V18.4.0 CAS plugin

Note that this version does not have Widevine Provisioning 4.0 support.
It is only suitable for device upgrades. A new patch with provisioning
4.0 support will be made later.

oemcrypto/include/level3_file_system.h

@@ -0,0 +1,32 @@
+// Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine
+// License Agreement.
+
+/*********************************************************************
+ * level3_file_system.h
+ *
+ * File system for OEMCrypto Level3 file operations.
+ *********************************************************************/
+
+#ifndef LEVEL3_FILE_SYSTEM_H_
+#define LEVEL3_FILE_SYSTEM_H_
+
+#include <stdlib.h>
+#include "platform.h"
+
+namespace wvoec3 {
+
+class OEMCrypto_Level3FileSystem {
+ public:
+  virtual ~OEMCrypto_Level3FileSystem() {}
+  virtual ssize_t Read(const char *filename, void *buffer, size_t size) = 0;
+  virtual ssize_t Write(const char *filename, const void *buffer,
+                        size_t size) = 0;
+  virtual bool Exists(const char *filename) = 0;
+  virtual ssize_t FileSize(const char *filename) = 0;
+  virtual bool Remove(const char *filename) = 0;
+};
+
+}  // namespace wvoec3
+
+#endif