LCOV - code coverage report
Current view: top level - contrib/xml2 - xpath.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 135 274 49.3 %
Date: 2023-10-02 04:11:32 Functions: 14 21 66.7 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*
       2             :  * contrib/xml2/xpath.c
       3             :  *
       4             :  * Parser interface for DOM-based parser (libxml) rather than
       5             :  * stream-based SAX-type parser
       6             :  */
       7             : #include "postgres.h"
       8             : 
       9             : #include "access/htup_details.h"
      10             : #include "executor/spi.h"
      11             : #include "fmgr.h"
      12             : #include "funcapi.h"
      13             : #include "lib/stringinfo.h"
      14             : #include "miscadmin.h"
      15             : #include "utils/builtins.h"
      16             : #include "utils/xml.h"
      17             : 
      18             : /* libxml includes */
      19             : 
      20             : #include <libxml/xpath.h>
      21             : #include <libxml/tree.h>
      22             : #include <libxml/xmlmemory.h>
      23             : #include <libxml/xmlerror.h>
      24             : #include <libxml/parserInternals.h>
      25             : 
      26           2 : PG_MODULE_MAGIC;
      27             : 
      28             : /* exported for use by xslt_proc.c */
      29             : 
      30             : PgXmlErrorContext *pgxml_parser_init(PgXmlStrictness strictness);
      31             : 
      32             : /* workspace for pgxml_xpath() */
      33             : 
      34             : typedef struct
      35             : {
      36             :     xmlDocPtr   doctree;
      37             :     xmlXPathContextPtr ctxt;
      38             :     xmlXPathObjectPtr res;
      39             : } xpath_workspace;
      40             : 
      41             : /* local declarations */
      42             : 
      43             : static xmlChar *pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
      44             :                                    xmlChar *toptagname, xmlChar *septagname,
      45             :                                    xmlChar *plainsep);
      46             : 
      47             : static text *pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag,
      48             :                                   xmlChar *septag, xmlChar *plainsep);
      49             : 
      50             : static xmlChar *pgxml_texttoxmlchar(text *textstring);
      51             : 
      52             : static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath,
      53             :                                      xpath_workspace *workspace);
      54             : 
      55             : static void cleanup_workspace(xpath_workspace *workspace);
      56             : 
      57             : 
      58             : /*
      59             :  * Initialize for xml parsing.
      60             :  *
      61             :  * As with the underlying pg_xml_init function, calls to this MUST be followed
      62             :  * by a PG_TRY block that guarantees that pg_xml_done is called.
      63             :  */
      64             : PgXmlErrorContext *
      65          12 : pgxml_parser_init(PgXmlStrictness strictness)
      66             : {
      67             :     PgXmlErrorContext *xmlerrcxt;
      68             : 
      69             :     /* Set up error handling (we share the core's error handler) */
      70          12 :     xmlerrcxt = pg_xml_init(strictness);
      71             : 
      72             :     /* Note: we're assuming an elog cannot be thrown by the following calls */
      73             : 
      74             :     /* Initialize libxml */
      75          12 :     xmlInitParser();
      76             : 
      77          12 :     xmlSubstituteEntitiesDefault(1);
      78          12 :     xmlLoadExtDtdDefaultValue = 1;
      79             : 
      80          12 :     return xmlerrcxt;
      81             : }
      82             : 
      83             : 
      84             : /* Encodes special characters (<, >, &, " and \r) as XML entities */
      85             : 
      86           2 : PG_FUNCTION_INFO_V1(xml_encode_special_chars);
      87             : 
      88             : Datum
      89           0 : xml_encode_special_chars(PG_FUNCTION_ARGS)
      90             : {
      91           0 :     text       *tin = PG_GETARG_TEXT_PP(0);
      92             :     text       *tout;
      93             :     xmlChar    *ts,
      94             :                *tt;
      95             : 
      96           0 :     ts = pgxml_texttoxmlchar(tin);
      97             : 
      98           0 :     tt = xmlEncodeSpecialChars(NULL, ts);
      99             : 
     100           0 :     pfree(ts);
     101             : 
     102           0 :     tout = cstring_to_text((char *) tt);
     103             : 
     104           0 :     xmlFree(tt);
     105             : 
     106           0 :     PG_RETURN_TEXT_P(tout);
     107             : }
     108             : 
     109             : /*
     110             :  * Function translates a nodeset into a text representation
     111             :  *
     112             :  * iterates over each node in the set and calls xmlNodeDump to write it to
     113             :  * an xmlBuffer -from which an xmlChar * string is returned.
     114             :  *
     115             :  * each representation is surrounded by <tagname> ... </tagname>
     116             :  *
     117             :  * plainsep is an ordinary (not tag) separator - if used, then nodes are
     118             :  * cast to string as output method
     119             :  */
     120             : static xmlChar *
     121           0 : pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
     122             :                    xmlChar *toptagname,
     123             :                    xmlChar *septagname,
     124             :                    xmlChar *plainsep)
     125             : {
     126             :     xmlBufferPtr buf;
     127             :     xmlChar    *result;
     128             :     int         i;
     129             : 
     130           0 :     buf = xmlBufferCreate();
     131             : 
     132           0 :     if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     133             :     {
     134           0 :         xmlBufferWriteChar(buf, "<");
     135           0 :         xmlBufferWriteCHAR(buf, toptagname);
     136           0 :         xmlBufferWriteChar(buf, ">");
     137             :     }
     138           0 :     if (nodeset != NULL)
     139             :     {
     140           0 :         for (i = 0; i < nodeset->nodeNr; i++)
     141             :         {
     142           0 :             if (plainsep != NULL)
     143             :             {
     144           0 :                 xmlBufferWriteCHAR(buf,
     145           0 :                                    xmlXPathCastNodeToString(nodeset->nodeTab[i]));
     146             : 
     147             :                 /* If this isn't the last entry, write the plain sep. */
     148           0 :                 if (i < (nodeset->nodeNr) - 1)
     149           0 :                     xmlBufferWriteChar(buf, (char *) plainsep);
     150             :             }
     151             :             else
     152             :             {
     153           0 :                 if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     154             :                 {
     155           0 :                     xmlBufferWriteChar(buf, "<");
     156           0 :                     xmlBufferWriteCHAR(buf, septagname);
     157           0 :                     xmlBufferWriteChar(buf, ">");
     158             :                 }
     159           0 :                 xmlNodeDump(buf,
     160           0 :                             nodeset->nodeTab[i]->doc,
     161           0 :                             nodeset->nodeTab[i],
     162             :                             1, 0);
     163             : 
     164           0 :                 if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     165             :                 {
     166           0 :                     xmlBufferWriteChar(buf, "</");
     167           0 :                     xmlBufferWriteCHAR(buf, septagname);
     168           0 :                     xmlBufferWriteChar(buf, ">");
     169             :                 }
     170             :             }
     171             :         }
     172             :     }
     173             : 
     174           0 :     if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     175             :     {
     176           0 :         xmlBufferWriteChar(buf, "</");
     177           0 :         xmlBufferWriteCHAR(buf, toptagname);
     178           0 :         xmlBufferWriteChar(buf, ">");
     179             :     }
     180           0 :     result = xmlStrdup(buf->content);
     181           0 :     xmlBufferFree(buf);
     182           0 :     return result;
     183             : }
     184             : 
     185             : 
     186             : /* Translate a PostgreSQL "varlena" -i.e. a variable length parameter
     187             :  * into the libxml2 representation
     188             :  */
     189             : static xmlChar *
     190           0 : pgxml_texttoxmlchar(text *textstring)
     191             : {
     192           0 :     return (xmlChar *) text_to_cstring(textstring);
     193             : }
     194             : 
     195             : /* Publicly visible XPath functions */
     196             : 
     197             : /*
     198             :  * This is a "raw" xpath function. Check that it returns child elements
     199             :  * properly
     200             :  */
     201           2 : PG_FUNCTION_INFO_V1(xpath_nodeset);
     202             : 
     203             : Datum
     204           0 : xpath_nodeset(PG_FUNCTION_ARGS)
     205             : {
     206           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     207           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     208           0 :     xmlChar    *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     209           0 :     xmlChar    *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(3));
     210             :     xmlChar    *xpath;
     211             :     text       *xpres;
     212             :     xmlXPathObjectPtr res;
     213             :     xpath_workspace workspace;
     214             : 
     215           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     216             : 
     217           0 :     res = pgxml_xpath(document, xpath, &workspace);
     218             : 
     219           0 :     xpres = pgxml_result_to_text(res, toptag, septag, NULL);
     220             : 
     221           0 :     cleanup_workspace(&workspace);
     222             : 
     223           0 :     pfree(xpath);
     224             : 
     225           0 :     if (xpres == NULL)
     226           0 :         PG_RETURN_NULL();
     227           0 :     PG_RETURN_TEXT_P(xpres);
     228             : }
     229             : 
     230             : /*
     231             :  * The following function is almost identical, but returns the elements in
     232             :  * a list.
     233             :  */
     234           2 : PG_FUNCTION_INFO_V1(xpath_list);
     235             : 
     236             : Datum
     237           0 : xpath_list(PG_FUNCTION_ARGS)
     238             : {
     239           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     240           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     241           0 :     xmlChar    *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     242             :     xmlChar    *xpath;
     243             :     text       *xpres;
     244             :     xmlXPathObjectPtr res;
     245             :     xpath_workspace workspace;
     246             : 
     247           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     248             : 
     249           0 :     res = pgxml_xpath(document, xpath, &workspace);
     250             : 
     251           0 :     xpres = pgxml_result_to_text(res, NULL, NULL, plainsep);
     252             : 
     253           0 :     cleanup_workspace(&workspace);
     254             : 
     255           0 :     pfree(xpath);
     256             : 
     257           0 :     if (xpres == NULL)
     258           0 :         PG_RETURN_NULL();
     259           0 :     PG_RETURN_TEXT_P(xpres);
     260             : }
     261             : 
     262             : 
     263           4 : PG_FUNCTION_INFO_V1(xpath_string);
     264             : 
     265             : Datum
     266           2 : xpath_string(PG_FUNCTION_ARGS)
     267             : {
     268           2 :     text       *document = PG_GETARG_TEXT_PP(0);
     269           2 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     270             :     xmlChar    *xpath;
     271             :     int32       pathsize;
     272             :     text       *xpres;
     273             :     xmlXPathObjectPtr res;
     274             :     xpath_workspace workspace;
     275             : 
     276           2 :     pathsize = VARSIZE_ANY_EXHDR(xpathsupp);
     277             : 
     278             :     /*
     279             :      * We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
     280             :      * at end
     281             :      */
     282             :     /* We could try casting to string using the libxml function? */
     283             : 
     284           2 :     xpath = (xmlChar *) palloc(pathsize + 9);
     285           2 :     memcpy((char *) xpath, "string(", 7);
     286           2 :     memcpy((char *) (xpath + 7), VARDATA_ANY(xpathsupp), pathsize);
     287           2 :     xpath[pathsize + 7] = ')';
     288           2 :     xpath[pathsize + 8] = '\0';
     289             : 
     290           2 :     res = pgxml_xpath(document, xpath, &workspace);
     291             : 
     292           2 :     xpres = pgxml_result_to_text(res, NULL, NULL, NULL);
     293             : 
     294           2 :     cleanup_workspace(&workspace);
     295             : 
     296           2 :     pfree(xpath);
     297             : 
     298           2 :     if (xpres == NULL)
     299           2 :         PG_RETURN_NULL();
     300           0 :     PG_RETURN_TEXT_P(xpres);
     301             : }
     302             : 
     303             : 
     304           2 : PG_FUNCTION_INFO_V1(xpath_number);
     305             : 
     306             : Datum
     307           0 : xpath_number(PG_FUNCTION_ARGS)
     308             : {
     309           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     310           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     311             :     xmlChar    *xpath;
     312             :     float4      fRes;
     313             :     xmlXPathObjectPtr res;
     314             :     xpath_workspace workspace;
     315             : 
     316           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     317             : 
     318           0 :     res = pgxml_xpath(document, xpath, &workspace);
     319             : 
     320           0 :     pfree(xpath);
     321             : 
     322           0 :     if (res == NULL)
     323           0 :         PG_RETURN_NULL();
     324             : 
     325           0 :     fRes = xmlXPathCastToNumber(res);
     326             : 
     327           0 :     cleanup_workspace(&workspace);
     328             : 
     329           0 :     if (xmlXPathIsNaN(fRes))
     330           0 :         PG_RETURN_NULL();
     331             : 
     332           0 :     PG_RETURN_FLOAT4(fRes);
     333             : }
     334             : 
     335             : 
     336           2 : PG_FUNCTION_INFO_V1(xpath_bool);
     337             : 
     338             : Datum
     339           0 : xpath_bool(PG_FUNCTION_ARGS)
     340             : {
     341           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     342           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     343             :     xmlChar    *xpath;
     344             :     int         bRes;
     345             :     xmlXPathObjectPtr res;
     346             :     xpath_workspace workspace;
     347             : 
     348           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     349             : 
     350           0 :     res = pgxml_xpath(document, xpath, &workspace);
     351             : 
     352           0 :     pfree(xpath);
     353             : 
     354           0 :     if (res == NULL)
     355           0 :         PG_RETURN_BOOL(false);
     356             : 
     357           0 :     bRes = xmlXPathCastToBoolean(res);
     358             : 
     359           0 :     cleanup_workspace(&workspace);
     360             : 
     361           0 :     PG_RETURN_BOOL(bRes);
     362             : }
     363             : 
     364             : 
     365             : 
     366             : /* Core function to evaluate XPath query */
     367             : 
     368             : static xmlXPathObjectPtr
     369           2 : pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
     370             : {
     371           2 :     int32       docsize = VARSIZE_ANY_EXHDR(document);
     372             :     PgXmlErrorContext *xmlerrcxt;
     373             :     xmlXPathCompExprPtr comppath;
     374             : 
     375           2 :     workspace->doctree = NULL;
     376           2 :     workspace->ctxt = NULL;
     377           2 :     workspace->res = NULL;
     378             : 
     379           2 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     380             : 
     381           2 :     PG_TRY();
     382             :     {
     383           2 :         workspace->doctree = xmlParseMemory((char *) VARDATA_ANY(document),
     384             :                                             docsize);
     385           2 :         if (workspace->doctree != NULL)
     386             :         {
     387           0 :             workspace->ctxt = xmlXPathNewContext(workspace->doctree);
     388           0 :             workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);
     389             : 
     390             :             /* compile the path */
     391           0 :             comppath = xmlXPathCompile(xpath);
     392           0 :             if (comppath == NULL)
     393           0 :                 xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
     394             :                             "XPath Syntax Error");
     395             : 
     396             :             /* Now evaluate the path expression. */
     397           0 :             workspace->res = xmlXPathCompiledEval(comppath, workspace->ctxt);
     398             : 
     399           0 :             xmlXPathFreeCompExpr(comppath);
     400             :         }
     401             :     }
     402           0 :     PG_CATCH();
     403             :     {
     404           0 :         cleanup_workspace(workspace);
     405             : 
     406           0 :         pg_xml_done(xmlerrcxt, true);
     407             : 
     408           0 :         PG_RE_THROW();
     409             :     }
     410           2 :     PG_END_TRY();
     411             : 
     412           2 :     if (workspace->res == NULL)
     413           2 :         cleanup_workspace(workspace);
     414             : 
     415           2 :     pg_xml_done(xmlerrcxt, false);
     416             : 
     417           2 :     return workspace->res;
     418             : }
     419             : 
     420             : /* Clean up after processing the result of pgxml_xpath() */
     421             : static void
     422           4 : cleanup_workspace(xpath_workspace *workspace)
     423             : {
     424           4 :     if (workspace->res)
     425           0 :         xmlXPathFreeObject(workspace->res);
     426           4 :     workspace->res = NULL;
     427           4 :     if (workspace->ctxt)
     428           0 :         xmlXPathFreeContext(workspace->ctxt);
     429           4 :     workspace->ctxt = NULL;
     430           4 :     if (workspace->doctree)
     431           0 :         xmlFreeDoc(workspace->doctree);
     432           4 :     workspace->doctree = NULL;
     433           4 : }
     434             : 
     435             : static text *
     436           2 : pgxml_result_to_text(xmlXPathObjectPtr res,
     437             :                      xmlChar *toptag,
     438             :                      xmlChar *septag,
     439             :                      xmlChar *plainsep)
     440             : {
     441             :     xmlChar    *xpresstr;
     442             :     text       *xpres;
     443             : 
     444           2 :     if (res == NULL)
     445           2 :         return NULL;
     446             : 
     447           0 :     switch (res->type)
     448             :     {
     449           0 :         case XPATH_NODESET:
     450           0 :             xpresstr = pgxmlNodeSetToText(res->nodesetval,
     451             :                                           toptag,
     452             :                                           septag, plainsep);
     453           0 :             break;
     454             : 
     455           0 :         case XPATH_STRING:
     456           0 :             xpresstr = xmlStrdup(res->stringval);
     457           0 :             break;
     458             : 
     459           0 :         default:
     460           0 :             elog(NOTICE, "unsupported XQuery result: %d", res->type);
     461           0 :             xpresstr = xmlStrdup((const xmlChar *) "<unsupported/>");
     462             :     }
     463             : 
     464             :     /* Now convert this result back to text */
     465           0 :     xpres = cstring_to_text((char *) xpresstr);
     466             : 
     467             :     /* Free various storage */
     468           0 :     xmlFree(xpresstr);
     469             : 
     470           0 :     return xpres;
     471             : }
     472             : 
     473             : /*
     474             :  * xpath_table is a table function. It needs some tidying (as do the
     475             :  * other functions here!
     476             :  */
     477           4 : PG_FUNCTION_INFO_V1(xpath_table);
     478             : 
     479             : Datum
     480          10 : xpath_table(PG_FUNCTION_ARGS)
     481             : {
     482             :     /* Function parameters */
     483          10 :     char       *pkeyfield = text_to_cstring(PG_GETARG_TEXT_PP(0));
     484          10 :     char       *xmlfield = text_to_cstring(PG_GETARG_TEXT_PP(1));
     485          10 :     char       *relname = text_to_cstring(PG_GETARG_TEXT_PP(2));
     486          10 :     char       *xpathset = text_to_cstring(PG_GETARG_TEXT_PP(3));
     487          10 :     char       *condition = text_to_cstring(PG_GETARG_TEXT_PP(4));
     488             : 
     489             :     /* SPI (input tuple) support */
     490             :     SPITupleTable *tuptable;
     491             :     HeapTuple   spi_tuple;
     492             :     TupleDesc   spi_tupdesc;
     493             : 
     494             : 
     495          10 :     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
     496             :     AttInMetadata *attinmeta;
     497             : 
     498             :     char      **values;
     499             :     xmlChar   **xpaths;
     500             :     char       *pos;
     501          10 :     const char *pathsep = "|";
     502             : 
     503             :     int         numpaths;
     504             :     int         ret;
     505             :     uint64      proc;
     506             :     int         j;
     507             :     int         rownr;          /* For issuing multiple rows from one original
     508             :                                  * document */
     509             :     bool        had_values;     /* To determine end of nodeset results */
     510             :     StringInfoData query_buf;
     511             :     PgXmlErrorContext *xmlerrcxt;
     512          10 :     volatile xmlDocPtr doctree = NULL;
     513             : 
     514          10 :     InitMaterializedSRF(fcinfo, MAT_SRF_USE_EXPECTED_DESC);
     515             : 
     516             :     /* must have at least one output column (for the pkey) */
     517          10 :     if (rsinfo->setDesc->natts < 1)
     518           0 :         ereport(ERROR,
     519             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     520             :                  errmsg("xpath_table must have at least one output column")));
     521             : 
     522             :     /*
     523             :      * At the moment we assume that the returned attributes make sense for the
     524             :      * XPath specified (i.e. we trust the caller). It's not fatal if they get
     525             :      * it wrong - the input function for the column type will raise an error
     526             :      * if the path result can't be converted into the correct binary
     527             :      * representation.
     528             :      */
     529             : 
     530          10 :     attinmeta = TupleDescGetAttInMetadata(rsinfo->setDesc);
     531             : 
     532          10 :     values = (char **) palloc(rsinfo->setDesc->natts * sizeof(char *));
     533          10 :     xpaths = (xmlChar **) palloc(rsinfo->setDesc->natts * sizeof(xmlChar *));
     534             : 
     535             :     /*
     536             :      * Split XPaths. xpathset is a writable CString.
     537             :      *
     538             :      * Note that we stop splitting once we've done all needed for tupdesc
     539             :      */
     540          10 :     numpaths = 0;
     541          10 :     pos = xpathset;
     542          14 :     while (numpaths < (rsinfo->setDesc->natts - 1))
     543             :     {
     544          10 :         xpaths[numpaths++] = (xmlChar *) pos;
     545          10 :         pos = strstr(pos, pathsep);
     546          10 :         if (pos != NULL)
     547             :         {
     548           4 :             *pos = '\0';
     549           4 :             pos++;
     550             :         }
     551             :         else
     552           6 :             break;
     553             :     }
     554             : 
     555             :     /* Now build query */
     556          10 :     initStringInfo(&query_buf);
     557             : 
     558             :     /* Build initial sql statement */
     559          10 :     appendStringInfo(&query_buf, "SELECT %s, %s FROM %s WHERE %s",
     560             :                      pkeyfield,
     561             :                      xmlfield,
     562             :                      relname,
     563             :                      condition);
     564             : 
     565          10 :     if ((ret = SPI_connect()) < 0)
     566           0 :         elog(ERROR, "xpath_table: SPI_connect returned %d", ret);
     567             : 
     568          10 :     if ((ret = SPI_exec(query_buf.data, 0)) != SPI_OK_SELECT)
     569           0 :         elog(ERROR, "xpath_table: SPI execution failed for query %s",
     570             :              query_buf.data);
     571             : 
     572          10 :     proc = SPI_processed;
     573          10 :     tuptable = SPI_tuptable;
     574          10 :     spi_tupdesc = tuptable->tupdesc;
     575             : 
     576             :     /*
     577             :      * Check that SPI returned correct result. If you put a comma into one of
     578             :      * the function parameters, this will catch it when the SPI query returns
     579             :      * e.g. 3 columns.
     580             :      */
     581          10 :     if (spi_tupdesc->natts != 2)
     582             :     {
     583           0 :         ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     584             :                         errmsg("expression returning multiple columns is not valid in parameter list"),
     585             :                         errdetail("Expected two columns in SPI result, got %d.", spi_tupdesc->natts)));
     586             :     }
     587             : 
     588             :     /*
     589             :      * Setup the parser.  This should happen after we are done evaluating the
     590             :      * query, in case it calls functions that set up libxml differently.
     591             :      */
     592          10 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     593             : 
     594          10 :     PG_TRY();
     595             :     {
     596             :         /* For each row i.e. document returned from SPI */
     597             :         uint64      i;
     598             : 
     599          20 :         for (i = 0; i < proc; i++)
     600             :         {
     601             :             char       *pkey;
     602             :             char       *xmldoc;
     603             :             xmlXPathContextPtr ctxt;
     604             :             xmlXPathObjectPtr res;
     605             :             xmlChar    *resstr;
     606             :             xmlXPathCompExprPtr comppath;
     607             :             HeapTuple   ret_tuple;
     608             : 
     609             :             /* Extract the row data as C Strings */
     610          10 :             spi_tuple = tuptable->vals[i];
     611          10 :             pkey = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
     612          10 :             xmldoc = SPI_getvalue(spi_tuple, spi_tupdesc, 2);
     613             : 
     614             :             /*
     615             :              * Clear the values array, so that not-well-formed documents
     616             :              * return NULL in all columns.  Note that this also means that
     617             :              * spare columns will be NULL.
     618             :              */
     619          30 :             for (j = 0; j < rsinfo->setDesc->natts; j++)
     620          20 :                 values[j] = NULL;
     621             : 
     622             :             /* Insert primary key */
     623          10 :             values[0] = pkey;
     624             : 
     625             :             /* Parse the document */
     626          10 :             if (xmldoc)
     627          10 :                 doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
     628             :             else                /* treat NULL as not well-formed */
     629           0 :                 doctree = NULL;
     630             : 
     631          10 :             if (doctree == NULL)
     632             :             {
     633             :                 /* not well-formed, so output all-NULL tuple */
     634           0 :                 ret_tuple = BuildTupleFromCStrings(attinmeta, values);
     635           0 :                 tuplestore_puttuple(rsinfo->setResult, ret_tuple);
     636           0 :                 heap_freetuple(ret_tuple);
     637             :             }
     638             :             else
     639             :             {
     640             :                 /* New loop here - we have to deal with nodeset results */
     641          10 :                 rownr = 0;
     642             : 
     643             :                 do
     644             :                 {
     645             :                     /* Now evaluate the set of xpaths. */
     646          16 :                     had_values = false;
     647          36 :                     for (j = 0; j < numpaths; j++)
     648             :                     {
     649          20 :                         ctxt = xmlXPathNewContext(doctree);
     650          20 :                         ctxt->node = xmlDocGetRootElement(doctree);
     651             : 
     652             :                         /* compile the path */
     653          20 :                         comppath = xmlXPathCompile(xpaths[j]);
     654          20 :                         if (comppath == NULL)
     655           0 :                             xml_ereport(xmlerrcxt, ERROR,
     656             :                                         ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
     657             :                                         "XPath Syntax Error");
     658             : 
     659             :                         /* Now evaluate the path expression. */
     660          20 :                         res = xmlXPathCompiledEval(comppath, ctxt);
     661          20 :                         xmlXPathFreeCompExpr(comppath);
     662             : 
     663          20 :                         if (res != NULL)
     664             :                         {
     665          20 :                             switch (res->type)
     666             :                             {
     667          20 :                                 case XPATH_NODESET:
     668             :                                     /* We see if this nodeset has enough nodes */
     669          20 :                                     if (res->nodesetval != NULL &&
     670          20 :                                         rownr < res->nodesetval->nodeNr)
     671             :                                     {
     672           8 :                                         resstr = xmlXPathCastNodeToString(res->nodesetval->nodeTab[rownr]);
     673           8 :                                         had_values = true;
     674             :                                     }
     675             :                                     else
     676          12 :                                         resstr = NULL;
     677             : 
     678          20 :                                     break;
     679             : 
     680           0 :                                 case XPATH_STRING:
     681           0 :                                     resstr = xmlStrdup(res->stringval);
     682           0 :                                     break;
     683             : 
     684           0 :                                 default:
     685           0 :                                     elog(NOTICE, "unsupported XQuery result: %d", res->type);
     686           0 :                                     resstr = xmlStrdup((const xmlChar *) "<unsupported/>");
     687             :                             }
     688             : 
     689             :                             /*
     690             :                              * Insert this into the appropriate column in the
     691             :                              * result tuple.
     692             :                              */
     693          20 :                             values[j + 1] = (char *) resstr;
     694             :                         }
     695          20 :                         xmlXPathFreeContext(ctxt);
     696             :                     }
     697             : 
     698             :                     /* Now add the tuple to the output, if there is one. */
     699          16 :                     if (had_values)
     700             :                     {
     701           6 :                         ret_tuple = BuildTupleFromCStrings(attinmeta, values);
     702           6 :                         tuplestore_puttuple(rsinfo->setResult, ret_tuple);
     703           6 :                         heap_freetuple(ret_tuple);
     704             :                     }
     705             : 
     706          16 :                     rownr++;
     707          16 :                 } while (had_values);
     708             :             }
     709             : 
     710          10 :             if (doctree != NULL)
     711          10 :                 xmlFreeDoc(doctree);
     712          10 :             doctree = NULL;
     713             : 
     714          10 :             if (pkey)
     715          10 :                 pfree(pkey);
     716          10 :             if (xmldoc)
     717          10 :                 pfree(xmldoc);
     718             :         }
     719             :     }
     720           0 :     PG_CATCH();
     721             :     {
     722           0 :         if (doctree != NULL)
     723           0 :             xmlFreeDoc(doctree);
     724             : 
     725           0 :         pg_xml_done(xmlerrcxt, true);
     726             : 
     727           0 :         PG_RE_THROW();
     728             :     }
     729          10 :     PG_END_TRY();
     730             : 
     731          10 :     if (doctree != NULL)
     732           0 :         xmlFreeDoc(doctree);
     733             : 
     734          10 :     pg_xml_done(xmlerrcxt, false);
     735             : 
     736          10 :     SPI_finish();
     737             : 
     738             :     /*
     739             :      * SFRM_Materialize mode expects us to return a NULL Datum. The actual
     740             :      * tuples are in our tuplestore and passed back through rsinfo->setResult.
     741             :      * rsinfo->setDesc is set to the tuple description that we actually used
     742             :      * to build our tuples with, so the caller can verify we did what it was
     743             :      * expecting.
     744             :      */
     745          10 :     return (Datum) 0;
     746             : }

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