File: shared_memory_mapping.cc

package info (click to toggle)
chromium 120.0.6099.224-1~deb11u1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 6,112,112 kB
  • sloc: cpp: 32,907,025; ansic: 8,148,123; javascript: 3,679,536; python: 2,031,248; asm: 959,718; java: 804,675; xml: 617,256; sh: 111,417; objc: 100,835; perl: 88,443; cs: 53,032; makefile: 29,579; fortran: 24,137; php: 21,162; tcl: 21,147; sql: 20,809; ruby: 17,735; pascal: 12,864; yacc: 8,045; lisp: 3,388; lex: 1,323; ada: 727; awk: 329; jsp: 267; csh: 117; exp: 43; sed: 37
file content (98 lines) | stat: -rw-r--r-- 3,545 bytes parent folder | download | duplicates (2)
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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/memory/shared_memory_mapping.h"

#include <cstdint>
#include <utility>

#include "base/bits.h"
#include "base/logging.h"
#include "base/memory/shared_memory_security_policy.h"
#include "base/memory/shared_memory_tracker.h"
#include "base/system/sys_info.h"
#include "base/unguessable_token.h"
#include "build/build_config.h"

namespace base {

SharedMemoryMapping::SharedMemoryMapping() = default;

SharedMemoryMapping::SharedMemoryMapping(SharedMemoryMapping&& mapping) noexcept
    : mapped_span_(std::exchange(mapping.mapped_span_, span<uint8_t>())),
      size_(mapping.size_),
      guid_(mapping.guid_),
      mapper_(mapping.mapper_) {}

SharedMemoryMapping& SharedMemoryMapping::operator=(
    SharedMemoryMapping&& mapping) noexcept {
  Unmap();
  mapped_span_ = std::exchange(mapping.mapped_span_, span<uint8_t>());
  size_ = mapping.size_;
  guid_ = mapping.guid_;
  mapper_ = mapping.mapper_;
  return *this;
}

SharedMemoryMapping::~SharedMemoryMapping() {
  Unmap();
}

SharedMemoryMapping::SharedMemoryMapping(span<uint8_t> mapped_span,
                                         size_t size,
                                         const UnguessableToken& guid,
                                         SharedMemoryMapper* mapper)
    : mapped_span_(mapped_span), size_(size), guid_(guid), mapper_(mapper) {
  // Note: except on Windows, `mapped_span_.size() == size_`.
  SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
}

void SharedMemoryMapping::Unmap() {
  if (!IsValid())
    return;

  SharedMemorySecurityPolicy::ReleaseReservationForMapping(size_);
  SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);

  SharedMemoryMapper* mapper = mapper_;
  if (!mapper)
    mapper = SharedMemoryMapper::GetDefaultInstance();

  // The backing mapper expects offset to be aligned to
  // `SysInfo::VMAllocationGranularity()`, so replicate the alignment that was
  // done when originally mapping in the region.
  uint8_t* aligned_data =
      bits::AlignDown(mapped_span_.data(), SysInfo::VMAllocationGranularity());
  size_t adjusted_size =
      mapped_span_.size() +
      static_cast<size_t>(mapped_span_.data() - aligned_data);
  span<uint8_t> span_to_unmap = make_span(aligned_data, adjusted_size);
  mapper->Unmap(span_to_unmap);
}

ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping() = default;
ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping(
    ReadOnlySharedMemoryMapping&&) noexcept = default;
ReadOnlySharedMemoryMapping& ReadOnlySharedMemoryMapping::operator=(
    ReadOnlySharedMemoryMapping&&) noexcept = default;
ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping(
    span<uint8_t> mapped_span,
    size_t size,
    const UnguessableToken& guid,
    SharedMemoryMapper* mapper)
    : SharedMemoryMapping(mapped_span, size, guid, mapper) {}

WritableSharedMemoryMapping::WritableSharedMemoryMapping() = default;
WritableSharedMemoryMapping::WritableSharedMemoryMapping(
    WritableSharedMemoryMapping&&) noexcept = default;
WritableSharedMemoryMapping& WritableSharedMemoryMapping::operator=(
    WritableSharedMemoryMapping&&) noexcept = default;
WritableSharedMemoryMapping::WritableSharedMemoryMapping(
    span<uint8_t> mapped_span,
    size_t size,
    const UnguessableToken& guid,
    SharedMemoryMapper* mapper)
    : SharedMemoryMapping(mapped_span, size, guid, mapper) {}

}  // namespace base