Add host filesystem files to tar and mount it

[pkit]

We need to mimic the behavior of host filesystem more closely.
For that I propose to create a tar file with all the host files mentioned on the zvsh command line. And then mount that tar. This way the paths to files will be the same on host and inside the session.
There are other features that will be added by implementing the above:

• ability to target a directory (the contents of a directory will be added to tar and then all the files will be accessible from inside the session)
• session will be able to create directories and multiple files on host (the resulting tar can be extracted on top of the host fs)
• session can use O_TRUNCATE or any other file operations that cannot be applied to channels

[larsbutler]

Seems like a good idea. How would you like to user interface to look? My initial thought is to implement it something like this:

$ zvsh --zvm-image=foo.tar --mount=/home/lars/bar,/usr/share myapp.nexe arg1 arg2

where /usr/share is optional mount point. I guess this could work for files or folders.

Thinking further, we could just use one command for everything; there is enough overlap between --mount and --zvm-image. Maybe we could deprecate --zvm-image?

[mgeisler]

I would like us to avoid introducing more foo,bar arguments — , is not a special character in character in filenames (CVS names files with ,).