1 files changed, 236 insertions, 0 deletions
diff --git a/include/o3tl/safeint.hxx b/include/o3tl/safeint.hxx
new file mode 100644
index 000000000..c697a9316
--- /dev/null
+++ b/include/o3tl/safeint.hxx
@@ -0,0 +1,236 @@
+/* -*- 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 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 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: */