[comp.sys.ibm.pc] Corrupted BACKUP disks running MS-DOS 3.3

noelroy@kean.mun.ca (Noel Roy, Economics Dept., Memorial University) (10/18/89)

I seem to be getting contaminated BACKUPID.@@@ files on my DOS BACKUP 
diskettes.  I am running DOS version 3.3+, from Zenith.

Symptoms are as follows:  normally, BACKUPID.@@@ is a file of 128 
bytes, with the last 122 padded with zeroes.  The first six bytes 
contain information on date written, diskette number, and whether the 
diskette is full.

The sixth byte (the one immediately before the padded zeroes) contains 
the month in hexadecimal.  It was working fine through November 
(months 01 through 09).  Beginning in October, instead of writing 0A, 
it writes 0D 0A, and then adds the zeroes.  The size of the file 
increases to 129.

As a result, RESTORE does not recognize the diskette as valid, and 
aborts.

This corruption occurs even after a clean boot, with no resident 
programs.

When the system date is reset to September, the corruption does not 
occur.

The patch to BACKUPID.@@@ is fairly trivial, but a nuisance 
nevertheless.

Has anyone else noticed this problem?  Is this a bug  in BACKUP.COM, 
or do I have system problems?

_________________________________________________________________________
|                                                                       |
| Dr. Noel Roy                                                          |
| Room A3048                                Phone (709) 737-8245/8      |
| Department of Economics                   FAX   (709) 737-4569        |
| Memorial University of Newfoundland                                   |
| St. John's, Newfoundland A1C 5S7 Canada                               |
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| bitnet:   NOELROY@MUN                                                 |
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Ralf.Brown@B.GP.CS.CMU.EDU (10/19/89)

In article <2576@dogie.macc.wisc.edu>, michaelb@vms.macc.wisc.edu (Michael Bloxham) wrote:
 >>Has anyone else noticed this problem?  Is this a bug  in BACKUP.COM, 
 >>or do I have system problems?
 >
 >I have heard from my contacts at Zenith that there may be either a bug or 
 >virus in ZENITH DOS 3.3+ RESTORE.COM.  This was sent to me via a email

Having the byte that is supposed to be 0Ah turn up as 0Dh 0Ah indicates to me
that the programmer forgot to make the "C" program write to the file in binary
mode (the above is precisely the NL -> CRLF translation MSDOS "C" libraries
perform in text mode).

--
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michaelb@vms.macc.wisc.edu (Michael Bloxham) (10/20/89)

In article <21856@kean.mun.ca>, noelroy@kean.mun.ca (Noel Roy, Economics Dept., Memorial University) writes...

>I seem to be getting contaminated BACKUPID.@@@ files on my DOS BACKUP 
>diskettes.  I am running DOS version 3.3+, from Zenith.
> 
[stuff deleted]
> 
>Has anyone else noticed this problem?  Is this a bug  in BACKUP.COM, 
>or do I have system problems?
>

I have heard from my contacts at Zenith that there may be either a bug or 
virus in ZENITH DOS 3.3+ RESTORE.COM.  This was sent to me via a email
message from a tech support guy at Zenith.  Along with the message was 
attached a copy of RESTORE.COM which was supposed to be clean.  I am not 
clear as to whether it is just a bug in the programming, or an actual virus 
infected restore.com from the ZENITH factory.

I don't use DOS's backup and restore, but rather FASTBACK+, so I 
never really looked into it.

I do have a copy of the 'good' RESTORE.COM at work.  If you would like, 
I'll try emailing you this good copy.

good luck,
mike
-----------------------------------------------------------------------
Michael L. Bloxham         | Real programmers don't comment their code. 
michaelb@vms.macc.wisc.edu | If it was hard to write, it should be hard
michaelb@WISCMACC.bitnet   | to understand.

noelroy@kean.mun.ca (Noel Roy, Economics Dept., Memorial University) (10/20/89)

In article <2576@dogie.macc.wisc.edu>, michaelb@vms.macc.wisc.edu (Michael Bloxham) writes:
> In article <21856@kean.mun.ca>, noelroy@kean.mun.ca (Noel Roy, Economics Dept., Memorial University) writes...
> 
>>I seem to be getting contaminated BACKUPID.@@@ files on my DOS BACKUP 
>>diskettes.  I am running DOS version 3.3+, from Zenith.
>> 
> [stuff deleted]
>> 
>>Has anyone else noticed this problem?  Is this a bug  in BACKUP.COM, 
>>or do I have system problems?
>>
> 
> I have heard from my contacts at Zenith that there may be either a bug or 
> virus in ZENITH DOS 3.3+ RESTORE.COM.  This was sent to me via a email
> message from a tech support guy at Zenith.  Along with the message was 
> attached a copy of RESTORE.COM which was supposed to be clean.  I am not 
> clear as to whether it is just a bug in the programming, or an actual virus 
> infected restore.com from the ZENITH factory.
> 
> I do have a copy of the 'good' RESTORE.COM at work.  If you would like, 
> I'll try emailing you this good copy.
> 
> good luck,
> mike
> -----------------------------------------------------------------------

It is definitely a problem with BACKUP.COM, not RESTORE.COM, since the 
backup disks get corrupted even before a RESTORE attempt.

Possibly RESTORE has been modified by ZENITH to ignore the corrupted
bytes.

I would appreciate your sending me the file.  UUDECODED is fine.

Regards/Noel

_________________________________________________________________________
|                                                                       |
| Dr. Noel Roy                                                          |
| Room A3048                                Phone (709) 737-8245/8      |
| Department of Economics                   FAX   (709) 737-4569        |
| Memorial University of Newfoundland                                   |
| St. John's, Newfoundland A1C 5S7 Canada                               |
|-----------------------------------------------------------------------|
| bitnet:   NOELROY@MUN                                                 |
| internet: noelroy%kean.mun.ca@CORNELLC.cit.cornell.edu                |
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| icbmnet:  lat 47 34'6"N   long 52 44'8"W  alt 69m                     |
|_______________________________________________________________________|

Wes@cup.portal.com (Wes H Cowley) (10/21/89)

> I seem to be getting contaminated BACKUPID.@@@ files on my DOS BACKUP 
> diskettes.  I am running DOS version 3.3+, from Zenith.

> The size of the file increases to 129.

Yes.  This is a bug in Zenith's 3.3+ Backup.  I ran into it the first weekend
in October.  The problem is apparently that Backup is opening the file in
text mode causing translation of LF's to CR/LF's.  October is coded as an LF.
The same problem will occur on the 10th of any month.

The fix is trivial.  Open the file in text mode, read the file in, delete the
file, create it in binary mode, then dump the data back out.  I will email you
the source to the program I wrote to fix the backups.  If anyone else needs
it let me know, I'll be happy to email the source to you.   

Wes Cowley
wes@cup.portal.com
PO BOX 280138
Tampa, FL 33682-0138

mikey@shuksan.UUCP (Mike Fields) (10/24/89)

In article <21856@kean.mun.ca>, noelroy@kean.mun.ca (Noel Roy, Economics Dept., Memorial University) writes:
> I seem to be getting contaminated BACKUPID.@@@ files on my DOS BACKUP 
> diskettes.  I am running DOS version 3.3+, from Zenith.
> 
> Symptoms are as follows:  normally, BACKUPID.@@@ is a file of 128 
> bytes, with the last 122 padded with zeroes.  The first six bytes 
> contain information on date written, diskette number, and whether the 
> diskette is full.
> 
> The sixth byte (the one immediately before the padded zeroes) contains 
> the month in hexadecimal.  It was working fine through November 
> (months 01 through 09).  Beginning in October, instead of writing 0A, 
> it writes 0D 0A, and then adds the zeroes.  The size of the file 
> increases to 129.



I have a sneaky suspicion ---  The 0D 0A pair is an ascii CR LF pair --
I have seen this type of problem before with print routines that just
have to "help you" by making the simple LF (or CR) into the CRLF pair.
That is just fine if indeed you are writing those chars BUT if you are
trying to do cursor positioning etc and the 0A is the col, or row and
the system "Helps" you, there is this strange behaviour when the row or
col is just the right number!!

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-- 
Mikey (yes "he likes it!")
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