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 d7caaaaca044423da69815b45da58d975d2dfd16..063c45b09a53d9d53751c31525d73c5ad83f3e22 100644 (file)
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -1545,6 +1545,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
    PG_TRY();
    {
        bool        parse_as_document = false;
+       int         options;
        int         res_code;
        size_t      count = 0;
        xmlChar    *version = NULL;
@@ -1552,11 +1553,6 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
 
        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;
@@ -1575,20 +1571,30 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
                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);
+
        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 throw */
@@ -1602,17 +1608,36 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
        }
        else
        {
+           xmlNodePtr  root;
+
+           /* set up document with empty root node to be the context node */
            doc = xmlNewDoc(version);
            Assert(doc->encoding == NULL);
            doc->encoding = xmlStrdup((const xmlChar *) "UTF-8");
            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, NULL);
-               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);
+
+               xmlFreeNodeList(node_list);
+
+               if (res != XML_ERR_OK || xmlerrcxt->err_occurred)
                    xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_CONTENT,
                                "invalid XML content");
            }
@@ -1631,7 +1656,8 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
    }
    PG_END_TRY();
 
-   xmlFreeParserCtxt(ctxt);
+   if (ctxt != NULL)
+       xmlFreeParserCtxt(ctxt);
 
    pg_xml_done(xmlerrcxt, false);
 
@@ -1812,6 +1838,19 @@ 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 55ac49be261c3b6080ffc45b08b0b5f54e38a1f5..5b6ae62c044744b499afe6ab8bbb03f648cc30dc 100644 (file)
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -223,17 +223,11 @@ ERROR:  invalid XML content
 DETAIL:  line 1: xmlParseEntityRef: no name
 <invalidentity>&</invalidentity>
                 ^
-line 1: chunk is not well balanced
-<invalidentity>&</invalidentity>
-                                ^
 SELECT xmlparse(content '<undefinedentity>&idontexist;</undefinedentity>');
 ERROR:  invalid XML content
 DETAIL:  line 1: Entity 'idontexist' not defined
 <undefinedentity>&idontexist;</undefinedentity>
                              ^
-line 1: chunk is not well balanced
-<undefinedentity>&idontexist;</undefinedentity>
-                                               ^
 SELECT xmlparse(content '<invalidns xmlns=''&lt;''/>');
          xmlparse          
 ---------------------------
@@ -252,9 +246,6 @@ DETAIL:  line 1: Entity 'idontexist' not defined
 <twoerrors>&idontexist;</unbalanced>
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-<twoerrors>&idontexist;</unbalanced>
-                                    ^
-line 1: chunk is not well balanced
 <twoerrors>&idontexist;</unbalanced>
                                     ^
 SELECT xmlparse(content '<nosuchprefix:tag/>');

diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index 493c6186e161318ffc9697ddf75967ef71be0694..6638458ba2ddc01fb8cbe1cce092dd9784a54150 100644 (file)
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -219,13 +219,11 @@ ERROR:  invalid XML content
 DETAIL:  line 1: xmlParseEntityRef: no name
 <invalidentity>&</invalidentity>
                 ^
-line 1: chunk is not well balanced
 SELECT xmlparse(content '<undefinedentity>&idontexist;</undefinedentity>');
 ERROR:  invalid XML content
 DETAIL:  line 1: Entity 'idontexist' not defined
 <undefinedentity>&idontexist;</undefinedentity>
                              ^
-line 1: chunk is not well balanced
 SELECT xmlparse(content '<invalidns xmlns=''&lt;''/>');
          xmlparse          
 ---------------------------
@@ -244,7 +242,6 @@ DETAIL:  line 1: Entity 'idontexist' not defined
 <twoerrors>&idontexist;</unbalanced>
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-line 1: chunk is not well balanced
 SELECT xmlparse(content '<nosuchprefix:tag/>');
       xmlparse       
 ---------------------