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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 "nsIFile.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "ErrorList.h"
namespace mozilla {
namespace devtools {
// # AutoMemMap
//
// AutoMemMap is an RAII class to manage mapping a file to memory. It is a
// wrapper around 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 {
// At the time of this writing, this class supports file imports up to
// UINT32_MAX bytes due to limitations in the underlying function PR_MemMap.
uint32_t fileSize;
PRFileDesc* fd;
PRFileMap* fileMap;
void* addr;
AutoMemMap(const AutoMemMap& aOther) = delete;
void operator=(const AutoMemMap& aOther) = delete;
public:
explicit AutoMemMap()
: fileSize(0), fd(nullptr), fileMap(nullptr), addr(nullptr){};
~AutoMemMap();
// Initialize this AutoMemMap.
nsresult init(nsIFile* file, 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(fd, "Should only call size() if init() succeeded.");
return fileSize;
}
// 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
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