1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_BOUNDS_CHECKER_H_
6#define MOJO_PUBLIC_CPP_BINDINGS_LIB_BOUNDS_CHECKER_H_
7
8#include <stdint.h>
9
10#include "mojo/public/cpp/system/macros.h"
11
12namespace mojo {
13
14class Handle;
15
16namespace internal {
17
18// BoundsChecker is used to validate object sizes, pointers and handle indices
19// for payload of incoming messages.
20class BoundsChecker {
21 public:
22  // [data, data + data_num_bytes) specifies the initial valid memory range.
23  // [0, num_handles) specifies the initial valid range of handle indices.
24  BoundsChecker(const void* data, uint32_t data_num_bytes,
25                size_t num_handles);
26
27  ~BoundsChecker();
28
29  // Claims the specified memory range.
30  // The method succeeds if the range is valid to claim. (Please see
31  // the comments for IsValidRange().)
32  // On success, the valid memory range is shrinked to begin right after the end
33  // of the claimed range.
34  bool ClaimMemory(const void* position, uint32_t num_bytes);
35
36  // Claims the specified encoded handle (which is basically a handle index).
37  // The method succeeds if:
38  // - |encoded_handle|'s value is |kEncodedInvalidHandleValue|.
39  // - the handle is contained inside the valid range of handle indices. In this
40  // case, the valid range is shinked to begin right after the claimed handle.
41  bool ClaimHandle(const Handle& encoded_handle);
42
43  // Returns true if the specified range is not empty, and the range is
44  // contained inside the valid memory range.
45  bool IsValidRange(const void* position, uint32_t num_bytes) const;
46
47 private:
48  bool InternalIsValidRange(uintptr_t begin, uintptr_t end) const;
49
50  // [data_begin_, data_end_) is the valid memory range.
51  uintptr_t data_begin_;
52  uintptr_t data_end_;
53
54  // [handle_begin_, handle_end_) is the valid handle index range.
55  uint32_t handle_begin_;
56  uint32_t handle_end_;
57
58  MOJO_DISALLOW_COPY_AND_ASSIGN(BoundsChecker);
59};
60
61}  // namespace internal
62}  // namespace mojo
63
64#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BOUNDS_CHECKER_H_
65