The Tor Browser: comparison security/sandbox/win/src/shared

--1:000000000000
+:cadca8b356a6
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#ifndef SANDBOX_SRC_SHARED_HANDLES_H__
+#define SANDBOX_SRC_SHARED_HANDLES_H__
+#include "base/basictypes.h"
+#ifndef HANDLE
+// We can provide our own windows compatilble handle definition, but
+// in general we want to rely on the client of this api to include
+// the proper windows headers. Note that we don't want to bring the
+// whole <windows.h> into scope if we don't have to.
+typedef void* HANDLE;
+#endif
+namespace sandbox {
+// SharedHandles is a simple class to stash and find windows object handles
+// given a raw block of memory which is shared between two processes.
+// It addresses the need to communicate a handle value between two windows
+// processes given that they are already sharing some memory.
+//
+// This class is not exposed directly to users of the sanbox API, instead
+// we expose the wrapper methods TargetProcess::TransferHandle( ) and
+// TargetServices::GetTransferHandle()
+//
+// Use it for a small number of items, since internaly uses linear seach
+//
+// The use is very simple. Given a shared memory between proces A and B:
+// process A:
+//  HANDLE handle = SomeFunction(..);
+//  SharedHandles shared_handes;
+//  shared_handles.Init(memory)
+//  shared_handles.SetHandle(3, handle);
+//
+// process B:
+//  SharedHandles shared_handes;
+//  shared_handles.Init(memory)
+//  HANDLE handle = shared_handles.GetHandle(3);
+//
+// Note that '3' in this example is a unique id, that must be agreed before
+// transfer
+//
+// Note2: While this class can be used in a single process, there are
+// better alternatives such as STL
+//
+// Note3: Under windows a kernel object handle in one process does not
+// make sense for another process unless there is a DuplicateHandle( )
+// call involved which this class DOES NOT do that for you.
+//
+// Note4: Under windows, shared memory when created is initialized to
+// zeros always. If you are not using shared memory it is your responsability
+// to zero it for the setter process and to copy it to the getter process.
+class SharedHandles {
+public:
+SharedHandles();
+// Initializes the shared memory for use.
+// Pass the shared memory base and size. It will internally compute
+// how many handles can it store. If initialization fails the return value
+// is false.
+bool Init(void* raw_mem, size_t size_bytes);
+// Sets a handle in the shared memory for transfer.
+// Parameters:
+// tag : an integer, different from zero that uniquely identfies the
+// handle to transfer.
+// handle: the handle value associated with 'tag' to tranfer
+// Returns false if there is not enough space in the shared memory for
+// this handle.
+bool SetHandle(uint32 tag, HANDLE handle);
+// Gets a handle previously stored by SetHandle.
+// Parameters:
+// tag: an integer different from zero that uniquely identfies the handle
+// to retrieve.
+// *handle: output handle value if the call was succesful.
+// If a handle with the provided tag is not found the return value is false.
+// If the tag is found the return value is true.
+bool GetHandle(uint32 tag, HANDLE* handle);
+private:
+// A single item is the tuple handle/tag
+struct SharedItem {
+uint32 tag;
+void* item;
+};
+// SharedMem is used to layout the memory as an array of SharedItems
+struct SharedMem {
+size_t max_items;
+SharedItem* items;
+};
+// Finds an Item tuple provided the handle tag.
+// Uses linear search because we expect the number of handles to be
+// small (say less than ~100).
+SharedItem* FindByTag(uint32 tag);
+SharedMem shared_;
+DISALLOW_COPY_AND_ASSIGN(SharedHandles);
+};
+}  // namespace sandbox
+#endif  // SANDBOX_SRC_SHARED_HANDLES_H__

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comparison: security/sandbox/win/src/shared_handles.h

security/sandbox/win/src/shared_handles.h