tar -P cannot extract hardlinks through symlinks

[mmatuska]

Issue created from FreeBSD bug 213255.

Tijl Coosemans writes:

... It can be reproduced with tar like this:

% mkdir dir2
% ln -s dir2 dir
% touch dir/file
% ln dir/file dir/file2
% tar cf dir.tar dir/file dir/file2
% rm dir/*
% tar xf dir.tar -P
dir/file2: Can't create 'dir/file2'
tar: Error exit delayed from previous errors.
tijl@kalimero:~/tmp/test% ls -l dir/
total 0
-rw-r--r--  1 tijl  wheel  0  6 Nov 20:05 file

With -P extraction through a symlink (dir->dir2) should work, but fails for hardlinks.

The patch fixes this. In archive_write_disk_posix.c the function create_filesystem_object() calls check_symlinks_fsobj() in the case of hardlinks, but not in the case of symlinks or regular files. The patch removes this call. check_symlinks_fsobj() is still called elsewhere in the same file and the 'tar xf' command above without -P still fails on both archive entries.

Proposed patch

[bapt]

IT would be really nice to see progress here: it is also inpacting pkg and in rather bad way: see FreeBSD bug 214381