llvm dev - Oct 2011 - [LLVMdev] [cfe-dev] Unicode path handling on Windows

Right, but maybe if you switch to using tolower_l() and pass an appropriate
locale you can get it to work the same way. I'm not sure what locale that
would have to be, but it needs to match whatever NTFS uses for its $upcase file.

On Oct 3, 2011, at 12:19 PM, Nikola Smiljanic wrote:
> CharLowerW does the right thing. But I still need Windows.h to use it :)
> 
> On Mon, Oct 3, 2011 at 8:43 PM, Bryce Cogswell <bryceco at gmail.com>
wrote:
> Locale-specific is not what we want, but I don't believe Windows
exposes an alternative API that does what we want. (Does CharLower give a
different answer than tolower?)
> 
> However, looking over the FileManager code a little more I'm not even
sure using the path is the best solution, it seems it would be better to use
inode like the unix code does. Windows doesn't support inode (the s_ino
field in stat), but it does have nFileIndexHigh/nFileIndexLow which are exposed
via ::GetFileInformationByHandle and is basically the same thing. This would
require refactoring FileSystemStatCache to use a new structure in place of stat
that could be shared between Windows and Unix. This would be a lot of small
changes but seems like it would be fairly straightforward.
> 
> 
> On Oct 3, 2011, at 9:21 AM, Nikola Smiljanic wrote:
> 
>> towlower doesn't seem to work with my test string in Cyrillic. This
function does locale-specific conversion, is this what we want?
>> 
>> Here's the whole thing, with all the calls to ::stat replaced with
llvm::sys::fs::Stat.
>> 
>> On Fri, Sep 30, 2011 at 8:04 PM, Bryce Cogswell <bryceco at
gmail.com> wrote:
>> You can use _iswupper and _towlower instead of CharLowerBuffW. They
don't require windows.h and work with /Za.
>> 
>> On Sep 30, 2011, at 12:24 AM, Nikola Smiljanic wrote:
>> 
>>> I tried to do the conversion to lowercase inside GetFullPath by
adding an additional bool parameter to this function. It's not perfect but
seems much better than repeating the whole UTF8 to UTF16 and UTF16 to UTF8
conversion again. The problem I have is with access to CharLowerBuffW. I need
Windows.h for this function but when I try to include it I get a bunch of errors
because Language Extensions are disabled, /Za switch. Do I just enable them and
include Windows.h inside and #ifdef section?
>>> 
>>> On Thu, Sep 29, 2011 at 7:57 AM, Bryce Cogswell <bryceco at
gmail.com> wrote:
>>> I agree they are broken on all platforms. However, FileManager.cpp
already contains an #if WIN32 conditional around the code calling
LowercaseString, so you can use MultiByteToWideChar and CharLowerBuffW directly
there, and not call the LowercaseString function. I don't think there are
any other places where LowercaseString is called with non-ascii data, so you can
punt on fixing it for now.
>>> 
>>> On Sep 28, 2011, at 10:11 PM, Nikola Smiljanic wrote:
>>> 
>>>> I have a problem with Lowercase and Uppercase functions. These
are broken on all platforms, not only Window, so I can't just #ifdef and use
CharLowerBuffW. I need a portable way to convert from UTF8 to UTF16. There is
set of functions inside clang/Basic/ConvertUTF, but LLVM can't depend on
this. What do I do?
>>>> 
>>>> On Tue, Sep 27, 2011 at 5:09 AM, Bryce Cogswell <bryceco at
yahoo.com> wrote:
>>>> I think the assert you have for _stat64i32 is fine. It is a
constant expression so should compile to nothing, and the chance of the
definition changing is pretty much zero.
>>>> 
>>>> LowercaseString appears to be used by ASM printers where the
output is expected to be ASCII, and then some WIN32-conditioned code in
FileManager.cpp. I hate to say it but you'll probably need to convert the
UTF-8 paths to wide char, lower case it using CharLowerBuffW (since it needs to
match the casing rules used by NTFS), and then convert back to UTF-8.
>>>> 
>>>> If you need to be pedantic about recognizing whether two paths
are the same on Windows you also need to call GetFullPathName in order to expand
any 8.3 path components, but this is an expensive function so I wouldn't do
it unless absolutely necessary.
>>>> 
>>>> There is also a call to _fullpath in there that needs to be
changed to _wfullpath.
>>>> 
>>>> The rest of the patch looks good.
>>>> 
>>>> On Sep 23, 2011, at 9:57 AM, Nikola Smiljanic wrote:
>>>> 
>>>>> Here's a new patch that fixes all the issues mentioned
before. Note that this isn't final, I didn't want to replace all calls
to ::stat so that it's easier to review.
>>>>> 
>>>>> I have only one more questions:
>>>>> 
>>>>> 1. _wopen accepts _stat64i32 instead of stat structure.
These two are exactly the same, the only difference is that stat uses time_t and
_stat64i32 uses __time64_t (time_t is a typedef for __time64_t but this depends
on one more macro). I check to see that size of these two structures is the
same, but is there something more that I could do? I'd also like to use some
kind of static assert instead of runtime assert.
>>>>> 
>>>>> I've also noticed that function LowercaseString (the
same applies to UppercaseString) doesn't work with UTF8 input. It's
calling isupper and tolower and these functions can't handle UTF8. This
should get a new issue probably?
>>>>> 
>>>>> On Wed, Sep 21, 2011 at 1:41 AM, Aaron Ballman <aaron at
aaronballman.com> wrote:
>>>>> On Tue, Sep 20, 2011 at 4:15 PM, Nikola Smiljanic
<popizdeh at gmail.com> wrote:
>>>>> > OK since this approach makes sense I'll shoot with
my questions :)
>>>>> > 1. Where should get_utf8_argv go and is the name of
this function OK? Right
>>>>> > now the function is inside llvm::sys::fs namespace
because I need access to
>>>>> > Windows.h, should I leave it there.
>>>>> 
>>>>> I don't think it belongs there as it has nothing to do
with the file
>>>>> system.  However, I'm not familiar enough to know of a
better place
>>>>> for it either.  Hopefully someone else can chime in with an
idea.
>>>>> 
>>>>> > 2. get_utf8_argv allocates new char** representing
utf8 argv, should I
>>>>> > deallocate this inside driver.cpp, use
std::vector<std::string> instead or
>>>>> > ignore the allocation completely?
>>>>> 
>>>>> Perhaps some SmallVectors would make sense here?  An inner
one to hold
>>>>> the arg data, and an outer one to hold the list of inner
vectors.
>>>>> Then you can do the cleanup within the call.
>>>>> 
>>>>> > 3. There is an #ifdef inside driver.cpp right now that
I don't like.
>>>>> > get_utf8_argv works for windows only, but I could
change the function to
>>>>> > accept argv and return it as vector of utf8 strings.
It would convert char*
>>>>> > to std::string on unix and use GetCommandLine + utf8
conversion on windows.
>>>>> 
>>>>> I have no concrete opinion one way or the other on this.
>>>>> 
>>>>> > 4. Should I wrap functions like ::fstat and ::close
for consistency even
>>>>> > though they don't work with paths?
>>>>> 
>>>>> I don't believe so.
>>>>> 
>>>>> > I'll fix everything that is formatting related.
You're right, current patch
>>>>> > has Open only for windows but I'll add the other
one as well.
>>>>> 
>>>>> Thanks for the help!
>>>>> 
>>>>> ~Aaron
>>>>> 
>>>>> <clang.patch><llvm.patch>
>>>> 
>>>> 
>>> 
>>> 
>> 
>> 
>> <clang.patch><llvm.patch>
> 
> 
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How about this:

for (int i = 0; i != NumWChars; ++i)
        absPath[i] = std::tolower(absPath[i], std::locale());

seems to be working just fine?

On Mon, Oct 3, 2011 at 9:27 PM, Bryce Cogswell <bryceco at gmail.com>
wrote:
> Right, but maybe if you switch to using tolower_l() and pass an appropriate
> locale you can get it to work the same way. I'm not sure what locale
that
> would have to be, but it needs to match whatever NTFS uses for its $upcase
> file.
>
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Am 03.10.2011 22:12, schrieb Nikola Smiljanic:
> How about this:
>
> for (int i = 0; i != NumWChars; ++i)
>          absPath[i] = std::tolower(absPath[i], std::locale());
>
> seems to be working just fine?
You have two assumptions here:

Assumption 1: For each lowercase character, there is an equivalent 
uppercase character, and vice versa.
This is not true in half a dozen languages according to
ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt .

Assumption 2: The transformation from lower case to upper case can be 
done for each character individually, without considering context.
This is not true in a couple of languages according to SpecialCasing.txt.

Do not do that. If you get complaints, they will be about scripts that 
you can't type on your keyboard, and that you know nothing about so you 
don't even know what the right behaviour would have been.
Rely on the relevant Unicode library. Which one that would be, and which 
functions to call, depends on what you need that to-lowercase 
transformation for. (It also depends on whether the names you get are 
already normalized or not; I'd want to run a normalization pass on the 
names first just to be on the safe side.)

Regards,
Jo