"A month of sundays ago Mike Galbraith wrote:"
> On Sun, 13 Feb 2000, Mike Galbraith wrote:
>
> diff -urN linux-2.3.44.virgin/fs/proc/generic.c linux-2.3.44.test/fs/proc/generic.c
> --- linux-2.3.44.virgin/fs/proc/generic.c Fri Feb 11 14:32:40 2000
> +++ linux-2.3.44.ikd/fs/proc/generic.c Fri Feb 11 12:50:39 2000
> @@ -106,6 +106,11 @@
> * return the bytes, and set `start' to the desired offset
> * as an unsigned int. - Paul.Russell@rustcorp.com.au
> */
> + /* Ensure that the data will fit when using the ppos hack,
> + * otherwise userland receives truncated data.
> + */
> + if (n > count-1 && start && start < page)
> + break;
> n -= copy_to_user(buf, start < page ? page : start, n);
> if (n == 0) {
> if (retval == 0)
>
Thanks for drawing my attention to this function. It's where the
proc_info functions are called from. Unless I am mad, its logic is
either weird or incorrect. It certainly needs attention. But ...
just setting start to the number of bytes returned each time seems
to do the trick for me. No patching required. Full data returned
and no truncation. I don't completely see why. That section
of code is awful!
Peter
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