🚀 go-pugleaf

matthew@sunpix.East.Sun.COM ( Sun Visualization Products) writes:

>  The following are a list of logic errors I have found in using Pcomm (1.2.8).
>I have corrected some of the problems unofficially, (I posted them to 
>comp.sources.bugs last night), but others still need to be resolved, and
>offical patches posted for all.

> [some stuff deleted]

>2) Pcomm does not handle dial-in/dial-out lines correctly.  It assumes that
>   if it can get a LCK file for a device, that it owns the device.  This is
>   partially correct.  An initial open() needs to be accomplished to test if
>   the device is currently being used as an dial-in line.  If 'open()' returns
>   and error code of 'EBUSY', the device is being used as a dial-in line, and
>   should be handles as a LCK'd device. (my patch for GETPORT fixes this)

Matthew, your patch shouldn't rely on the error code `EBUSY' because this
code is created by the driver itself and may therefor be vendor dependant.
Actually, my INTRO(2) man page says that `EBUSY' has to do with re- or
unmounting devices or resources. An open call is *no* mount operation.
I think it is more common that a device driver returns an `EIO' error if
it is already used as a dial-in line. At least the driver I posted recently
does this (FAS 2.05). :-) As well as Microport's and Interactive's drivers
do (I think, at least). Correct me if I'm wrong.

     Uwe
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