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