Simplify "diff-tree" output, and only keep track of one single name-b…

…ase.

During original development I had different name-bases for source and
destination, so that I could make the output show how it got removed 
from "tree a" and added to "tree b", but we don't want that. We only
do recursive diffs on anything where the bases are exactly the same,
so we might as well just work with a single base.

Also, make the output for "changed" be a single line, since people
hated the separate '<' / '>' format. They were right. It sucked.

diff-tree.c

@@ -2,7 +2,7 @@
 
 static int recursive = 0;
 
-static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *src, const char *dst);
+static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base);
 
 static void update_tree_entry(void **bufp, unsigned long *sizep)
 {
@@ -36,12 +36,13 @@ static void show_file(const char *prefix, void *tree, unsigned long size, const
 	printf("%s%o %s %s%s%c", prefix, mode, sha1_to_hex(sha1), base, path, 0);
 }
 
-static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *src, const char *dst)
+static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *base)
 {
 	unsigned mode1, mode2;
 	const char *path1, *path2;
 	const unsigned char *sha1, *sha2;
 	int cmp, pathlen1, pathlen2;
+	char old_sha1_hex[50];
 
 	sha1 = extract(tree1, size1, &path1, &mode1);
 	sha2 = extract(tree2, size2, &path2, &mode2);
@@ -50,48 +51,46 @@ static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, uns
 	pathlen2 = strlen(path2);
 	cmp = cache_name_compare(path1, pathlen1, path2, pathlen2);
 	if (cmp < 0) {
-		show_file("-", tree1, size1, src);
+		show_file("-", tree1, size1, base);
 		return -1;
 	}
 	if (cmp > 0) {
-		show_file("+", tree2, size2, dst);
+		show_file("+", tree2, size2, base);
 		return 1;
 	}
 	if (!memcmp(sha1, sha2, 20) && mode1 == mode2)
 		return 0;
 	if (recursive && S_ISDIR(mode1) && S_ISDIR(mode2)) {
-		int srclen = strlen(src);
-		int dstlen = strlen(dst);
-		char *srcbase = malloc(srclen + pathlen1 + 2);
-		char *dstbase = malloc(srclen + pathlen1 + 2);
-		memcpy(srcbase, src, srclen);
-		memcpy(srcbase + srclen, path1, pathlen1);
-		memcpy(srcbase + srclen + pathlen1, "/", 2);
-		memcpy(dstbase, dst, dstlen);
-		memcpy(dstbase + dstlen, path2, pathlen2);
-		memcpy(dstbase + dstlen + pathlen2, "/", 2);
-		return diff_tree_sha1(sha1, sha2, srcbase, dstbase);
+		int retval;
+		int baselen = strlen(base);
+		char *newbase = malloc(baselen + pathlen1 + 2);
+		memcpy(newbase, base, baselen);
+		memcpy(newbase + baselen, path1, pathlen1);
+		memcpy(newbase + baselen + pathlen1, "/", 2);
+		retval = diff_tree_sha1(sha1, sha2, newbase);
+		free(newbase);
+		return retval;
 	}
 
-	show_file("<", tree1, size1, src);
-	show_file(">", tree2, size2, dst);
+	strcpy(old_sha1_hex, sha1_to_hex(sha1));
+	printf("*%o->%o %s->%s %s%s%c", mode1, mode2, old_sha1_hex, sha1_to_hex(sha2), base, path1, 0);
 	return 0;
 }
 
-static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *src, const char *dst)
+static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *base)
 {
 	while (size1 | size2) {
 		if (!size1) {
-			show_file("+", tree2, size2, dst);
+			show_file("+", tree2, size2, base);
 			update_tree_entry(&tree2, &size2);
 			continue;
 		}
 		if (!size2) {
-			show_file("-", tree1, size1, src);
+			show_file("-", tree1, size1, base);
 			update_tree_entry(&tree1, &size1);
 			continue;
 		}
-		switch (compare_tree_entry(tree1, size1, tree2, size2, src, dst)) {
+		switch (compare_tree_entry(tree1, size1, tree2, size2, base)) {
 		case -1:
 			update_tree_entry(&tree1, &size1);
 			continue;
@@ -107,7 +106,7 @@ static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned lon
 	return 0;
 }
 
-static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *src, const char *dst)
+static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base)
 {
 	void *tree1, *tree2;
 	unsigned long size1, size2;
@@ -120,7 +119,7 @@ static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, co
 	tree2 = read_sha1_file(new, type, &size2);
 	if (!tree2 || strcmp(type, "tree"))
 		usage("unable to read destination tree");
-	retval = diff_tree(tree1, size1, tree2, size2, src, dst);
+	retval = diff_tree(tree1, size1, tree2, size2, base);
 	free(tree1);
 	free(tree2);
 	return retval;
@@ -143,5 +142,5 @@ int main(int argc, char **argv)
 
 	if (argc != 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
 		usage("diff-tree <tree sha1> <tree sha1>");
-	return diff_tree_sha1(old, new, "", "");
+	return diff_tree_sha1(old, new, "");
 }