1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
base / memory / platform_shared_memory_mapper_win.cc [blame]
// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif
#include "base/memory/platform_shared_memory_mapper.h"
#include "base/logging.h"
#include "partition_alloc/page_allocator.h"
#include <aclapi.h>
namespace base {
namespace {
// Returns the length of the memory section starting at the supplied address.
size_t GetMemorySectionSize(void* address) {
MEMORY_BASIC_INFORMATION memory_info;
if (!::VirtualQuery(address, &memory_info, sizeof(memory_info)))
return 0;
return memory_info.RegionSize -
static_cast<size_t>(static_cast<char*>(address) -
static_cast<char*>(memory_info.AllocationBase));
}
} // namespace
std::optional<span<uint8_t>> PlatformSharedMemoryMapper::Map(
subtle::PlatformSharedMemoryHandle handle,
bool write_allowed,
uint64_t offset,
size_t size) {
// Try to map the shared memory. On the first failure, release any reserved
// address space for a single retry.
void* address;
for (int i = 0; i < 2; ++i) {
address = MapViewOfFile(
handle, FILE_MAP_READ | (write_allowed ? FILE_MAP_WRITE : 0),
static_cast<DWORD>(offset >> 32), static_cast<DWORD>(offset), size);
if (address)
break;
partition_alloc::ReleaseReservation();
}
if (!address) {
DPLOG(ERROR) << "Failed executing MapViewOfFile";
return std::nullopt;
}
return span(static_cast<uint8_t*>(address), GetMemorySectionSize(address));
}
void PlatformSharedMemoryMapper::Unmap(span<uint8_t> mapping) {
if (!UnmapViewOfFile(mapping.data()))
DPLOG(ERROR) << "UnmapViewOfFile";
}
} // namespace base