[pdf-devel] Re: Disk filesystem module questions

[Zac Brown]

Aleksander Morgado wrote:
> Hi Jose & Zac,
> 
> I started to work in the Disk Filesystem to finish it, and I have a
> couple of comments regarding pdf_fsys_disk_get_free_space (but I guess
> some of them also apply to other functions):
> 
>  * First thing in the function is calling pdf_fsys_get_host_path(),
> which internally calls pdf_text_get_host(). After that call, we get a
> host_path and a host_path_size. The problem is that it seems assumed in
> the source code that the host encoded string is NUL-terminated, as the
> host_path_size is no longer used. But this may be false. That string
> is used in GetDiskFreeSpace() or statfs(), and both expect a
> NUL-terminated string. For GetDiskFreeSpace, the NUL-terminated string
> should really be a double-NUL terminated string "\0\0", as the expected
> data is a Unicode string (in UTF-16BE). For statfs I guess it should be
> UTF-8 encoded string. So, instead of getting the host-encoded
> representation of the filepath, I think that we should get the
> UTF-16BE-encoded representation in Windows and the UTF-8 representation
> in Posix systems. Note that in Windows, you can also use
> single-NUL-terminated ASCII path in the same function, if the path is
> only composed of ASCII characters; but to do it correctly we should only
> use the Unicode representation.
> 
Thats probably a good plan. Though I'll have to think about it further. My gut
feeling right now is that its good.

> 
> * GetVolumePathName (windows). I saw the #if 0 deactivating the usage of
> GetVolumePathName in the code. Is it only deactivated because it's not
> available in mingw? The provided approach won't work for UTF-16BE
> encoded filesystem paths.
> http://msdn.microsoft.com/en-us/library/aa364996(VS.85).aspx
> 
Thats a question for Jose because I'm pretty sure he wrote that portion.

> 
> * GetDiskFreeSpace (windows). From the info in MSDN: "The
> GetDiskFreeSpace function cannot report volume sizes that are greater
> than 2 gigabytes". We should use GetDiskFreeSpaceEx, which has a
> different API.
> http://msdn.microsoft.com/en-us/library/aa364937(VS.85).aspx
> 
Think Jose wrote that, but good catch no less. I hope we aren't reading PDF's
that big though :-| (haha).

> 
> BTW, the unit tests to test the Disk Filesystem are the generic ones
> that Hans is doing, right? FS#24?
> 
Think so, it interfaces with the "Filesystem" interface, not actually the disk
filesystem implementation which is the default.

-Zac