Re: Access violation from palloc, Visual Studio 2005, C-language function

Aha. I'd read that the build process for the contrib modules involved
generating a .DEF file for the necessary exports. I had the impression that
defining BUILDING_DLL was an alternative, addressing (part) of the issue
(that is, PG_FUNCTION_INFO_V1 declares functions as 'extern PGDLLIMPORT',
and if you define BUILDING_DLL, then PGDLLIMPORT is defined as ' __declspec
(dllexport)'). But you're quite right, if I take out the BUILDING_DLL
definition, and put the __declspec (dllexport) stuff in piecemeal, the
access violation goes away. Thank goodness.

Thanks, that really helped me out.

Kevin.



-----Original Message-----
From: pgsql-hackers-owner@postgresql.org
[mailto:pgsql-hackers-owner@postgresql.org] On Behalf Of Tom Lane
Sent: 10 March 2010 18:51
To: Kevin Flanagan
Cc: 'PostgreSQL-development'
Subject: Re: [HACKERS] Access violation from palloc, Visual Studio 2005,
C-language function 

"Kevin Flanagan" <kevin-f@linkprior.com> writes:
>>> Hard to tell without seeing the actual code and a stack trace, but I'd
>>> bet that you haven't fully resolved the build process problems you
>>> mentioned earlier.  

> I've attached a zip of the (tiny) project, and a text file with the
contents
> of the module containing the C-language functions. The only difference
from
> sample code is that (as pointed out by Takahiro Itagaki in his post here
of
> 8th March) the function implementations need decorating with
> __declspec(dllexport).

Mph.  I don't actually believe that, nor do I believe the #define
BUILDING_DLL you put in, because neither of those are needed in any of
our contrib modules.  What I suspect at this point is that the reference
to CurrentMemoryContext in the palloc() macro is being bollixed by
having the wrong value for BUILDING_DLL.  However, not having a Windows
build environment to experiment with, I'll have to defer to somebody
with more experience in that.

(I wonder BTW if we should rename BUILDING_DLL, because it seems a bit
misnamed.  AIUI it's supposed to be set while building the core backend,
not while building loadable modules.)
        regards, tom lane

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