cid#1608296 silence Overflowed integer argument

and

cid#1606815 Overflowed integer argument
cid#1606617 Overflowed integer argument

Change-Id: I4569190edd9b8d65e9b080a7ad0fac391f4a657e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/172348
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/o3tl/safeint.hxx b/include/o3tl/safeint.hxx
index a32c6beea142..80f8b45c4042 100644
--- a/include/o3tl/safeint.hxx
+++ b/include/o3tl/safeint.hxx
@@ -231,6 +231,42 @@ template<typename T> [[nodiscard]] inline T sanitizing_min(T a, T b)
     return std::min(a, b);
 }
 
+// To sanitize in/de-crementing value where the result is known by the caller to be guaranteed to fit in
+// the source type range without over/under-flow
+[[nodiscard]] inline unsigned short sanitizing_inc(unsigned short value)
+{
+    int res = value + 1;
+    assert(res <= std::numeric_limits<unsigned short>::max() &&
+           "nValue was supposed to be incrementable without overflow");
+    return static_cast<unsigned short>(res);
+}
+
+[[nodiscard]] inline unsigned short sanitizing_dec(unsigned short value)
+{
+    int res = value - 1;
+    assert(res >= 0 &&
+           "nValue was supposed to be decrementable without underflow");
+    return static_cast<unsigned short>(res);
+}
+
+[[nodiscard]] inline short sanitizing_inc(short value)
+{
+    int res = value + 1;
+    assert(res >= std::numeric_limits<short>::min() &&
+           res <= std::numeric_limits<short>::max() &&
+           "nValue was supposed to be incrementable without overflow");
+    return static_cast<short>(res);
+}
+
+[[nodiscard]] inline short sanitizing_dec(short value)
+{
+    int res = value - 1;
+    assert(res >= std::numeric_limits<short>::min() &&
+           res <= std::numeric_limits<short>::max() &&
+           "nValue was supposed to be decrementable without underflow");
+    return static_cast<short>(res);
+}
+
 }
 
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