1// Copyright 2013 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#include "mojo/system/memory.h"
6
7#include <limits>
8
9#include "base/logging.h"
10#include "build/build_config.h"
11
12namespace mojo {
13namespace system {
14namespace internal {
15
16template <size_t alignment>
17bool IsAligned(const void* pointer) {
18  return reinterpret_cast<uintptr_t>(pointer) % alignment == 0;
19}
20
21// MSVS (2010, 2013) sometimes (on the stack) aligns, e.g., |int64_t|s (for
22// which |__alignof(int64_t)| is 8) to 4-byte boundaries. http://goo.gl/Y2n56T
23#if defined(COMPILER_MSVC) && defined(ARCH_CPU_32_BITS)
24template <>
25bool IsAligned<8>(const void* pointer) {
26  return reinterpret_cast<uintptr_t>(pointer) % 4 == 0;
27}
28#endif
29
30template <size_t size, size_t alignment>
31void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer(const void* pointer) {
32  CHECK(pointer && IsAligned<alignment>(pointer));
33}
34
35// Explicitly instantiate the sizes we need. Add instantiations as needed.
36template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<1, 1>(const void*);
37template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<4, 4>(const void*);
38template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<8, 4>(const void*);
39template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<8, 8>(const void*);
40
41template <size_t size, size_t alignment>
42void MOJO_SYSTEM_IMPL_EXPORT
43CheckUserPointerWithCount(const void* pointer, size_t count) {
44  CHECK_LE(count, std::numeric_limits<size_t>::max() / size);
45  CHECK(count == 0 || (pointer && IsAligned<alignment>(pointer)));
46}
47
48// Explicitly instantiate the sizes we need. Add instantiations as needed.
49template void MOJO_SYSTEM_IMPL_EXPORT
50    CheckUserPointerWithCount<1, 1>(const void*, size_t);
51template void MOJO_SYSTEM_IMPL_EXPORT
52    CheckUserPointerWithCount<4, 4>(const void*, size_t);
53template void MOJO_SYSTEM_IMPL_EXPORT
54    CheckUserPointerWithCount<8, 4>(const void*, size_t);
55template void MOJO_SYSTEM_IMPL_EXPORT
56    CheckUserPointerWithCount<8, 8>(const void*, size_t);
57
58template <size_t alignment>
59void CheckUserPointerWithSize(const void* pointer, size_t size) {
60  // TODO(vtl): If running in kernel mode, do a full verification. For now, just
61  // check that it's non-null and aligned. (A faster user mode implementation is
62  // also possible if this check is skipped.)
63  CHECK(size == 0 || (!!pointer && internal::IsAligned<alignment>(pointer)));
64}
65
66// Explicitly instantiate the sizes we need. Add instantiations as needed.
67template void MOJO_SYSTEM_IMPL_EXPORT
68    CheckUserPointerWithSize<1>(const void*, size_t);
69template void MOJO_SYSTEM_IMPL_EXPORT
70    CheckUserPointerWithSize<4>(const void*, size_t);
71// Whereas the other |Check...()| functions are usually used with integral typs
72// or arrays of integral types, this one is used with Options structs for which
73// alignment has been explicitly been specified (using |MOJO_ALIGNAS()|), which
74// MSVS *does* respect.
75#if defined(COMPILER_MSVC) && defined(ARCH_CPU_32_BITS)
76template <>
77void MOJO_SYSTEM_IMPL_EXPORT
78CheckUserPointerWithSize<8>(const void* pointer, size_t size) {
79  CHECK(size == 0 ||
80        (!!pointer && reinterpret_cast<uintptr_t>(pointer) % 8 == 0));
81}
82#else
83template void MOJO_SYSTEM_IMPL_EXPORT
84    CheckUserPointerWithSize<8>(const void*, size_t);
85#endif
86
87}  // namespace internal
88}  // namespace system
89}  // namespace mojo
90