Re: sha512sum-error at debian-live-11.5.0-amd64-gnome.iso
Hi,
Gerd Mühlenbruch wrote:
> So, it seems to be a problem of nautilus on my computer.
wget -c still has a share in this.
But currently i have no ideas how to find out what makes an incomplete
nautilus download so confusing for wget.
> dd if=debian-11.5.0-amd64-netinst.iso bs=1 skip=400556032 | od -c | less
> >Ausgabe.txt
(My proposal to pipe into the pager "less" was meant to avoid the need
for redirection.)
> 1177740 \0 \0 \0 E F I P A R T \0 \0 001 \0 \
> 1177760 \0 \0 \0 302 354 241 223 \0 \0 \0 \0 377 357 \v \0 \0
> 1200000 \0 \0 \0 001 \0 \0 \0 \0 \0 \0 \0 @ \0 \0 \0 \0
This is a GPT header block signature, but not aligned to a full block
of 512 bytes, as GPT prescribes.
The "E" of "E F I" is supposed to be at the start of the block.
24 bytes from there on we have a little-endian 8-byte number which tells
the intended block address:
(gdb) p 0377 + 0357 * 256 + '\v' * 256 * 256
782335
This is the address of the last 512-block of the original ISO:
782335 = 400556032 / 512 - 1
So we have a displaced copy of a GPT backup header with the proper
block address which it would have in the netinst ISO.
Checking this theory:
dd if=debian-11.5.0-amd64-netinst.iso bs=512 skip=782335 | od -c
yields
0000000 E F I P A R T \0 \0 001 \0 \ \0 \0 \0
0000020 302 354 241 223 \0 \0 \0 \0 377 357 \v \0 \0 \0 \0 \0
0000040 001 \0 \0 \0 \0 \0 \0 \0 @ \0 \0 \0 \0 \0 \0 \0
0000060 312 357 \v \0 \0 \0 \0 \0 f 027 253 N 247 r 5 B
0000100 215 256 z 9 353 M 314 313 357 \v \0 \0 \0 \0 \0
0000120 320 \0 \0 \0 200 \0 \0 \0 1 231 o 227 \0 \0 \0 \0
0000140 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
*
0001000
Both, the existence of the copy 327648 after the original end of the ISO
and its non-alignment by -29 (or 483) bytes are hard to explain.
Have a nice day :)
Thomas
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