Add support for "tp" format. tp was the standard system

archiver for Fourth Edition through Sixth Edition Unix; it was
replaced by tar in Seventh Edition.  (First Edition through
Third Edition used "tap.")

Unfortunately, tp was not so very standard; there were a
few different variants.  The code here attempts to support
what I believe were the most common variants.

tp support is not yet enabled by archive_read_support_format_all(),
as I'm not yet entirely comfortable with the detection
heuristics.  People interested in experimenting can
add archive_read_support_format_tp() just after any calls
to archive_read_support_format_all() in bsdtar to see how
well this works.

TODO: tp format is roughly similar in structure to dump/restore
   archive formats used by many systems.  It should be possible
   to generalize this code to handle many dump/restore variants.
   Format detection heuristics are going to be rough, though.

Thanks to: Warren Toomey, whose very basic tp extraction programs
   and documentation made this possible.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/libarchive/libarchive-formats.5 b/lib/libarchive/libarchive-formats.5
index 7ed18da..8dc2d2a 100644
--- a/lib/libarchive/libarchive-formats.5
+++ b/lib/libarchive/libarchive-formats.5
@@ -235,6 +235,16 @@ compressed with the
 .Dq deflate
 algorithm.
 Older zip compression algorithms are not supported.
+.Ss Tp Formats
+The libarchive library has experimental support for tp format,
+which was used in Fourth Edition through Sixth Edition Unix.
+(It was supplanted by tar in Seventh Edition Unix.)
+There were several distinct variants of this format; libarchive
+supports the original tp format and the itp variant.
+Currently, tp format support is not enabled by
+.Fn archive_read_support_format_all ,
+it must be explicitly enabled by calling
+.Fn archive_read_support_format_tp .
 .Sh SEE ALSO
 .Xr cpio 1 ,
 .Xr mkisofs 1 ,