bug#8294: Minor nit with dd

[Paul Eggert]

On 03/19/2011 11:26 AM, John Morris wrote:
> On a 64bit platform shouldn't the following command have done the
> expected thing instead of quietly clipping to 231?

It depends on what your platform's 64-bit 'read'
system call does.  My guess is that your platform's
'read' syscall refuses to read more than
2**31 - 2**12 bytes at a time from /dev/zero,
so the problem (if any :-) is with 'read', not
with 'dd'.