[Tremor] Some issues with Nicholas' comment truncation patch

[Andy Grundman]

Hi Nicholas,

I'm working on implementing your comment truncation patch into our  
Tremor code.  I have a few questions about it.

Comparing Tremor3.patch [3] and your original patch [1], #3 seems to  
have removed the extra code in _vorbis_unpack_comment that breaks out  
of the comment reading loop if the data was truncated.  Using patch #3  
this loop always tries to allocate space for the truncated comment and  
fails, so I think what you did in #1 is the right solution.  However,  
using #1 I end up failing on my test file with ENOTVORBIS because the  
check for the "vorbis" string in vorbis_dsp_headerin fails when  
looking for the codebooks header.

Thanks,
-Andy

[1] http://x256.org/~hb/Tremor.patch
[2] http://x256.org/~hb/Tremor3.patch