Initial checkin from CRI-O repo

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/system/xattrs_linux.go

@@ -0,0 +1,35 @@
+package system
+
+import "golang.org/x/sys/unix"
+
+// Returns a []byte slice if the xattr is set and nil otherwise
+// Requires path and its attribute as arguments
+func Lgetxattr(path string, attr string) ([]byte, error) {
+	var sz int
+	// Start with a 128 length byte array
+	dest := make([]byte, 128)
+	sz, errno := unix.Lgetxattr(path, attr, dest)
+
+	switch {
+	case errno == unix.ENODATA:
+		return nil, errno
+	case errno == unix.ENOTSUP:
+		return nil, errno
+	case errno == unix.ERANGE:
+		// 128 byte array might just not be good enough,
+		// A dummy buffer is used to get the real size
+		// of the xattrs on disk
+		sz, errno = unix.Lgetxattr(path, attr, []byte{})
+		if errno != nil {
+			return nil, errno
+		}
+		dest = make([]byte, sz)
+		sz, errno = unix.Lgetxattr(path, attr, dest)
+		if errno != nil {
+			return nil, errno
+		}
+	case errno != nil:
+		return nil, errno
+	}
+	return dest[:sz], nil
+}