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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#pragma once
#include <sal/config.h>
#include <algorithm>
#include <cassert>
#include <limits>
#include <type_traits>
#if defined(_MSC_VER)
#include <safeint.h>
#else
#ifndef __has_builtin
# define __has_builtin(x) 0
#endif
#endif
namespace o3tl
{
template <typename T> inline constexpr T saturating_add(T a, T b)
{
if (b >= 0) {
if (a <= std::numeric_limits<T>::max() - b) {
return a + b;
} else {
return std::numeric_limits<T>::max();
}
} else {
if (a >= std::numeric_limits<T>::min() - b) {
return a + b;
} else {
return std::numeric_limits<T>::min();
}
}
}
template <typename T> inline constexpr T saturating_sub(T a, T b)
{
if (b >= 0) {
if (a >= std::numeric_limits<T>::min() + b) {
return a - b;
} else {
return std::numeric_limits<T>::min();
}
} else {
if (a <= std::numeric_limits<T>::max() + b) {
return a - b;
} else {
return std::numeric_limits<T>::max();
}
}
}
template<typename T> inline
typename std::enable_if<std::is_signed<T>::value, T>::type saturating_toggle_sign(
T a)
{
if (a == std::numeric_limits<T>::min())
return std::numeric_limits<T>::max();
return a * -1;
}
#if defined(_MSC_VER)
template<typename T> inline bool checked_multiply(T a, T b, T& result)
{
return !msl::utilities::SafeMultiply(a, b, result);
}
template<typename T> inline bool checked_add(T a, T b, T& result)
{
return !msl::utilities::SafeAdd(a, b, result);
}
template<typename T> inline bool checked_sub(T a, T b, T& result)
{
return !msl::utilities::SafeSubtract(a, b, result);
}
#elif (defined __GNUC__ && !defined __clang__) || (__has_builtin(__builtin_mul_overflow) && !(defined ANDROID && defined __clang__) && !(defined(__clang__) && (defined(__arm__) || defined(__i386__))))
// 32-bit clang fails with undefined reference to `__mulodi4'
template<typename T> inline bool checked_multiply(T a, T b, T& result)
{
return __builtin_mul_overflow(a, b, &result);
}
template<typename T> inline bool checked_add(T a, T b, T& result)
{
return __builtin_add_overflow(a, b, &result);
}
template<typename T> inline bool checked_sub(T a, T b, T& result)
{
return __builtin_sub_overflow(a, b, &result);
}
#else
//https://www.securecoding.cert.org/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
template<typename T> inline typename std::enable_if<std::is_signed<T>::value, bool>::type checked_multiply(T a, T b, T& result)
{
if (a > 0) { /* a is positive */
if (b > 0) { /* a and b are positive */
if (a > (std::numeric_limits<T>::max() / b)) {
return true; /* Handle error */
}
} else { /* a positive, b nonpositive */
if (b < (std::numeric_limits<T>::min() / a)) {
return true; /* Handle error */
}
} /* a positive, b nonpositive */
} else { /* a is nonpositive */
if (b > 0) { /* a is nonpositive, b is positive */
if (a < (std::numeric_limits<T>::min() / b)) {
return true; /* Handle error */
}
} else { /* a and b are nonpositive */
if ( (a != 0) && (b < (std::numeric_limits<T>::max() / a))) {
return true; /* Handle error */
}
} /* End if a and b are nonpositive */
} /* End if a is nonpositive */
result = a * b;
return false;
}
//https://www.securecoding.cert.org/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap
template<typename T> inline typename std::enable_if<std::is_unsigned<T>::value, bool>::type checked_multiply(T a, T b, T& result)
{
if (b && a > std::numeric_limits<T>::max() / b) {
return true;/* Handle error */
}
result = a * b;
return false;
}
//https://www.securecoding.cert.org/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
template<typename T> inline typename std::enable_if<std::is_signed<T>::value, bool>::type checked_add(T a, T b, T& result)
{
if (((b > 0) && (a > (std::numeric_limits<T>::max() - b))) ||
((b < 0) && (a < (std::numeric_limits<T>::min() - b)))) {
return true;
}
result = a + b;
return false;
}
//https://www.securecoding.cert.org/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap
template<typename T> inline typename std::enable_if<std::is_unsigned<T>::value, bool>::type checked_add(T a, T b, T& result)
{
if (std::numeric_limits<T>::max() - a < b) {
return true;/* Handle error */
}
result = a + b;
return false;
}
//https://www.securecoding.cert.org/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
template<typename T> inline typename std::enable_if<std::is_signed<T>::value, bool>::type checked_sub(T a, T b, T& result)
{
if ((b > 0 && a < std::numeric_limits<T>::min() + b) ||
(b < 0 && a > std::numeric_limits<T>::max() + b)) {
return true;
}
result = a - b;
return false;
}
//https://www.securecoding.cert.org/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap
template<typename T> inline typename std::enable_if<std::is_unsigned<T>::value, bool>::type checked_sub(T a, T b, T& result)
{
if (a < b) {
return true;
}
result = a - b;
return false;
}
#endif
template<typename T> constexpr std::enable_if_t<std::is_signed_v<T>, std::make_unsigned_t<T>>
make_unsigned(T value)
{
assert(value >= 0);
return value;
}
template<typename T1, typename T2> constexpr std::enable_if_t<std::is_unsigned_v<T1>, T1>
clamp_to_unsigned(T2 value) {
if constexpr (std::is_unsigned_v<T2>) {
// coverity[result_independent_of_operands] - suppress warning for template
return value <= std::numeric_limits<T1>::max() ? value : std::numeric_limits<T1>::max();
} else {
static_assert(std::is_signed_v<T2>);
return value < 0 ? 0 : clamp_to_unsigned<T1>(make_unsigned(value));
}
}
// An implicit conversion from T2 to T1, useful in places where an explicit conversion from T2 to
// T1 is needed (e.g., in list initialization, if the implicit conversion would be narrowing) but
// tools like -fsanitize=implicit-conversion should still be able to detect truncation:
template<typename T1, typename T2> constexpr T1 narrowing(T2 value) { return value; }
// std::min wrapped to inform coverity that the result is now deemed sanitized
// coverity[ -taint_source ]
template<typename T> [[nodiscard]] inline T sanitizing_min(T a, T b)
{
return std::min(a, b);
}
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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