Re: Possible Bug (clarification) in Cygwin 1.7.5 -- findfirstfile (and findnextfile) yeild bad cfilename when file names have special characters. Works in cygwin 1.5, fails in 1.7

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Nov  3 17:56, Charles Wilson wrote:
> On 11/3/2011 4:48 PM, Leon Vanderploeg wrote:
> > With cygwin 1.7.5, cFileName with a special characters such as à (n
> > with tidle above it) fail be properly extracted from a
> > WIN32_FIND_DATA structure with findFirstFile (or findNextFile).
> > 
> > To set up a simple test scenario, I created a file in C:\Testing
> > named  MaÃana.docx.  I compiled the code at the end of this message
> > on Cygwin 1.7.9 with GCC version 3.4.4 on Server 2008 32 bit system.
> > On this system (and on a Windows 7 32 bit machine), it returns:
> 
> a) Why are you using native Win32 APIs in a cygwin program? You should
> be using the POSIX interfaces instead -- see /usr/include/dirent.h.
> 
> DIR *opendir (const char *);
> DIR *fdopendir (int);
> struct dirent *readdir (DIR *);
> int readdir_r (DIR *, struct dirent *, struct dirent **);
> void rewinddir (DIR *);
> int closedir (DIR *);

ACK++

> b) What you observe is an artifact of cygwin-1.7's new *support* for
> i18n.  In cygwin-1.5, it just didn't care and passed all the bytes back
> exactly as found without transliteration.  In 1.7, it (correctly)
> transcodes strings into the current locale -- and your current locale
> does not appear to support à -- or, at least, you haven't told cygwin to
> use the correct one.
> 
> (I'm probably thoroughly botching this explanation, but the point is,

Just a bit.  What you have to keep in mind is that Windows stores all
object names, including filenames, as UTF-16 strings, UNICODE in Windows
terminology.  When you use the ANSI Win32 API as in this example, then
the UTF-16 names are converted to the currently defined ANSI charset on
output, for instance codepage 1252 for Western Europe languages.

Cygwin 1.5 either used the ANSI API, or it converted strings from UTF-16
to the current Windows ANSI charset or vice versa.

Cygwin 1.7 doesn't use the ANSI API anymore, rather it uses UNICODE to
talk to Windows only, and the multibyte charset is defined through the
environment(*) as defined in POSIX.  UTF-8 is the default now.

> you need to check your LC_* and LANG env vars, and maybe call
> setlocale(LC_ALL, "") in your application.)

And even than the code won't work.  If you don't define UNICODE,
FindFirstFile/FindNextFile will use the ANSI versions of this API,
FindFirstFileA/FindNextFileA.  If you didn't set your LANG/LC_CTYPE/LC_ALL
variables to use your current Windows ANSI charset *and* called
setlocale, Cygwin will use UTF-8 by default.  Therefore, the character Ã
will have another multibyte encoding, 0xc3 0xb1, rather than, say, 0xf1
in Windows codepage 1252.  To avoid this problem, you can use the
UNICODE API FindFirstFileW/ FindNextFileW and convert the filename the
current multibyte charset via wcstombs and friends.

However, as Chuck has pointed out, the obviously right thing to do is to
use the POSIX API opendir/readdir/closedir instead.


Corinna

(*) http://cygwin.com/cygwin-ug-net/setup-locale.html
    http://cygwin.com/cygwin-ug-net/using-utils.html#locale

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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