Fix silent data loss binding numeric to VARCHAR via stored procedure

IscDbc/Connection.h

@@ -528,6 +528,7 @@ class HeadSqlVar
 	virtual char *		getSqlData() = 0;
 	virtual short *		getSqlInd() = 0;
 	virtual void		setSqlData( char *data ) = 0;
+	virtual void		writeStringData( const char *src, int len ) = 0;
 	//virtual void		setSqlInd( short *ind ) = 0;
 
 	virtual bool		isReplaceForParamArray () = 0;

IscDbc/IscHeadSqlVar.h

@@ -103,6 +103,27 @@ class IscHeadSqlVar : public HeadSqlVar
 	inline char *	getSqlData() { return sqlvar->sqldata; }
 	inline short *	getSqlInd() { return sqlvar->sqlind; }
 
+	// Write `len` bytes from `src` into the sqlvar's pre-allocated buffer,
+	// honoring Firebird's in-buffer layout for the prepared type:
+	//   SQL_VARYING : [uint16 len][data...] — leaves sqltype/sqllen untouched
+	//                 so checkAndRebuild() sees no override and Firebird reads
+	//                 the buffer using the original VARCHAR(N) metadata.
+	//   SQL_TEXT    : bare bytes; reports the effective length via sqllen.
+	inline void		writeStringData(const char *src, int len)
+	{
+		char *buf = sqlvar->sqldata;
+		if (sqlvar->sqltype == SQL_VARYING)
+		{
+			*(unsigned short*)buf = (unsigned short)len;
+			memcpy(buf + sizeof(short), src, len);
+		}
+		else
+		{
+			memcpy(buf, src, len);
+			sqlvar->sqllen = (short)len;
+		}
+	}
+
 	// not used
 	//void		setSqlInd( short *ind ) { sqlvar->sqlind = ind; }
 	//void		setSqlType ( short type ) { sqlvar->sqltype = type; }

IscDbc/Sqlda.cpp

@@ -759,7 +759,18 @@ const char* Sqlda::getColumnName(int index)
 
 int Sqlda::getPrecision(int index)
 {
-	CAttrSqlVar *var = Var(index);
+	CAttrSqlVar *curVar = Var(index);
+	// INPUT parameter precision is immutable from prepare time, even if the
+	// conversion layer later mutates sqllen on the CAttrSqlVar (e.g. the
+	// SQL_TEXT branch of writeStringData reports the effective length that
+	// way).  Read from the orgSqlProperties snapshot so re-binding never
+	// sees a shrunken precision — this mirrors getColumnDisplaySize above.
+	// OUTPUT always uses the current sqlvar; SQL_ARRAY needs the mutable
+	// CAttrSqlVar for its `array` pointer.
+	const SqlProperties *var =
+		(SqldaDir == SQLDA_INPUT && curVar->sqltype != SQL_ARRAY)
+			? orgVarSqlProperties(index)
+			: curVar;
 
 	switch (var->sqltype)
 	{
@@ -798,8 +809,8 @@ int Sqlda::getPrecision(int index)
 										MAX_DECIMAL_LENGTH,
 										MAX_QUAD_LENGTH);
 
-	case SQL_ARRAY:	
-		return var->array->arrOctetLength;
+	case SQL_ARRAY:
+		return curVar->array->arrOctetLength;
 //		return MAX_ARRAY_LENGTH;
 
 	case SQL_BLOB: