[PATCH] Optionally tell show-diff to show only named files

SCMs have ways to say "I want diff only this particular file",
or "I want diff files under this directory".  This patch teaches
show-diff to do something similar.  Without command line
arguments, it still examines everything in the dircache as
before.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/show-diff.c b/show-diff.c
index 6f343c5..f9e8c12 100644 (file)
--- a/show-diff.c
+++ b/show-diff.c
@@ -55,6 +55,23 @@ static void show_diff_empty(struct cache_entry *ce)
        }
 }
 
+static const char *show_diff_usage = "show-diff [-s] [-q] [paths...]";
+
+static int matches_pathspec(struct cache_entry *ce, char **spec, int cnt)
+{
+       int i;
+       int namelen = ce_namelen(ce);
+       for (i = 0; i < cnt; i++) {
+               int speclen = strlen(spec[i]);
+               if (! strncmp(spec[i], ce->name, speclen) &&
+                   speclen <= namelen &&
+                   (ce->name[speclen] == 0 ||
+                    ce->name[speclen] == '/'))
+                       return 1;
+       }
+       return 0;
+}
+
 int main(int argc, char **argv)
 {
        int silent = 0;
@@ -62,18 +79,19 @@ int main(int argc, char **argv)
        int entries = read_cache();
        int i;
 
-       for (i = 1; i < argc; i++) {
-               if (!strcmp(argv[i], "-s")) {
+       while (1 < argc && argv[1][0] == '-') {
+               if (!strcmp(argv[1], "-s"))
                        silent_on_nonexisting_files = silent = 1;
-                       continue;
-               }
-               if (!strcmp(argv[i], "-q")) {
+               else if (!strcmp(argv[1], "-q"))
                        silent_on_nonexisting_files = 1;
-                       continue;
-               }
-               usage("show-diff [-s] [-q]");
+               else
+                       usage(show_diff_usage);
+               argv++; argc--;
        }
 
+       /* At this point, if argc == 1, then we are doing everything.
+        * Otherwise argv[1] .. argv[argc-1] have the explicit paths.
+        */
        if (entries < 0) {
                perror("read_cache");
                exit(1);
@@ -86,6 +104,10 @@ int main(int argc, char **argv)
                char type[20];
                void *new;
 
+               if (1 <argc &&
+                   ! matches_pathspec(ce, argv+1, argc-1))
+                       continue;
+
                if (stat(ce->name, &st) < 0) {
                        if (errno == ENOENT && silent_on_nonexisting_files)
                                continue;