RE: [Bug-tar] tar 1.23: Problem under Solaris 10 - incorrect GNU header contents

[Armistead, Jason]

Dustin wrote:

>The entire original email was focused on ustar functionality, by my
>read.  Perhaps you can repeat your experiment, bearing in mind that
>you're expecting a GNU Tar archive, and let us know what happens?

My original experiment WAS with GNU formatted tar archives.  Some work, and 
some don't.  I have far larger tar files that are working OK.  But this one, 
from a very important filesystem, is not.  That is what led me to look more 
closely at the bytes in the file header records.

With regard to my e-mail, I made a newbie blunder (having never looked under 
the hood of tar before), and assumed that because the resulting files contained 
"ustar" in the header, they must have been in Ustar format.

If I'm correct it my understanding, a GNU formatted achive should also contain 
"ustar" (followd by a null) at offset 257 and "00" at offset 263.  Is this 
correct for GNU format archives ?

>Also, 7-zip claims to support "TAR" format, but doesn't say which
>format - are you sure it's designed to support GNU Tar archives?  If
>you create a tar file with --format=ustar, can you read it with 7-zip?

7-Zip is decidedly vague on what sort of TAR it supports.  I now have the 
source code, but it still doesn't explain what TAR format(s) it supports. Time 
permitting, I'll try to instrument it to figure out where it's breaking, and to 
understand what format(s) it supports.  7-Zip's author didn't leave many 
comments in his code, and doesn't have the ability to conditionally add in 
debugging.  It could take me some time.

7-Zip will read many other TAR files.  I have been able to download many of 
them from the Internet without problems. 

My concern is, that for whatever reason, my Solaris 10 box with GNU tar 1.14 or 
1.23 produces what appear to be incorrect contents in the two fields I 
mentioned.

From what I've seen of 7-Zip's source, it isn't checking that the "ustar" and 
"00" fields are correct.  But, nevertheless, my installations of GNU tar are 
NOT producing the same binary output for these as other TAR files I get off the 
internet.  This troubles me, and makes me wonder what else is being screwed up. 
 I don't want to discover years from now that my old system is dead and buried, 
and the TAR files it produced are worthless ...   Maybe the same bug is also 
causing other problems elsewhere.  I just can't be sure !

Regards,
Jason