[Qt-interest] Non-Ascii filenames with QFile

[Santosh Puranik]

Hello,

Thanks for your mail.

ext Thiago Macieira wrote, On Wednesday 10 February 2010 05:23 PM, UTC 
+0530:
> When trying to access the file, Qt converts from UTF-16 to the locale's 
> encoding, which from what you described is UTF-8. And that failed.
> 
> The reason why it failed is because your source code is ALSO in UTF-8. And you 
> told Qt to decode your UTF-8 literal as Latin 1. That's your error.
> 
> Try instead:
> 	QFile f(QString::fromUtf8("/home/user/áèîõü.mp3"));
> 

I do not think that is the problem, even if I use fromUtf8() as above, I 
still have the same issue. I'll explain my actual use case in more detail:

1) We get the filename from a PC over USB.
2) The strings that we receive are encoded in UTF-16 LE. So, we make a 
path out of this: QString filePath = QString(<Root path>) + 
QString::fromUtf16(<raw UTF-16 LE data>).
3) Then create that file with QFile: QFile f(filePath); 
f.open(QIODevice::ReadWrite).
4) And this still fails.

The problem IMO is in when QT tries to encode the file path to the 
system locale's charset ... which is not UTF-8 on my system:

~ $ locale charmap
ANSI_X3.4-1968

This basically causes QString::toLocal8Bit() to lose data.

Which was my question, and I guess you answered that too:
> In Qt, filenames are represented by Unicode strings, in UTF-16. We cannot give 
> you a non-encoded filename access, because there are far too many places in Qt 
> that take filenames. They all take QString. And on Windows, filenames are 
> encoded in UTF-16.

My reason for asking (also) a QFile constructor where we can provide the 
path encoding along with the path name was so that this would still work 
if the locale settings on my system were missing/incorrect... but 
probably that is out of QT's scope.

Best Regards,
Santosh