OK, I'm stumped. Maybe I'm making this more complicated than it has to
be. Posing my question as simply as possible: If plan9port's vac is
used to archive a Linux file system to venti, is there any way to access
that file system in a way that exposes symbolic links, device nodes,
sockets, and FIFOs in the archive?
There are a number of possibilities I can think of (listed in
approximate order of increasing obscurity):
(1) plan9port's vacfs
(2) plan9port's unvac
(3) Netfiles (under acme)
(4) plan9port's 9p command
(5) Inferno
I have a small "test" Linux filesystem with a mixture of regular files,
directories, and character and block devices which I've archived
(successfully!) using plan9port's vac. I can see the special files in
the venti data. They're in there! But...
(1) When using Linux's v9fs to mount a file system served by plan9port's
vacfs, the symlinks and device nodes all stat as regular files. The
file size of symlinks reflects the length of the link target, and the
device files have a size of 3 bytes (for type, major, and minor). This
happens whether or not I include version=9p2000.u or 9p2000.L as mount
options.
When I use 9pfuse to mount the file system, I get a little further:
lrw-rw---- 1 root root 6 Mar 10 2005 video ->
-rw-rw---- 1 root root 3 Mar 10 2005 video10
The symbolic links show up as links, but with the null string ("") as
target. The Linux kernel interperets null symlinks to mean "./",
causing all the links to refer to the directory in which they reside. :(
The device files still present as ordinary files with a size of 3 bytes.
Running "readlink" on the symbolic links always returns the null string.
(2) plan9port's unvac explicitly skips extraction of files which are not
regular files or directories. So, unvac-ing the archive isn't possible,
either. :(
(3) According to the Plan 9 wiki, Netfiles will only work with versions
of OpenSSH older than the version I have.
(4) The 9p utility provided by plan9port gets me access to a little more
metadata. Using the 9p "ls" command:
-Lrwxrwxrwx M 0 root root 5 Jan 2 03:16 modem
D-rw-rw---- M 0 root disk 3 Mar 10 2005 hda
You can see the symlink and device bits set in the mode. (The "D"
represents a device node; "d" indicates a directory.)
Using the 9p "stat" command:
'modem' 'root' 'root' '' q (0000000000000003 0 ) m 0200000777 at 1325474216 mt
1325474215 l 5 t 0 d 0
'tty3' 'root' 'tty' '' q (0000000000001528 0 ) m 040000660 at 1110476900 mt
1110476900 l 3 t 0 d 0
The targets of symlinks are still showing up as the null string. (I'm
assuming that's what the '' represents.)
(5) Installing Inferno just to access vac'd Linux file systems would
really be tantamount to throwing up my hands and giving up on plan9port.
I'd like use plan9port, if possible, rather than have to layer a whole
new OS on top of Linux+p9p.
So, I'm fresh out of ideas. Is there any way, at all, to present the
full contents of a Linux filesystem that's been archived using the
plan9port vac command?
Thanks!
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