/* -*- 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)

      : fileInfo()

      , 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