On Wed, Sep 18, 2013 at 09:48:44PM -0700, Roy Franz wrote:
> On Wed, Sep 18, 2013 at 8:44 PM, Adam Borowski <kilobyte@xxxxxxxxxx> wrote:
> > [UCS2 truncation]
>
> I stuck to re-arranging the code that was there, as I don't know enough
> about character encodings to propose changes.
I on the other hand don't know the kernel (lurking because of my first
patch), but I'm on a crusade against mangled Unicode (so far in the
userland). Can't let such a blatant error slip through on my watch :)
> Also, this code is running as part of the kernel decompressor, rather than
> the kernel itself, so it doesn't have access to any kernel facilities, and
> it also needs to be position independent.
Ok, so it can't reuse common libraries. No problem, a simplified, sanitized
and optimized copy of utf16s_to_utf8s() can be done in quite less code than
the original.
> It's running in a quite limited environment - the decompressor has
> its own copy of strstr(), and other string functions.
I'd need nothing but a way to alloc the new string. And I see this is
already done (efi_{low,high_alloc()).
> I checked the UEFI specification, and it states that all 16 bit strings
> are UCS-2, unless otherwise noted.
... which means it will either get upgraded to UTF-16 in a subsequent
version, or some Unicode strings get mangled. I'd ignore this bit and
implement full UTF-16 from the start: every legal UCS-2 string can be
decoded as UTF-16 so it's a strict superset.
> The load options that the command line is provided through a void pointer
> specified as: [snip]
Either a null pointer or a 16-bit string, that sounds clear enough.
I see not a word about endianness (does anything do EFI on big endian?),
but "same as host" seems to be a reasonable assumption.
> Would it be acceptable to fix the naming/comments, and convert values
> above 126 to '?' in the current patchset, and address a more thorough fix
> in another patch set? The ARM and ARM64 EFI stub patchsets that are
> mostly complete depend on this one, so getting this merged soon would be
> helpful.
I don't want to hinder your work, so what about putting in your version
as-is and fixing it later?
> > There's just one problem: which encoding to use, but
> > these days, most distributions have either dropped non-UTF8 or hardly pay
> > lip service, so we could get away with hard-coding UTF-8: those few who
> > use ancient charsets can stick to ASCII.
Not being able to use regular kernel facilities makes supporting ancient
charsets a lost cause. I'm so weeping about them... not.
> I would certainly appreciate your help improving this
Are we on the same page so far? If so, I can make a patch atop yours.
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