Re: [Bug-cpio] wrong handling of write(2) errors

[Vasiliy Kulikov]

Hi Sergey,

On Mon, Sep 19, 2011 at 03:19 +0300, Sergey Poznyakoff wrote:
> @@ -136,13 +136,16 @@ disk_empty_output_buffer (int out_des)
>      }
>  
>    if (sparse_flag)
> -    bytes_written = sparse_write (out_des, output_buffer, output_size);
> +    bytes_written = sparse_write (out_des, output_buffer, output_size, 
> flush);
>    else
>      bytes_written = write (out_des, output_buffer, output_size);
>  
>    if (bytes_written != output_size)
>      {
> -      error (1, errno, _("write error"));
> +      if (bytes_written == -1)
> +     error (1, errno, _("write error"));
> +      else
> +     error (1, 0, _("write error: partial write"));
>      }
>    output_bytes += output_size;
>    out_buff = output_buffer;
[...]
> +static ssize_t
> +sparse_write (int fildes, char *buf, size_t nbytes, bool flush)
>  {
[...]
> +               n = write (fildes, start_ptr, bytes);
> +               if (n == -1)
> +                 return -1;
> +               nwritten += n;
> +               if (n < bytes)
> +                 return nwritten + seek_count;

Do we really want to alert in the case of a partial write?  Probably it's
better to retry from the interrupted point as it is a fully valid case.
Of course 0 and -1 returned are good to propagate to the upper level (to
disk_empty_output_buffer()).

Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments