rsync replacing symlinks without warning (resend)

[Andreas Gruenbacher]

Hello,

when trying to rsync files between hosts, I ran into a surprising case
in which rsync replaces a symlink with a directory, with no indication
of any kind.

In the following reproducer, rsync is called as follows:

  rsync --verbose --recursive --relative --delete a/./lib/modules b/

Directory b contains a 'lib' symlink pointing to 'usr/lib', and rsync
removes that and replaces it with a directory.

In my real-world use case, this caused '/lib' -> '/usr/lib' symlinks
to be replaced with '/lib' directories, which left the receiving test
machines in a fairly sad state.

I have since figured out that I can get rsync to behave as expected by
adding the --keep-dirlinks option, but ...

it's very unfortunate that when rsync does that kind of thing, it
leaves no indication in the 'rsync --dry-run' and 'rsync -v' output.
Could that please be fixed?

Thanks,
Andreas


#! /bin/sh

tmp=$(mktemp -dt ${0##*/}.XXXXXXXXXX)
trap 'cd /; rm -rf $tmp' EXIT
cd "$tmp"

umask 022

mkdir -p a/lib/modules
echo foo > a/lib/modules/foo

mkdir -p b/usr/lib/modules
ln -s usr/lib b/lib

show() {
    find "$@" | xargs stat -c "%F %N" | sort -k2
}

echo "from:"
show a

echo
echo "to:"
show b

echo
echo "rsync:"
rsync \
    --verbose \
    --recursive \
    --relative \
    --delete \
    a/./lib/modules \
    b/

echo
echo "to:"
show b

# SCRIPT OUTPUT with rsync 3.2.7:
# ==============================
=
# from:
# directory 'a'
# directory 'a/lib'
# directory 'a/lib/modules'
# regular file 'a/lib/modules/foo'
#
# to:
# directory 'b'
# directory 'b/usr'
# directory 'b/usr/lib'
# directory 'b/usr/lib/modules'
# symbolic link 'b/lib' -> 'usr/lib'
#
# rsync:
# sending incremental file list
# lib/
# lib/modules/
# lib/modules/foo
#
# sent 160 bytes  received 47 bytes  414.00 bytes/sec
# total size is 4  speedup is 0.02
#
# to:
# directory 'b'
# directory 'b/lib'
# directory 'b/lib/modules'
# directory 'b/usr'
# directory 'b/usr/lib'
# directory 'b/usr/lib/modules'
# regular file 'b/lib/modules/foo'