Re: [PATCH] dd: don't discard data with if=fullblock

[Pádraig Brady]

On 28/02/11 09:28, Pádraig Brady wrote:
> I just noticed that dd may discard read data
> in the presence of I/O errors.
> Would something like this suffice?
> 
> cheers,
> Pádraig.
> 
> diff --git a/src/dd.c b/src/dd.c
> index 1a0e177..a1d47ff 100644
> --- a/src/dd.c
> +++ b/src/dd.c
> @@ -811,12 +811,28 @@ static ssize_t
>  iread_fullblock (int fd, char *buf, size_t size)
>  {
>    ssize_t nread = 0;
> +  static iread_errno;
> +
> +  /* Return a pending error.  */
> +  if (iread_errno)
> +    {
> +      errno = iread_errno;
> +      iread_errno = 0;
> +      return -1;
> +    }
> 
>    while (0 < size)
>      {
>        ssize_t ncurr = iread (fd, buf, size);
>        if (ncurr < 0)
> -        return ncurr;
> +        {
> +          if (nread > 0)
> +            {
> +              iread_errno = errno;
> +              ncurr = nread;
> +            }
> +          return ncurr;
> +        }
>        if (ncurr == 0)
>          break;
>        nread += ncurr;

Hmm, this issue is largely theoretical as we won't
be getting short reads from files in the first place
where we could get EIO.

I'll leave this for the moment