Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!kuhub.cc.ukans.edu!markv
From: markv@kuhub.cc.ukans.edu
Newsgroups: comp.sys.amiga.tech
Subject: Re: Children and message ports
Message-ID: <26629.27393c74@kuhub.cc.ukans.edu>
Date: 8 Nov 90 16:07:32 GMT
References: <9011021641.AA18389@luke.eecs.wsu.edu>
Organization: University of Kansas Academic Computing Services
Lines: 69

> I have created a child process using CreateProc. In the child I call
> FindTask to find my task (process) pointer. I then wait on my process
> message port
> 
> proc = (struct Process *)FindTask(0);
> port = proc->pr_MsgPort;
> WaitPort(proc);
> 
> In the parent I send a message to the child.
> 
> procid = CreateProc(name,pri,seg,stack);
> PutMsg(procid,msg);
> 
> The result, Task held ...
> 
> The eventual guru is 8700004 (not sure on the # of 0). I think this means
> bad packet to the dos library. Does it? How did I do that?
> 
> I have commented out the PutMsg to see if that was the problem. It is.
> what is wrong with my PutMsg? Did I miss something?

Your process message port (pr_MsgPort) is not yours to play with, it
belongs to DOS.  DOS uses it to send DOSPackets back and forth for
your process' file IO.  A non-Handler task should never play with its
process message port.  When you send your message, DOS tries to
interpret it as a DOS packet.  Sooo...

Try creating your own port and sending to it... like: (off the top of
my head, all parameters not guarenteed correct.)

child:

	struct MsgPort	*FooPort;

	FooPort = CreatePort("APORTNAME", 0);
	WaitPort(FooPort);
	...etc...
	when done...
	DeletePort(FooPort);

parent:
	struct MsgPort	*Foo2Port=NULL;
	
	...CreateProc(...)

	while (Foo2Port == NULL) {
		Foo2Port = FindPort("APORTNAME");
		WaitTOF();	/* Dont busy wait, check 30 times p/sec	*/
		WaitTOF();
	}
	PutMsg(Foo2Port, AMessage);

Note that this code is extremely simplified.  The loop around
FindPort() wouldn't be needed if the child could notify a parent with
a signal or message to a MsgPort of the parent.  CreatePort() might
fail too.

> By the way the child task is running.
> 
> Please reply by email, post, homing pigeon, any way you can! Thanks
-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mark Gooderum			Only...		\    Good Cheer !!!
Academic Computing Services	       ///	  \___________________________
University of Kansas		     ///  /|         __    _
Bix:	  markgood	      \\\  ///  /__| |\/| | | _   /_\  makes it
Bitnet:   MARKV@UKANVAX		\/\/  /    | |  | | |__| /   \ possible...
Internet: markv@kuhub.cc.ukans.edu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~