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Re: e2dis: a Jigdo-like tool for Ext2+ FS images

>>>>> Steve McIntyre <steve@einval.com> writes:
>>>>> Ivan Shmakov wrote:

	BTW, the primary Git repository for the project is now located
	at Gitorious:


	The most notable improvement that I made recently is the message
	digest recording.


 >> IIRC, Debian's genisoimage(1) was altered to prepare a Jigdo's
 >> .template file as part of the image generation, which is much more
 >> efficient.  I believe that a similar approach could be, and should
 >> be, used for the other filesystems as well.

 > That would be absolutely the best way to go, yes. I added the code
 > into mkisofs and genisoimage, but it has since been abstracted out
 > into libjte, part of the cdrkit package in Debian.

	I'm yet to take a look at the code, but do I understand it
	correctly that Jigdo's .template only allows for a file (as
	identified by the SHA-1 digest of its contents) to be associated
	with a contiguous part of the destination image?

	Such an approach is hardly applicable to Ext2+ FS images.
	Consider, e. g.:

$ /sbin/debugfs +b21e37e0-c722-11e0-9094-001966aaa0b6.ext2 
debugfs 1.41.12 (17-May-2010)
debugfs:  stat <12>
Inode: 12   Type: regular    Mode:  0644   Flags: 0x0
Generation: 3178327445    Version: 0x00000000
User:     0   Group:     0   Size: 16384
File ACL: 0    Directory ACL: 0
Links: 1   Blockcount: 34
Fragment:  Address: 0    Number: 0    Size: 0
ctime: 0x4e48e9c1 -- Mon Aug 15 09:41:21 2011
atime: 0x4e48e9c1 -- Mon Aug 15 09:41:21 2011
mtime: 0x4e48e9c1 -- Mon Aug 15 09:41:21 2011
(0-11):21-32, (IND):33, (12-15):34-37


	There, the file's contents in two parts: one occupies image's
	blocks 21 to 32, inclusive, and the other one 34 to 37,

	It was my understanding that Jigdo's .template cannot associate
	one SHA-1 with such a non-contiguous chunk.

FSF associate member #7257

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