PartedMagic distro detection Fails due to SuperGrubDisk detection rule

[GabrielLPAbreu]

Since the latest versions of MultibootUSB, detection of the PartedMagic distro fails and the distro is detected as SuperGrubDisc (sgrubd2), which causes initialization failure (both in Legacy and EFI).

I tried to read some of the source code with my little understanding of python and found that the error is caused by the logic used in detecting distros into distro.py script, in the case of PartedMagic, the script does the iterations and first finds strings containing "Super Grub Disk" instead of "pmagic" or "partedmagic" and returns 'sgrubd2'. This bug may possibly occur with any distro that uses Super Grub Disk to boot.

Since the order of the rules don't realy matter, the only way i could find to mitigate the problem is commenting out the entire rule for SuperGrubDisk detection (line 46 and 47 for distro.py in 9.2.0 release) and then everything worked fine, PartedMagic boots in legacy and EFI flawlessly.

Tested ISOs: pmagic_2017_09_05.iso pmagic_2017_06_12.iso pmagic_2018_03_27.iso

The bug occurs with the following versions:

• 8.9
• 9.0
• 9.1
• 9.2

Last version which i think everything worked fine: 8.8

My suggestions for solving the problem since I do not know python:

• Removing the detection rule for SuperGrubDisk (unfortunately is not ideal and also it is a regression);
• Add another treatment to the Super Grub Disk rule so it does not overlap with other rules (I think this is not a very elegant thing, unfortunately, and I have no idea how this can be done within the iterative logic, loops etc. used by the distro.py script).
• Fully rewrite script logic to prevent false detections. I've been for a while looking at the source code and I think eventually this will have to be done, I believe there are a lot of possibilities for wrong detection to happen with the addition of new rules in the future, and PartedMagic may not be the only distro currently affected .

I would like to thank everyone for this great piece of software, and also to say that English is not my native language and to apologize if I have been rude in any part of the text.

Thank you for your attention, Gabriel L. P. Abreu.

[shinji-s]

Thank you very much for not only reporting but also analyzing the problem. Actually the order of checks does matter and I think more specific checks (partedmagic) should precede less specific ones (supergrubdisk). I'll post a patch to the devel branch.

On a side note, I think many of contributors here are not English native and judging by my non-native ability yours is good enough, certainly at similar level or better than mine. Please continue exploring the source code and join the club.