4.3 Tahoe rrestore bug

[Guy Harris]

># 	1) dirfile is NOT a directory but a file (created by rrestore)
>
>I don't know about the rest of your article, but this I can answer: it knows
>it's trying to open a dirfile, it just copied it in from the tape.  The ndir(3)
>routines don't care if it's really a directory, just as long as the format is
>compatible.  The routines are read-only since they run in user-mode; if you
>point 'em at a file that happens to look like a directory, they work fine.

Note that under SunOS:

	1) The directory library routines use "getdirentries()" in 2.x
	   and 3.x releases, and "getdents()" in 4.0.

	2) Those routines transform the contents of the file; they are
	   not equivalent to "read()" on a directory file.

	3) I don't know whether those routines work on non-directory
	   files.

	4) In any case, "opendir()" returns an error when you try to
	   open a file that isn't a directory.

The bottom line is that the format isn't compatible, so you can't point
the directory library routines at a non-directory, even if it happens to
look like one.

The SunOS version of "restore" contains what amounts to a copy of the
"old" directory library (the one that directly reads the directory file).