Path: utzoo!utgpu!watmath!clyde!att!ucbvax!bloom-beacon!apple!well!ewhac
From: ewhac@well.UUCP (Leo L. Schwab)
Newsgroups: comp.sys.amiga.tech
Subject: Re: How to close a device
Message-ID: <10120@well.UUCP>
Date: 25 Dec 88 09:55:30 GMT
References: <587@abo.fi>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Count Pointer-count.
Lines: 53
Quote: "I am not interested in trying to compensate for your amazing lack of
	observation."  -- Orac

In article <587@abo.fi> vinsci@abo.fi (Leonard Norrgard) writes:
>  What is the *correct* order to close a device and free buffer memory &
>replyports?
>
>  Currently, I'm doing this (where ReadRequest is a struct IOExtSer *):
>
>  if (ReadRequest) {
>      CloseDevice(ReadRequest);
>      DeletePort(ReadRequest->IOSer.io_Message.mn_ReplyPort);
>      FreeMem(ReadRequest, sizeof(*ReadRequest));
	ReadRequest = NULL;	/*  <----  I'd add this  */
>  }
>
	You may want to add that line in case you plan on re-using the
ReadRequest pointer after FreeMem()ing the memory it points to.  If you do
what I do:

opencrud ()
{
	if (!(librarybase = OpenLibrary(...)))
		die ();
	if (!(ReadRequest = CreateStdReq()))
		die ();
	.
	.
	.
}

closecrud ()
{
	.
	.
	.
	if (ReadRequest)
		/*  Close it  */
	if (librarybase)
		CloseLibrary (librarybase);
}

	...and plan on calling opencrud()/closecrud() multiple times, then
you'll want to set ReadRequest, and all other global pointers, to NULL in
your closecrud() routine.  This is so that, when you call opencrud() again,
all the pointers will start out as NULL, and in case something fails to
open, you won't end up trying to close something that you didn't open
because the pointer was left non-NULL.

	Did this make sense?

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Leo L. Schwab -- The Guy in The Cape	INET: well!ewhac@ucbvax.Berkeley.EDU
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