From: Martin Krischik <krischik@users.sourceforge.net>
Subject: Re: Filenames in Ada
Date: Sun, 27 Nov 2005 11:21:19 +0100
Date: 2005-11-27T11:21:19+01:00 [thread overview]
Message-ID: <1255659.7PSTQaQJvX@linux1.krischik.com> (raw)
In-Reply-To: lNOhf.151346$dP1.509079@newsc.telia.net
Bjï¿œrn Persson wrote:
> Let's see if I understand the problem. Windows has two functions for
> each file operation, one -A version that expects or returns a file name
> in some 8-bit encoding like Windows-1252, and one -W version that
> expects or returns a file name in UTF-16 or maybe UCS-2?
Well the Windows API in question where designed at a time when UTF-16 and
UCS-2 where still the same - that is Unicode had no codes defined above the
65535 border. At that time programmers did not care - or understood - the
difference between the two.
VFAT-32 is most likely a UCS-2 filesystem (anyone from china to confirm
that?). I remember an article about the "new" VFAT technology wasting
"enormous" amount of storrage using UCS-2 for character encoding.
Obviously the article came from an Latin-1 based country ;-) .
> And all the
> file operations in the Ada library take and return file names as String,
> that is, Latin-1? And Gnat's implementation pretends that Latin-1 is
> identical to whatever 8-bit encoding Windows is using, and passes these
> Strings to Windows' -A functions, leaving you with no way to handle
> filenames that can't be expressed in said 8-bit encoding? Is that right?
Yes indeed. But I take it that on a Russian system the Windows-1251 code
page is active and all filenames are expressed using that and not Latin 1.
> It is my intention to add an encoding-aware interface to Ada.Directories
> under EAstrings.OS. For that to work reasonably on Windows, this problem
> needs to be solved. I suppose I also need to fix this in EAstrings.IO. I
> will need help from a Windows programmer to do this. (Of course I also
> need to get transcoding implemented on Windows before EAstrings will be
> of any use there.)
It is sad that XML/Ada has no UCS-2 and UCS-4 convertion available - but
AdaCL allready has that - so not problem for you really.
> It seems that the right thing to do would be to tap into the Gnat
> library and make UTF-16 (or UCS-2) versions of the file operations. It
> could be as easy as changing the parameter type and replacing calls to
> the Windows functions with their -W equivalents, or it could be very
> hairy.
I had that idea as well and did take a look. Lots of "pragma Import" there.
> We'll need to determine whether it is UTF-16 or UCS-2. This page lists
> code page numbers for a whole lot of encodings, but UTF-16 is missing:
>
>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/intl/unicode_81rn.asp
>
> I take that as a hint that UTF-16 is Windows' idea of wide strings, and
> that all the others are considered "multi-byte character sets" or
> whatever the term is.
Well there seems an better article:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/naming_a_file.asp
I wonder about that \\?\ stuff and what it really means
Martin
--
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com
next prev parent reply other threads:[~2005-11-27 10:21 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-23 17:36 Filenames in Ada Martin Krischik
2005-11-23 18:09 ` Martin Dowie
2005-11-24 19:16 ` Martin Krischik
2005-11-23 18:59 ` Dmitry A. Kazakov
2005-11-24 19:13 ` Martin Krischik
2005-11-24 20:49 ` Dmitry A. Kazakov
2005-11-24 21:23 ` Larry Kilgallen
2005-11-25 7:12 ` krischik
2005-11-25 12:25 ` [OT] VMS ODS-5 filesystems, was: " Simon Clubley
2005-11-25 18:01 ` Martin Krischik
2005-11-25 18:27 ` Georg Bauhaus
2005-11-25 19:54 ` Martin Krischik
[not found] ` <gjqeo157udsnbfuq8ak4dosf6nep5fomss@4ax.com>
2005-11-27 9:31 ` [OT] VMS DCL prompt, was: " Martin Krischik
2005-11-30 0:16 ` [OT] Administrator accounts (was: VMS DCL prompt) Björn Persson
2005-11-30 4:23 ` Larry Kilgallen
2005-11-23 22:18 ` Filenames in Ada Randy Brukardt
2005-11-24 3:21 ` Silly question about strings (was: Filenames in Ada) Steve
2005-11-24 4:58 ` Larry Kilgallen
2005-11-24 9:15 ` Martin Dowie
2005-11-24 11:30 ` Silly question about strings Brian May
2005-11-24 13:06 ` Silly question about strings (was: Filenames in Ada) Larry Kilgallen
2005-11-29 3:17 ` Randy Brukardt
2005-11-29 5:53 ` tmoran
2005-11-29 21:48 ` Randy Brukardt
2005-11-30 0:15 ` Björn Persson
2005-11-24 19:05 ` Filenames in Ada Martin Krischik
2005-11-25 6:54 ` Martin Dowie
2005-11-26 1:22 ` Björn Persson
2005-11-27 10:21 ` Martin Krischik [this message]
2005-11-30 0:13 ` Björn Persson
2005-12-01 6:59 ` Martin Krischik
2005-12-03 1:07 ` Björn Persson
2005-12-14 6:59 ` Dave Thompson
2005-12-15 20:23 ` Martin Krischik
2005-12-17 0:22 ` program privileges (was: Filenames in Ada) Georg Bauhaus
2005-12-17 16:59 ` Filenames in Ada Simon Wright
2005-12-17 23:18 ` Larry Kilgallen
2005-12-18 13:30 ` privileges in Unix and VMS (was: Filenames in Ada) Björn Persson
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