On 2013-01-20 17:21, gregor herrmann wrote:
Control: severity -1 minor
On Sun, 20 Jan 2013 13:21:13 -0500, Filipus Klutiero wrote:
Package: cdck
Version: 0.7.0-5
Severity: serious
Ehm, are you sure about the severity?
This is a security bug, but I don't see it as grave given that someone
using cdck is unlikely to follow its instructions blindly. The exact
severity - if such a thing exists - is yours to determine.
On this machine, cdck gives this verdict for the second of a series
of 10 home-made DVDs that contain personal videos:
CD overall:
Sectors total: 2295104:
Good sectors: 2295088:
Bad sectors (incl. with poor timing): 16
[..]
Conclusion:
Disc contains BAD or even unreadable sectors, put it into trash can!
This install clearly has problems reading optical discs.
Ok, so cdck's output about 16 bad sectors is not implausible,
correct?
Not really correct. Taken to the extreme, this install's issue with
optical discs would cause it to declare any disc as bad (or worst, to be
so slow that it would never complete a check). That doesn't mean the
discs are actually bad. It seems the install is more sensitive to "weak
sectors". It takes a huge time to read weak sectors, and in this rare
case, it simply failed. My desktop confirmed that the 16 sectors are not
actually bad. Even the problematic install confirms they're not really
bad in this second run on the same CD:
Track list (1-1):
1: 00:02:00 (sec: 000000) data
170: 35:02:64 (sec: 157564) data (leadout)
sectors = 157564
Disc status: data mode 1
Multisession: 0
Audio status: failed to get, reason: No medium found
Try to find out what sort of CD this is...
CD-ROM with iso9660 fs
iso9660: 4367 MB size, label 'SOUVENIRS '
XA sectors
NB! For disks written with some burners cdck might
report about unreadable sectors at the end of the disk.
In such cases you can just ignore those warnings.
! TOC and lseek() return different information about size , using
lseek()'s number of sectors which is 2295104
Reading sectors 1-2295104
! unable to read sector 1718419, reason: Input/output error
! unable to read sector 1718745, reason: Input/output error
173326^Zok
[1]+ Stoppé cdck -t -v
real 560m31.067s
user 0m0.000s
sys 0m0.000s
chealer@vinci:~$ fg 1
cdck -t -v
2295104 ok
CD overall:
Sectors total: 2295104:
Good sectors: 2295102:
Bad sectors (incl. with poor timing): 2
CD timings:
Minimal = 0 usec (0.000000s)
Maximal = 1580263158 usec (1580.263158s)
Average = 15226 usec (0.015226s)
Conclusion:
Disc contains BAD or even unreadable sectors, put it into trash can!
chealer@vinci:~$
(This second run shows cdck declaring 2 bad sectors it hadn't considered
bad in its first run, and not declaring as bad any of the 16 sectors it
had declared bad in its first run. cdck was stopped and resumed so that
it would finish before breaking the ODD.)
From these, the disk is only BAD in case 3.1. And even if there are
actually BAD sectors on the disc, that doesn't mean all sectors are
bad.
Right, and in the output above we see 2295088 good and 16 bad
sectors.
Right... but the conclusion instructs to get rid of the entire disc, not
just of the 16 bad sectors. It is generally a good idea to get rid of
the entire disc, but only after making sure at least the good sectors
are not needed.
In many cases, discs are the only stores of some data. In these
cases, cdck should instruct to recover the recoverable data and only
then to get rid of the disc.
So the issue your pointing at is the output or more precisely the
last part "put it into trash can!"?
The issue I'm pointing at is the output. The output says 2 things:
1. The disc contains unreadable (or even BAD) sectors.
2. The disc should be discarded.
2. is definitely a problem. As for 1., it might be true in a certain
sense. In a given context, some sectors were unreadable by the install.
On the other hand, it is not that it contains *generally* unreadable
sectors, as these sectors could be read in a different install.
I agree that a damaged disc should in
general be discarded to avoid giving a false impression that the
data is available, but that's a secondary concern. The primary
concern with a damaged disc should be to save the data which it
uniquely stores. Putting a disk right in the trash can just because
it has bad sectors is likely to cause data loss.
I agree that saving data makes more sense than blindly throwing away
the disk. And I also see the point that the wording out the output is
not optimal; I always interpreted it as colloquial / tongue-in-cheek.
I hope you can agree that throwing away a disk is still the owner's
decision and responsibility and not the one of a piece of software
that write a slightly sloppy message to the screen :)
Of course. I think at this stage of development cdck should avoid
colloquiality and focus on utility and clarity.
I'm happy to treat this as a language problem and to either drop the
"trash can" part or replace it with something like "you might want to
save data from it" or something similar. -- Severity adjusted
accordingly.
Cheers,
gregor
