[Bug-tar] Possible bug in auto detection of extraction program

[Sasa Vilic]

We are letting tar itself to determine compression program/algorithm (i.e: tar 
xvf <filename>) when extract number of bzip2 archives, but on particular 
archive tar did not work. We got following errors: 

   tar: Archive contains address@hidden' where numeric off_t value expected 
   tar: Archive contains `\t%\f\224\0\0\025' where numeric mode_t value 
expected 
   tar: Archive contains address@hidden' where numeric time_t value expected 
   tar: Archive contains `\250\001J\0054P4' where numeric uid_t value expected 
   tar: Archive contains `\0\002\212\0\0\221A' where numeric gid_t value 
expected
   BZh91AY&SYb\336:a\005\317b\177\377\377\377\377\377\377\377\377\377\377
      
\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\342\324;address@hidden
 
   tar: 
BZh91AY&SYb\336\:a\005\317b\177\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377
      
\377\377\377\377\377\377\377\377\377\377\377\377\377\342\324;address@hidden: 
Unknown file type `@', extracted as normal file 
   tar: BZh91AY&SYb�:a�b�����������������������������������;�@: implausibly old 
time stamp 1970-01-01 00:59:59
   tar: Skipping to next header
   tar: Exiting with failure status due to previous errors

We looked shortly in source code of tar, and it seams that it tries first to 
compute tar_checksum and if it is correct, it will try to extract tar archive. 
Only when checksum is wrong, it will try to determine compression 
algorithm/program.

I guess that in out particular case it just might be that accidentally checksum 
is correct.

We are using using tar version 1.26. We also tried compiling and testing 
version 1.27.1 and we got same errors. 

Unfortunately, I can not share whole archive but only first 1024 bytes of 
archive (hexdump is provided as attachment).

Kind regards,

Sasa Vilic

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