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// 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.
#ifndef UI_ACCESSIBILITY_PLATFORM_IACCESSIBLE2_SCOPED_CO_MEM_ARRAY_H_
#define UI_ACCESSIBILITY_PLATFORM_IACCESSIBLE2_SCOPED_CO_MEM_ARRAY_H_
#include <objbase.h>
#include <algorithm>
#include <cstddef>
#include <utility>
#include <vector>
#include "base/check_op.h"
#include "base/compiler_specific.h"
#include "base/component_export.h"
#include "base/containers/span.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/numerics/safe_conversions.h"
#include "base/process/memory.h"
#include "base/win/windows_types.h"
struct IA2TextSelection;
struct IUnknown;
namespace ui {
// RAII type for COM arrays.
// Example:
// base::win::ScopedCoMemArray<LONG> columns;
// get_selectedColumns(columns.Receive(), columns.ReceiveSize())
// ...
// return; <-- memory released
template <typename T>
class COMPONENT_EXPORT(AX_PLATFORM) ScopedCoMemArray {
public:
ScopedCoMemArray() = default;
// Constructs an instance from the contents of `data`.
explicit ScopedCoMemArray(std::vector<T>&& data);
ScopedCoMemArray(const ScopedCoMemArray&) = delete;
ScopedCoMemArray& operator=(const ScopedCoMemArray&) = delete;
ScopedCoMemArray(ScopedCoMemArray&& o)
: mem_ptr_(std::exchange(o.mem_ptr_, nullptr)),
size_(std::exchange(o.size_, 0)) {}
ScopedCoMemArray& operator=(ScopedCoMemArray&& o) {
if (&o != this)
Reset(std::exchange(o.mem_ptr_, nullptr), std::exchange(o.size_, 0));
return *this;
}
~ScopedCoMemArray() { Reset(nullptr, 0); }
LONG size() const { return size_; }
const T* data() const { return mem_ptr_; }
T* data() { return mem_ptr_; }
base::span<const T> as_span() const {
// SAFETY: mem_ptr_ and size_ originate from accessibility COM calls.
return UNSAFE_BUFFERS(
base::span(mem_ptr_, base::checked_cast<size_t>(size_)));
}
const T& operator[](std::size_t pos) const { return as_span()[pos]; }
T** Receive() {
DCHECK_EQ(mem_ptr_, nullptr); // To catch memory leaks.
return &mem_ptr_;
}
LONG* ReceiveSize() { return &size_; }
private:
// Releases resources held in the elements of the array.
static void FreeContents(base::span<const T> contents) {}
void Reset(T* ptr, LONG size) {
FreeContents(as_span());
::CoTaskMemFree(std::exchange(mem_ptr_, ptr));
size_ = size;
}
// RAW_PTR_EXCLUSION: #addr-of (address returned from a function, also points
// to memory managed by the COM Allocator rather than partition_alloc).
RAW_PTR_EXCLUSION T* mem_ptr_ = nullptr;
LONG size_ = 0;
};
template <typename T>
ScopedCoMemArray<T>::ScopedCoMemArray(std::vector<T>&& data)
: mem_ptr_(reinterpret_cast<T*>(::CoTaskMemAlloc(data.size() * sizeof(T)))),
size_(base::checked_cast<LONG>(data.size())) {
if (!mem_ptr_) {
base::TerminateBecauseOutOfMemory(data.size() * sizeof(T));
}
// SAFETY: mem_ptr_ is sized based on the contents of `data`.
std::ranges::move(
data,
UNSAFE_BUFFERS(base::span(mem_ptr_, base::checked_cast<size_t>(size_)))
.begin());
data.clear();
}
// Release the references to the two IAccessibleText pointers in each element.
template <>
void ScopedCoMemArray<IA2TextSelection>::FreeContents(
base::span<const IA2TextSelection> contents);
// Release the reference to each IUnknown pointer in the array.
template <>
void ScopedCoMemArray<IUnknown*>::FreeContents(
base::span<IUnknown* const> contents);
} // namespace ui
#endif // UI_ACCESSIBILITY_PLATFORM_IACCESSIBLE2_SCOPED_CO_MEM_ARRAY_H_
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