[Vorbis-dev] patch for non-seekable streams on Windows

[Vidur Apparao]

Monty wrote:

>
>On Thu, Oct 14, 2004 at 04:59:34PM -0700, Vidur Apparao wrote:
>  
>
>>I've been trying to get oggdec to work with input streamed in through a 
>>pipe or a socket. This seems to work on Linux and OS X, but not on 
>>Windows. I've found that code in vorbisfile.c tests the input stream for 
>>seekability by invoking fseek in the following way:
>>
>> int offsettest=(f?callbacks.seek_func(f,0,SEEK_CUR) : -1);
>>
>>Unfortunately, fseek succeeds for a socket on Windows (even though it's 
>>not seekable) with the parameters specified. A more definitive test (and 
>>one that does work on Windows) is to attempt to seek to the end. I've 
>>attached a patch to vorbisfile.c that fixes my problem.
>>    
>>
>
>Oh, and I forgot to say:  Thanks for tracking it down :-)
>
>Perhaps only some versions of windows have this bug?
>  
>
The problem occurs on Windows XP, suggesting that it's been around for a 
while in the NT flavors of Windows. FWIW, the Microsoft developer site 
(see 
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt_fseek.asp) 
says the following about its implementation of fseek:

"If successful, fseek returns 0. Otherwise, it returns a nonzero value. 
On devices incapable of seeking, the return value is undefined."

The last sentence implies that the implementation is not ANSI and POSIX 
compliant, no?