bug#9157: [PATCH] dd: sparse conv flag

[Paul Eggert]

Thanks for looking into this!  Some nits:

On 02/27/2012 07:20 AM, Pádraig Brady wrote:
> +is_nul (const char* buf, size_t bufsize)

The usual spacing style is "const char *buf", since the
"*" really belongs to the "buf" in C.

> +  memset (obuf + output_blocksize, 1, sizeof (uintptr_t));

This constraint on OUTPUT_BLOCK_SLOP should be documented, thus:

#define OUTPUT_BLOCK_SLOP MAX (sizeof (uintptr_t), page_size - 1)

> +  /* write sentinel to slop after the buffer,
> +     to allow efficient checking for NUL blocks.  */

Initial cap for sentence.  The next comment has a similar issue.