Re: [TTY] exclusive mode question

[Russell King]

On Thu, Jun 09, 2005 at 04:22:49PM +0200, moreau francis wrote:
> --- Frederik Deweerdt <dev.deweerdt@xxxxxxxxxxx> a écrit :
> > Le 09/06/05 13:41 +0200, moreau francis écrivit:
> > > 
> > > oh ok...sorry I misunderstood TIOEXCL meaning ;)
> > > Do you know how I could implement such exclusive mode (the one I described)
> > ?
> > > 
> > This is handled through lock files, google for LCK..ttyS0
> >
> 
> This lock mechanism is a convention but nothing prevent a user application to
> issue a "echo foo > /dev/ttyS0" command while "LCK..ttyS0" file exists...

Which is absolutely necessary to work if you think about an application
like minicom and its file transfer helpers, which may need to re-open
the serial port.

TTY locking is done via lock files only, and all non-helper applications
must coordinate their access via the lock files.  There is no other
mechanism.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core
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