Technical Q&A NW36

Calling CloseOpenTransport When Writing an App

Q:I read somewhere that you don't have to call CloseOpenTransport if you're writing an application. Is this true?

A: Yes and no. The original OT programming documentation stated that calling CloseOpenTransport was optional for applications. There is however a bug in OT 1.1 and earlier which will not properly clean up PPC native applications when they terminate unless CloseOpenTransport is called.

Here are some rules of thumb:

1. Non-application code must always call CloseOpenTransport when it terminates.
2. It is best if 68K applications call CloseOpenTransport, but they will be cleaned up automatically if they don't.
3. Make sure that PPC applications running under OT 1.1 or earlier call CloseOpenTransport when terminating.

One way of ensuring that you comply with point 3 is to use a CFM terminate procedure in your main application fragment, such as:

static Boolean gOTInited = false;
void CFMTerminate(void)
{
   if (gOTInited) {
       gOTInited = false;
       (void) CloseOpenTransport();
   }
}
void main(void)
{
    OSStatus err;
    err = InitOpenTransport();
    gOTInited = (err == noErr);
    // the rest of your application
    if (gOTInited) {
        (void) CloseOpenTransport();
        gOTInited = false;
    }
}