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Tonis Tiigi 23b6435e6b Optimize tar stream generation 
- New writeTo method allows to avoid creating extra pipe.
- Copy with a pooled buffer instead of allocating new buffer for each file.
- Avoid extra object allocations inside the loop.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
 		2015-12-01 14:08:53 -08:00
..
testdata tar/asm: work with non-utf8 entry names 2015-09-23 15:27:33 -04:00
README.md tar/asm: another thought on clobbered files 2015-02-25 16:53:31 -05:00
assemble.go Optimize tar stream generation 2015-12-01 14:08:53 -08:00
assemble_test.go tar/asm: remove useless test 2015-09-25 14:35:12 -04:00
disassemble.go tar/asm: work with non-utf8 entry names 2015-09-23 15:27:33 -04:00
doc.go *: golint and docs 2015-03-09 14:11:11 -04:00

README.md

asm

This library for assembly and disassembly of tar archives, facilitated by github.com/vbatts/tar-split/tar/storage.

Concerns

For completely safe assembly/disassembly, there will need to be a Content Addressable Storage (CAS) directory, that maps to a checksum in the storage.Entity of storage.FileType.

This is due to the fact that tar archives can allow multiple records for the same path, but the last one effectively wins. Even if the prior records had a different payload.

In this way, when assembling an archive from relative paths, if the archive has multiple entries for the same path, then all payloads read in from a relative path would be identical.

Thoughts

Have a look-aside directory or storage. This way when a clobbering record is encountered from the tar stream, then the payload of the prior/existing file is stored to the CAS. This way the clobbering record's file payload can be extracted, but we'll have preserved the payload needed to reassemble a precise tar archive.

clobbered/path/to/file.[0-N]

alternatively

We could just not support tar streams that have clobbering file paths. Appending records to the archive is not incredibly common, and doesn't happen by default for most implementations. Not supporting them wouldn't be a security concern either, as if it did occur, we would reassemble an archive that doesn't validate signature/checksum, so it shouldn't be trusted anyway.

Otherwise, this will allow us to defer support for appended files as a FUTURE FEATURE.