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Re: moot and unposixy error message
From: |
Benno Schulenberg |
Subject: |
Re: moot and unposixy error message |
Date: |
Tue, 19 Aug 2008 23:03:58 +0200 |
User-agent: |
KMail/1.9.9 |
Andreas Schwab wrote:
> But the sum can overflow, and since the involved types are
> unsigned this has defined (wrap-around) behaviour.
Thanks. I felt I must be overlooking something, but couldn't figure
out what.
> > Further, the Open Group says that 'od' should not produce an
> > error when '-j' plus '-N' is longer than the file, so the above
> > section can be removed.
>
> This is a good point, however. But end_offset should then be set
> to (uintmax_t)-1 on overflow.
Setting end_offset to the largest possible integer upon overflow
will probably do the right thing in all practical cases; but if the
file is really longer than an integer can represent, it would then
output the wrong number of bytes. Better print an error message
instead then.
$ od -j1 -N18446744073709551615 testfile
od: skip-bytes + read-bytes is too large
$ od -j1 -N18446744073709551616 testfile
od: -N argument `18446744073709551616' too large
$ od -j18446744073709551616 -N1 testfile
od: -j argument `18446744073709551616' too large
$ od -j18446744073709551615 -N1 testmail.k
od: skip-bytes + read-bytes is too large
Benno