On the 03-19-95, Peter Fitzsimmons was chatting with Ian Timms:

PF> IT> One point to note however is that the process that you are running
PF> IT> the RxAsync based script in should be a child of the process which
PF> IT> opened the com port so that it can inherit access to it. This is an
PF> IT> OS/2 restriction (I think this still holds in 2.x). Also the open
PF> IT> needs to be of an appropriate type, ie. OPEN_SHARE_DENYNONE so
PF>
PF>A process that is inheriting a file handle does NOT require that the handle 
PF>have been opened with OPEN_SHARE_DENYNONE,  since it is not 
PF>reopening the file/port!!  This is the whole point of 
PF>passing the hot handle.

I'm mixing child processes with child sessions here, your quite right
about the mode not being important when it is a child process. It _IS_
important when it's a child session.

PF>The parent probably should have (and DEFINITELY should have 
PF>for OS/2 comm programs) opened the port in 
PF>OPEN_SHARE_DENYREADWRITE mode.  This is exactly what 
PF>Maximus does (I wrote it).

This prevents processes in other sessions getting access to the port,
something that prevents the user from shooting themselves in the foot
under normal circumstances, however many a user (including me) does
not like the idea of being prevented from using the full capabilities
of this OS.

PF>
PF> IT> that you are permitted to read and write to it. Unfortunately,
PF> IT> some things (nameley IBM's SLIP) open in OPEN_SHARE_DENYREADWRITE
PF> IT> which is down right ornery! If opened via RxAsyncOpen you'll get
PF>
PF>Nope -- it's downright CORRECT.  You can't leave the door 
PF>open for another uninvited process/session to open a device 
PF>that is inherently single-user,  like a serial port.

I can't agree.

What you're forgetting here is that this is a multi-tasking single-user
who wants to be able to have another process in another session
monitor the status of the port so that a lost connection can be 
re-started, or a lengthy hung connection can be terminated.

 Cheers, Ian.

 Internet:itimms{at}ariel.ucs.unimelb.edu.au   CIS:100236,1404   [Team OS/2]
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