cvs commit: src/bin/mv mv.c

[Bruce Evans]

On Thu, 27 Dec 2007, Diomidis Spinellis wrote:

> dds         2007-12-27 11:33:42 UTC
>
>  FreeBSD src repository
>
>  Modified files:
>    bin/mv               mv.c
>  Log:
>  - Roll-back attempts to mimic rename(2) atomicity introduced in 1.47,
>    and follow the letter of the POSIX specification.
>
>  - Moving a directory to an existing non-empty directory will now fail,
>    as required.

It should be noted that the previous behaviour was very dangerous.  It
could destroy target directory trees of any size in order to replace
them with a typo, but of course a local rename() can only destroy the
target directory tree if that tree consists of an empty target directory.
The destroyed target directory tree cannot quite be /, but it can be
almost as important:

 	mkdir /tmp/usr
 	cd /tmp
 	mv usr /		# when /tmp and /usr are on different fs's.
 				# this replaced /usr by the empty usr,
 				# using esentially the following:
 	mv /usr /usr.backup
 	cp -pRp usr /
 	rm -rf /usr.backup
 	rm -rf usr

Bruce