+ ent->base[pfxlen + 3] = '/';
+ ent->base[pfxlen] = ent->base[entlen-1] = 0;
+
+ /* Detect cases where alternate disappeared */
+ if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
+ error("object directory %s does not exist; "
+ "check .git/objects/info/alternates.",
+ ent->base);
+ goto bad;
+ }
+ ent->base[pfxlen] = '/';
+
+ /* Prevent the common mistake of listing the same
+ * thing twice, or object directory itself.
+ */
+ for (alt = alt_odb_list; alt; alt = alt->next)
+ if (!memcmp(ent->base, alt->base, pfxlen))
+ goto bad;
+ if (!memcmp(ent->base, objdir, pfxlen)) {
+ bad:
+ free(ent);
+ }
+ else {
+ *alt_odb_tail = ent;
+ alt_odb_tail = &(ent->next);
+ ent->next = NULL;
+ }