bug#17149: shred - tape data

[Paul Eggert]

Pádraig Brady wrote:
> shred(1) doesn't rewind the tape.

But shred is supposed to rewind the tape, using lseek.

Can you find out what system calls are executed?  Use the command

shred -o tracefile -v /dev/st0

Warning: 'tracefile' will get quite large.  The point is to see what 
happens near the start of execution, and around the time that the write 
files.

My guess is that 'shred' is incorrectly calculating the tape size; it 
does that by seeking to the end of the tape, and perhaps this is going awry.