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
12 namespace mojo {
13 namespace system {
14 namespace internal {
15
16 template <size_t alignment>
IsAligned(const void * pointer)17 bool 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)
24 template <>
IsAligned(const void * pointer)25 bool IsAligned<8>(const void* pointer) {
26 return reinterpret_cast<uintptr_t>(pointer) % 4 == 0;
27 }
28 #endif
29
30 template <size_t size, size_t alignment>
CheckUserPointer(const void * pointer)31 void 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.
36 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<1, 1>(const void*);
37 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<4, 4>(const void*);
38 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<8, 4>(const void*);
39 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<8, 8>(const void*);
40
41 template <size_t size, size_t alignment>
42 void MOJO_SYSTEM_IMPL_EXPORT
CheckUserPointerWithCount(const void * pointer,size_t count)43 CheckUserPointerWithCount(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.
49 template void MOJO_SYSTEM_IMPL_EXPORT
50 CheckUserPointerWithCount<1, 1>(const void*, size_t);
51 template void MOJO_SYSTEM_IMPL_EXPORT
52 CheckUserPointerWithCount<4, 4>(const void*, size_t);
53 template void MOJO_SYSTEM_IMPL_EXPORT
54 CheckUserPointerWithCount<8, 4>(const void*, size_t);
55 template void MOJO_SYSTEM_IMPL_EXPORT
56 CheckUserPointerWithCount<8, 8>(const void*, size_t);
57
58 template <size_t alignment>
CheckUserPointerWithSize(const void * pointer,size_t size)59 void 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.
67 template void MOJO_SYSTEM_IMPL_EXPORT
68 CheckUserPointerWithSize<1>(const void*, size_t);
69 template 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)
76 template <>
77 void MOJO_SYSTEM_IMPL_EXPORT
CheckUserPointerWithSize(const void * pointer,size_t size)78 CheckUserPointerWithSize<8>(const void* pointer, size_t size) {
79 CHECK(size == 0 ||
80 (!!pointer && reinterpret_cast<uintptr_t>(pointer) % 8 == 0));
81 }
82 #else
83 template 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