(ITS#6125) back-sql support via Windows API ODBC

[slapd@hannebauer.name]

Full_Name: Christoph Hannebauer
Version: 2.4.16
OS: Windows/cygwin
URL: www.hannebauer.name/openldap-sql/configure.in.patch
Submission from: (NULL) (77.189.227.183)


I wasn't able to build slapd with back-sql in cygwin, because libodbc32 is not
detected by configure. The console prints the error

configure: error: could not locate suitable ODBC library

and config.log contains:

configure:31357: mgcc -o conftest.exe -g -O2 -I/usr/local/mingw/include
-L/usr/local/mingw/lib conftest.c -lodbc32   >&5
/cygdrive/c/Users/CHANNE~1/AppData/Local/Temp/ccy74wDp.o: In function `main':
/cygdrive/d/TestProgs/openldap-2.4.16/conftest.c:81: undefined reference to
`_SQLDriverConnect'

This means there is a library libodbc32, but it doesn't define SQLDriverConnect
as a _cdecl function. When the current configure script searches for an ODBC
library, it only checks whether one of the libraries iodbc, odbc, or odbc32 has
SQLDriverConnect defined as _cdecl, which is not the case if odbc32 provides its
functions as _stdcall. All Windows API functions are mangled as _stdcall
functions, so I assume this error occurs on most MSYS and cygwin systems.

With the attached patch, configure uses windows.h and sqlext.h to compile
SQLDriverConnect and then tries to link it with -lodbc32 if no other ODBC
library can be linked. This way, SQLDriverConnect is compiled the way sqlext.h
defines it, which is _stdcall in case of cygwin.

I have tested the patch in my environment: slapd with back-sql builds
successfully.

Glueck & Kanja Consulting AG (www.glueckkanja.com) hereby places the
following modifications to OpenLDAP Software (and only these modifications) into
the public domain. Hence, these modifications may be freely used and/or
redistributed for any purpose with or without attribution and/or other notice.