Thanks for that.
I do have a simple stdcall dll that sits in between my VB6 ActiveX dll and
sqlite3.dll
This does nil else than simply things like this:
SQLITE3_STDCALL_API int __stdcall
sqlite3_stdcall_column_count(sqlite3_stmt* pStmt)
{
return sqlite3_column_count(pStmt);
}
So, that takes care of your point 1 and this works all perfectly fine.
> I think that using the AddressOf keyword won't really work with SQLite
in this context due to mismatched calling conventions (cdecl versus
stdcall).
This is interesting as I do use VB6 AddressOf to pass the pointer of the
UDF to SQLite.
It must be working OK though as I pass this pointer again via that stdcall
dll and also because there is no problem with only one UDF in a SQL
statement.
I have to mention that I do use a .tlb that sits in between my ActiveX dll
and that stdcall dll.
I don't think this is the problem, because it makes no difference if I do
instead plain Declares in my VB6 dll.
I take it your .net dll handles UDF's fine, even when there are 2 in one
SQL statement?
I agree it is all tricky, but apart from this particular UDF problem all
runs perfectly fine (both data producing SQL and non-data producing SQL)
and very fast as well. See also my reply to Mr Hipp.
RBS
On Thu, Dec 24, 2015 at 9:56 PM, Joe Mistachkin <sflists at mistachkin.com>
wrote:
>
> It's been quite a long while since I used vb6 on a regular basis; however,
> integrating with native DLLs can be quite tricky for several reasons:
>
> 1. It cannot call any native function that does not conform to the
> "stdcall" calling convention.
>
> 2. It has a very Win32-centric way of marshalling data types.
>
> 3. Using 64-bit integers at all is somewhat tricky, IIRC. You may need
> to use a ByVal structure to pass them and I cannot remember how to use them
> as returned values.
>
> 4. Properly declaring and calling (e.g. using the ByVal keyword
> strategically) is critically important. Another issue is ANSI versus
> Unicode (UCS2 for COM) versus UTF-8 (SQLite) and knowing when to use which
> and how to convert between them (or marshal them).
>
> 5. Doing inbound callbacks to VB6 code is very very tricky, mostly due to
> [apartment] threading issues. I think that using the AddressOf keyword
> won't really work with SQLite in this context due to mismatched calling
> conventions (cdecl versus stdcall).
>
> I'll try looking for my old VB6 SQLite integration code when I have some
> spare cycles.
>
> Sent from my iPhone
>
> > On Dec 24, 2015, at 11:10 AM, Bart Smissaert <bart.smissaert at gmail.com>
> wrote:
> >
> > OK, thanks
> > I don't use any of 1 to 3, I only use the standard SQLite functions such
> as
> > sqlite3_open_v2, sqlite3_prepare16_v2, sqlite3_step, sqlite3_bind,
> > sqlite3_column, sqlite3_create_function_v2, sqlite3_finalize,
> > sqlite3_reset, sqlite3_result, sqlite3_value and qlite3_close.
> > So, in that case I don't need sqlite3_free, sqlite3_malloc or
> > sqlite3_realloc, I take it.
> > Given that I don't use theses it then likely that my problem is to do
> with
> > a buffer overwrite?
> >
> > RBS
> >
> >
> >
> >> On Thu, Dec 24, 2015 at 8:35 PM, Richard Hipp <drh at sqlite.org> wrote:
> >>
> >>> On 12/24/15, Bart Smissaert <bart.smissaert at gmail.com> wrote:
> >>> My question is if there is ever any need in this situation to run one
> of
> >>> the sqlite3 memory procedures, that is
> >>> sqlite3_free, sqlite3_malloc or sqlite3_realloc?
> >>> Currently I am not using this anywhere in my VB6 code.
> >>> Should I?
> >>
> >> Cases when you might use sqlite3_malloc():
> >>
> >> (1) You are using on of SQLite's built-in memory allocators. The
> >> built-in memory allocators are disabled unless you use certain
> >> compile-time options. And even then, you have to turn them on using
> >> sqlite3_config(SQLITE_CONFIG_HEAP,...).
> >>
> >> (2) You need to use sqlite3_msize().
> >>
> >> (3) If you use sqlite3_mprintf(), then sqlite3_free() must be used to
> >> release the string once you are done with it.
> >>
> >> Otherwise, there is no real advantage to using SQLite memory allocator
> >> interface in place of your standards system memory allocator.
> >>
> >> --
> >> D. Richard Hipp
> >> drh at sqlite.org
> >> _______________________________________________
> >> sqlite-users mailing list
> >> sqlite-users at mailinglists.sqlite.org
> >> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
> > _______________________________________________
> > sqlite-users mailing list
> > sqlite-users at mailinglists.sqlite.org
> > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
> >
> _______________________________________________
> sqlite-users mailing list
> sqlite-users at mailinglists.sqlite.org
> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
>
