[Octave-bug-tracker] [bug #66399] fseek and ftell functions don't always work correctly on Win11 with filesizes >2GB

[Paul Eggert]

Follow-up Comment #13, bug #66399 (group octave):


> Should we also avoid to use `fseek` with pipes?

C code should avoid fseek; always use fseeko. Although fseek should work with
small-enough offsets why ask for trouble?

If you use fseeko on a pipe, it should either work (if it's a small seek that
stays within the I/O buffer) or fail with errno=ESPIPE; it can also fail for
other reasons.

I don't know about std::fseeko, as I don't use C++. However, Gnulib does
attempt to make its fseeko replacement visible to C++ using the usual
namespace rules. Perhaps this is relevant to your problem, but you'll need a
C++ expert to diagnose it.

I see that you do appear to be trying to work around the issue with
octave_fseeko_wrapper, which I don't fully understand. If you have that, why
use std::fseek in libinterp/corefcn/gl2ps-print.cc? Shouldn't that code use
octave_lseeko_wrapper instead?

Bruno Haible knows C++ and MS-Windows (I know neither), and I hope he'll reply
again on bug-gnulib and clear up some of the confusion here.


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