qgsstyle.cpp: avoid minor memleaks in use of sqlite3_mprintf()

Author: rouault

python/core/auto_generated/symbology/qgsstyle.sip.in

@@ -466,12 +466,11 @@ Is emitted every time a tag or smartgroup has been added, removed, or renamed
 Convenience function to open the DB and return a sqlite3 object
 %End
 
-    bool runEmptyQuery( char *query, bool freeQuery = true );
+    bool runEmptyQuery( const QString &query );
 %Docstring
 Convenience function that would run queries which don't generate return values
 
 :param query: query to run
-:param freeQuery: release query memory
 
 :return: success true on success
 %End

src/core/qgssqliteutils.cpp

@@ -18,6 +18,7 @@
 #include "qgssqliteutils.h"
 
 #include <sqlite3.h>
+#include <stdarg.h>
 
 void QgsSqlite3Closer::operator()( sqlite3 *database )
 {
@@ -89,3 +90,14 @@ sqlite3_statement_unique_ptr sqlite3_database_unique_ptr::prepare( const QString
   s.reset( preparedStatement );
   return s;
 }
+
+QString QgsSqlite3Mprintf( const char *format, ... )
+{
+  va_list ap;
+  va_start( ap, format );
+  char *c_str = sqlite3_vmprintf( format, ap );
+  va_end( ap );
+  QString res( QString::fromUtf8( c_str ) );
+  sqlite3_free( c_str );
+  return res;
+}

src/core/qgssqliteutils.h

@@ -135,7 +135,15 @@ class CORE_EXPORT sqlite3_database_unique_ptr : public std::unique_ptr< sqlite3,
      * argument will be filled with the sqlite3 result code.
      */
     sqlite3_statement_unique_ptr prepare( const QString &sql, int &resultCode ) const;
-
 };
 
+
+/**
+ * Wraps sqlite3_mprintf() by automatically freeing the memory.
+ * \note not available in Python bindings.
+ * \since QGIS 3.2
+ */
+QString CORE_EXPORT QgsSqlite3Mprintf( const char *format, ... );
+
+
 #endif // QGSSQLITEUTILS_H