myrsync.new

#! /usr/bin/env bash

set -eu
set -o pipefail

prog="$(basename "$0")"

function usage {
    [ "${*-}" ] && echo "$prog: $*" 1>&2
    cat 1>&2 <<EOF
Usage: $prog [--max-delete N] [--no-max-delete] [--debug]
             [rsync(1) args] ...

Just like rsync(1), but it has these additional arguments:

--max-delete N
  if --delete or --delete-before is given, then do not delete more than
  N files.  The default is 250.

--no-max-delete
  Put no limit on the number of files which can be deleted in one
  invocation of rsync.

--debug
  Do not execute any commands, but print them.

Also, there are some macOS hacks included in here that allow the copying
of sparse bundles.  Not certain I got that part right.

All other arguments to this script must be valid arguments to rsync,
since any unknown arguments are passed directly to it.
EOF
    exit 1
}

function errordie {
    [ "${*-}" ] && echo "$prog: $*" 1>&2
    exit 1
}

debug=
exclude=
maxdelete=250
verbose=-q

while [ $# -gt 0 ]; do
    case $1 in
        --debug) debug=$1 ;;
	--exclude)
	    exclude="$1 $2"
	    shift
	    ;;
	--max-delete)
	    maxdelete=$2
	    shift
	    ;;
	--no-max-delete) maxdelete= ;;
	-q) verbose=-q ;;
	-v) verbose=-v ;;
	-*) break ;;
    esac
    shift
done

function d {
    if [ "$debug" ]; then
	echo "would: $*"
    else
	echo "+ $*"
        "$@"
    fi
}

function find_rsync {
    local rsync=
    if [ -x /opt/local/bin/rsync ]; then
	# Mac OS X, use the macports version
	rsync=/opt/local/bin/rsync
    elif [ -x /usr/local/bin/rsync ]; then
	# HomeBrew or Linux, use the locally installed version, which
	# understand the flags we need to preserve Mac OS X
	# file attributes.
	rsync=/usr/local/bin/rsync
    elif rsync --version | grep -q -F 3.0.9; then
	rsync=rsync
    elif rsync --version | grep -q -F 3.1.2; then
	rsync=rsync
    fi
    if [ "${rsync}" ]; then
	echo $rsync
	return
    else
	return 1
    fi
}

# usage: error_if_mounted_sparse_bundle path
#   check if 'path' is a mounted sparse bundle
# Ideas from:
#   http://www.lbackup.org/synchronizing_disk_images_between_machines
function mounted_sparse_bundle_p {
    # First, see if the source is a .sparsebundle and make sure it is not
    # mounted
    local source=$(echo "$1" | sed -e 's,/$,,')
    case "$(basename "$source")" in
	*.sparsebundle)
	    if hdiutil info | grep "image-path" | grep "$source" > /dev/null; then
		errordie Error: cannot rsync while $source is mounted
	    fi
	    return 0
	    ;;
    esac
    return 1
}

# main body is in a list so the script can be changed while in use
{

if ! rsync=$(find_rsync); then
    errordie Could not a good version of rsync
fi

# -E :: preserve the file's executability
# -x :: don't cross filesystem boundaries
baseargs="-E -x -a --delete --delete-before --exclude lost+found $verbose"
baseargs="$baseargs --exclude .fseventsd --exclude .Trashes"
baseargs="$baseargs --exclude .DocumentRevisions-V100"
baseargs="$baseargs --exclude .Spotlight-V100 --exclude .TemporaryItems"

# Tweaks needed to copy macOS sparse bundles
if [ "$(uname)" = "Darwin" ]; then
    if mounted_sparse_bundle_p "$1"; then
	# -N             preserve create times
	# -H             preserve hard links
	# -A             preserve ACLs (implies --perms)
	# -X             preserve extended attributes
	# --fileflags    preserve file-flags (aka chflags)
	# --force-change affect user-/system-immutable files/dirs
	baseargs="$baseargs -NHAX --fileflags --force-change"
    fi
fi

[ "$exclude" ]   && baseargs="$baseargs $exclude"
[ "$maxdelete" ] && baseargs="$baseargs --max-delete=${maxdelete}"

sshargs="ssh -T -o Compression=no -x -i $HOME/.ssh/id_rsa_nopw"

d $rsync $baseargs -e "$sshargs" "$@"

exit 0
}