rem: while (n_lines)
add: while (1)
context: start_lines (const char *pretty_filename, int fd, long int n_lines){  char buffer[BUFSIZ];  size_t bytes_read = 0;  size_t bytes_to_skip = 0;  if (n_lines == 0)    return 0;  while (n_lines)    {      bytes_to_skip = 0;      bytes_read = safe_read (fd, buffer, BUFSIZ);      if (bytes_read == 0) /* EOF */	return -1;      if (bytes_read == SAFE_READ_ERROR) /* error */	{	  error (0, errno, "%s", pretty_filename);	  return 1;	}      while (bytes_to_skip < bytes_read)	if (buffer[bytes_to_skip++] == '\n' && --n_lines == 0)	  break;    }  if (bytes_to_skip < bytes_read)    {      xwrite (STDOUT_FILENO, &buffer[bytes_to_skip],	      bytes_read - bytes_to_skip);    }  return 0;}