[Insight-developers] Unicode filenames, VS6 and fdstream (was:Unicode filenames and borland issue)

[Tom Vercauteren]

All right, the easiest would then be to not allow unicode filenames on VS6.0.

I'll try an get something for tomorrow or Friday.

Tom

On Wed, Nov 11, 2009 at 06:01, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> VS6 does not have a wide string constructor for (i/o)fstream. I'm not
> sure in what VS version they added thw wide string constructor.
>
> Bill
>
>
> On Tue, Nov 10, 2009 at 8:41 PM, Tom Vercauteren
> <tom.vercauteren at m4x.org> wrote:
>> Hi Bill,
>>
>> I just finished implementing your suggestion. I created some stream
>> classes that inherits from (i/o)fstream on all systems except for
>> mingw and borland where
>> 1) they inherit from (i/o)stream
>> 2) they implement some functions that are only in (i/o)fstream to get
>> a uniform API
>> 3) use the c-style open and code from fdstream to allow unicode filenames
>>
>> On MSVC, the new implementation takes advantage of the MSVC-specific
>> wide string constructor of (i/o)fstream [1]. This could thus be easier
>> for VS6.
>>
>> The file is here:
>> http://www.itk.org/Bug/file_download.php?file_id=2646&type=bug
>>
>> I tested it on windows xp with
>> * visual c++ 2008 express
>> * mingw with gcc 3.4
>> * borland 5.5
>> * cygwin 1.7 with gcc 4.3
>>
>> Could you give it a try on VS6?
>>
>> Thanks,
>> Tom
>>
>> [1] This constructor is not available on both borland and mingw which
>> implies that stdio_filebuf is not sufficient and we need a more
>> portable solution such as fdstream.
>>
>> On Tue, Nov 10, 2009 at 22:25, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>> fdstream is the problem on vs6 I think. We might be able to modify the
>>> fdstream header with ifdef's for VS6. Really make fdstream look like
>>> (i/o)stream. Maybe with (uggh!) #defines to redefine fd(i/o)stream to
>>> be (i/o)stream only on VS6 (and maybe VS7).
>>>
>>> On Tue, Nov 10, 2009 at 4:11 PM, Tom Vercauteren
>>> <tom.vercauteren at m4x.org> wrote:
>>>> Hi Bill,
>>>>
>>>> Thanks for taking a look at this!
>>>>
>>>> Are the problems you found related to the use of _wfopen and _wopen or
>>>> to the use of fdstream? This is an important distinction for the
>>>> unicode filename porting because the plan I had in mind relies on
>>>> fdstream being used in all cases (ITK_USE_REVIEW_UTF8_STRINGS on or
>>>> off).
>>>>
>>>> Indeed here is what I found (VS6 not taken into account here):
>>>>
>>>> 1) c-style file IO can be ported relatively easily to utf8 on windows
>>>> (msvc, borland, mingw). Just replace fopen by _wfopen and open by
>>>> _wopen together with some string conversion
>>>>
>>>> 2) c++-style IO is more involved. There is a wide string version of
>>>> ofstream.open() and ifstream.open() on msvc but not on mingw (did not
>>>> try with on borland).
>>>>
>>>> Since the fstreams cannot be opened with a unicode filename on mingw,
>>>> the workaround is to open the file using c-style functions and then
>>>> create a stream from the result of the c-style open.
>>>>
>>>> A gcc specific extension exists for that (stdio_filebuf) but it is
>>>> obviously non-portable. fdstream does the same thing but appeared to
>>>> be portable.
>>>>
>>>> So to get unicode filename enabled streams, we need to replace code like
>>>>
>>>> A)
>>>> std::ifstream readstream(filename, std::ios::binary | std::ios::in)
>>>>
>>>> by code like
>>>>
>>>> B)
>>>> int fd = _wopen(filename, _O_RDONLY);
>>>> boost::fdistream readstream(fd);
>>>> [...]
>>>> close(fd)
>>>>
>>>> We might of course pepper the code with ifdefs each time a stream is
>>>> used (as is already done to workaround a sgi bug in metaImage.cxx
>>>> http://public.kitware.com/cgi-bin/viewcvs.cgi/Utilities/MetaIO/metaImage.cxx?root=Insight&view=markup
>>>> ) but I wanted to avoid that by restricting these ifdefs to live in a
>>>> specified file/module. Hence my plan to wrap only the c-style (f)open
>>>> functions and use fdstreams everywhere.
>>>>
>>>> Note that since we need to close the file descriptor and because
>>>> fd(i/o)streams do not inherit from (i/o)fstream but only from
>>>> (i/o)stream, it is not obvious to have a function that uses either the
>>>> A mode or B mode above.
>>>>
>>>> Sorry for this long email,
>>>> Tom
>>>>
>>>> P.S.: some information is also available on the bug tracker:
>>>> http://public.kitware.com/Bug/view.php?id=9623
>>>>
>>>> On Tue, Nov 10, 2009 at 21:11, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>>>> My first try with VS6 is not encouraging. I suggest that we instrument
>>>>> the code so that VS6 ITK cannot use Unicode.
>>>>
>>>
>>
>