Unix/C program modularity

[Guy Harris]

(Redirected to net.unix because it has nothing to do with C.)

> I'm afraid that jss shows his UCB orientation in the above.

Well, actually the "Berkeley.EDU" in his name was there because his message
was to the ARPANET INFO-C mailing list, and got gatewayed onto "net.lang.c"
by the gateway machine for that mailing list/newsgroup, which is (surprise!)
UCB-VAX.Berkeley.EDU.

> UNIX does have file and record locking (byterange) in the kernel.

Make that "some UNIX implementations have file and record locking (byte
range) in the kernel."  Some which don't include

	V7
	2.9BSD
	32/V
	4.xBSD
	System III
	System V, Release 1
	System V, Release 2, Version N, for values of N less than some
		machine-dependent value - yes, it seems to be a different
		value for VAX S5R2 and 3B20 S5R2

> (I know that there are no named semaphores in UNIX.  It sounds like an
> interesting idea.)

What's in a name?  S5's semaphores can be referred to by a 32-bit unique
identifier, which could be considered a name.  There is a routine "ftok"
which turns a file name into a 32-bit unique identifier by jamming the
device and i-number of that file together with an 8-bit code; this can be
used as a way of binding a name in the file system to a semaphore set.

	Guy Harris