Move functions useful for crypto test into their own file

More refactoring in advance of work on bug.

Bug: 36029169
Test: compiles.
Change-Id: Ic4cdd4761e4c2b11a3ddca5c3bbc4d5e42fac9d4
diff --git a/FileDeviceUtils.h b/FileDeviceUtils.h
new file mode 100644
index 0000000..4c1d49a
--- /dev/null
+++ b/FileDeviceUtils.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef ANDROID_VOLD_FILEDEVICEUTILS_H
+#define ANDROID_VOLD_FILEDEVICEUTILS_H
+
+#include <string>
+#include <linux/fiemap.h>
+
+namespace android {
+namespace vold {
+
+// Given a file path, look for the corresponding block device in /proc/mount
+std::string BlockDeviceForPath(const std::string &path);
+
+// Read the file's FIEMAP
+std::unique_ptr<struct fiemap> PathFiemap(const std::string &path, uint32_t extent_count);
+
+}  // namespace vold
+}  // namespace android
+
+#endif