1. Checking file integrity
- Posted by rforno at tutopia.com
Apr 19, 2003
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Rob:
The attached program tries to verify file integrity.
I ran this program on a data CDROM, which I know has errors because Nero
stops with "read error" when trying to copy it. However, the program does
not detect
any error. Am I doing something wrong?
Regards.
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2. Re: Checking file integrity
- Posted by r.schr at t-online.de
Apr 20, 2003
Hi,
the CD-ROM you read from might be in a bad condition, i.e., everything
is readable but the read process has to try it several times for some
items. The copy process normally affords a continuous flow of data,
which may be broken by the slow reading process. Try to copy the CD-ROM
with the slowest burning speed possible. Also an other CD-ROM drive
might be the solution.
Have a nice day, Rolf
rforno at tutopia.com wrote:
>
>
> Rob:
> The attached program tries to verify file integrity.
> I ran this program on a data CDROM, which I know has errors because Nero
> stops with "read error" when trying to copy it. However, the program does
> not detect
> any error. Am I doing something wrong?
> Regards.
>
>
>
> TOPICA - Start your own email discussion group. FREE!
>
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> verify.ZIP Type: Zip Compressed Data (application/x-zip-compressed)
> Encoding: base64
3. Re: Checking file integrity
I can sympathise with that.
My Rollercoaster Tycoon CD was getting old, so it was quite scratched from
the day-to-day wear it had endured. I tried installing it on one of my
computers, and it would hang EVERY time. It wouldn't install over the
network, and it wouldn't work if you copied the files over manually.
Funny thing was, it installed on another computer just fine!
I tried copying it onto a CD-R at regular speed (x32)... but it still didn't
work... waste of a CD. I ended up going back to the computer that read it,
copying the files onto a temporary directory, then manually creating a new
CD with the same attributes (label, etc) as the old. I burnt it at 4x on to
the CD-R, and it worked fine.... just wierd.
=====================================================
.______<-------------------\__
/ _____<--------------------__|===
||_ <-------------------/
\__| Mr Trick
>From: r.schr at t-online.de
>Reply-To: EUforum at topica.com
>To: EUforum <EUforum at topica.com>
>Subject: Re: Checking file integrity
>Date: Sun, 20 Apr 2003 09:06:12 +0200
>
>
>the CD-ROM you read from might be in a bad condition, i.e., everything
>is readable but the read process has to try it several times for some
>items. The copy process normally affords a continuous flow of data,
>which may be broken by the slow reading process. Try to copy the CD-ROM
>with the slowest burning speed possible. Also an other CD-ROM drive
>might be the solution.
>
>Have a nice day, Rolf
>
>
>rforno at tutopia.com wrote:
> >
> >
> > Rob:
> > The attached program tries to verify file integrity.
> > I ran this program on a data CDROM, which I know has errors because Nero
> > stops with "read error" when trying to copy it. However, the program
>does
> > not detect
> > any error. Am I doing something wrong?
> > Regards.
> >
> >
> > TOPICA - Start your own email discussion group. FREE!
> >
> >
>
>
>TOPICA - Start your own email discussion group. FREE!
>
>
4. Re: Checking file integrity
rforno at tutopia.com wrote:
> The attached program tries to verify file integrity.
> I ran this program on a data CDROM, which I know has errors because Nero
> stops with "read error" when trying to copy it. However, the program does
> not detect
> any error. Am I doing something wrong?
I don't know what you expected to happen.
Your program seems to just read each file
until it encounters a -1 (end of file).
If a file has been corrupted, maybe you will
get a -1 prematurely. Euphoria itself will never
report an error. Maybe you should count the number of
bytes and compare with the size in the dir() entry.
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
5. Re: Checking file integrity
x
x
rforno at tutopia.com wrote:
> Wouldn't be it possible for Euphoria to return an error report in such a
> case, for example with a negative number different from -1 (EOF)?
> Maybe I'm wrong, but I think the OS has a variable called errno (under C)
> that can be accessed by the user. Couldn't it be used to that end?
I'm not aware of any test that I could make that would
detect an error on the disk media. Even if there were
such a test, would it be worth wasting a couple of machine
cycles on *every* byte read by *every* program?
I believe that each disk sector has a checksum on it.
Perhaps your "Nero" program sees if the checksum is correct.
I would have thought that the O/S would complain loudly
if a sector were bad (i.e. bad checksum).
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
6. Re: Checking file integrity
rforno at tutopia.com wrote:
> Rob Craig wrote:
> > I believe that each disk sector has a checksum on it.
> > Perhaps your "Nero" program sees if the checksum is correct.
> >
>
> I also think so. Would it be possible for Euphoria to access this
> information?
I don't know how to do that.
If it's possible at all, it seems like a
specialized thing that's better suited to a special
user-contributed library routine. Maybe there's a Windows .dll
you can access for that.
----
By the way, I added a few lines of code to ListFilter
(a few messages ago) that might solve the problem
where Topica drops the first part of messages (either
on the Web interface, or in delivered e-mail).
Topica seems to be very slow in correcting
this silly problem.
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
7. Re: Checking file integrity
empty lines, just in case
empty lines, just in case
empty lines, just in case
empty lines, just in case
Hi Ricardo,
I think you'll have to access direct writing to the device, I don't
know how to do it with Win32 API's but i do with BIOS int's. It's not
that hard.
Btw, if you want some broken floppies just come to Santa Rosa, La
Pampa where I live, i've tons of them here. =)
Best Regards,
Guillermo Bonvehi
--- rforno at tutopia.com wrote:
>
> Pete:
> The CD I was speaking of is not protected, as far as I know. Once
> upon a
> time it was completely readable, but later on it developed a scratch.
> As a
> matter of fact, I have good copies of it.
> My aim was to develop a program that detects unreadable files in a
> medium,
> like hard disks, CD-ROMs, diskettes or whatever. Believe it or not,
> at this
> very moment I have no bad diskettes at hand, so I can't test it. But
> I hope
> to have one soon...
> Regards.
