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Date: Wed, 7 Mar 2012 15:55:27 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Oracle OCI under cygwin
Message-ID: <20120307145527.GI5159@calimero.vinschen.de>
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On Mar  7 15:46, Corinna Vinschen wrote:
> On Mar  7 14:38, Michel Bardiaux wrote:
> > I have an up-to-date cygwin on XP SP3 (and yes, rebasealled). I have
> > also installed the Oracle basic (NOT instant) client for Win32. And I
> > have a C application that queries an Oracle DB using OCI. Another
> > relevant bit of setup info: environment variable TNS_ADMIN =
> > \\besprd01\techdoc\database\oracle\OracleNet_WinClient (set in XP
> > Control Panel).
> > 
> > Now, when compiled with MS Visual Studio 2010 Express, and run from a
> > DOS (sic) box, the app works fine, which proves both the app and the
> > setup are basically fine. Ditto when run from a Cygwin mintty.
> > 
> > But if I compile my app with cygwin, and run it in mintty (of course), I
> > get an error message meaning essentially that OCILogon failed because it
> > did not find an Oracle config file called tnsnames.ora that is supposed
> > to be in $TNS_ADMIN.
> > 
> > Strace gives no clue - because the app WORKS when run by strace! The
> > Win32 PROCMON shows that tnsnames.ora is looked for in %TNS_ADMIN% for
> > the pure win32 app, but in the local directory for the cygwin app.
> > Indeed, if I kluge my code in the cygwin case to temporarily chdir to
> > $TNS_ADMIN (rewritten as a cygwin path of course) just before calling
> > OCILogon, it works.
> 
> Cygwin applications don't use the WIN32 environment.  Rather they have
> their own copy of the environment in a POSIX layout.  What happens is
> probably that the OCI lib calls GetEnvironmentString ("TNS_ADMIN",...)
> and gets nothing back, since the variable is just not in the Win32
> environment of the Cygwin application.
> 
> The workaround is to do this before calling ani OCI lib function:
> 
>   #include <sys/cygwin.h>
> 
>   cygwin_internal (CW_SYNC_WINENV);
> 
> This call copies the POSIX environment over to the Win32 environment
> correctly in 

Hups, there has something gone wrong.  Let me try again:

  This call copies the POSIX environment over to the Win32 environment
  of the calling process, so the OCI lib functions should find the
  TNS_ADMIN variable when called *after* the above call.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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