+/* Moves the bytes in ST following offset OFS + OLD_LEN in ST to offset OFS +
+ NEW_LEN and returns the byte at offset OFS. The first min(OLD_LEN, NEW_LEN)
+ bytes at the returned position are unchanged; if NEW_LEN > OLD_LEN then the
+ following NEW_LEN - OLD_LEN bytes are initially indeterminate.
+
+ The intention is that the caller should write NEW_LEN bytes at the returned
+ position, to effectively replace the OLD_LEN bytes previously at that
+ position. */
+char *
+ds_splice_uninit (struct string *st,
+ size_t ofs, size_t old_len, size_t new_len)
+{
+ if (new_len != old_len)
+ {
+ if (new_len > old_len)
+ ds_extend (st, ds_length (st) + (new_len - old_len));
+ memmove (ds_data (st) + (ofs + new_len),
+ ds_data (st) + (ofs + old_len),
+ ds_length (st) - (ofs + old_len));
+ st->ss.length += new_len - old_len;
+ }
+ return ds_data (st) + ofs;
+}
+