Function output

src/tac.c:152–183

   If START is null, just flush the buffer. */

static void
output (char const *start, char const *past_end)
{
  static char buffer[WRITESIZE];
  static size_t bytes_in_buffer = 0;
  size_t bytes_to_add = past_end - start;
  size_t bytes_available = WRITESIZE - bytes_in_buffer;

  if (!start)
    {
      if (full_write (STDOUT_FILENO, buffer, bytes_in_buffer)
          != bytes_in_buffer)
        write_error ();
      bytes_in_buffer = 0;
      return;
    }

  /* Write out as many full buffers as possible. */
  while (bytes_to_add >= bytes_available)
    {
      memcpy (buffer + bytes_in_buffer, start, bytes_available);
      bytes_to_add -= bytes_available;
      start += bytes_available;
      if (full_write (STDOUT_FILENO, buffer, WRITESIZE) != WRITESIZE)
        write_error ();
      bytes_in_buffer = 0;
      bytes_available = WRITESIZE;
    }

  memcpy (buffer + bytes_in_buffer, start, bytes_to_add);
  bytes_in_buffer += bytes_to_add;
}

/* Print in reverse the file open on descriptor FD for reading FILE.
   The file is already positioned at FILE_POS, which should be near its end.