2015-02-20 15:29:48 +00:00
|
|
|
Overview
|
2015-02-20 18:47:57 +00:00
|
|
|
========
|
2015-02-20 15:29:48 +00:00
|
|
|
|
|
|
|
Extend the upstream golang stdlib `archive/tar` library, to expose the raw
|
|
|
|
bytes of the TAR, rather than just the marshalled headers and file stream.
|
|
|
|
|
|
|
|
The goal being that by preserving the raw bytes of each header, padding bytes,
|
|
|
|
and the raw file payload, one could reassemble the original archive.
|
|
|
|
|
|
|
|
|
|
|
|
Caveat
|
2015-02-20 18:47:57 +00:00
|
|
|
------
|
2015-02-20 15:29:48 +00:00
|
|
|
|
|
|
|
Eventually this should detect TARs that this is not possible with.
|
|
|
|
|
|
|
|
For example stored sparse files that have "holes" in them, will be read as a
|
|
|
|
contiguous file, though the archive contents may be recorded in sparse format.
|
|
|
|
Therefore when adding the file payload to a reassembled tar, to achieve
|
|
|
|
identical output, the file payload would need be precisely re-sparsified. This
|
|
|
|
is not something I seek to fix imediately, but would rather have an alert that
|
|
|
|
precise reassembly is not possible.
|
2015-02-20 15:30:18 +00:00
|
|
|
(see more http://www.gnu.org/software/tar/manual/html_node/Sparse-Formats.html)
|
2015-02-20 15:29:48 +00:00
|
|
|
|
|
|
|
|
|
|
|
Contract
|
2015-02-20 18:47:57 +00:00
|
|
|
--------
|
2015-02-20 15:29:48 +00:00
|
|
|
|
|
|
|
Do not break the API of stdlib `archive/tar`
|
|
|
|
|
|
|
|
|
2015-02-20 21:12:01 +00:00
|
|
|
Std Version
|
|
|
|
-----------
|
|
|
|
|
|
|
|
The version of golang stdlib `archive/tar` is from go1.4.1, and their master branch around [a9dddb53f](https://github.com/golang/go/tree/a9dddb53f)
|
|
|
|
|
|
|
|
|
|
|
|
Docs
|
|
|
|
----
|
|
|
|
|
|
|
|
https://godoc.org/github.com/vbatts/tar-split/archive/tar
|
|
|
|
|
|
|
|
|
2015-02-20 20:02:31 +00:00
|
|
|
Example
|
|
|
|
-------
|
|
|
|
|
|
|
|
First we'll get an archive to work with. For repeatability, we'll make an
|
|
|
|
archive from what you've just cloned:
|
|
|
|
|
|
|
|
```
|
|
|
|
git archive --format=tar -o tar-split.tar HEAD .
|
|
|
|
```
|
|
|
|
|
|
|
|
Then build the example main.go:
|
|
|
|
|
|
|
|
```
|
|
|
|
go build ./main.go
|
|
|
|
```
|
|
|
|
|
|
|
|
Now run the example over the archive:
|
|
|
|
|
|
|
|
```
|
|
|
|
$ ./main tar-split.tar
|
|
|
|
2015/02/20 15:00:58 writing "tar-split.tar" to "tar-split.tar.out"
|
|
|
|
pax_global_header pre: 512 read: 52 post: 0
|
|
|
|
LICENSE pre: 972 read: 1075 post: 0
|
|
|
|
README.md pre: 973 read: 1004 post: 0
|
|
|
|
archive/ pre: 532 read: 0 post: 0
|
|
|
|
archive/tar/ pre: 512 read: 0 post: 0
|
|
|
|
archive/tar/common.go pre: 512 read: 7790 post: 0
|
|
|
|
archive/tar/example_test.go pre: 914 read: 1659 post: 0
|
|
|
|
archive/tar/reader.go pre: 901 read: 25303 post: 0
|
|
|
|
archive/tar/reader_test.go pre: 809 read: 17513 post: 0
|
|
|
|
archive/tar/stat_atim.go pre: 919 read: 414 post: 0
|
|
|
|
archive/tar/stat_atimespec.go pre: 610 read: 414 post: 0
|
|
|
|
archive/tar/stat_unix.go pre: 610 read: 716 post: 0
|
|
|
|
archive/tar/tar_test.go pre: 820 read: 6673 post: 0
|
|
|
|
archive/tar/testdata/ pre: 1007 read: 0 post: 0
|
|
|
|
archive/tar/testdata/gnu.tar pre: 512 read: 3072 post: 0
|
|
|
|
archive/tar/testdata/nil-uid.tar pre: 512 read: 1024 post: 0
|
|
|
|
archive/tar/testdata/pax.tar pre: 512 read: 10240 post: 0
|
|
|
|
archive/tar/testdata/small.txt pre: 512 read: 5 post: 0
|
|
|
|
archive/tar/testdata/small2.txt pre: 1019 read: 11 post: 0
|
|
|
|
archive/tar/testdata/sparse-formats.tar pre: 1013 read: 17920 post: 0
|
|
|
|
archive/tar/testdata/star.tar pre: 512 read: 3072 post: 0
|
|
|
|
archive/tar/testdata/ustar.tar pre: 512 read: 2048 post: 0
|
|
|
|
archive/tar/testdata/v7.tar pre: 512 read: 3584 post: 0
|
|
|
|
archive/tar/testdata/writer-big-long.tar pre: 512 read: 4096 post: 0
|
|
|
|
archive/tar/testdata/writer-big.tar pre: 512 read: 4096 post: 0
|
|
|
|
archive/tar/testdata/writer.tar pre: 512 read: 3584 post: 0
|
|
|
|
archive/tar/testdata/xattrs.tar pre: 512 read: 5120 post: 0
|
|
|
|
archive/tar/writer.go pre: 512 read: 11867 post: 0
|
|
|
|
archive/tar/writer_test.go pre: 933 read: 12436 post: 0
|
|
|
|
main.go pre: 876 read: 1568 post: 0
|
|
|
|
old.go pre: 992 read: 4918 post: 0
|
|
|
|
Size: 174080; Sum: 174080
|
|
|
|
```
|
|
|
|
|
|
|
|
Ideally the input tar and output `*.out`, will match:
|
|
|
|
|
|
|
|
```
|
|
|
|
$ sha1sum tar-split.tar*
|
|
|
|
ca9e19966b892d9ad5960414abac01ef585a1e22 tar-split.tar
|
|
|
|
ca9e19966b892d9ad5960414abac01ef585a1e22 tar-split.tar.out
|
|
|
|
```
|
|
|
|
|
2015-02-20 20:44:07 +00:00
|
|
|
What's Next?
|
|
|
|
------------
|
|
|
|
|
2015-02-20 20:46:21 +00:00
|
|
|
* Add tests for different types of tar options/extensions
|
2015-02-20 20:44:07 +00:00
|
|
|
* Package for convenience handling around collecting the RawBytes()
|
|
|
|
* Marshalling and storing index, ordering, file size and perhaps relative path of extracted files
|
|
|
|
- perhaps have an API to allow user to provided a `hash.Hash` to checksum and store for the file payloads
|
|
|
|
- though not enabled by default
|
|
|
|
- this way, users wanting to implement an on disk tree validation could do so
|
|
|
|
- but otherwise, we rely on the resulting re-assembled tar be validated
|
|
|
|
* Using stored index information, make an API for providing `io.Reader` and perhaps `tar.Reader` from re-assembled tar
|
|
|
|
|
2015-02-20 15:29:48 +00:00
|
|
|
License
|
2015-02-20 18:47:57 +00:00
|
|
|
-------
|
2015-02-20 15:29:48 +00:00
|
|
|
|
|
|
|
See LICENSE
|
|
|
|
|
|
|
|
|