From 915abb346a43f18199cb4cc56b846dac430c6a43 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Sat, 27 Jan 2007 14:50:51 +0000
Subject: [PATCH] Reactivate libxml memory management via palloc, now that I
think I've classified the conditions under which this is safe to do (see
source code comment).
---
src/backend/utils/adt/xml.c | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index c4c2690e947..7d963148d0e 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.23 2007/01/27 11:48:31 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.24 2007/01/27 14:50:51 petere Exp $
*
*-------------------------------------------------------------------------
*/
@@ -23,6 +23,21 @@
* else does.
*/
+/*
+ * Note on memory management: Via callbacks, libxml is told to use
+ * palloc and friends for memory management. Sometimes, libxml
+ * allocates global structures in the hope that it can reuse them
+ * later on, but if "later" is much later, the memory context
+ * management of PostgreSQL will have blown those structures away
+ * without telling libxml about it. Therefore, it is important to
+ * call xmlCleanupParser() or perhaps some other cleanup function
+ * after using such functions, for example something from
+ * libxml/parser.h or libxml/xmlsave.h. Unfortunately, you cannot
+ * readily tell from the API documentation when that happens, so
+ * careful evaluation is necessary when introducing new libxml APIs
+ * here.
+ */
+
#include "postgres.h"
#ifdef USE_LIBXML
@@ -31,7 +46,6 @@
#include <libxml/tree.h>
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
-#include <libxml/xmlsave.h>
#include <libxml/xmlwriter.h>
#endif /* USE_LIBXML */
@@ -54,12 +68,10 @@
static StringInfo xml_err_buf = NULL;
static void xml_init(void);
-#ifdef NOT_USED
static void *xml_palloc(size_t size);
static void *xml_repalloc(void *ptr, size_t size);
static void xml_pfree(void *ptr);
static char *xml_pstrdup(const char *string);
-#endif
static void xml_ereport(int level, int sqlcode,
const char *msg);
static void xml_errorHandler(void *ctxt, const char *msg, ...);
@@ -782,14 +794,8 @@ xml_init(void)
/* Now that xml_err_buf exists, safe to call xml_errorHandler */
xmlSetGenericErrorFunc(NULL, xml_errorHandler);
-#ifdef NOT_USED
- /*
- * FIXME: This doesn't work because libxml assumes that whatever
- * libxml allocates, only libxml will free, so we can't just drop
- * memory contexts behind it. This needs to be refined.
- */
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
-#endif
+
xmlInitParser();
LIBXML_TEST_VERSION;
}
@@ -1098,7 +1104,6 @@ xml_text2xmlChar(text *in)
}
-#ifdef NOT_USED
/*
* Wrappers for memory management functions
*/
@@ -1128,7 +1133,6 @@ xml_pstrdup(const char *string)
{
return pstrdup(string);
}
-#endif /* NOT_USED */
/*
--
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