[Mono-dev] PtrToStringAnsi

[Atsushi Eno]

Hello,

Mono does not support non-UTF8 multibyte conversion by design. We
shouldn't change its behavior from current one. Actually it is pretty
classic matter which has been stated since 2003.
http://lists.ximian.com/archives/public/mono-list/2003-June/014500.html

It is Microsoft who should provide additional marshaling flags so that
it will be truly functional on every platforms (especially considering
that there is also Gtk+ on Windows which is apparently designed to work
on Windows and uses UTF-8 based marshaling). AFAIK they are also aware
on this matter through ECMA meetings.

Atsushi Eno


> While debugging a SqliteClient issue, I came across an interesting bug.
>  The following returns null when I'm pretty sure it should not (it
> doesn't on Windows):
> 
> Marshal.PtrToStringAnsi(Marshal.StringToCoTaskMemAnsi("ü"))
> 
> In case the encoding of this email gets messed up, that's a u with
> umlauts, (char)0xFC.
> 
> The encoding half "works" (Marshal.ReadByte reports the bytes (0xFC
> 0x00)), on the assumption that I'm supposed to get ANSI out of this
> method.  Internally, g_utf16_to_utf8 is used, which means that (besides
> being surprised this call doesn't actually do ANSI encoding) I would
> actually expect a multibyte representation of that character.  That's
> from a few minutes of Googling for info on UTF-8.
> 
> So I'm confused.  Can someone with more knowledge about encodings tell
> me whether this really doesn't make sense?
> 
> I'm using the latest RPMs.  Here's a test program:
> 
> using System;
> using System.Runtime.InteropServices;
> 
> public class Test {
>     public static void Main() 		
> Console.WriteLine(Marshal.PtrToStringAnsi(Marshal.StringToCoTaskMemAnsi("ü")));
> 	}
> }
>