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Re: Filename encodings under Win32

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  • Glenn Maynard
    ... It s not at all a myth if you want code that is 1: portable and 2: works on 9x, too. (If you can deal with nonportable code, you can use Windows s TCHAR
    Message 1 of 29 , Oct 14, 2003
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      > While that may sound attractive at first, I would strongly dissuade from
      > that solution. I consider it to be a myth that using multilingual
      > filenames on Windows is hard. Under NT, it's should be a breeze for any

      It's not at all a myth if you want code that is 1: portable and 2: works
      on 9x, too. (If you can deal with nonportable code, you can use Windows's
      TCHAR mechanism, and if you don't care about anything but NT, you can write
      a UTF-16-only app. Neither of these are the case here, though.)

      It's not "hard", it's just "incredibly annoying".

      On Tue, Oct 14, 2003 at 02:20:27PM +0200, Bram Moolenaar wrote:
      > This is still complicated, but probably requires less changes than using
      > Unicode functions for all file access. I only foresee trouble when
      > 'encoding' is set to a non-Unicode codepage different from the active
      > codepage and using a filename that contains non-ASCII characters.
      > Perhaps this situation is too weird to take into account?

      If "encoding" is not the ACP codepage, then the main problem is that the
      user can enter characters that Vim simply can't put into a filename
      (and in 9x, that the system can't, either).

      I'd just do a conversion, and if the conversion fails, warn appropriately.

      > Eh, what happens when I use fopen() or stat()? There is no ANSI or wide
      > version of these functions. And certainly not one that also works on
      > non-Win32 systems. And when using the wide version conversion needs to
      > be done from 'encoding' to Unicode, thus the conversion has to be there
      > as well. That's going to be a lot of work (many #ifdefs) and will
      > probably introduce new bugs.

      It's not that much work. Windows has _wfopen and _wstat. Vim already
      has those abstracted (mch_fopen, mch_stat), so conversions would only
      happen in one place (and in a place that's intended to be platform-
      specific, mch_*). I believe the code I linked earlier did exactly this.

      The only thing needed is sane error recovery.

      > Yep, using conversions means failure is possible. And failure mostly
      > means the text is in a different encoding than expected. It would take
      > some time to figure out how to do this in a way that the user isn't
      > confused.

      Well, bear in mind the non-ACP case that already exists. If I create
      "foo ♡.txt", and try to edit it with Vim, it edits "foo ?.txt" (which
      it can't write, either, since "?" is an invalid character in Windows
      filenames). I'd suggest that editing a file with an invalid character
      (eg. invalid SJIS sequence) behave identically to editing a file with
      a valid character that can't be referenced (eg. "foo ♡.txt").

      --
      Glenn Maynard
    • Camillo Särs
      ... Agreed. There s no way around that. ... Sounds very promising. It would be really great if it turns out that the changes are fairly minor. That way
      Message 2 of 29 , Oct 14, 2003
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        Glenn Maynard wrote:
        > If "encoding" is not the ACP codepage, then the main problem is that the
        > user can enter characters that Vim simply can't put into a filename
        > (and in 9x, that the system can't, either).
        >
        > I'd just do a conversion, and if the conversion fails, warn appropriately.

        Agreed. There's no way around that.

        > It's not that much work. Windows has _wfopen and _wstat. Vim already
        > has those abstracted (mch_fopen, mch_stat), so conversions would only
        > happen in one place (and in a place that's intended to be platform-
        > specific, mch_*). I believe the code I linked earlier did exactly this.
        >
        > The only thing needed is sane error recovery.

        Sounds very promising. It would be really great if it turns out that the
        changes are fairly minor. That way there's a chance they would get
        implemented. :)

        If you decide to try the proposed changes out, I'm prepared to do some
        testing on a Win32 binary build. Sorry, can't build myself. :(

        Camillo
        --
        Camillo Särs <+ged+@...> ** Aim for the impossible and you
        <http://www.iki.fi/+ged> ** will achieve the improbable.
        PGP public key available **
      • Bram Moolenaar
        ... It s more complicated then that. You can have filenames in the ACP, encoding and Unicode. Filenames are stored in various places inside Vim, which
        Message 3 of 29 , Oct 15, 2003
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          Glenn Maynard wrote:

          > On Tue, Oct 14, 2003 at 02:20:27PM +0200, Bram Moolenaar wrote:
          > > This is still complicated, but probably requires less changes than using
          > > Unicode functions for all file access. I only foresee trouble when
          > > 'encoding' is set to a non-Unicode codepage different from the active
          > > codepage and using a filename that contains non-ASCII characters.
          > > Perhaps this situation is too weird to take into account?
          >
          > If "encoding" is not the ACP codepage, then the main problem is that the
          > user can enter characters that Vim simply can't put into a filename
          > (and in 9x, that the system can't, either).
          >
          > I'd just do a conversion, and if the conversion fails, warn appropriately.

          It's more complicated then that. You can have filenames in the ACP,
          'encoding' and Unicode. Filenames are stored in various places inside
          Vim, which encoding is used for each of them? Obviously, a filename
          stored in buffer text and registers has to use 'encoding'.

          It's less obvious what to use for internal structures, such as
          curbuf->b_ffname. When 'encoding' is a Unicode encoding we can use
          UTF-8, that can be converted to anything else. That also works when the
          active codepage is not Unicode, we can use the wide functions then.

          When 'encoding' is the active codepage (this is the default, should
          happen a lot), we can use the active codepage. That avoids conversions
          (which may fail). No need to use wide functions then.

          The real problem is when 'encoding' is not the active codepage and it's
          also not a Unicode encoding. We could simply skip the conversion then.
          That doesn't work properly for non-ASCII characters, but it's how it
          already works right now. The right way would be to convert the file
          name to Unicode and use the wide functions.

          I guess this means all filenames inside Vim are in 'encoding'. Where
          needed, conversion needs to be done from/to Unicode and the wide
          functions are to be used then.

          The main thing to implement now is using the wide functions when
          'encoding' is UTF-8. This only requires a simple conversion between
          UTF-8 and UCS-16. I'll be waiting for a patch...

          --
          hundred-and-one symptoms of being an internet addict:
          231. You sprinkle Carpet Fresh on the rugs and put your vacuum cleaner
          in the front doorway permanently so it always looks like you are
          actually attempting to do something about that mess that has amassed
          since you discovered the Internet.

          /// Bram Moolenaar -- Bram@... -- http://www.Moolenaar.net \\\
          /// Creator of Vim - Vi IMproved -- http://www.Vim.org \\\
          \\\ Project leader for A-A-P -- http://www.A-A-P.org ///
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