[Devil-linux-develop] [PATCH] save-config - Adds deterministic save location, fixes issues with ISO/config on same device

[Tim T. <t....@co...>]

This patch includes the following:

1. Adds new command switches, and this help output:

    save-config [-hqs] [-d DEVICE] [-f FILE]
      Saves the Devil-Linux configuration (/etc and /root trees) to a 
bzip2 compressed tar file.
      By default, the file loaded during boot will updated.
   
      -d <devicename>  Device to use for configuration file.
      -f <filename>    Name of configuration file (default is 
"etc.tar.bz2").
      -h               This help text
      -q               Quiet operation, no status ouput.
      -s               Force search of all devices for configuration file.
  
2. Deterministic save location -  By default, the /shm/DL_CONFIG_SOURCE 
file exists (created by linuxrc during boot), the device listed inside 
is used rather than a search list. Thus the addition of new hot-plug 
devices after bootup won't cause your config save to go astray as the 
search list changes. The "-d" option can be used to force a device, or 
"-s" can be used to force a search.

3. Fix errors caused when the config and bootcd.iso file live on the 
same device. This requires always mounting the device in the same mode 
as was used to mount the device when looking for the bootcd.iso (ie ro), 
then remounting to rw as required, doing the writes, remounting to ro, 
then umounting. This also means the device is only opened rw for the 
mininial time required, so less chance of corruption if the user swaps 
the floppy at the wrong moment. (Note: Small fixes to linuxrc and 
mount_cdrom are also needed due to this. Coming up next:)

4. In the event that the chosen device has no config file on it, simply 
inform the user and create a new one. This means that a fresh floppy can 
be popped in to capture a changed config without having to copy a dummy 
config to it first. Makes sense to me anyway.

5. Pass the "post-save-config" script info that it might need about the 
file just saved.

Tim