[comp.sys.apple] ProDos "access control" bits

TMPLee@DOCKMASTER.ARPA (01/17/88)

Does anyone know what the intention of "read-permitted" access control
bit in ProDos is, especially with regard to directories?  Its
implemetnation seesm a littel half-baked.  If you clear it (on a
directory) it does what one would think it should:  a catalog of the
directory (or attempt to open a window on it in the finder) shows an
"empty" directory.  On the other hand, if you try to read something
contained IN the directory, say just LOADing a basic program, that works
fine.  (I claim it shouldn't -- if you can't read a directory you
shouldn't be able to read through it, but then there could be arguments
about that.)  There is one other anomaly in the way the bit is
implemented:  the basic "unlock" command sets that bit (as well as the
other protection bits); clicking the lock/unlock box from the finder
file-info window does NOT affect the "read-permitted", which I think is
how the basic command ought to work too.

I'm asking because I just installed a hard drive and was digging through
the ProDos documentation to see if there was any fairly easy way to
protect different users from accidentally browsing through each others
files (without two-state hardware you can't really protect anything.)
It looks like that bit could be used to do the job, except that the
basic "unlock" command is just too easy a way to set it when it's been
cleared.