for_each_loose_file_in_objdir: take an optional strbuf path

We feed a root "objdir" path to this iterator function,
which then copies the result into a strbuf, so that it can
repeatedly append the object sub-directories to it. Let's
make it easy for callers to just pass us a strbuf in the
first place.

We leave the original interface as a convenience for callers
who want to just pass a const string like the result of
get_object_directory().

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1256,6 +1256,10 @@ extern int unpack_object_header(struct packed_git *, struct pack_window **, off_
  *
  * Any callback that is NULL will be ignored. Callbacks returning non-zero
  * will end the iteration.
+ *
+ * In the "buf" variant, "path" is a strbuf which will also be used as a
+ * scratch buffer, but restored to its original contents before
+ * the function returns.
  */
 typedef int each_loose_object_fn(const unsigned char *sha1,
 				 const char *path,
@@ -1271,6 +1275,11 @@ int for_each_loose_file_in_objdir(const char *path,
 				  each_loose_cruft_fn cruft_cb,
 				  each_loose_subdir_fn subdir_cb,
 				  void *data);
+int for_each_loose_file_in_objdir_buf(struct strbuf *path,
+				      each_loose_object_fn obj_cb,
+				      each_loose_cruft_fn cruft_cb,
+				      each_loose_subdir_fn subdir_cb,
+				      void *data);
 
 /*
  * Iterate over loose and packed objects in both the local

sha1_file.c

@@ -3358,31 +3358,42 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
 	return r;
 }
 
-int for_each_loose_file_in_objdir(const char *path,
+int for_each_loose_file_in_objdir_buf(struct strbuf *path,
 			    each_loose_object_fn obj_cb,
 			    each_loose_cruft_fn cruft_cb,
 			    each_loose_subdir_fn subdir_cb,
 			    void *data)
 {
-	struct strbuf buf = STRBUF_INIT;
-	size_t baselen;
+	size_t baselen = path->len;
 	int r = 0;
 	int i;
 
-	strbuf_addstr(&buf, path);
-	strbuf_addch(&buf, '/');
-	baselen = buf.len;
-
 	for (i = 0; i < 256; i++) {
-		strbuf_addf(&buf, "%02x", i);
-		r = for_each_file_in_obj_subdir(i, &buf, obj_cb, cruft_cb,
+		strbuf_addf(path, "/%02x", i);
+		r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
 						subdir_cb, data);
-		strbuf_setlen(&buf, baselen);
+		strbuf_setlen(path, baselen);
 		if (r)
 			break;
 	}
 
+	return r;
+}
+
+int for_each_loose_file_in_objdir(const char *path,
+				  each_loose_object_fn obj_cb,
+				  each_loose_cruft_fn cruft_cb,
+				  each_loose_subdir_fn subdir_cb,
+				  void *data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int r;
+
+	strbuf_addstr(&buf, path);
+	r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
+					      subdir_cb, data);
 	strbuf_release(&buf);
+
 	return r;
 }