Real disk devices should be block devices anyway. One user reported the disksize check causing a system reboot during vac of a tree with an "interesting" device. Fixes #103.

This brings mk's behavior when using rc in line with Plan 9's. The existing code is for Unix environment data structures but also was assuming Unix shell semantics where empty and missing variables are mostly equivalent. The Plan 9 code (/sys/src/cmd/mk/plan9.c in the distribution) explicitly removes /env/name (creating an empty list) when the value is missing or an empty string. Fixes #255.

Fixes #233.

Fixes #9. Fixes #219. Fixes #222. Fixes #330.

When a directory has lots of children, vac crashes because it runs out of cache. Fixes #266.

f is open, so walk will fail. The comments say we only need one directory anyway. Fixes #277.

They return 0 on failure, not -1. Bug introduced in my original libthread-for-Unix code. Fixes #230.

Improved error message in case of unexpected open flags. The message unexpected open flags requested=0100040 unhandled=040 prompted me to clear the FMODE_EXEC flag, although I wonder if I shouldn't have set OEXEC (0x3) instead.

Fixes #250.

Fixes #238.

Fixes #273.

Need to think a bit more about locking, but overall it's a working devdraw. Multiclient mode may not be working but nothing is using it yet.