wvdial postinst script bugs

Forest Bond forest at alittletooquiet.net
Thu Jan 28 14:33:02 UTC 2010


The wvdial postinst script runs wvdialconf which tries to detect modems and
write out /etc/wvdial.conf.  There have been several bugs reported where
wvdialconf hangs while probing serial ports and the wvdialconf process must be
killed, leaving the package unconfigured.

You may wish to scan the bug list briefly:


I have just run into this issue and have reported bug #513787.  It is indeed a
bug if wvdialconf hangs when probing serial devices.

However, I wanted to bring this issue up here because I don't think it's
appropriate for a postinst script to probe serial devices without at least
asking the user first.

It's impossible to probe serial devices without possibly disrupting
communication for processes that are already making use of the device.
Depending upon what sort of device is connected to the port, probing may cause a
network connection to fail, introduce data corruption on a connection, or a
variety of potentially worse problems, depending on what sort of device is on
the other end (consider what might happen if someone tries to install wvdial on
a machine that is using the serial ports to control some mechanical device).

wvdial does use debconf to decide if it should automatically detect modems, but
this setting is given priority "low" and defaults to "yes", so most users are
never asked.  I think the priority should be higher, and I think the default
should be "no" to avoid problems with noninteractive installation.


Forest Bond
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