archive/tar: Fix support for long links and improve PAX support.
The tar/archive code from golang has a problem with linknames with length >
100. A pax header is added but the original header still written with a too
long field length.
As it is clear that pax support is incomplete I have added missing
implementation parts.
This commit contains code from the golang project in the folder tar/archiv.
The following pax header records are now automatically written:
- gname)
- linkpath
- path
- uname
The following fields can be written with PAX, but the default is to use the
star binary extension.
- gid (value >
2097151)
- size (value >
8589934591)
- uid (value >
2097151)
The string fields are written when the value is longer as the field or if the
string contains a char that is not encodable as 7-bit ASCII value.
The change was tested against a current ubuntu-cloud image tarball comparing
the compressed result.
+ added some automated tests for the new functionality.
Fixes #6056.
R=dsymonds
CC=golang-dev
https://golang.org/cl/
12561043