dd: catch OOM

tests/by-util/test_dd.rs

@@ -115,6 +115,14 @@ fn help() {
     new_ucmd!().args(&["--help"]).succeeds();
 }
 
+#[test]
+fn test_out_of_memory() {
+    new_ucmd!()
+        .arg("bs=1PB")
+        .fails_with_code(1)
+        .stderr_contains("memory"); //todo: improve error message at all platforms
+}
+
 #[test]
 fn test_stdin_stdout() {
     let input = build_ascii_block(521);