TAR Extractor

How to use the tar extractor

1. Choose a .tar file; a .tar.gz must be decompressed first.
2. Read the entry list, with sizes, modes and modification dates.
3. Save the files you want individually.

About this tool

This reads a `.tar` archive, verifies each header's checksum, and lists what is inside with sizes, permissions and modification times before anything is saved. A checksum that does not match means the file is damaged or is not a TAR at all, and saying so is more useful than producing garbled files.

Entry names are rebuilt from their components before any file is written. An archive is only a list of names, and nothing stops one containing `../../.ssh/authorized_keys` — extracting that name writes outside the folder you chose. This is the path traversal bug that has been exploited in archive tools repeatedly, so `..` components are discarded rather than followed.

GNU long-name entries are honoured, since real archives use them for paths the ustar header cannot hold, and pax extended headers are skipped rather than misreported as files with strange names. Older implementations disagreed about whether header bytes were signed when summed, so both checksums are accepted.

The honest limitation is the browser: a web page cannot write a folder tree to disk. Files come back one at a time, which is fine for pulling one thing out of an archive and tedious for restoring a whole tree — your operating system's own tar is the better tool when you have one.

Common uses

• Looking inside a .tar before trusting it.
• Pulling one file out of an archive without a terminal.
• Checking whether a downloaded archive is intact.

Frequently asked questions

Can it open a .tar.gz file?

Not directly — that is a gzip file containing a tar. Decompress it first, then open the .tar it produces.

Why can it not extract a whole folder at once?

A web page cannot write a directory tree to disk. Files are offered one at a time, which is why a system tar remains the better tool for restoring a full archive.

What does a checksum error mean?

Each TAR header stores a checksum of itself. A mismatch means the archive is damaged or is not a TAR, and stopping is safer than producing files from misread headers.