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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 AutoObjectMapper_h
+#define AutoObjectMapper_h
+
+#include <string>
+
+#include "mozilla/Attributes.h"
+#include "PlatformMacros.h"
+
+// A (nearly-) RAII class that maps an object in and then unmaps it on
+// destruction. This base class version uses the "normal" POSIX
+// functions: open, fstat, close, mmap, munmap.
+
+class MOZ_STACK_CLASS AutoObjectMapperPOSIX {
+ public:
+ // The constructor does not attempt to map the file, because that
+ // might fail. Instead, once the object has been constructed,
+ // call Map() to attempt the mapping. There is no corresponding
+ // Unmap() since the unmapping is done in the destructor. Failure
+ // messages are sent to |aLog|.
+ explicit AutoObjectMapperPOSIX(void (*aLog)(const char*));
+
+ // Unmap the file on destruction of this object.
+ ~AutoObjectMapperPOSIX();
+
+ // Map |fileName| into the address space and return the mapping
+ // extents. If the file is zero sized this will fail. The file is
+ // mapped read-only and private. Returns true iff the mapping
+ // succeeded, in which case *start and *length hold its extent.
+ // Once a call to Map succeeds, all subsequent calls to it will
+ // fail.
+ bool Map(/*OUT*/ void** start, /*OUT*/ size_t* length, std::string fileName);
+
+ protected:
+ // If we are currently holding a mapped object, these record the
+ // mapped address range.
+ void* mImage;
+ size_t mSize;
+
+ // A logging sink, for complaining about mapping failures.
+ void (*mLog)(const char*);
+
+ private:
+ // Are we currently holding a mapped object? This is private to
+ // the base class. Derived classes need to have their own way to
+ // track whether they are holding a mapped object.
+ bool mIsMapped;
+
+ // Disable copying and assignment.
+ AutoObjectMapperPOSIX(const AutoObjectMapperPOSIX&);
+ AutoObjectMapperPOSIX& operator=(const AutoObjectMapperPOSIX&);
+ // Disable heap allocation of this class.
+ void* operator new(size_t);
+ void* operator new[](size_t);
+ void operator delete(void*);
+ void operator delete[](void*);
+};
+
+#endif // AutoObjectMapper_h