Support a fine-grained diff-tree

This is based on a patch by David Woodhouse, but with the selection
tests much simplified and streamlined.

It makes diff-tree take extra arguments, specifying the files or
directories which should be considered "interesting". Changes in
uninteresting directories are not reported.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/diff-tree.c b/diff-tree.c
index 0f37092..618fdb6 100644 (file)
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -3,6 +3,11 @@
 static int recursive = 0;
 static int line_termination = '\n';
 
+// What paths are we interested in?
+static int nr_paths = 0;
+static char **paths = NULL;
+static int *pathlens = NULL;
+
 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)
@@ -131,9 +136,63 @@ static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, uns
        return 0;
 }
 
+static int interesting(void *tree, unsigned long size, const char *base)
+{
+       const char *path;
+       unsigned mode;
+       int i;
+       int baselen, pathlen;
+
+       if (!nr_paths)
+               return 1;
+
+       (void)extract(tree, size, &path, &mode);
+
+       pathlen = strlen(path);
+       baselen = strlen(base);
+
+       for (i=0; i < nr_paths; i++) {
+               const char *match = paths[i];
+               int matchlen = pathlens[i];
+
+               if (baselen >= matchlen) {
+                       /* If it doesn't match, move along... */
+                       if (strncmp(base, match, matchlen))
+                               continue;
+
+                       /* The base is a subdirectory of a path which was specified. */
+                       return 1;
+               }
+
+               /* Does the base match? */
+               if (strncmp(base, match, baselen))
+                       continue;
+
+               match += baselen;
+               matchlen -= baselen;
+
+               if (pathlen > matchlen)
+                       continue;
+
+               if (strncmp(path, match, pathlen))
+                       continue;
+
+               return 1;
+       }
+       return 0; /* No matches */
+}
+
 static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2, const char *base)
 {
        while (size1 | size2) {
+               if (nr_paths && size1 && !interesting(tree1, size1, base)) {
+                       update_tree_entry(&tree1, &size1);
+                       continue;
+               }
+               if (nr_paths && size2 && !interesting(tree2, size2, base)) {
+                       update_tree_entry(&tree2, &size2);
+                       continue;
+               }
                if (!size1) {
                        show_file("+", tree2, size2, base);
                        update_tree_entry(&tree2, &size2);
@@ -184,8 +243,12 @@ int main(int argc, char **argv)
 {
        unsigned char old[20], new[20];
 
-       while (argc > 3) {
+       for (;;) {
                char *arg = argv[1];
+
+               if (!arg || *arg != '-')
+                       break;
+
                argv++;
                argc--;
                if (!strcmp(arg, "-r")) {
@@ -199,7 +262,18 @@ int main(int argc, char **argv)
                usage(diff_tree_usage);
        }
 
-       if (argc != 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
+       if (argc < 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
                usage(diff_tree_usage);
+
+       if (argc > 3) {
+               int i;
+
+               paths = &argv[3];
+               nr_paths = argc - 3;
+               pathlens = malloc(nr_paths * sizeof(int));
+               for (i=0; i<nr_paths; i++)
+                       pathlens[i] = strlen(paths[i]);
+       }
+
        return diff_tree_sha1(old, new, "");
 }