[Firebird-net-provider] Unable to start Firebird client on Ubuntu/Mono

[Danny G. <da...@ab...>]

I was chasing this problem 
(http://tracker.firebirdsql.org/browse/DNET-327) and was about to post 
to the list to try to find a solution when I found this 
http://blog.cincura.net/232192-ado-net-provider-2-6-0-for-firebird-released/ 
and in one of the comments (DEC 20, 2010) Jiri said:

"I was testing it with Mono 2.8.1 and 2.8.0 on Slackware, but maybe Mac 
version is missing some charsets. Simply comment out the line in 
FirebirdSql.Data.Common.Charset."

That tipped me off to an easy workaround so I started putting the #if 
(!MONO) around Charsets until I stopped getting the error.  This solved 
my problem (for now, until I put my code on a different platform or 
version of my platform), but don't see this as a good solution for the 
Firebird provider project.  In all I had to eliminate 15 character sets 
from that type initializer to get it to work, and it took the better 
part of a day to track down the root cause and do that elimination process.

So I'm posting to try to get an understanding of how this part of the 
code could work better, and contribute an enhancement.  I'm not all that 
familiar with how the different OS, runtime and DB platforms deal with 
character sets, so I may be guilty of wishful thinking...so my question 
was: Is there a way to detect the character sets supported by the 
platform?  We could then merge that with the character sets supported by 
Firebird and this provider and prevent this problem from reoccurring.

I tried a very straightforward approach using Encoding.GetEncodings and 
trying to search that list to eliminate unsupported encodings before 
problems were encountered, but that didn't work because accessing the 
EncodingInfo data (as returned from that method) throws an exception if 
the CodePage isn't supported, apparently because it is trying to 
initialize it's internal encoding when accessed*.  So I mangled it to 
the less elegant version that I've attached.  I've tested it here and it 
solves my problem without conditional compilation or commenting out 
unsupported encodings.  Look for "InitializeSupportedCharsets".  The old 
version is present, but commented out.

*This doesn't happen on MS.NET.  My environments are:

danno@puma:~/dev/firebird$ mono --version
Mono JIT compiler version 2.6.7 (Debian 2.6.7-5ubuntu1~dhx1)
Copyright (C) 2002-2010 Novell, Inc and Contributors. www.mono-project.com
	TLS:           __thread
	GC:            Included Boehm (with typed GC and Parallel Mark)
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none

Firebird.NET Provider 2.6.0 (compiled on Ubuntu Desktop 10.04.2) testing 
on Ubuntu Server 10.04.2 (Lucid Lynx)

...and...

Windows.NET 2.0, Firebird.NET Provider 2.5.1 from download running on 
Windows XP (development and unit test with VS.NET 2005).


Also, one side note: when compiling 2.6.0 without the ENTITY_FRAMEWORK 
directive, I got errors on Entity.SSDLToFB.cs (added sometime after 
2.5.2).  Adding #if (NET_35 && ENTITY_FRAMEWORK) condition solved that 
problem.  Is that missing conditional an oversight, or should I not need 
that conditional and is there something else wrong with my setup?

Cheers,
Danny


-- 
Danny Gorton II
Co-founder
Absolute Power and Control, LLC
www.absolutepowerandcontrol.com