Replace deprecated PyUnicode_FromUnicode(NULL, size) calls (mkleehamm…

…er#998)

Current versions of Python write a deprecation warning message to
stderr, which breaks CGI scripts running under web servers which
fold stderr into stdout. Likely breaks other software. This change
replaces the deprecated calls with PyUnicode_New(size, 0x10ffff).
The second argument represents the highest code point for Unicode
characters, which is used because the calls being replaced have
no string value from which we can determine the smallest number
of bytes needed to represent any value which can be stored in the
newly-created object.

src/pyodbccompat.h

@@ -66,13 +66,17 @@ inline void PyString_ConcatAndDel(PyObject** lhs, PyObject* rhs)
 
 #endif
 
+#ifndef MAX_UNICODE
+  #define MAX_UNICODE 0x10ffff
+#endif
+
 inline PyObject* Text_New(Py_ssize_t length)
 {
     // Returns a new, uninitialized String (Python 2) or Unicode object (Python 3) object.
 #if PY_MAJOR_VERSION < 3
     return PyString_FromStringAndSize(0, length);
 #else
-    return PyUnicode_FromUnicode(0, length);
+    return PyUnicode_New(length, MAX_UNICODE);
 #endif
 }
 

src/pyodbcmodule.cpp

@@ -1357,7 +1357,7 @@ static PyObject* MakeConnectionString(PyObject* existing, PyObject* parts)
         length += Text_Size(key) + 1 + Text_Size(value) + 1; // key=value;
     }
 
-    PyObject* result = PyUnicode_FromUnicode(0, length);
+    PyObject* result = PyUnicode_New(length, MAX_UNICODE);
     if (!result)
         return 0;
 

tests3/issue998.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+"""
+Verify that no warning is emitted for `PyUnicode_FromUnicode(NULL, size)`.
+
+See https://github.com/mkleehammer/pyodbc/issues/998.
+See also https://bugs.python.org/issue36346.
+"""
+
+import io
+import os
+import sys
+import unittest
+
+# pylint: disable-next=import-error
+from tests3.testutils import add_to_path, load_setup_connection_string
+
+add_to_path()
+import pyodbc  # pylint: disable=wrong-import-position
+
+KB = 1024
+MB = KB * 1024
+
+CONNECTION_STRING = None
+
+CONNECTION_STRING_ERROR_MESSAGE = (
+    "Please create tmp/setup.cfg file or "
+    "set a valid value to CONNECTION_STRING."
+)
+NO_ERROR = None
+
+
+class SQLPutDataUnicodeToBytesMemoryLeakTestCase(unittest.TestCase):
+    """Test case for issue998 bug fix."""
+
+    driver = pyodbc
+
+    @classmethod
+    def setUpClass(cls):
+        """Set the connection string."""
+
+        filename = os.path.splitext(os.path.basename(__file__))[0]
+        cls.connection_string = (
+            load_setup_connection_string(filename) or CONNECTION_STRING
+        )
+
+        if cls.connection_string:
+            return NO_ERROR
+        return ValueError(CONNECTION_STRING_ERROR_MESSAGE)
+
+    def test_use_correct_unicode_factory_function(self):
+        """Verify that the obsolete function call has been replaced."""
+
+        # Create a results set.
+        with pyodbc.connect(self.connection_string, autocommit=True) as cnxn:
+            cursor = cnxn.cursor()
+            cursor.execute("SELECT 1 AS a, 2 AS b")
+            rows = cursor.fetchall()
+
+        # Redirect stderr so we can detect the warning.
+        sys.stderr = redirected_stderr = io.StringIO()
+
+        # Convert the results object to a string.
+        self.assertGreater(len(str(rows)), 0)
+
+        # Restore stderr to the original stream.
+        sys.stderr = sys.__stderr__
+
+        # If the bug has been fixed, nothing will have been written to stderr.
+        self.assertEqual(len(redirected_stderr.getvalue()), 0)
+
+
+def main():
+    """Top-level driver for the test."""
+    unittest.main()
+
+
+if __name__ == "__main__":
+    main()