[Mono-list] Native code receiving incorrect pointer addresses from custom marshaler

[Patrick Hartling]

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I have run into a problem with custom marshaling of pointers being 
passed from C# to natively compiled code.  The essense of it is that my 
custom marshaler's MarshalManagedToNative() returns an address to be 
passed to a native function, but the native function always receives an 
address that is four bytes greater than what my MarshalManagedToNative() 
returned.  My code works with versions of Mono as new as 0.30.2, but it 
does not work with 0.31 or Beta 1.  It also works with the .NET 
Framework 1.0 and 1.1.

I have attached a small example that demonstrates the problem.  The code 
is culled down from what I am actually attempting to do so that it 
demonstrates the problem while still implementing the basic 
functionality that I need.  With Mono 0.31 and Beta 1, the native 
function handleBase() determines that the pointer passed into it from 
the managed environment does not match the pointer allocated by new_Base().

As I said, the value is consistently off by four bytes, but only when a 
custom marshaler is involved.  Has there been a semantic change in Mono 
that I need to take into account, or (worst case for me) has my code 
been flawed from the beginning?

  -Patrick


-- 
Patrick L. Hartling                     | Research Assistant, VRAC
patrick@vrac.iastate.edu                | 2274 Howe Hall Room 2624
http://www.vrac.iastate.edu/~patrick/   | http://www.vrac.iastate.edu/
PGP: http://wwwkeys.gpg.cz:11371/pks/lookup?op=get&search=0xEBF86398

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