[PATCH v2 02/19] builtin/diff-tree: convert to struct object_id

["brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx>]

Convert most leaf functions to struct object_id.  Rewrite several
hardcoded numbers in terms of GIT_SHA1_HEXSZ, using an intermediate
variable where that makes sense.

Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx>
---
 builtin/diff-tree.c | 38 ++++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index 806dd7a885..516860e4f9 100644
--- a/builtin/diff-tree.c
+++ b/builtin/diff-tree.c
@@ -7,9 +7,9 @@
 
 static struct rev_info log_tree_opt;
 
-static int diff_tree_commit_sha1(const unsigned char *sha1)
+static int diff_tree_commit_sha1(const struct object_id *oid)
 {
-	struct commit *commit = lookup_commit_reference(sha1);
+	struct commit *commit = lookup_commit_reference(oid->hash);
 	if (!commit)
 		return -1;
 	return log_tree_commit(&log_tree_opt, commit);
@@ -18,22 +18,22 @@ static int diff_tree_commit_sha1(const unsigned char *sha1)
 /* Diff one or more commits. */
 static int stdin_diff_commit(struct commit *commit, char *line, int len)
 {
-	unsigned char sha1[20];
-	if (isspace(line[40]) && !get_sha1_hex(line+41, sha1)) {
+	struct object_id oid;
+	if (isspace(line[GIT_SHA1_HEXSZ]) && !get_oid_hex(line+GIT_SHA1_HEXSZ+1, &oid)) {
 		/* Graft the fake parents locally to the commit */
-		int pos = 41;
+		int pos = GIT_SHA1_HEXSZ + 1;
 		struct commit_list **pptr;
 
 		/* Free the real parent list */
 		free_commit_list(commit->parents);
 		commit->parents = NULL;
 		pptr = &(commit->parents);
-		while (line[pos] && !get_sha1_hex(line + pos, sha1)) {
-			struct commit *parent = lookup_commit(sha1);
+		while (line[pos] && !get_oid_hex(line + pos, &oid)) {
+			struct commit *parent = lookup_commit(oid.hash);
 			if (parent) {
 				pptr = &commit_list_insert(parent, pptr)->next;
 			}
-			pos += 41;
+			pos += GIT_SHA1_HEXSZ + 1;
 		}
 	}
 	return log_tree_commit(&log_tree_opt, commit);
@@ -42,11 +42,13 @@ static int stdin_diff_commit(struct commit *commit, char *line, int len)
 /* Diff two trees. */
 static int stdin_diff_trees(struct tree *tree1, char *line, int len)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct tree *tree2;
-	if (len != 82 || !isspace(line[40]) || get_sha1_hex(line + 41, sha1))
+	const int chunksz = GIT_SHA1_HEXSZ + 1;
+	if (len != 2 * chunksz || !isspace(line[chunksz-1]) ||
+		get_sha1_hex(line + chunksz, oid.hash))
 		return error("Need exactly two trees, separated by a space");
-	tree2 = lookup_tree(sha1);
+	tree2 = lookup_tree(oid.hash);
 	if (!tree2 || parse_tree(tree2))
 		return -1;
 	printf("%s %s\n", oid_to_hex(&tree1->object.oid),
@@ -60,15 +62,15 @@ static int stdin_diff_trees(struct tree *tree1, char *line, int len)
 static int diff_tree_stdin(char *line)
 {
 	int len = strlen(line);
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct object *obj;
 
 	if (!len || line[len-1] != '\n')
 		return -1;
 	line[len-1] = 0;
-	if (get_sha1_hex(line, sha1))
+	if (get_oid_hex(line, &oid))
 		return -1;
-	obj = parse_object(sha1);
+	obj = parse_object(oid.hash);
 	if (!obj)
 		return -1;
 	if (obj->type == OBJ_COMMIT)
@@ -76,7 +78,7 @@ static int diff_tree_stdin(char *line)
 	if (obj->type == OBJ_TREE)
 		return stdin_diff_trees((struct tree *)obj, line, len);
 	error("Object %s is a %s, not a commit or tree",
-	      sha1_to_hex(sha1), typename(obj->type));
+	      oid_to_hex(&oid), typename(obj->type));
 	return -1;
 }
 
@@ -141,7 +143,7 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 		break;
 	case 1:
 		tree1 = opt->pending.objects[0].item;
-		diff_tree_commit_sha1(tree1->oid.hash);
+		diff_tree_commit_sha1(&tree1->oid);
 		break;
 	case 2:
 		tree1 = opt->pending.objects[0].item;
@@ -166,9 +168,9 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 			opt->diffopt.setup |= (DIFF_SETUP_USE_SIZE_CACHE |
 					       DIFF_SETUP_USE_CACHE);
 		while (fgets(line, sizeof(line), stdin)) {
-			unsigned char sha1[20];
+			struct object_id oid;
 
-			if (get_sha1_hex(line, sha1)) {
+			if (get_oid_hex(line, &oid)) {
 				fputs(line, stdout);
 				fflush(stdout);
 			}
-- 
2.11.0