flac dev - May 2013 - Bug fix and compatibility patches for 1.3.0pre4

Timothy B. Terriberry wrote:
> Instead I've attached a patch that uses fgetpos/fsetpos. This is 
> totally untested (I haven't even checked it compiles), but the idea 
> should work.
MSDN says "The pos value is stored in an internal format and is intended 
for use only by *fgetpos* and *fsetpos*." 
(http://msdn.microsoft.com/en-us/library/70hdhh4t%28v=vs.80%29.aspx), so 
I don't think it's a good idea to use it this way even if tests 
suggested it works.

I'll write a test program tomorrow to try the fflush+_lseeki64 approach.

Another solution - although a bit ugly - might be to disable buffering 
on Windows using setvbuf.

Robert Kausch wrote:
> MSDN says "The pos value is stored in an internal format and is
intended
> for use only by *fgetpos* and *fsetpos*."
> (http://msdn.microsoft.com/en-us/library/70hdhh4t%28v=vs.80%29.aspx), so
> I don't think it's a good idea to use it this way even if tests
> suggested it works.
FWIW, I verified that this is the approach used by mingw32 to implement 
fseeko/ftello.

Timothy B. Terriberry wrote:
>> "The pos value is stored in an internal format and is intended
>> for use only by *fgetpos* and *fsetpos*."
> FWIW, I verified that this is the approach used by mingw32 to implement
> fseeko/ftello.
>
Yes, they do - I also had a look at the libmingwex source. But still, 
with that sentence Microsoft basically reserves the right to change the 
behaviour of fgetpos/fsetpos at any time without notice...

I wrote a small test program in the meantime and verified that 
fgetpos/fsetpos indeed work, even back to Windows 98. _lseeki64 on the 
other hand totally messes up with buffered streams and cannot be used 
here. Calling fflush beforehand doesn't help and even fflush alone 
breaks the stream (i.e. with 4kB buffers, 
fopen()->fread()->fflush()->fread() will start at byte #4096 with the 
second read, so don't use fflush for reading).

However, as Janne already pointed out, libFLAC is statically linked by 
default, so there's no real problem with _fseeki64/_ftelli64 indeed.

I'll still have to decide whether to link statically or use your 
fgetpos/fsetpos patch for my build, but no need to change anything in 
the official FLAC code. In any case, please disregard my _lseeki64 patch.