rsync on first sync patch for rsnapshot 1.4.2.

rsnapshot.patch

--- a/rsnapshot
+++ b/rsnapshot
@@ -3470,14 +3470,14 @@ sub rotate_lowest_snapshots {
 
 			if (-d "$config_vars{'snapshot_root'}/.sync") {
 				print_cmd(
-					"mv",
+					"rsync -a --link-dest=../.sync/",
 					"$config_vars{'snapshot_root'}/.sync/",
 					"$config_vars{'snapshot_root'}/$interval.0/"
 				);
 
 				if (0 == $test) {
 					my $result =
-					  safe_rename("$config_vars{'snapshot_root'}/.sync", "$config_vars{'snapshot_root'}/$interval.0");
+					  safe_rename("$config_vars{'snapshot_root'}/.sync", "$config_vars{'snapshot_root'}/$interval.0", 1);
 					if (0 == $result) {
 						my $errstr = '';
 						$errstr .= "Error! safe_rename(\"$config_vars{'snapshot_root'}/.sync/\", \"";
@@ -6183,6 +6183,7 @@ sub file_diff {
 sub safe_rename {
 	my $src  = shift(@_);
 	my $dest = shift(@_);
+	my $is_initial_rotate = shift(@_) // 0;
 
 	my $st;
 	my $retval;
@@ -6198,6 +6199,17 @@ sub safe_rename {
 		return (0);
 	}
 
+	# touch .sync before stat
+	if ($is_initial_rotate) {
+		print_cmd("touch", "$src");
+
+		my $result = utime(time(), time(), "$src");
+		if (!$result) {
+			print_err("Warning! Could not set utime(time(), time(), \"$src\") : $!", 2);
+			return (0);
+		}
+	}
+
 	# stat file before rename
 	$st = stat($src);
 	if (!defined($st)) {
@@ -6206,7 +6218,12 @@ sub safe_rename {
 	}
 
 	# rename the file
-	$retval = rename("$src", "$dest");
+	if ($is_initial_rotate) {
+		$retval = rename_using_rsync("$src", "$dest");
+	}
+	else{
+		$retval = rename("$src", "$dest");
+	}
 	if (1 != $retval) {
 		print_err("Could not rename(\"$src\", \"$dest\")", 2);
 		return (0);
@@ -6223,6 +6240,42 @@ sub safe_rename {
 	return (1);
 }
 
+# accepts src, dest (file paths)
+# sync files using rsync instead of simple rename()
+# returns 1 on success, 0 on failure
+sub rename_using_rsync {
+	my $src  = shift(@_);
+	my $dest = shift(@_);
+
+	my @cmd_stack;
+	push(@cmd_stack, $config_vars{'cmd_rsync'});
+	push(@cmd_stack, "-a");	# TODO: merge rsync_short_args or something?
+	push(@cmd_stack, "--link-dest=../.sync/");
+	push(@cmd_stack, "$src/");
+	push(@cmd_stack, "$dest/");
+
+	print_cmd(@cmd_stack);
+
+	# prepare dest for rsync
+	if (not -e $dest) {
+		mkpath("$dest", 0, 0755);
+	}
+
+	my ($rsync_in, $rsync_out);
+	my $pid = open3($rsync_in, $rsync_out, undef, @cmd_stack)
+		or die "Couldn't fork rsync: $!\n";
+
+	# add autoflush to get output by time and not at the end when rsync is finished
+	$rsync_out->autoflush();
+
+	while (<$rsync_out>) {
+		print_msg($_, 4);
+	}
+
+	waitpid($pid, 0);
+	return (get_retval($?) == 0);
+}
+
 # accepts no args
 # checks the config file for version number
 # prints the config version to stdout