unify the handling of string position arguments, fdo#75971 related

Only two text functions had the full set of checks as introduced by the
fix for fdo#75971. Let all text functions check their arguments in the
same way. Additionally this will ease a transition to accept string
lengths >64k in spreadsheet functions as now we have only one place that
checks for SAL_MAX_UINT16 instead of having that scattered all over the
place.

Change-Id: I454e617a59d0b3c2ca725047e7f8c7370bc0bb1f

1 files changed, 48 insertions, 0 deletions

diff --git a/sc/source/core/inc/interpre.hxx b/sc/source/core/inc/interpre.hxx
index 6022c8ea7f6b..642699a5a0be 100644
--- a/sc/source/core/inc/interpre.hxx
+++ b/sc/source/core/inc/interpre.hxx
@@ -368,6 +368,24 @@ void ScTableOp();                                       // repeated operations
 void SetMaxIterationCount(sal_uInt16 n);
 inline void CurFmtToFuncFmt()
     { nFuncFmtType = nCurFmtType; nFuncFmtIndex = nCurFmtIndex; }
+
+/** Check if a double is suitable as string position or length argument.
+
+    If fVal is Inf or NaN it is changed to -1, if it is less than 0 it is
+    sanitized to 0, if it is greater than some implementation defined max
+    string length it is sanitized to that max.
+
+    @return TRUE if double value fVal is suitable as string argument and was
+            not sanitized.
+            FALSE if not and fVal was adapted.
+ */
+inline bool CheckStringPositionArgument( double & fVal );
+
+/** Obtain a double suitable as string position or length argument.
+    Returns -1 if the number is Inf or NaN or less than 0 or greater than some
+    implementation defined max string length. */
+inline double GetStringPositionArgument();
+
 // Check for String overflow of rResult+rAdd and set error and erase rResult
 // if so. Return true if ok, false if overflow
 inline bool CheckStringResultLen( OUString& rResult, const OUString& rAdd );
@@ -921,6 +939,36 @@ inline bool ScInterpreter::MustHaveParamCountMin( short nAct, short nMin )
     return false;
 }
 
+inline bool ScInterpreter::CheckStringPositionArgument( double & fVal )
+{
+    if (!rtl::math::isFinite( fVal))
+    {
+        fVal = -1.0;
+        return false;
+    }
+    else if (fVal < 0.0)
+    {
+        fVal = 0.0;
+        return false;
+    }
+    else if (fVal > SAL_MAX_UINT16)
+    {
+        fVal = static_cast<double>(SAL_MAX_UINT16);
+        return false;
+    }
+    return true;
+}
+
+inline double ScInterpreter::GetStringPositionArgument()
+{
+    double fVal = rtl::math::approxFloor( GetDouble());
+    if (!CheckStringPositionArgument( fVal))
+    {
+        fVal = -1.0;
+    }
+    return fVal;
+}
+
 inline bool ScInterpreter::CheckStringResultLen( OUString& rResult, const OUString& rAdd )
 {
     if ( rResult.getLength() + rAdd.getLength() > SAL_MAX_UINT16 )