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Avoid regression in the size of XML input that we will accept.

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This mostly reverts commit 6082b3d5d, "Use xmlParseInNodeContext
not xmlParseBalancedChunkMemory".  It turns out that
xmlParseInNodeContext will reject text chunks exceeding 10MB, while
(in most libxml2 versions) xmlParseBalancedChunkMemory will not.
The bleeding-edge libxml2 bug that we needed to work around a year
ago is presumably no longer a factor, and the argument that
xmlParseBalancedChunkMemory is semi-deprecated is not enough to
justify a functionality regression.  Hence, go back to doing it
the old way.

Reported-by: Michael Paquier <michael@paquier.xyz>
Author: Michael Paquier <michael@paquier.xyz>
Co-authored-by: Erik Wienhold <ewie@ewie.name>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/aIGknLuc8b8ega2X@paquier.xyz
Backpatch-through: 13
REL_13_STABLE
Tom Lane 2 months ago
parent f32a471612
commit 589d6e6408
1 changed files with 28 additions and 29 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 57
      src/backend/utils/adt/xml.c

57
src/backend/utils/adt/xml.c
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@ -1529,6 +1529,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
PgXmlErrorContext *xmlerrcxt;
volatile xmlParserCtxtPtr ctxt = NULL;
volatile xmlDocPtr doc = NULL;
volatile int save_keep_blanks = -1;
len = VARSIZE_ANY_EXHDR(data); /* will be useful later */
string = xml_text2xmlChar(data);
@ -1545,7 +1546,6 @@ 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;
@ -1571,25 +1571,28 @@ 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)
{
int options;
/* set up parser context used by xmlCtxtReadDoc */
ctxt = xmlNewParserCtxt();
if (ctxt == NULL || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate parser context");
/*
* 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);
doc = xmlCtxtReadDoc(ctxt, utf8string,
NULL, /* no URL */
"UTF-8",
@ -1608,36 +1611,27 @@ 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 */
/* set up document that xmlParseBalancedChunkMemory will add to */
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);
/* set parse options --- have to do this the ugly way */
save_keep_blanks = xmlKeepBlanksDefault(preserve_whitespace ? 1 : 0);
/* allow empty content */
if (*(utf8string + count))
{
xmlNodePtr node_list = NULL;
xmlParserErrors res;
res = xmlParseInNodeContext(root,
(char *) utf8string + count,
strlen((char *) utf8string + count),
options,
&node_list);
res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0,
utf8string + count,
&node_list);
xmlFreeNodeList(node_list);
if (res != XML_ERR_OK || xmlerrcxt->err_occurred)
if (res_code != 0 || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_CONTENT,
"invalid XML content");
}
@ -1645,6 +1639,8 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
}
PG_CATCH();
{
if (save_keep_blanks != -1)
xmlKeepBlanksDefault(save_keep_blanks);
if (doc != NULL)
xmlFreeDoc(doc);
if (ctxt != NULL)
@ -1656,6 +1652,9 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
}
PG_END_TRY();
if (save_keep_blanks != -1)
xmlKeepBlanksDefault(save_keep_blanks);
if (ctxt != NULL)
xmlFreeParserCtxt(ctxt);

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