Make our back branches compatible with libxml2 2.13.x.

This back-patches HEAD commits 066e8ac6e, 6082b3d5d, e7192486d,
and 896cd266f into supported branches.  Changes:

* Use xmlAddChildList not xmlAddChild in XMLSERIALIZE
(affects v16 and up only).  This was a flat-out coding mistake
that we got away with due to lax checking in previous versions
of xmlAddChild.

* Use xmlParseInNodeContext not xmlParseBalancedChunkMemory.
This is to dodge a bug in xmlParseBalancedChunkMemory in libxm2
releases 2.13.0-2.13.2.  While that bug is now fixed upstream and
will probably never be seen in any production-oriented distro, it is
currently a problem on some more-bleeding-edge-friendly platforms.

* Suppress "chunk is not well balanced" errors from libxml2,
unless it is the only error.  This eliminates an error-reporting
discrepancy between 2.13 and older releases.  This error is
almost always redundant with previous errors, if not flat-out
inappropriate, which is why 2.13 changed the behavior and why
nobody's likely to miss it.

Erik Wienhold and Tom Lane, per report from Frank Streitzig.

Discussion: https://postgr.es/m/trinity-b0161630-d230-4598-9ebc-7a23acdb37cb-1720186432160@3c-app-gmx-bap25
Discussion: https://postgr.es/m/trinity-361ba18b-541a-4fe7-bc63-655ae3a7d599-1720259822452@3c-app-gmx-bs01

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 3e4ca874d81ade71d5034040d2a1a950c9648321..447e72b21eb4454dc52f043f03a3ede4393d0b8e 100644 (file)
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -757,7 +757,7 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
 
            /* This attaches root to doc, so we need not free it separately. */
            xmlDocSetRootElement(doc, root);
-           xmlAddChild(root, content_nodes);
+           xmlAddChildList(root, content_nodes);
 
            /*
             * We use this node to insert newlines in the dump.  Note: in at
@@ -1696,9 +1696,9 @@ xml_doctype_in_content(const xmlChar *str)
  * XmlOptionType actually used to parse the input (typically the same as
  * xmloption_arg, but a DOCTYPE node in the input can force DOCUMENT mode).
  *
- * If parsed_nodes isn't NULL and the input is not an XML document, the list
- * of parsed nodes from the xmlParseBalancedChunkMemory call will be returned
- * to *parsed_nodes.
+ * If parsed_nodes isn't NULL and we parse in CONTENT mode, the list
+ * of parsed nodes from the xmlParseInNodeContext call will be returned
+ * to *parsed_nodes.  (It is caller's responsibility to free that.)
  *
  * Errors normally result in ereport(ERROR), but if escontext is an
  * ErrorSaveContext, then "safe" errors are reported there instead, and the
@@ -1750,6 +1750,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
    PG_TRY();
    {
        bool        parse_as_document = false;
+       int         options;
        int         res_code;
        size_t      count = 0;
        xmlChar    *version = NULL;
@@ -1758,11 +1759,6 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
        /* Any errors here are reported as hard ereport's */
        xmlInitParser();
 
-       ctxt = xmlNewParserCtxt();
-       if (ctxt == NULL || xmlerrcxt->err_occurred)
-           xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
-                       "could not allocate parser context");
-
        /* Decide whether to parse as document or content */
        if (xmloption_arg == XMLOPTION_DOCUMENT)
            parse_as_document = true;
@@ -1785,6 +1781,18 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
                parse_as_document = true;
        }
 
+       /*
+        * Select parse options.
+        *
+        * Note that here we try to apply DTD defaults (XML_PARSE_DTDATTR)
+        * according to SQL/XML:2008 GR 10.16.7.d: 'Default values defined by
+        * internal DTD are applied'.  As for external DTDs, we try to support
+        * them too (see SQL/XML:2008 GR 10.16.7.e), but that doesn't really
+        * happen because xmlPgEntityLoader prevents it.
+        */
+       options = XML_PARSE_NOENT | XML_PARSE_DTDATTR
+           | (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS);
+
        /* initialize output parameters */
        if (parsed_xmloptiontype != NULL)
            *parsed_xmloptiontype = parse_as_document ? XMLOPTION_DOCUMENT :
@@ -1794,18 +1802,16 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
 
        if (parse_as_document)
        {
-           /*
-            * Note, that here we try to apply DTD defaults
-            * (XML_PARSE_DTDATTR) according to SQL/XML:2008 GR 10.16.7.d:
-            * 'Default values defined by internal DTD are applied'. As for
-            * external DTDs, we try to support them too, (see SQL/XML:2008 GR
-            * 10.16.7.e)
-            */
+           ctxt = xmlNewParserCtxt();
+           if (ctxt == NULL || xmlerrcxt->err_occurred)
+               xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
+                           "could not allocate parser context");
+
            doc = xmlCtxtReadDoc(ctxt, utf8string,
-                                NULL,
+                                NULL,  /* no URL */
                                 "UTF-8",
-                                XML_PARSE_NOENT | XML_PARSE_DTDATTR
-                                | (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS));
+                                options);
+
            if (doc == NULL || xmlerrcxt->err_occurred)
            {
                /* Use original option to decide which error code to report */
@@ -1822,6 +1828,9 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
        }
        else
        {
+           xmlNodePtr  root;
+
+           /* set up document with empty root node to be the context node */
            doc = xmlNewDoc(version);
            if (doc == NULL || xmlerrcxt->err_occurred)
                xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
@@ -1834,19 +1843,38 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
                            "could not allocate XML document");
            doc->standalone = standalone;
 
+           root = xmlNewNode(NULL, (const xmlChar *) "content-root");
+           if (root == NULL || xmlerrcxt->err_occurred)
+               xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
+                           "could not allocate xml node");
+           /* This attaches root to doc, so we need not free it separately. */
+           xmlDocSetRootElement(doc, root);
+
            /* allow empty content */
            if (*(utf8string + count))
            {
-               res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0,
-                                                      utf8string + count,
-                                                      parsed_nodes);
-               if (res_code != 0 || xmlerrcxt->err_occurred)
+               xmlNodePtr  node_list = NULL;
+               xmlParserErrors res;
+
+               res = xmlParseInNodeContext(root,
+                                           (char *) utf8string + count,
+                                           strlen((char *) utf8string + count),
+                                           options,
+                                           &node_list);
+
+               if (res != XML_ERR_OK || xmlerrcxt->err_occurred)
                {
+                   xmlFreeNodeList(node_list);
                    xml_errsave(escontext, xmlerrcxt,
                                ERRCODE_INVALID_XML_CONTENT,
                                "invalid XML content");
                    goto fail;
                }
+
+               if (parsed_nodes != NULL)
+                   *parsed_nodes = node_list;
+               else
+                   xmlFreeNodeList(node_list);
            }
        }
 
@@ -1866,7 +1894,8 @@ fail:
    }
    PG_END_TRY();
 
-   xmlFreeParserCtxt(ctxt);
+   if (ctxt != NULL)
+       xmlFreeParserCtxt(ctxt);
 
    pg_xml_done(xmlerrcxt, false);
 
@@ -2085,6 +2114,19 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)
    switch (domain)
    {
        case XML_FROM_PARSER:
+
+           /*
+            * XML_ERR_NOT_WELL_BALANCED is typically reported after some
+            * other, more on-point error.  Furthermore, libxml2 2.13 reports
+            * it under a completely different set of rules than prior
+            * versions.  To avoid cross-version behavioral differences,
+            * suppress it so long as we already logged some error.
+            */
+           if (error->code == XML_ERR_NOT_WELL_BALANCED &&
+               xmlerrcxt->err_occurred)
+               return;
+           /* fall through */
+
        case XML_FROM_NONE:
        case XML_FROM_MEMORY:
        case XML_FROM_IO:

diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index 6500cff885d10a78dad632c6807c7e2939d89a0a..93a79cda8fd4e7ad99fc3df31b1f70a8053ea9a2 100644 (file)
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -254,17 +254,11 @@ ERROR:  invalid XML content
 DETAIL:  line 1: xmlParseEntityRef: no name
 &
                 ^
-line 1: chunk is not well balanced
-&
-                                ^
 SELECT xmlparse(content '&idontexist;');
 ERROR:  invalid XML content
 DETAIL:  line 1: Entity 'idontexist' not defined
 &idontexist;
                              ^
-line 1: chunk is not well balanced
-&idontexist;
-                                               ^
 SELECT xmlparse(content '');
          xmlparse          
 ---------------------------
@@ -283,9 +277,6 @@ DETAIL:  line 1: Entity 'idontexist' not defined
 &idontexist;
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-&idontexist;
-                                    ^
-line 1: chunk is not well balanced
 &idontexist;
                                     ^
 SELECT xmlparse(content '');

diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index e1d165c6c936005cbc0f724d9a175d604068b549..f956322c69384d6f67fb61b89333c733f5c71349 100644 (file)
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -250,13 +250,11 @@ ERROR:  invalid XML content
 DETAIL:  line 1: xmlParseEntityRef: no name
 &
                 ^
-line 1: chunk is not well balanced
 SELECT xmlparse(content '&idontexist;');
 ERROR:  invalid XML content
 DETAIL:  line 1: Entity 'idontexist' not defined
 &idontexist;
                              ^
-line 1: chunk is not well balanced
 SELECT xmlparse(content '');
          xmlparse          
 ---------------------------
@@ -275,7 +273,6 @@ DETAIL:  line 1: Entity 'idontexist' not defined
 &idontexist;
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-line 1: chunk is not well balanced
 SELECT xmlparse(content '');
       xmlparse       
 ---------------------