- memcpy(save, buf + brk, sf);
- buf[brk + sf - 1] = buf[brk - 1];
- memcpy(buf + brk - 1, suffix, sf);
- safe_write(err, buf, brk + sf);
- memcpy(buf + brk, save, sf);
- } else
- safe_write(err, buf, brk);
+ memcpy(save, b + brk, sf);
+ b[brk + sf - 1] = b[brk - 1];
+ memcpy(b + brk - 1, suffix, sf);
+ safe_write(err, b, brk + sf);
+ memcpy(b + brk, save, sf);
+ len -= brk;
+ } else {
+ int l = brk ? brk : len;
+ safe_write(err, b, l);
+ len -= l;
+ }