[Unix-jun72] sh.s

[Tim Newsham]

I did a comparison of s2's /bin/sh and the sh.s we have (notes in
the notes file about this).  There were a few changes, but they were
pretty similar.  I added a patch in the patches directory that reflects
the changes and I verified that if you build with the patch you get
an identical binary (modulo the padding bytes that the assembler
fills in for ".." and ".even").  It's currently marked as an optional
patch and the sh.s build isn't being installed over /bin/sh in the
rf0.dsk image.

I think the sh.s listing itself might be defective in two ways:

    - There's an rts missing at the end of the "error" function
    - It doesn't check for the "*" character when looking for globbing.

The 1e man page does list "*" as one of the globbing characters,
so its likely that these three instructions (1 rts, 2 for comparison)
somehow got dropped from the commented jun72 listing.  I'm torn between
adding them to the original "pages" sources as obvious mistakes or
just leaving it out and using a patch to fix it.  Right now we don't
have a patch that adds just these two fixes.  I guess if we did that and
made it a mandatory patch, we could use the sh we build from sh.s as
/bin/sh in the images.

I look forward to seeing what shell sources we might get from the s1
fragments recovery.

Tim Newsham
http://www.thenewsh.com/~newsham/