[Bug-tar] tar -tf is slow when encountering a large member

[Walter de Jong]

Hi,

I made a tar archive file on disk of a couple of small files and one 
large file (10 GB). When doing a 'tar -tf' of this archive, there is a 
noticeable long pause when it lists the large member, like it is reading 
all the way through the archive.

Why doesn't it use seek() to skip the member data, and get on with the 
next header?
I made a little Python script that does exactly this, and it lists the 
members much quicker than the tar command itself.

The manual states that tar uses seek() when the device is capable of 
seeking, but this doesn't seem to be the case for the -t/--list option.
Mind that my archive is a file on disk, and it is possible to use seek().

I'm using tar on SLES10 ia64, the rpm is named tar-1.15.1-23.13


Greets,

     --Walter

--
                  *** If you build it, they will come ***

HPC Systems Programmer at SARA Computing and Network Services
People should be able to e-mail me, spambots should not.

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