read(2) and thus bsdiff is limited to 2^31 bytes

[Conrad Meyer]

On Sun, May 22, 2016 at 4:10 PM, Joerg Sonnenberger <joerg at bec.de> wrote:
> On Sun, May 22, 2016 at 03:56:33PM -0700, Conrad Meyer wrote:
>> ERRORS
>>      The read(), readv(), pread() and preadv() system calls will succeed
>>      unless:
>> ...
>>      [EINVAL]           The value nbytes is greater than INT_MAX.
>>
>> It does seem silly to me given nbytes is a size_t.  I think it should
>> error if nbytes is greater than SSIZE_T_MAX, but on platforms where
>> size_t is larger than int (e.g. amd64) it shouldn't error for nbytes
>> in [INT_MAX, SSIZE_T_MAX - 1].
>
> There are a lot of valid reasons for not doing arbitrarily large
> operations, especially since a certain amount of atomicity is expected
> for local IO. That doesn't mean that it can't be turned into a short
> read/write instead. Erroring out seeems completely unjustified.

Sure; those reasons also apply to INT_MAX-sized IOs (2 GB).

Conrad