Re: Cheatcode "knoppix testcd"
Hello Werner,
On Sat, Sep 08, 2012 at 11:49:58AM +0200, Werner P. Schulz wrote:
> There is a lack with "knoppix testcd". This cheatcode only calculates
> the sha1sum of the big filesystem image KNOPPIX, not the sha1sums from
> all the other files of a CD/DVD. If there is a download or burn error
> for example within '/mnt-system/boot/', you'll not be warned.
Right, but I had a reason to exclude boot/* and other files from checksumming :
1. When switching from isolinux to syslinux, the isolinux-dir and
isolinux/isolinux.bin vanishes, causing an error on "testcd" if the
files in sha1sums are not renamed as well.
2. If kernel or ramdisk are unreadable, the system does not boot
anyways, and testdisk won't work either.
3. Sometimes, vendors change CD or DVD content such as index.html, boot
logo or orther graphics for "branding", which then failed checksums
because nobody thought of changing the checksum in the sha1sums file as
well.
So for now, only the critical and most often defective (when
incompletely downloaded) compressed file(s) KNOPPIX/KNOPPIX* are checked
for errors. If you want to create a derivate, you can freely add new files
to sha1sums, though.
The case that the kernel wouldn't match the modules inside the compressed
file system is not covered, though. For this case, I'm thinking about a
versioning scheme using .version files inside the initial ramdisk and
file system that are supposed to match. The checksum alone is a weak
test, the compressed file system should not even get mounted if the
modules contained don't match the kernel.
Regards
-Klaus
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