From: Thomas Demmer <demmer AT LSTM DOT Ruhr-UNI-Bochum DOT De>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Error in BCD
Date: Tue, 28 Apr 1998 09:33:37 +0200
Organization: Lehrstuhl fuer Stroemungsmechanik
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Bjorn De Meyer wrote:
> 
> On Mon, 27 Apr 1998, Lennart Poettering wrote:
> 
> > I think i have found a heavy error in BCD (The only CDROM-library for
> > DJGPP): BCD doesn't alloc anough memory for its track-list:
> > it will write intro memory as long as this error is not fixed. this will
> > cause break downs of programs written with bcd on places nobody expects.
> >
> > int "bcd_get_audio_info" you will find the following code: (roundabout
> > line 460)
> >
> >   tracks = calloc(num_tracks, sizeof(Track));
[...]
> > you can fix this - it is not elegant, i know - with the following change
> >   tracks = calloc(num_tracks+1, sizeof(Track));
> >
> > than everything works fine....
> 
> Or if you are sure that tracks[0] is never used do a
> 
>  tracks--;
> 
> This will decrement the pointer to point
> one adress before the allocated memory starts, making 1 a valid lower
> value, but disabling the use of Track[0]. I hope this is more elegant.

I don't think so. You will probably forget to
say
  free(++tracks);
sooner or later and blow mallocs() internal lists. This may
give funny results at occasions seemingly totally unrelated
to the free() statement, and some hours of frustration.

Rather give a damn about the overhead...

-- 
Ciao
Tom

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* Thomas Demmer                                             *
* Lehrstuhl fuer Stroemungsmechanik                         *
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