log-tree: convert to struct object_id

Convert the remaining functions to take pointers to struct object_id
instead of pointers to unsigned char, and update the internals of these
functions as well.  Among these functions is a caller of lookup_tag,
which we will convert shortly.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

log-tree.c

@@ -184,7 +184,7 @@ static const struct name_decoration *current_pointed_by_HEAD(const struct name_d
 {
 	const struct name_decoration *list, *head = NULL;
 	const char *branch_name = NULL;
-	unsigned char unused[20];
+	struct object_id unused;
 	int rru_flags;
 
 	/* First find HEAD */
@@ -197,7 +197,7 @@ static const struct name_decoration *current_pointed_by_HEAD(const struct name_d
 		return NULL;
 
 	/* Now resolve and find the matching current branch */
-	branch_name = resolve_ref_unsafe("HEAD", 0, unused, &rru_flags);
+	branch_name = resolve_ref_unsafe("HEAD", 0, unused.hash, &rru_flags);
 	if (!(rru_flags & REF_ISSYMREF))
 		return NULL;
 
@@ -456,13 +456,13 @@ static void show_signature(struct rev_info *opt, struct commit *commit)
 	strbuf_release(&signature);
 }
 
-static int which_parent(const unsigned char *sha1, const struct commit *commit)
+static int which_parent(const struct object_id *oid, const struct commit *commit)
 {
 	int nth;
 	const struct commit_list *parent;
 
 	for (nth = 0, parent = commit->parents; parent; parent = parent->next) {
-		if (!hashcmp(parent->item->object.oid.hash, sha1))
+		if (!oidcmp(&parent->item->object.oid, oid))
 			return nth;
 		nth++;
 	}
@@ -481,14 +481,14 @@ static void show_one_mergetag(struct commit *commit,
 			      void *data)
 {
 	struct rev_info *opt = (struct rev_info *)data;
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct tag *tag;
 	struct strbuf verify_message;
 	int status, nth;
 	size_t payload_size, gpg_message_offset;
 
-	hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), sha1);
-	tag = lookup_tag(sha1);
+	hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), oid.hash);
+	tag = lookup_tag(oid.hash);
 	if (!tag)
 		return; /* error message already given */
 
@@ -500,7 +500,7 @@ static void show_one_mergetag(struct commit *commit,
 			  &commit->parents->next->item->object.oid))
 		strbuf_addf(&verify_message,
 			    "merged tag '%s'\n", tag->tag);
-	else if ((nth = which_parent(tag->tagged->oid.hash, commit)) < 0)
+	else if ((nth = which_parent(&tag->tagged->oid, commit)) < 0)
 		strbuf_addf(&verify_message, "tag %s names a non-parent %s\n",
 				    tag->tag, tag->tagged->oid.hash);
 	else
@@ -536,7 +536,7 @@ void show_log(struct rev_info *opt)
 	struct strbuf msgbuf = STRBUF_INIT;
 	struct log_info *log = opt->loginfo;
 	struct commit *commit = log->commit, *parent = log->parent;
-	int abbrev_commit = opt->abbrev_commit ? opt->abbrev : 40;
+	int abbrev_commit = opt->abbrev_commit ? opt->abbrev : GIT_SHA1_HEXSZ;
 	const char *extra_headers = opt->extra_headers;
 	struct pretty_print_context ctx = {0};