Add "git-prune-packed" that removes objects that exist in a pack.

This, together with "git repack" can be used to clean up unpacked
git archives.

Makefile

@@ -43,7 +43,7 @@ PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-get-tar-commit-id git-apply git-stripspace \
 	git-cvs2git git-diff-stages git-rev-parse git-patch-id \
 	git-pack-objects git-unpack-objects git-verify-pack \
-	git-receive-pack git-send-pack
+	git-receive-pack git-send-pack git-prune-packed
 
 all: $(PROG)
 
@@ -138,6 +138,7 @@ git-unpack-objects: unpack-objects.c
 git-verify-pack: verify-pack.c
 git-receive-pack: receive-pack.c
 git-send-pack: send-pack.c
+git-prune-packed: prune-packed.c
 
 git-http-pull: LIBS += -lcurl
 git-rev-list: LIBS += -lssl

prune-packed.c

@@ -0,0 +1,66 @@
+#include "cache.h"
+
+static const char prune_packed_usage[] = "git-prune-packed: usage: git-prune-packed";
+
+static void prune_dir(int i, DIR *dir, char *pathname, int len)
+{
+	struct dirent *de;
+	char hex[40];
+
+	sprintf(hex, "%02x", i);
+	while ((de = readdir(dir)) != NULL) {
+		unsigned char sha1[20];
+		if (strlen(de->d_name) != 38)
+			continue;
+		memcpy(hex+2, de->d_name, 38);
+		if (get_sha1_hex(hex, sha1))
+			continue;
+		if (!has_sha1_pack(sha1))
+			continue;
+		memcpy(pathname + len, de->d_name, 38);
+		if (unlink(pathname) < 0)
+			error("unable to unlink %s", pathname);
+	}
+}
+
+static void prune_packed_objects(void)
+{
+	int i;
+	static char pathname[PATH_MAX];
+	const char *dir = get_object_directory();
+	int len = strlen(dir);
+
+	if (len > PATH_MAX - 42)
+		die("impossible object directory");
+	memcpy(pathname, dir, len);
+	if (len && pathname[len-1] != '/')
+		pathname[len++] = '/';
+	for (i = 0; i < 256; i++) {
+		DIR *d;
+
+		sprintf(pathname + len, "%02x/", i);
+		d = opendir(pathname);
+		if (!d)
+			die("unable to open %s", pathname);
+		prune_dir(i, d, pathname, len + 3);
+		closedir(d);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int i;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+
+		if (*arg == '-') {
+			/* Handle flags here .. */
+			usage(prune_packed_usage);
+		}
+		/* Handle arguments here .. */
+		usage(prune_packed_usage);
+	}
+	prune_packed_objects();
+	return 0;
+}