add checked_add

Reviewed-on: https://gerrit.libreoffice.org/43779
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit 9cfb27ae6cb94f0a853ff70e9ad9f3109d305a94)

android:update safeint header to use the else implementation with clang

Clang toolchain does not defines the __builtin_mul_overflow for 32-bit
ARM. So, fallback to else implementation of checked_multiply when
building Android with Clang

Reviewed-on: https://gerrit.libreoffice.org/39005
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
(cherry picked from commit 2149d4a88e9dc88c30e7475f8ea317e5c7b78529)

Change-Id: If7582005ff6eacf8d9ee846c895776a60709f7a4
Reviewed-on: https://gerrit.libreoffice.org/49485
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/91045
Tested-by: Michael Stahl <michael.stahl@cib.de>
Reviewed-by: Michael Stahl <michael.stahl@cib.de>

1 files changed, 124 insertions, 0 deletions

diff --git a/include/o3tl/safeint.hxx b/include/o3tl/safeint.hxx
new file mode 100644
index 000000000000..5ebf353b6bd6
--- /dev/null
+++ b/include/o3tl/safeint.hxx
@@ -0,0 +1,124 @@
+/* -*- 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/.
+ */
+
+#ifndef INCLUDED_O3TL_SAFEINT_HXX
+#define INCLUDED_O3TL_SAFEINT_HXX
+
+#include <limits>
+#if defined(_MSC_VER)
+#include <safeint.h>
+#else
+#ifndef __has_builtin
+#   define __has_builtin(x) 0
+#endif
+#endif
+
+namespace o3tl
+{
+
+#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);
+}
+
+#elif (defined __GNUC__ && __GNUC__ >= 5) || (__has_builtin(__builtin_mul_overflow) && !(defined ANDROID && defined __clang__))
+
+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);
+}
+
+#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;
+}
+
+#endif
+
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */