Compile for FreeBSD

Signed-off-by: Samuel Karp <me@samuelkarp.com>

archive/tar_mostunix.go

@@ -0,0 +1,36 @@
+// +build !windows,!freebsd
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package archive
+
+import "golang.org/x/sys/unix"
+
+// mknod wraps Unix.Mknod and casts dev to int
+func mknod(path string, mode uint32, dev uint64) error {
+	return unix.Mknod(path, mode, int(dev))
+}
+
+// lsetxattrCreate wraps unix.Lsetxattr, passes the unix.XATTR_CREATE flag on
+// supported operating systems,and ignores appropriate errors
+func lsetxattrCreate(link string, attr string, data []byte) error {
+	err := unix.Lsetxattr(link, attr, data, unix.XATTR_CREATE)
+	if err == unix.ENOTSUP || err == unix.ENODATA || err == unix.EEXIST {
+		return nil
+	}
+	return err
+}