running partimage in batch mode

A continuation of the partimage project.

As it would appear that stdout support doesn't work due the user interface making use of stdout, I have been figuring out how to make the program run in batch mode, with a little help from KDevelop.

My continued findings:

The help presents a fully batch mode, -B

$ ./partimage --help
===============================================================================
Partition Image (http://www.partimage.org/) version 0.6.5_beta4 [stable]
---- distributed under the GPL 2 license (GNU General Public License) ----

Supported file systems:....Ext2/3, Reiser3, FAT16/32, HPFS, JFS, XFS,
                           UFS(beta), HFS(beta), NTFS(experimental)

usage: partimage [options] <action> <device> <image_file>
       partimage <imginfo/restmbr> <image_file>

ex: partimage -z1 -o -d save /dev/hda12 /mnt/backup/redhat-6.2.partimg.gz
ex: partimage restore /dev/hda13 /mnt/backup/suse-6.4.partimg
ex: partimage restmbr /mnt/backup/debian-potato-2.2.partimg.bz2
ex: partimage -z1 -om save /dev/hda9 /mnt/backup/win95-osr2.partimg.gz
ex: partimage imginfo /mnt/backup/debian-potato-2.2.partimg.bz2
ex: partimage -a/dev/hda6#/mnt/partimg#vfat -V 700 save /dev/hda12 /mnt/partimg/redhat-6.2.partimg.gz

Arguments:
* <action>:
  - save: save the partition datas in an image file
  - restore: restore the partition from an image file
  - restmbr: restore a MBR of the image file to an hard disk
  - imginfo: show informations about the image file
* <device>: partition to save/restore (example: /dev/hda1)
* <image_file>: file where data will be read/written. Can be very big.
                For restore, <image_file> can have the value 'stdin'. This allows
                for providing image files through a pipe.

Options:
* -z,  --compress      (image file compression level):
  -z0, --compress=0    don't compress: very fast but very big image file
  -z1, --compress=1    compress using gzip: fast and small image file (default)
  -z2, --compress=2    (compress using bzip2: very slow and very small image file):
* -c,  --nocheck       don't check the partition before saving
* -o,  --overwrite     overwrite the existing image file without confirmation
* -d,  --nodesc        don't ask any description for the image file
* -V,  --volume        (split image into multiple volumes files)
  -VX, --volume=X      create volumes with a size of X MB
* -w,  --waitvol       wait for a confirmation after each volume change
* -e,  --erase         erase empty blocks on restore with zero bytes
* -m,  --allowmnt      don't fail if the partition is mounted. Dangerous !
* -M,  --nombr         don't create a backup of the MBR (Mast Boot Record) in the image file
* -h,  --help          show help
* -v,  --version       show version
* -i,  --compilinfo    show compilation options used
* -f,  --finish        (action to do if finished successfully):
  -f0, --finish=0      wait: don't make anything
  -f1, --finish=1      halt (power off) the computer
  -f2, --finish=2      reboot (restart the computer):
  -f3, --finish=3      quit
* -b,  --batch         batch mode: the GUI won't wait for an user action
* -BX, --fully-batch=X batch mode without GUI, X is a challenge response string
* -y,  --nosync        don't synchronize the disks at the end of the operation (dangerous)
* -sX, --server=X      give partimaged server's ip address
* -pX, --port=X        give partimaged server's listening port
* -g,  --debug=X       set the debug level to X (default: 1):
* -n,  --nossl         disable SSL in network mode
* -S,  --simulate      simulation of restoration mode
* -aX, --automnt=X     automatic mount with X options. Read the doc for more details
* -UX  --username=X    username to authenticate to server
* -PX  --password=X    password for authentication of user to server
===============================================================================

It is not immediately obvious what "X is a challenge response string" means.
I was able to get the program to run to a limited extend after a bit of searching the internet and trial and error with the option "-B x=y".

Having stepped through the program, it transpires that where I have put "x", the program expects a pattern to match with the title and content of any messages that would otherwise have been shown to the user, and "y" is the pre-programmed response. This is in the "interface_none" section.
"x" has to match the question in the form "message title/message content" and is compared using fnmatch which allows * as a wildcard (anyone got a good reference for fnmatch?).
If the program hits a question for the user, and cannot find a matching answer in the command arguments, "CInterfaceNone::invalid_programmed_response()" fires "exit(8)" and the program dies.

So far I have been running the program as a normal user, which will inevitably fail where it attempts to work with block devices / root owned files & folders. This produces a warning in the user interface, followed by program termination.

To bypass this first "not root" warning, I successfully used this pre-programmed answer:
./partimage -B Warning*=Continue
Alternatively the following is more specific and also works:
./partimage -B Warning*root*=continue

I haven't figured out how to pass more than one predefined answer in batch mode.

The run arguments can be set in KDevelop here:
project > options > debugger > program arguments

Side note:
The program has a base class of user interface defined, and then either instantiates interface_none or interface_newt depending on command line arguments.

If not using full batch mode it helps to set "enable separate terminal for application IO" in KDevelop (project > options > debugger) so that you can see the full user interface. However if the program exits then the console closes and any output is lost.

As part of stepping through the code, I came across a macro, which makes the program harder to follow while debugging due to not being able to step through. So I figured out what it did, and wrote out its output C++ code in full:

interface_none.cpp, line 103

#define MB_2(One,Other,ONE,OTHER)       \
int CInterfaceNone::msgBox##One##Other(char *title, char *text, ...) {  \
char *result= lookup(title,text,"(unspecified)");     \
va_list al;          \
va_start(al,text);         \
message_only(#One "/" #Other, title, text, al, result);    \
va_end(al);          \
if (!strcasecmp(result,#One)) return MSGBOX_##ONE;     \
if (!strcasecmp(result,#Other)) return MSGBOX_##OTHER;    \
invalid_programmed_response();       \
return 0;                                                             \
}

MB_2(Continue,Cancel,CONTINUE,CANCEL)
MB_2(Yes,No,YES,NO)

my expanded version:

//notes: have expanded out macro so I can step through it.
int CInterfaceNone::msgBoxContinueCancel(char *title, char *text, ...) {
 char *result= lookup(title,text,"(unspecified)");
 va_list al;          
 va_start(al,text);         
 message_only("Continue" "/" "Cancel", title, text, al, result);    
 va_end(al);          
 if (!strcasecmp(result,"Continue")) return MSGBOX_CONTINUE;    
 if (!strcasecmp(result,"Cancel")) return MSGBOX_CANCEL;    
 invalid_programmed_response();       
return 0;                                                             
}

int CInterfaceNone::msgBoxYesNo(char *title, char *text, ...) {  
 char *result= lookup(title,text,"(unspecified)");     
 va_list al;          
 va_start(al,text);         
 message_only("Yes" "/" "No", title, text, al, result);    
 va_end(al);          
 if (!strcasecmp(result,"Yes")) return MSGBOX_YES;     
 if (!strcasecmp(result,"No")) return MSGBOX_NO;    
 invalid_programmed_response();       
 return 0;                                                             
}

creating a ramdisk for testing.
http://www.vanemery.com/Linux/Ramdisk/ramdisk.html
(I am on ubuntu 6.10 here, details may vary)

$ ls -l /dev/ram*
brw-rw---- 1 root disk 1,  0 2007-04-08 20:10 /dev/ram0
brw-rw---- 1 root disk 1,  1 2007-04-08 20:10 /dev/ram1
brw-rw---- 1 root disk 1, 10 2007-04-08 20:10 /dev/ram10
brw-rw---- 1 root disk 1, 11 2007-04-08 20:10 /dev/ram11
brw-rw---- 1 root disk 1, 12 2007-04-08 20:10 /dev/ram12
brw-rw---- 1 root disk 1, 13 2007-04-08 20:10 /dev/ram13
brw-rw---- 1 root disk 1, 14 2007-04-08 20:10 /dev/ram14
brw-rw---- 1 root disk 1, 15 2007-04-08 20:10 /dev/ram15
brw-rw---- 1 root disk 1,  2 2007-04-08 20:10 /dev/ram2
brw-rw---- 1 root disk 1,  3 2007-04-08 20:10 /dev/ram3
brw-rw---- 1 root disk 1,  4 2007-04-08 20:10 /dev/ram4
brw-rw---- 1 root disk 1,  5 2007-04-08 20:10 /dev/ram5
brw-rw---- 1 root disk 1,  6 2007-04-08 20:10 /dev/ram6
brw-rw---- 1 root disk 1,  7 2007-04-08 20:10 /dev/ram7
brw-rw---- 1 root disk 1,  8 2007-04-08 20:10 /dev/ram8
brw-rw---- 1 root disk 1,  9 2007-04-08 20:10 /dev/ram9

create and mount test ramdisk

# mke2fs /dev/ram0
# mkdir /media/ram0
# mount /dev/ram0 /media/ram0

add a test file and unmount the disk

# echo "test data #1." >> /media/ram0/foo.txt
# umount /media/ram0

the above, as a script:

#!/bin/bash
# create and mount test ramdisk
mke2fs /dev/ram0
if [ ! -d /media/ram0 ]; then
    mkdir /media/ram0
fi
mount /dev/ram0 /media/ram0
#add a test file and unmount the disk
echo "test file." >> /media/ram0/foo.txt
date >> /media/ram0/foo.txt
cat /media/ram0/foo.txt
umount /media/ram0

Create & run script (as root, because it (un)mounts a file system, and creates a dir in a root owned folder):

$ gedit mkram.sh
$ chmod ug+x mkram.sh
$ sudo ./mkram.sh

Wierdly, partimage won't run in full batch mode without a second part to the -B switch, even if it's set up to not need to ask any questions. Supplying a dummy "x=y" seems sufficient to fool it.

Runing as root without asking for partition description works:

$ sudo ./partimage -d -B x=y save /dev/ram0 ram0.img

Restore image to a different ramdisk and check file:

$ sudo ./partimage -B x=y restore /dev/ram1 ram0.img.000
$ sudo mount /dev/ram1 /media/ram1
$ cat /media/ram1/foo.txt
test file.
Mon Apr  9 12:56:59 BST 2007

Success!

Script for checking file in saved partition:

#!/bin/bash
# mount and check restored ramdisk
if [ ! -d /media/ram1 ]; then
    mkdir /media/ram1
fi
mount /dev/ram1 /media/ram1
cat /media/ram1/foo.txt
umount /media/ram1

To debug in KDevelop as root (in ubuntu):
alt-F2 (run)
gksudo kdevelop
open project... (go find existing copy)

So in summary, I have made progress in understanding the ways of this useful utility, and am a step closer to making a useful contribution to the project.

The rambling nature of this post reflects the way in which one begins to understand a new program. Hopefully it's not too hard to follow, or pick out the useful pieces. All feedback gratefully appreciated.

Tim.