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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_devtools_AutoMemMap_h
+#define mozilla_devtools_AutoMemMap_h
+
+#include <prio.h>
+#include "mozilla/GuardObjects.h"
+
+namespace mozilla {
+namespace devtools {
+
+// # AutoMemMap
+//
+// AutoMemMap is an RAII class to manage mapping a file to memory. It is a
+// wrapper aorund managing opening and closing a file and calling PR_MemMap and
+// PR_MemUnmap.
+//
+// Example usage:
+//
+// {
+// AutoMemMap mm;
+// if (NS_FAILED(mm.init("/path/to/desired/file"))) {
+// // Handle the error however you see fit.
+// return false;
+// }
+//
+// doStuffWithMappedMemory(mm.address());
+// }
+// // The memory is automatically unmapped when the AutoMemMap leaves scope.
+class MOZ_RAII AutoMemMap
+{
+ MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER;
+
+ PRFileInfo64 fileInfo;
+ PRFileDesc* fd;
+ PRFileMap* fileMap;
+ void* addr;
+
+ AutoMemMap(const AutoMemMap& aOther) = delete;
+ void operator=(const AutoMemMap& aOther) = delete;
+
+public:
+ explicit AutoMemMap(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM)
+ : fd(nullptr)
+ , fileMap(nullptr)
+ , addr(nullptr)
+ {
+ MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+ };
+ ~AutoMemMap();
+
+ // Initialize this AutoMemMap.
+ nsresult init(const char* filePath, int flags = PR_RDONLY, int mode = 0,
+ PRFileMapProtect prot = PR_PROT_READONLY);
+
+ // Get the size of the memory mapped file.
+ uint32_t size() const {
+ MOZ_ASSERT(fileInfo.size <= UINT32_MAX,
+ "Should only call size() if init() succeeded.");
+ return uint32_t(fileInfo.size);
+ }
+
+ // Get the mapped memory.
+ void* address() { MOZ_ASSERT(addr); return addr; }
+ const void* address() const { MOZ_ASSERT(addr); return addr; }
+};
+
+} // namespace devtools
+} // namespace mozilla
+
+#endif // mozilla_devtools_AutoMemMap_h