Looks like I was overly cautious about decrementing an unsigned...

size_t n = bytes_read;
while (n)
  {
    if (all_lines)
      n -= n ? 1 : 0;        // ...here.
    else

As it is under `while (n)' statement, n is always true here, and thus the ternary operator, though makes no
harm, is needless, and the whole line can be replaced with just `n--;'. Sorry for that.

The fixed version of the original patch is attached.

-- 
Алексей Шилин