/builtin/show-ref.c
index 013d241ab..41e5e71ca 100644
--- a/builtin/show-ref.c
+++ b/builtin/show-ref.c
@@ -38,7 +38,7 @@ static void show_one(const char *refname, const struct object_id *oid)
 	if (!deref_tags)
 		return;
 
-	if (!peel_ref(refname, peeled.hash)) {
+	if (!peel_ref(refname, &peeled)) {
 		hex = find_unique_abbrev(peeled.hash, abbrev);
 		printf("%s %s^{}\n", hex, refname);
 	}
@@ -197,7 +197,7 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 			struct object_id oid;
 
 			if ((starts_with(*pattern, "refs/") || !strcmp(*pattern, "HEAD")) &&
-			    !read_ref(*pattern, oid.hash)) {
+			    !read_ref(*pattern, &oid)) {
 				show_one(*pattern, &oid);
 			}
 			else if (!quiet)
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d366e8e7b..2086f0eb0 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1382,7 +1382,7 @@ static int push_check(int argc, const char **argv, const char *prefix)
 	argv++;
 	argc--;
 	/* Get the submodule's head ref and determine if it is detached */
-	head = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
+	head = resolve_refdup("HEAD", 0, &head_oid, NULL);
 	if (!head)
 		die(_("Failed to resolve HEAD as a valid ref."));
 	if (!strcmp(head, "HEAD"))
diff --git a/builtin/tag.c b/builtin/tag.c
index b38329b59..a7e6a5b0f 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -82,7 +82,7 @@ static int for_each_tag_name(const char **argv, each_tag_name_fn fn,
 	for (p = argv; *p; p++) {
 		strbuf_reset(&ref);
 		strbuf_addf(&ref, "refs/tags/%s", *p);
-		if (read_ref(ref.buf, oid.hash)) {
+		if (read_ref(ref.buf, &oid)) {
 			error(_("tag '%s' not found."), *p);
 			had_error = 1;
 			continue;
@@ -97,7 +97,7 @@ static int for_each_tag_name(const char **argv, each_tag_name_fn fn,
 static int delete_tag(const char *name, const char *ref,
 		      const struct object_id *oid, const void *cb_data)
 {
-	if (delete_ref(NULL, ref, oid->hash, 0))
+	if (delete_ref(NULL, ref, oid, 0))
 		return 1;
 	printf(_("Deleted tag '%s' (was %s)\n"), name, find_unique_abbrev(oid->hash, DEFAULT_ABBREV));
 	return 0;
@@ -518,7 +518,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	if (strbuf_check_tag_ref(&ref, tag))
 		die(_("'%s' is not a valid tag name."), tag);
 
-	if (read_ref(ref.buf, prev.hash))
+	if (read_ref(ref.buf, &prev))
 		oidclr(&prev);
 	else if (!force)
 		die(_("tag '%s' already exists"), tag);
@@ -544,7 +544,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 
 	transaction = ref_transaction_begin(&err);
 	if (!transaction ||
-	    ref_transaction_update(transaction, ref.buf, object.hash, prev.hash,
+	    ref_transaction_update(transaction, ref.buf, &object, &prev,
 				   create_reflog ? REF_FORCE_CREATE_REFLOG : 0,
 				   reflog_msg.buf, &err) ||
 	    ref_transaction_commit(transaction, &err))
diff --git a/builtin/update-index.c b/builtin/update-index.c
index bf7420b80..fefbe6016 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -328,7 +328,7 @@ static int process_directory(const char *path, int len, struct stat *st)
 		if (S_ISGITLINK(ce->ce_mode)) {
 
 			/* Do nothing to the index if there is no HEAD! */
-			if (resolve_gitlink_ref(path, "HEAD", oid.hash) < 0)
+			if (resolve_gitlink_ref(path, "HEAD", &oid) < 0)
 				return 0;
 
 			return add_one_path(ce, path, len, st);
@@ -354,7 +354,7 @@ static int process_directory(const char *path, int len, struct stat *st)
 	}
 
 	/* No match - should we add it as a gitlink? */
-	if (!resolve_gitlink_ref(path, "HEAD", oid.hash))
+	if (!resolve_gitlink_ref(path, "HEAD", &oid))
 		return add_one_path(NULL, path, len, st);
 
 	/* Error out. */
@@ -679,9 +679,9 @@ static int unresolve_one(const char *path)
 
 static void read_head_pointers(void)
 {
-	if (read_ref("HEAD", head_oid.hash))
+	if (read_ref("HEAD", &head_oid))
 		die("No HEAD -- no initial commit yet?");
-	if (read_ref("MERGE_HEAD", merge_head_oid.hash)) {
+	if (read_ref("MERGE_HEAD", &merge_head_oid)) {
 		fprintf(stderr, "Not in the middle of a merge.\n");
 		exit(0);
 	}
@@ -721,7 +721,7 @@ static int do_reupdate(int ac, const char **av,
 		       PATHSPEC_PREFER_CWD,
 		       prefix, av + 1);
 
-	if (read_ref("HEAD", head_oid.hash))
+	if (read_ref("HEAD", &head_oid))
 		/* If there is no HEAD, that means it is an initial
 		 * commit.  Update everything in the index.
 		 */
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 6b90c5dea..cf1552b47 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -200,7 +200,7 @@ static const char *parse_cmd_update(struct ref_transaction *transaction,
 		die("update %s: extra input: %s", refname, next);
 
 	if (ref_transaction_update(transaction, refname,
-				   new_oid.hash, have_old ? old_oid.hash : NULL,
+				   &new_oid, have_old ? &old_oid : NULL,
 				   update_flags | create_reflog_flag,
 				   msg, &err))
 		die("%s", err.buf);
@@ -232,7 +232,7 @@ static const char *parse_cmd_create(struct ref_transaction *transaction,
 	if (*next != line_termination)
 		die("create %s: extra input: %s", refname, next);
 
-	if (ref_transaction_create(transaction, refname, new_oid.hash,
+	if (ref_transaction_create(transaction, refname, &new_oid,
 				   update_flags | create_reflog_flag,
 				   msg, &err))
 		die("%s", err.buf);
@@ -269,7 +269,7 @@ static const char *parse_cmd_delete(struct ref_transaction *transaction,
 		die("delete %s: extra input: %s", refname, next);
 
 	if (ref_transaction_delete(transaction, refname,
-				   have_old ? old_oid.hash : NULL,
+				   have_old ? &old_oid : NULL,
 				   update_flags, msg, &err))
 		die("%s", err.buf);
 
@@ -298,7 +298,7 @@ static const char *parse_cmd_verify(struct ref_transaction *transaction,
 	if (*next != line_termination)
 		die("verify %s: extra input: %s", refname, next);
 
-	if (ref_transaction_verify(transaction, refname, old_oid.hash,
+	if (ref_transaction_verify(transaction, refname, &old_oid,
 				   update_flags, &err))
 		die("%s", err.buf);
 
@@ -434,10 +434,10 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 		 * NULL_SHA1 as "don't care" here:
 		 */
 		return delete_ref(msg, refname,
-				  (oldval && !is_null_oid(&oldoid)) ? oldoid.hash : NULL,
+				  (oldval && !is_null_oid(&oldoid)) ? &oldoid : NULL,
 				  flags);
 	else
-		return update_ref(msg, refname, oid.hash, oldval ? oldoid.hash : NULL,
+		return update_ref(msg, refname, &oid, oldval ? &oldoid : NULL,
 				  flags | create_reflog_flag,
 				  UPDATE_REFS_DIE_ON_ERR);
 }
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 7b9307aa5..ed043d5f1 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -410,7 +410,7 @@ static void show_worktree_porcelain(struct worktree *wt)
 	if (wt->is_bare)
 		printf("bare\n");
 	else {
-		printf("HEAD %s\n", sha1_to_hex(wt->head_sha1));
+		printf("HEAD %s\n", oid_to_hex(&wt->head_oid));
 		if (wt->is_detached)
 			printf("detached\n");
 		else if (wt->head_ref)
@@ -430,7 +430,7 @@ static void show_worktree(struct worktree *wt, int path_maxlen, int abbrev_len)
 		strbuf_addstr(&sb, "(bare)");
 	else {
 		strbuf_addf(&sb, "%-*s ", abbrev_len,
-				find_unique_abbrev(wt->head_sha1, DEFAULT_ABBREV));
+				find_unique_abbrev(wt->head_oid.hash, DEFAULT_ABBREV));
 		if (wt->is_detached)
 			strbuf_addstr(&sb, "(detached HEAD)");
 		else if (wt->head_ref) {
@@ -455,7 +455,7 @@ static void measure_widths(struct worktree **wt, int *abbrev, int *maxlen)
 
 		if (path_len > *maxlen)
 			*maxlen = path_len;
-		sha1_len = strlen(find_unique_abbrev(wt[i]->head_sha1, *abbrev));
+		sha1_len = strlen(find_unique_abbrev(wt[i]->head_oid.hash, *abbrev));
 		if (sha1_len > *abbrev)
 			*abbrev = sha1_len;
 	}