+typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
+
+struct disambiguate_state {
+ disambiguate_hint_fn fn;
+ void *cb_data;
+ unsigned char candidate[20];
+ unsigned candidate_exists:1;
+ unsigned candidate_checked:1;
+ unsigned candidate_ok:1;
+ unsigned disambiguate_fn_used:1;
+ unsigned ambiguous:1;
+ unsigned always_call_fn:1;
+};
+
+static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
+{
+ if (ds->always_call_fn) {
+ ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
+ return;
+ }
+ if (!ds->candidate_exists) {
+ /* this is the first candidate */
+ hashcpy(ds->candidate, current);
+ ds->candidate_exists = 1;
+ return;
+ } else if (!hashcmp(ds->candidate, current)) {
+ /* the same as what we already have seen */
+ return;
+ }
+
+ if (!ds->fn) {
+ /* cannot disambiguate between ds->candidate and current */
+ ds->ambiguous = 1;
+ return;
+ }
+
+ if (!ds->candidate_checked) {
+ ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
+ ds->disambiguate_fn_used = 1;
+ ds->candidate_checked = 1;
+ }
+
+ if (!ds->candidate_ok) {
+ /* discard the candidate; we know it does not satisify fn */
+ hashcpy(ds->candidate, current);
+ ds->candidate_checked = 0;
+ return;
+ }
+
+ /* if we reach this point, we know ds->candidate satisfies fn */
+ if (ds->fn(current, ds->cb_data)) {
+ /*
+ * if both current and candidate satisfy fn, we cannot
+ * disambiguate.
+ */
+ ds->candidate_ok = 0;
+ ds->ambiguous = 1;
+ }
+
+ /* otherwise, current can be discarded and candidate is still good */
+}
+
+static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)