Fix signed 32bit integer overflow in PostgreSQL provider

Fixes #13958
Includes test for signed integer attributes

Author: Sandro Santilli

src/providers/postgres/qgspostgresconn.cpp

@@ -1221,6 +1221,9 @@ qint64 QgsPostgresConn::getBinaryInt( QgsPostgresResult &queryResult, int row, i
       oid = *( quint16 * )p;
       if ( mSwapEndian )
         oid = ntohs( oid );
+      /* cast to signed 16bit
+       * See http://hub.qgis.org/issues/14262 */
+      oid = ( qint16 )oid;
       break;
 
     case 6:
@@ -1268,6 +1271,9 @@ qint64 QgsPostgresConn::getBinaryInt( QgsPostgresResult &queryResult, int row, i
       oid = *( quint32 * )p;
       if ( mSwapEndian )
         oid = ntohl( oid );
+      /* cast to signed 32bit
+       * See http://hub.qgis.org/issues/14262 */
+      oid = ( qint32 )oid;
       break;
   }
 

tests/src/python/test_provider_postgres.py

@@ -147,6 +147,25 @@ def test_unique(features, num_features):
         self.assertTrue(vl.isValid())
         test_unique([f for f in vl.getFeatures()], 4)
 
+    # See http://hub.qgis.org/issues/14262
+    def testSignedIdentifiers(self):
+        def test_query_attribute(dbconn, query, att, val, fidval):
+            ql = QgsVectorLayer('%s table="%s" (g) key=\'%s\' sql=' % (dbconn, query.replace('"', '\\"'), att), "testgeom", "postgres")
+            print query, att
+            assert(ql.isValid())
+            features = ql.getFeatures()
+            att_idx = ql.fieldNameIndex(att)
+            count = 0
+            for f in features:
+                count += 1
+                self.assertEqual(f.attributes()[att_idx], val)
+                #self.assertEqual(f.id(), val)
+            self.assertEqual(count, 1)
+        test_query_attribute(self.dbconn, '(SELECT -1::int4 i, NULL::geometry(Point) g)', 'i', -1, 1)
+        test_query_attribute(self.dbconn, '(SELECT -1::int2 i, NULL::geometry(Point) g)', 'i', -1, 1)
+        test_query_attribute(self.dbconn, '(SELECT -1::int8 i, NULL::geometry(Point) g)', 'i', -1, 1)
+        test_query_attribute(self.dbconn, '(SELECT -65535::int8 i, NULL::geometry(Point) g)', 'i', -65535, 1)
+
 
 if __name__ == '__main__':
     unittest.main()