mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-31 04:37:23 +02:00
9e98583
introduced a helper to centralize building their needed state
(tuplestore, tuple descriptors, etc.), checking for any errors. This
commit updates all places of contrib/ that can be switched to use
SetSingleFuncCall() as a drop-in replacement, resulting in the removal
of a lot of boilerplate code in all the modules updated by this commit.
Per analysis, some places remain as they are:
- pg_logdir_ls() in adminpack/ uses historically TYPEFUNC_RECORD as
return type, and I suspect that changing it may cause issues at run-time
with some of its past versions, down to 1.0.
- dblink/ uses a wrapper function doing exactly the work of
SetSingleFuncCall(). Here the switch should be possible, but rather
invasive so it does not seem the extra backpatch maintenance cost.
- tablefunc/, similarly, uses multiple helper functions with portions of
SetSingleFuncCall() spread across the code paths of this module.
Author: Melanie Plageman
Discussion: https://postgr.es/m/CAAKRu_bvDPJoL9mH6eYwvBpPtTGQwbDzfJbCM-OjkSZDu5yTPg@mail.gmail.com
747 lines
17 KiB
C
747 lines
17 KiB
C
/*
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* contrib/xml2/xpath.c
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*
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* Parser interface for DOM-based parser (libxml) rather than
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* stream-based SAX-type parser
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "executor/spi.h"
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#include "fmgr.h"
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#include "funcapi.h"
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#include "lib/stringinfo.h"
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#include "miscadmin.h"
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#include "utils/builtins.h"
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#include "utils/xml.h"
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/* libxml includes */
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#include <libxml/xpath.h>
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#include <libxml/tree.h>
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#include <libxml/xmlmemory.h>
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#include <libxml/xmlerror.h>
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#include <libxml/parserInternals.h>
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PG_MODULE_MAGIC;
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/* exported for use by xslt_proc.c */
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PgXmlErrorContext *pgxml_parser_init(PgXmlStrictness strictness);
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/* workspace for pgxml_xpath() */
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typedef struct
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{
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xmlDocPtr doctree;
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xmlXPathContextPtr ctxt;
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xmlXPathObjectPtr res;
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} xpath_workspace;
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/* local declarations */
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static xmlChar *pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
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xmlChar *toptagname, xmlChar *septagname,
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xmlChar *plainsep);
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static text *pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag,
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xmlChar *septag, xmlChar *plainsep);
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static xmlChar *pgxml_texttoxmlchar(text *textstring);
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static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath,
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xpath_workspace *workspace);
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static void cleanup_workspace(xpath_workspace *workspace);
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/*
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* Initialize for xml parsing.
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*
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* As with the underlying pg_xml_init function, calls to this MUST be followed
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* by a PG_TRY block that guarantees that pg_xml_done is called.
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*/
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PgXmlErrorContext *
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pgxml_parser_init(PgXmlStrictness strictness)
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{
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PgXmlErrorContext *xmlerrcxt;
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/* Set up error handling (we share the core's error handler) */
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xmlerrcxt = pg_xml_init(strictness);
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/* Note: we're assuming an elog cannot be thrown by the following calls */
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/* Initialize libxml */
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xmlInitParser();
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xmlSubstituteEntitiesDefault(1);
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xmlLoadExtDtdDefaultValue = 1;
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return xmlerrcxt;
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}
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/* Encodes special characters (<, >, &, " and \r) as XML entities */
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PG_FUNCTION_INFO_V1(xml_encode_special_chars);
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Datum
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xml_encode_special_chars(PG_FUNCTION_ARGS)
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{
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text *tin = PG_GETARG_TEXT_PP(0);
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text *tout;
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xmlChar *ts,
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*tt;
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ts = pgxml_texttoxmlchar(tin);
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tt = xmlEncodeSpecialChars(NULL, ts);
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pfree(ts);
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tout = cstring_to_text((char *) tt);
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xmlFree(tt);
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PG_RETURN_TEXT_P(tout);
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}
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/*
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* Function translates a nodeset into a text representation
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*
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* iterates over each node in the set and calls xmlNodeDump to write it to
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* an xmlBuffer -from which an xmlChar * string is returned.
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*
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* each representation is surrounded by <tagname> ... </tagname>
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*
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* plainsep is an ordinary (not tag) separator - if used, then nodes are
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* cast to string as output method
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*/
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static xmlChar *
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pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
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xmlChar *toptagname,
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xmlChar *septagname,
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xmlChar *plainsep)
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{
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xmlBufferPtr buf;
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xmlChar *result;
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int i;
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buf = xmlBufferCreate();
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if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
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{
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xmlBufferWriteChar(buf, "<");
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xmlBufferWriteCHAR(buf, toptagname);
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xmlBufferWriteChar(buf, ">");
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}
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if (nodeset != NULL)
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{
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for (i = 0; i < nodeset->nodeNr; i++)
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{
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if (plainsep != NULL)
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{
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xmlBufferWriteCHAR(buf,
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xmlXPathCastNodeToString(nodeset->nodeTab[i]));
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/* If this isn't the last entry, write the plain sep. */
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if (i < (nodeset->nodeNr) - 1)
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xmlBufferWriteChar(buf, (char *) plainsep);
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}
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else
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{
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if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
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{
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xmlBufferWriteChar(buf, "<");
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xmlBufferWriteCHAR(buf, septagname);
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xmlBufferWriteChar(buf, ">");
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}
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xmlNodeDump(buf,
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nodeset->nodeTab[i]->doc,
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nodeset->nodeTab[i],
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1, 0);
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if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
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{
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xmlBufferWriteChar(buf, "</");
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xmlBufferWriteCHAR(buf, septagname);
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xmlBufferWriteChar(buf, ">");
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}
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}
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}
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}
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if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
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{
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xmlBufferWriteChar(buf, "</");
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xmlBufferWriteCHAR(buf, toptagname);
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xmlBufferWriteChar(buf, ">");
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}
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result = xmlStrdup(buf->content);
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xmlBufferFree(buf);
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return result;
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}
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/* Translate a PostgreSQL "varlena" -i.e. a variable length parameter
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* into the libxml2 representation
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*/
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static xmlChar *
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pgxml_texttoxmlchar(text *textstring)
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{
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return (xmlChar *) text_to_cstring(textstring);
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}
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/* Publicly visible XPath functions */
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/*
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* This is a "raw" xpath function. Check that it returns child elements
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* properly
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*/
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PG_FUNCTION_INFO_V1(xpath_nodeset);
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Datum
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xpath_nodeset(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_PP(0);
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text *xpathsupp = PG_GETARG_TEXT_PP(1); /* XPath expression */
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xmlChar *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
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xmlChar *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(3));
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xmlChar *xpath;
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, toptag, septag, NULL);
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cleanup_workspace(&workspace);
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pfree(xpath);
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if (xpres == NULL)
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PG_RETURN_NULL();
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PG_RETURN_TEXT_P(xpres);
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}
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/*
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* The following function is almost identical, but returns the elements in
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* a list.
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*/
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PG_FUNCTION_INFO_V1(xpath_list);
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Datum
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xpath_list(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_PP(0);
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text *xpathsupp = PG_GETARG_TEXT_PP(1); /* XPath expression */
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xmlChar *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
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xmlChar *xpath;
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, NULL, NULL, plainsep);
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cleanup_workspace(&workspace);
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pfree(xpath);
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if (xpres == NULL)
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PG_RETURN_NULL();
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PG_RETURN_TEXT_P(xpres);
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}
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PG_FUNCTION_INFO_V1(xpath_string);
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Datum
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xpath_string(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_PP(0);
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text *xpathsupp = PG_GETARG_TEXT_PP(1); /* XPath expression */
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xmlChar *xpath;
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int32 pathsize;
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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pathsize = VARSIZE_ANY_EXHDR(xpathsupp);
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/*
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* We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
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* at end
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*/
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/* We could try casting to string using the libxml function? */
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xpath = (xmlChar *) palloc(pathsize + 9);
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memcpy((char *) xpath, "string(", 7);
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memcpy((char *) (xpath + 7), VARDATA_ANY(xpathsupp), pathsize);
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xpath[pathsize + 7] = ')';
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xpath[pathsize + 8] = '\0';
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, NULL, NULL, NULL);
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cleanup_workspace(&workspace);
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pfree(xpath);
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if (xpres == NULL)
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PG_RETURN_NULL();
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PG_RETURN_TEXT_P(xpres);
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}
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PG_FUNCTION_INFO_V1(xpath_number);
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Datum
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xpath_number(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_PP(0);
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text *xpathsupp = PG_GETARG_TEXT_PP(1); /* XPath expression */
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xmlChar *xpath;
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float4 fRes;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(document, xpath, &workspace);
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pfree(xpath);
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if (res == NULL)
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PG_RETURN_NULL();
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fRes = xmlXPathCastToNumber(res);
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cleanup_workspace(&workspace);
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if (xmlXPathIsNaN(fRes))
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PG_RETURN_NULL();
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PG_RETURN_FLOAT4(fRes);
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}
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PG_FUNCTION_INFO_V1(xpath_bool);
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Datum
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xpath_bool(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_PP(0);
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text *xpathsupp = PG_GETARG_TEXT_PP(1); /* XPath expression */
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xmlChar *xpath;
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int bRes;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(document, xpath, &workspace);
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pfree(xpath);
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if (res == NULL)
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PG_RETURN_BOOL(false);
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bRes = xmlXPathCastToBoolean(res);
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cleanup_workspace(&workspace);
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PG_RETURN_BOOL(bRes);
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}
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/* Core function to evaluate XPath query */
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static xmlXPathObjectPtr
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pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
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{
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int32 docsize = VARSIZE_ANY_EXHDR(document);
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PgXmlErrorContext *xmlerrcxt;
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xmlXPathCompExprPtr comppath;
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workspace->doctree = NULL;
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workspace->ctxt = NULL;
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workspace->res = NULL;
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xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
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PG_TRY();
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{
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workspace->doctree = xmlParseMemory((char *) VARDATA_ANY(document),
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docsize);
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if (workspace->doctree != NULL)
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{
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workspace->ctxt = xmlXPathNewContext(workspace->doctree);
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workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);
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/* compile the path */
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comppath = xmlXPathCompile(xpath);
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if (comppath == NULL)
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xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
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"XPath Syntax Error");
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/* Now evaluate the path expression. */
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workspace->res = xmlXPathCompiledEval(comppath, workspace->ctxt);
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xmlXPathFreeCompExpr(comppath);
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}
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}
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PG_CATCH();
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{
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cleanup_workspace(workspace);
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pg_xml_done(xmlerrcxt, true);
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PG_RE_THROW();
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}
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PG_END_TRY();
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if (workspace->res == NULL)
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cleanup_workspace(workspace);
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pg_xml_done(xmlerrcxt, false);
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return workspace->res;
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}
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/* Clean up after processing the result of pgxml_xpath() */
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static void
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cleanup_workspace(xpath_workspace *workspace)
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{
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if (workspace->res)
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xmlXPathFreeObject(workspace->res);
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workspace->res = NULL;
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if (workspace->ctxt)
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xmlXPathFreeContext(workspace->ctxt);
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workspace->ctxt = NULL;
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if (workspace->doctree)
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xmlFreeDoc(workspace->doctree);
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workspace->doctree = NULL;
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}
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static text *
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pgxml_result_to_text(xmlXPathObjectPtr res,
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xmlChar *toptag,
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xmlChar *septag,
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xmlChar *plainsep)
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{
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xmlChar *xpresstr;
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text *xpres;
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if (res == NULL)
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return NULL;
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switch (res->type)
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{
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case XPATH_NODESET:
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xpresstr = pgxmlNodeSetToText(res->nodesetval,
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toptag,
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septag, plainsep);
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break;
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case XPATH_STRING:
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xpresstr = xmlStrdup(res->stringval);
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break;
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default:
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elog(NOTICE, "unsupported XQuery result: %d", res->type);
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xpresstr = xmlStrdup((const xmlChar *) "<unsupported/>");
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}
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/* Now convert this result back to text */
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xpres = cstring_to_text((char *) xpresstr);
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/* Free various storage */
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xmlFree(xpresstr);
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return xpres;
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}
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|
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/*
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* xpath_table is a table function. It needs some tidying (as do the
|
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* other functions here!
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*/
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PG_FUNCTION_INFO_V1(xpath_table);
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|
|
Datum
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xpath_table(PG_FUNCTION_ARGS)
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{
|
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/* Function parameters */
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char *pkeyfield = text_to_cstring(PG_GETARG_TEXT_PP(0));
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char *xmlfield = text_to_cstring(PG_GETARG_TEXT_PP(1));
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char *relname = text_to_cstring(PG_GETARG_TEXT_PP(2));
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char *xpathset = text_to_cstring(PG_GETARG_TEXT_PP(3));
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char *condition = text_to_cstring(PG_GETARG_TEXT_PP(4));
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|
|
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/* SPI (input tuple) support */
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|
SPITupleTable *tuptable;
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HeapTuple spi_tuple;
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TupleDesc spi_tupdesc;
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|
|
|
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|
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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|
AttInMetadata *attinmeta;
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|
|
|
char **values;
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xmlChar **xpaths;
|
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char *pos;
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const char *pathsep = "|";
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|
|
|
int numpaths;
|
|
int ret;
|
|
uint64 proc;
|
|
int j;
|
|
int rownr; /* For issuing multiple rows from one original
|
|
* document */
|
|
bool had_values; /* To determine end of nodeset results */
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|
StringInfoData query_buf;
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|
PgXmlErrorContext *xmlerrcxt;
|
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volatile xmlDocPtr doctree = NULL;
|
|
|
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SetSingleFuncCall(fcinfo, SRF_SINGLE_USE_EXPECTED);
|
|
|
|
/* must have at least one output column (for the pkey) */
|
|
if (rsinfo->setDesc->natts < 1)
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|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
errmsg("xpath_table must have at least one output column")));
|
|
|
|
/*
|
|
* At the moment we assume that the returned attributes make sense for the
|
|
* XPath specified (i.e. we trust the caller). It's not fatal if they get
|
|
* it wrong - the input function for the column type will raise an error
|
|
* if the path result can't be converted into the correct binary
|
|
* representation.
|
|
*/
|
|
|
|
attinmeta = TupleDescGetAttInMetadata(rsinfo->setDesc);
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|
|
|
values = (char **) palloc(rsinfo->setDesc->natts * sizeof(char *));
|
|
xpaths = (xmlChar **) palloc(rsinfo->setDesc->natts * sizeof(xmlChar *));
|
|
|
|
/*
|
|
* Split XPaths. xpathset is a writable CString.
|
|
*
|
|
* Note that we stop splitting once we've done all needed for tupdesc
|
|
*/
|
|
numpaths = 0;
|
|
pos = xpathset;
|
|
while (numpaths < (rsinfo->setDesc->natts - 1))
|
|
{
|
|
xpaths[numpaths++] = (xmlChar *) pos;
|
|
pos = strstr(pos, pathsep);
|
|
if (pos != NULL)
|
|
{
|
|
*pos = '\0';
|
|
pos++;
|
|
}
|
|
else
|
|
break;
|
|
}
|
|
|
|
/* Now build query */
|
|
initStringInfo(&query_buf);
|
|
|
|
/* Build initial sql statement */
|
|
appendStringInfo(&query_buf, "SELECT %s, %s FROM %s WHERE %s",
|
|
pkeyfield,
|
|
xmlfield,
|
|
relname,
|
|
condition);
|
|
|
|
if ((ret = SPI_connect()) < 0)
|
|
elog(ERROR, "xpath_table: SPI_connect returned %d", ret);
|
|
|
|
if ((ret = SPI_exec(query_buf.data, 0)) != SPI_OK_SELECT)
|
|
elog(ERROR, "xpath_table: SPI execution failed for query %s",
|
|
query_buf.data);
|
|
|
|
proc = SPI_processed;
|
|
tuptable = SPI_tuptable;
|
|
spi_tupdesc = tuptable->tupdesc;
|
|
|
|
/*
|
|
* Check that SPI returned correct result. If you put a comma into one of
|
|
* the function parameters, this will catch it when the SPI query returns
|
|
* e.g. 3 columns.
|
|
*/
|
|
if (spi_tupdesc->natts != 2)
|
|
{
|
|
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
|
|
errmsg("expression returning multiple columns is not valid in parameter list"),
|
|
errdetail("Expected two columns in SPI result, got %d.", spi_tupdesc->natts)));
|
|
}
|
|
|
|
/*
|
|
* Setup the parser. This should happen after we are done evaluating the
|
|
* query, in case it calls functions that set up libxml differently.
|
|
*/
|
|
xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
|
|
|
|
PG_TRY();
|
|
{
|
|
/* For each row i.e. document returned from SPI */
|
|
uint64 i;
|
|
|
|
for (i = 0; i < proc; i++)
|
|
{
|
|
char *pkey;
|
|
char *xmldoc;
|
|
xmlXPathContextPtr ctxt;
|
|
xmlXPathObjectPtr res;
|
|
xmlChar *resstr;
|
|
xmlXPathCompExprPtr comppath;
|
|
HeapTuple ret_tuple;
|
|
|
|
/* Extract the row data as C Strings */
|
|
spi_tuple = tuptable->vals[i];
|
|
pkey = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
|
|
xmldoc = SPI_getvalue(spi_tuple, spi_tupdesc, 2);
|
|
|
|
/*
|
|
* Clear the values array, so that not-well-formed documents
|
|
* return NULL in all columns. Note that this also means that
|
|
* spare columns will be NULL.
|
|
*/
|
|
for (j = 0; j < rsinfo->setDesc->natts; j++)
|
|
values[j] = NULL;
|
|
|
|
/* Insert primary key */
|
|
values[0] = pkey;
|
|
|
|
/* Parse the document */
|
|
if (xmldoc)
|
|
doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
|
|
else /* treat NULL as not well-formed */
|
|
doctree = NULL;
|
|
|
|
if (doctree == NULL)
|
|
{
|
|
/* not well-formed, so output all-NULL tuple */
|
|
ret_tuple = BuildTupleFromCStrings(attinmeta, values);
|
|
tuplestore_puttuple(rsinfo->setResult, ret_tuple);
|
|
heap_freetuple(ret_tuple);
|
|
}
|
|
else
|
|
{
|
|
/* New loop here - we have to deal with nodeset results */
|
|
rownr = 0;
|
|
|
|
do
|
|
{
|
|
/* Now evaluate the set of xpaths. */
|
|
had_values = false;
|
|
for (j = 0; j < numpaths; j++)
|
|
{
|
|
ctxt = xmlXPathNewContext(doctree);
|
|
ctxt->node = xmlDocGetRootElement(doctree);
|
|
|
|
/* compile the path */
|
|
comppath = xmlXPathCompile(xpaths[j]);
|
|
if (comppath == NULL)
|
|
xml_ereport(xmlerrcxt, ERROR,
|
|
ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
|
|
"XPath Syntax Error");
|
|
|
|
/* Now evaluate the path expression. */
|
|
res = xmlXPathCompiledEval(comppath, ctxt);
|
|
xmlXPathFreeCompExpr(comppath);
|
|
|
|
if (res != NULL)
|
|
{
|
|
switch (res->type)
|
|
{
|
|
case XPATH_NODESET:
|
|
/* We see if this nodeset has enough nodes */
|
|
if (res->nodesetval != NULL &&
|
|
rownr < res->nodesetval->nodeNr)
|
|
{
|
|
resstr = xmlXPathCastNodeToString(res->nodesetval->nodeTab[rownr]);
|
|
had_values = true;
|
|
}
|
|
else
|
|
resstr = NULL;
|
|
|
|
break;
|
|
|
|
case XPATH_STRING:
|
|
resstr = xmlStrdup(res->stringval);
|
|
break;
|
|
|
|
default:
|
|
elog(NOTICE, "unsupported XQuery result: %d", res->type);
|
|
resstr = xmlStrdup((const xmlChar *) "<unsupported/>");
|
|
}
|
|
|
|
/*
|
|
* Insert this into the appropriate column in the
|
|
* result tuple.
|
|
*/
|
|
values[j + 1] = (char *) resstr;
|
|
}
|
|
xmlXPathFreeContext(ctxt);
|
|
}
|
|
|
|
/* Now add the tuple to the output, if there is one. */
|
|
if (had_values)
|
|
{
|
|
ret_tuple = BuildTupleFromCStrings(attinmeta, values);
|
|
tuplestore_puttuple(rsinfo->setResult, ret_tuple);
|
|
heap_freetuple(ret_tuple);
|
|
}
|
|
|
|
rownr++;
|
|
} while (had_values);
|
|
}
|
|
|
|
if (doctree != NULL)
|
|
xmlFreeDoc(doctree);
|
|
doctree = NULL;
|
|
|
|
if (pkey)
|
|
pfree(pkey);
|
|
if (xmldoc)
|
|
pfree(xmldoc);
|
|
}
|
|
}
|
|
PG_CATCH();
|
|
{
|
|
if (doctree != NULL)
|
|
xmlFreeDoc(doctree);
|
|
|
|
pg_xml_done(xmlerrcxt, true);
|
|
|
|
PG_RE_THROW();
|
|
}
|
|
PG_END_TRY();
|
|
|
|
if (doctree != NULL)
|
|
xmlFreeDoc(doctree);
|
|
|
|
pg_xml_done(xmlerrcxt, false);
|
|
|
|
SPI_finish();
|
|
|
|
/*
|
|
* SFRM_Materialize mode expects us to return a NULL Datum. The actual
|
|
* tuples are in our tuplestore and passed back through rsinfo->setResult.
|
|
* rsinfo->setDesc is set to the tuple description that we actually used
|
|
* to build our tuples with, so the caller can verify we did what it was
|
|
* expecting.
|
|
*/
|
|
return (Datum) 0;
|
|
}
|