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// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_
#define CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_
#include <limits>
#include <tuple>
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "base/numerics/safe_math.h"
#include "util/misc/implicit_cast.h"
namespace crashpad {
//! \brief Ensures that a range, composed of a base and size, does not overflow
//! its data type.
template <typename ValueType, typename SizeType = ValueType>
class CheckedRange {
public:
CheckedRange(ValueType base, SizeType size) {
static_assert(!std::numeric_limits<SizeType>::is_signed,
"SizeType must be unsigned");
SetRange(base, size);
}
//! \brief Sets the range’s base and size to \a base and \a size,
//! respectively.
void SetRange(ValueType base, SizeType size) {
base_ = base;
size_ = size;
}
//! \brief The range’s base.
ValueType base() const { return base_; }
//! \brief The range’s size.
SizeType size() const { return size_; }
//! \brief The range’s end (its base plus its size).
ValueType end() const { return base_ + size_; }
//! \brief Returns the validity of the range.
//!
//! \return `true` if the range is valid, `false` otherwise.
//!
//! A range is valid if its size can be converted to the range’s data type
//! without data loss, and if its end (base plus size) can be computed without
//! overflowing its data type.
bool IsValid() const {
if (!base::IsValueInRangeForNumericType<ValueType, SizeType>(size_)) {
return false;
}
base::CheckedNumeric<ValueType> checked_end(base_);
checked_end += implicit_cast<ValueType>(size_);
return checked_end.IsValid();
}
//! \brief Returns whether the range contains another value.
//!
//! \param[in] value The (possibly) contained value.
//!
//! \return `true` if the range contains \a value, `false` otherwise.
//!
//! A range contains a value if the value is greater than or equal to its
//! base, and less than its end (base plus size).
//!
//! This method must only be called if IsValid() would return `true`.
bool ContainsValue(ValueType value) const {
DCHECK(IsValid());
return value >= base() && value < end();
}
//! \brief Returns whether the range contains another range.
//!
//! \param[in] that The (possibly) contained range.
//!
//! \return `true` if `this` range, the containing range, contains \a that,
//! the contained range. `false` otherwise.
//!
//! A range contains another range when the contained range’s base is greater
//! than or equal to the containing range’s base, and the contained range’s
//! end is less than or equal to the containing range’s end.
//!
//! This method must only be called if IsValid() would return `true` for both
//! CheckedRange objects involved.
bool ContainsRange(const CheckedRange<ValueType, SizeType>& that) const {
DCHECK(IsValid());
DCHECK(that.IsValid());
return that.base() >= base() && that.end() <= end();
}
//! \brief Returns whether the range overlaps another range.
//!
//! \param[in] that The (possibly) overlapping range.
//!
//! \return `true` if `this` range, the first range, overlaps \a that,
//! the provided range. `false` otherwise.
//!
//! Ranges are considered to be closed-open [base, end) for this test. Zero
//! length ranges are never considered to overlap another range.
//!
//! This method must only be called if IsValid() would return `true` for both
//! CheckedRange objects involved.
bool OverlapsRange(const CheckedRange<ValueType, SizeType>& that) const {
DCHECK(IsValid());
DCHECK(that.IsValid());
if (size() == 0 || that.size() == 0)
return false;
return base() < that.end() && that.base() < end();
}
bool operator<(const CheckedRange& other) const {
return std::tie(base_, size_) < std::tie(other.base_, other.size_);
}
private:
ValueType base_;
SizeType size_;
};
} // namespace crashpad
#endif // CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_