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From: drysdale@cbmvax.commodore.com (Scott Drysdale)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Message Ports
Message-ID: <22192@cbmvax.commodore.com>
Date: 5 Jun 91 22:38:06 GMT
References: <BQAcp*wk@asgard.pub.uu.oz.au>
Reply-To: drysdale@cbmvax.commodore.com (Scott Drysdale)
Distribution: comp
Organization: Commodore, West Chester, PA
Lines: 74

In article <BQAcp*wk@asgard.pub.uu.oz.au> bart@asgard.pub.uu.oz.au (John Butcher) writes:
>Ive been trying to do message ports, but I havent had lots of success, my ports
>wont get properly recognized by name.  Below small test program I wrote :
>
>main( argc, argv )
>  int argc;
>  char *argv[];
>{
>  struct MsgPort *mp;
>
>  mp = FindPort( argv[1] );
>  if ( mp == NULL )                            /* No port with that name */
>  {
>    mp = CreatePort( argv[1], 0 );                    /* so create one ! */

CreatePort() simply points to the name you give it (argv[1] in your case).
you want to do something like this:

	char *name;
	name = AllocMem(strlen(argv[1]) + 1, MEMF_PUBLIC);
	strcpy(name, argv[1]);
	mp = CreatePort(name, 0);

*note* do NOT free(name) - you want the port to live forever (or until
you delete it, whichever comes first).

>    printf("Created \"%s\" at 0x%0x\n", argv[1], mp );
>  }
>  else                                           /* found the given port */
>  {
>    printf("Found \"%s\" at 0x%0x\n", argv[1], mp );

	FreeMem(mp->mp_Node.ln_Name, strlen(mp->mp_Node.ln_Name) + 1);

>    DeletePort( mp );                                    /* so remove it */
>  }
>}
>
>And here is some test runs.... ( with added comments ;-)
>
>2.RAMB0:> port crud        
>Created "crud" at 0x208d28        Yay, it created ok !!

seems to behave as you desire.  the port is allocated and initialized.
however, the port's name points to argv[1], which is transient.

>2.RAMB0:> port anticrud     
>Found "anticrud" at 0x208d28      Whats this, I thought I called you crud !

this time it runs, the port's name still points to the memory for argv[1],
which just happens to be the same physical address as before.  ie, the
port's name now points to the name on the command line, so of course it'll
find the port.

>2.RAMB0:> port crud        
>Created "crud" at 0x208d28        Yep, well it created ok

ad nauseum.

>2.RAMB0:> port zzzz        
>Found "zzzz" at 0x208d28          But a different name is found at the address

>So....Can anyone tell me what is going on ??

> John Butcher : bart@asgard.pub.uu.oz.au

  --Scotty
-- 
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Scott Drysdale           Software Engineer
Commodore Amiga Inc.     UUCP {allegra|burdvax|rutgers|ihnp4}!cbmvax!drysdale
		         PHONE - yes.
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