+static int do_reupdate(int ac, const char **av,
+ const char *prefix, int prefix_length)
+{
+ /* Read HEAD and run update-index on paths that are
+ * merged and already different between index and HEAD.
+ */
+ int pos;
+ int has_head = 1;
+ const char **pathspec = get_pathspec(prefix, av + 1);
+
+ if (read_ref(git_path("HEAD"), head_sha1))
+ /* If there is no HEAD, that means it is an initial
+ * commit. Update everything in the index.
+ */
+ has_head = 0;
+ redo:
+ for (pos = 0; pos < active_nr; pos++) {
+ struct cache_entry *ce = active_cache[pos];
+ struct cache_entry *old = NULL;
+ int save_nr;
+
+ if (ce_stage(ce) || !ce_path_match(ce, pathspec))
+ continue;
+ if (has_head)
+ old = read_one_ent(NULL, head_sha1,
+ ce->name, ce_namelen(ce), 0);
+ if (old && ce->ce_mode == old->ce_mode &&
+ !memcmp(ce->sha1, old->sha1, 20)) {
+ free(old);
+ continue; /* unchanged */
+ }
+ /* Be careful. The working tree may not have the
+ * path anymore, in which case, under 'allow_remove',
+ * or worse yet 'allow_replace', active_nr may decrease.
+ */
+ save_nr = active_nr;
+ update_one(ce->name + prefix_length, prefix, prefix_length);
+ if (save_nr != active_nr)
+ goto redo;
+ }
+ return 0;
+}
+