[vorbis] Seekable test

[Olaf van der Spek]

----- Original Message -----
From: "Michael Smith" <msmith at labyrinth.net.au>
To: <vorbis at xiph.org>
Sent: Thursday, December 28, 2000 4:47 PM
Subject: Re: [vorbis] Seekable test

> At 04:23 PM 12/28/00 +0100, you wrote:
> >Hi,
> >
> >I'm trying to get the callbacks to work.
> >In my docs, I read this:
> >If successful, fseek returns 0. Otherwise, it returns a nonzero value. On
> >devices incapable of seeking, the return value is undefined.
> >
>
> >I think this should be: if (!offset) or if (offset != 0)
>
> Probably so. Every implementation of stdio I've seen actually returns -1
in
> this case, though (since that's what lseek returns for the error case, and
> unixes as well as windows use lseek as the underlying call).

Yes, but if you don't use those calls in normal code and return 1 (as the
docs say), you get a wrong error.
Maybe this should be added to the docs?

>
> I suspect there's a (possibly historical, or related to broken
> implementations) reasons for this being this way, though, so I'm hesistant
> to change it. Just return -1, makes things easier.
>
> Of course, that documentation says that the return value is undefined for
> unseekable devices. Which means it could return 0 (success), which is
> completely useless.

Indeed. Maybe a better seekable test would be:
To try to seek and check with the tell func if the seek worked.

>
> Michael
>
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