From 817b489422f15b2aeee132c24bdc94d8de2b6ed9 Mon Sep 17 00:00:00 2001
From: Thomas Heller <theller@ctypes.org>
Date: Thu, 25 Jan 2007 19:19:35 +0000
Subject: Merged revisions 53556 via svnmerge from
 svn+ssh://pythondev@svn.python.org/python/trunk/Modules/_ctypes

........
  r53556 | thomas.heller | 2007-01-25 19:34:14 +0100 (Do, 25 Jan 2007) | 3 lines

  Fix for #1643874: When calling SysAllocString, create a PyCObject
  which will eventually call SysFreeString to free the BSTR resource.
........
---
 Misc/NEWS                |  2 ++
 Modules/_ctypes/cfield.c | 29 +++++++++++++++++++++--------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/Misc/NEWS b/Misc/NEWS
index 8cff951..21742f3 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -154,6 +154,8 @@ Extension Modules
 Library
 -------
 
+- Patch #1643874: memory leak in ctypes fixed.
+
 - Bug #1598181: Avoid O(N**2) bottleneck in subprocess communicate(). 
 
 - Patch #1627441: close sockets properly in urllib2.
diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
index c16a387..31c3b99 100644
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -1424,10 +1424,19 @@ Z_get(void *ptr, unsigned size)
 #endif
 
 #ifdef MS_WIN32
+/* We cannot use SysFreeString as the PyCObject_FromVoidPtr
+   because of different calling convention
+*/
+static void _my_SysFreeString(void *p)
+{
+	SysFreeString((BSTR)p);
+}
+
 static PyObject *
 BSTR_set(void *ptr, PyObject *value, unsigned size)
 {
 	BSTR bstr;
+	PyObject *result;
 
 	/* convert value into a PyUnicodeObject or NULL */
 	if (Py_None == value) {
@@ -1455,15 +1464,19 @@ BSTR_set(void *ptr, PyObject *value, unsigned size)
 	} else
 		bstr = NULL;
 
-	/* free the previous contents, if any */
-	if (*(BSTR *)ptr)
-		SysFreeString(*(BSTR *)ptr);
-	
-	/* and store it */
-	*(BSTR *)ptr = bstr;
+	if (bstr) {
+		result = PyCObject_FromVoidPtr((void *)bstr, _my_SysFreeString);
+		if (result == NULL) {
+			SysFreeString(bstr);
+			return NULL;
+		}
+	} else {
+		result = Py_None;
+		Py_INCREF(result);
+	}
 
-	/* We don't need to keep any other object */
-	_RET(value);
+	*(BSTR *)ptr = bstr;
+	return result;
 }
 
 
-- 
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