As noted in the PR, cp -R has some surprising behavior. Typically, when
you `cp -R foo bar` where both foo and bar exist, foo is cleanly copied
to foo/bar. When you `cp -R foo foo` (where foo clearly exists), cp(1)
goes a little off the rails as it creates foo/foo, then discovers that
and creates foo/foo/foo, so on and so forth, until it eventually fails.
POSIX doesn't seem to disallow this behavior, but it isn't very useful.
GNU cp(1) will detect the recursion and squash it, but emit a message in
the process that it has done so.
This change seemingly follows the GNU behavior, but it currently doesn't
warn about the situation -- the author feels that the final product is
about what one might expect from doing this and thus, doesn't need a
warning. The author doesn't feel strongly about this.
PR: 235438
Reviewed by: bapt
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D33944
There are some tests available in the NetBSD test suite, but we don't
currently pass all of those; further investigation will go into that. For
now, just add a basic test as well as a test that copies from /dev/null to a
file.
The /dev/null test confirms that the file gets created if it's empty, then
that it truncates the file if it's non-empty. This matches some usage that
was previously employed in the build and was replaced in r366042 by a
simpler shell construct.
I will also plan on coming back to expand these in due time.
MFC after: 1 week
Kyle Evans