+/*
+ * Adjacent cache entries tend to share the leading paths, so it makes
+ * sense to only store the differences in later entries. In the v4
+ * on-disk format of the index, each on-disk cache entry stores the
+ * number of bytes to be stripped from the end of the previous name,
+ * and the bytes to append to the result, to come up with its name.
+ */
+static unsigned long expand_name_field(struct strbuf *name, const char *cp_)
+{
+ const unsigned char *ep, *cp = (const unsigned char *)cp_;
+ size_t len = decode_varint(&cp);
+
+ if (name->len < len)
+ die("malformed name field in the index");
+ strbuf_remove(name, name->len - len, len);
+ for (ep = cp; *ep; ep++)
+ ; /* find the end */
+ strbuf_add(name, cp, ep - cp);
+ return (const char *)ep + 1 - cp_;
+}
+