LCOV - code coverage report
Current view: top level - contrib/xml2 - xpath.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 133 272 48.9 %
Date: 2024-02-28 05:11:08 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 :     return xmlerrcxt;
      78             : }
      79             : 
      80             : 
      81             : /* Encodes special characters (<, >, &, " and \r) as XML entities */
      82             : 
      83           2 : PG_FUNCTION_INFO_V1(xml_encode_special_chars);
      84             : 
      85             : Datum
      86           0 : xml_encode_special_chars(PG_FUNCTION_ARGS)
      87             : {
      88           0 :     text       *tin = PG_GETARG_TEXT_PP(0);
      89             :     text       *tout;
      90             :     xmlChar    *ts,
      91             :                *tt;
      92             : 
      93           0 :     ts = pgxml_texttoxmlchar(tin);
      94             : 
      95           0 :     tt = xmlEncodeSpecialChars(NULL, ts);
      96             : 
      97           0 :     pfree(ts);
      98             : 
      99           0 :     tout = cstring_to_text((char *) tt);
     100             : 
     101           0 :     xmlFree(tt);
     102             : 
     103           0 :     PG_RETURN_TEXT_P(tout);
     104             : }
     105             : 
     106             : /*
     107             :  * Function translates a nodeset into a text representation
     108             :  *
     109             :  * iterates over each node in the set and calls xmlNodeDump to write it to
     110             :  * an xmlBuffer -from which an xmlChar * string is returned.
     111             :  *
     112             :  * each representation is surrounded by <tagname> ... </tagname>
     113             :  *
     114             :  * plainsep is an ordinary (not tag) separator - if used, then nodes are
     115             :  * cast to string as output method
     116             :  */
     117             : static xmlChar *
     118           0 : pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
     119             :                    xmlChar *toptagname,
     120             :                    xmlChar *septagname,
     121             :                    xmlChar *plainsep)
     122             : {
     123             :     xmlBufferPtr buf;
     124             :     xmlChar    *result;
     125             :     int         i;
     126             : 
     127           0 :     buf = xmlBufferCreate();
     128             : 
     129           0 :     if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     130             :     {
     131           0 :         xmlBufferWriteChar(buf, "<");
     132           0 :         xmlBufferWriteCHAR(buf, toptagname);
     133           0 :         xmlBufferWriteChar(buf, ">");
     134             :     }
     135           0 :     if (nodeset != NULL)
     136             :     {
     137           0 :         for (i = 0; i < nodeset->nodeNr; i++)
     138             :         {
     139           0 :             if (plainsep != NULL)
     140             :             {
     141           0 :                 xmlBufferWriteCHAR(buf,
     142           0 :                                    xmlXPathCastNodeToString(nodeset->nodeTab[i]));
     143             : 
     144             :                 /* If this isn't the last entry, write the plain sep. */
     145           0 :                 if (i < (nodeset->nodeNr) - 1)
     146           0 :                     xmlBufferWriteChar(buf, (char *) plainsep);
     147             :             }
     148             :             else
     149             :             {
     150           0 :                 if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     151             :                 {
     152           0 :                     xmlBufferWriteChar(buf, "<");
     153           0 :                     xmlBufferWriteCHAR(buf, septagname);
     154           0 :                     xmlBufferWriteChar(buf, ">");
     155             :                 }
     156           0 :                 xmlNodeDump(buf,
     157           0 :                             nodeset->nodeTab[i]->doc,
     158           0 :                             nodeset->nodeTab[i],
     159             :                             1, 0);
     160             : 
     161           0 :                 if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     162             :                 {
     163           0 :                     xmlBufferWriteChar(buf, "</");
     164           0 :                     xmlBufferWriteCHAR(buf, septagname);
     165           0 :                     xmlBufferWriteChar(buf, ">");
     166             :                 }
     167             :             }
     168             :         }
     169             :     }
     170             : 
     171           0 :     if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     172             :     {
     173           0 :         xmlBufferWriteChar(buf, "</");
     174           0 :         xmlBufferWriteCHAR(buf, toptagname);
     175           0 :         xmlBufferWriteChar(buf, ">");
     176             :     }
     177           0 :     result = xmlStrdup(buf->content);
     178           0 :     xmlBufferFree(buf);
     179           0 :     return result;
     180             : }
     181             : 
     182             : 
     183             : /* Translate a PostgreSQL "varlena" -i.e. a variable length parameter
     184             :  * into the libxml2 representation
     185             :  */
     186             : static xmlChar *
     187           0 : pgxml_texttoxmlchar(text *textstring)
     188             : {
     189           0 :     return (xmlChar *) text_to_cstring(textstring);
     190             : }
     191             : 
     192             : /* Publicly visible XPath functions */
     193             : 
     194             : /*
     195             :  * This is a "raw" xpath function. Check that it returns child elements
     196             :  * properly
     197             :  */
     198           2 : PG_FUNCTION_INFO_V1(xpath_nodeset);
     199             : 
     200             : Datum
     201           0 : xpath_nodeset(PG_FUNCTION_ARGS)
     202             : {
     203           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     204           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     205           0 :     xmlChar    *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     206           0 :     xmlChar    *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(3));
     207             :     xmlChar    *xpath;
     208             :     text       *xpres;
     209             :     xmlXPathObjectPtr res;
     210             :     xpath_workspace workspace;
     211             : 
     212           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     213             : 
     214           0 :     res = pgxml_xpath(document, xpath, &workspace);
     215             : 
     216           0 :     xpres = pgxml_result_to_text(res, toptag, septag, NULL);
     217             : 
     218           0 :     cleanup_workspace(&workspace);
     219             : 
     220           0 :     pfree(xpath);
     221             : 
     222           0 :     if (xpres == NULL)
     223           0 :         PG_RETURN_NULL();
     224           0 :     PG_RETURN_TEXT_P(xpres);
     225             : }
     226             : 
     227             : /*
     228             :  * The following function is almost identical, but returns the elements in
     229             :  * a list.
     230             :  */
     231           2 : PG_FUNCTION_INFO_V1(xpath_list);
     232             : 
     233             : Datum
     234           0 : xpath_list(PG_FUNCTION_ARGS)
     235             : {
     236           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     237           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     238           0 :     xmlChar    *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     239             :     xmlChar    *xpath;
     240             :     text       *xpres;
     241             :     xmlXPathObjectPtr res;
     242             :     xpath_workspace workspace;
     243             : 
     244           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     245             : 
     246           0 :     res = pgxml_xpath(document, xpath, &workspace);
     247             : 
     248           0 :     xpres = pgxml_result_to_text(res, NULL, NULL, plainsep);
     249             : 
     250           0 :     cleanup_workspace(&workspace);
     251             : 
     252           0 :     pfree(xpath);
     253             : 
     254           0 :     if (xpres == NULL)
     255           0 :         PG_RETURN_NULL();
     256           0 :     PG_RETURN_TEXT_P(xpres);
     257             : }
     258             : 
     259             : 
     260           4 : PG_FUNCTION_INFO_V1(xpath_string);
     261             : 
     262             : Datum
     263           2 : xpath_string(PG_FUNCTION_ARGS)
     264             : {
     265           2 :     text       *document = PG_GETARG_TEXT_PP(0);
     266           2 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     267             :     xmlChar    *xpath;
     268             :     int32       pathsize;
     269             :     text       *xpres;
     270             :     xmlXPathObjectPtr res;
     271             :     xpath_workspace workspace;
     272             : 
     273           2 :     pathsize = VARSIZE_ANY_EXHDR(xpathsupp);
     274             : 
     275             :     /*
     276             :      * We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
     277             :      * at end
     278             :      */
     279             :     /* We could try casting to string using the libxml function? */
     280             : 
     281           2 :     xpath = (xmlChar *) palloc(pathsize + 9);
     282           2 :     memcpy((char *) xpath, "string(", 7);
     283           2 :     memcpy((char *) (xpath + 7), VARDATA_ANY(xpathsupp), pathsize);
     284           2 :     xpath[pathsize + 7] = ')';
     285           2 :     xpath[pathsize + 8] = '\0';
     286             : 
     287           2 :     res = pgxml_xpath(document, xpath, &workspace);
     288             : 
     289           2 :     xpres = pgxml_result_to_text(res, NULL, NULL, NULL);
     290             : 
     291           2 :     cleanup_workspace(&workspace);
     292             : 
     293           2 :     pfree(xpath);
     294             : 
     295           2 :     if (xpres == NULL)
     296           2 :         PG_RETURN_NULL();
     297           0 :     PG_RETURN_TEXT_P(xpres);
     298             : }
     299             : 
     300             : 
     301           2 : PG_FUNCTION_INFO_V1(xpath_number);
     302             : 
     303             : Datum
     304           0 : xpath_number(PG_FUNCTION_ARGS)
     305             : {
     306           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     307           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     308             :     xmlChar    *xpath;
     309             :     float4      fRes;
     310             :     xmlXPathObjectPtr res;
     311             :     xpath_workspace workspace;
     312             : 
     313           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     314             : 
     315           0 :     res = pgxml_xpath(document, xpath, &workspace);
     316             : 
     317           0 :     pfree(xpath);
     318             : 
     319           0 :     if (res == NULL)
     320           0 :         PG_RETURN_NULL();
     321             : 
     322           0 :     fRes = xmlXPathCastToNumber(res);
     323             : 
     324           0 :     cleanup_workspace(&workspace);
     325             : 
     326           0 :     if (xmlXPathIsNaN(fRes))
     327           0 :         PG_RETURN_NULL();
     328             : 
     329           0 :     PG_RETURN_FLOAT4(fRes);
     330             : }
     331             : 
     332             : 
     333           2 : PG_FUNCTION_INFO_V1(xpath_bool);
     334             : 
     335             : Datum
     336           0 : xpath_bool(PG_FUNCTION_ARGS)
     337             : {
     338           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     339           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     340             :     xmlChar    *xpath;
     341             :     int         bRes;
     342             :     xmlXPathObjectPtr res;
     343             :     xpath_workspace workspace;
     344             : 
     345           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     346             : 
     347           0 :     res = pgxml_xpath(document, xpath, &workspace);
     348             : 
     349           0 :     pfree(xpath);
     350             : 
     351           0 :     if (res == NULL)
     352           0 :         PG_RETURN_BOOL(false);
     353             : 
     354           0 :     bRes = xmlXPathCastToBoolean(res);
     355             : 
     356           0 :     cleanup_workspace(&workspace);
     357             : 
     358           0 :     PG_RETURN_BOOL(bRes);
     359             : }
     360             : 
     361             : 
     362             : 
     363             : /* Core function to evaluate XPath query */
     364             : 
     365             : static xmlXPathObjectPtr
     366           2 : pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
     367             : {
     368           2 :     int32       docsize = VARSIZE_ANY_EXHDR(document);
     369             :     PgXmlErrorContext *xmlerrcxt;
     370             :     xmlXPathCompExprPtr comppath;
     371             : 
     372           2 :     workspace->doctree = NULL;
     373           2 :     workspace->ctxt = NULL;
     374           2 :     workspace->res = NULL;
     375             : 
     376           2 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     377             : 
     378           2 :     PG_TRY();
     379             :     {
     380           2 :         workspace->doctree = xmlReadMemory((char *) VARDATA_ANY(document),
     381             :                                            docsize, NULL, NULL,
     382             :                                            XML_PARSE_NOENT);
     383           2 :         if (workspace->doctree != NULL)
     384             :         {
     385           0 :             workspace->ctxt = xmlXPathNewContext(workspace->doctree);
     386           0 :             workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);
     387             : 
     388             :             /* compile the path */
     389           0 :             comppath = xmlXPathCompile(xpath);
     390           0 :             if (comppath == NULL)
     391           0 :                 xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
     392             :                             "XPath Syntax Error");
     393             : 
     394             :             /* Now evaluate the path expression. */
     395           0 :             workspace->res = xmlXPathCompiledEval(comppath, workspace->ctxt);
     396             : 
     397           0 :             xmlXPathFreeCompExpr(comppath);
     398             :         }
     399             :     }
     400           0 :     PG_CATCH();
     401             :     {
     402           0 :         cleanup_workspace(workspace);
     403             : 
     404           0 :         pg_xml_done(xmlerrcxt, true);
     405             : 
     406           0 :         PG_RE_THROW();
     407             :     }
     408           2 :     PG_END_TRY();
     409             : 
     410           2 :     if (workspace->res == NULL)
     411           2 :         cleanup_workspace(workspace);
     412             : 
     413           2 :     pg_xml_done(xmlerrcxt, false);
     414             : 
     415           2 :     return workspace->res;
     416             : }
     417             : 
     418             : /* Clean up after processing the result of pgxml_xpath() */
     419             : static void
     420           4 : cleanup_workspace(xpath_workspace *workspace)
     421             : {
     422           4 :     if (workspace->res)
     423           0 :         xmlXPathFreeObject(workspace->res);
     424           4 :     workspace->res = NULL;
     425           4 :     if (workspace->ctxt)
     426           0 :         xmlXPathFreeContext(workspace->ctxt);
     427           4 :     workspace->ctxt = NULL;
     428           4 :     if (workspace->doctree)
     429           0 :         xmlFreeDoc(workspace->doctree);
     430           4 :     workspace->doctree = NULL;
     431           4 : }
     432             : 
     433             : static text *
     434           2 : pgxml_result_to_text(xmlXPathObjectPtr res,
     435             :                      xmlChar *toptag,
     436             :                      xmlChar *septag,
     437             :                      xmlChar *plainsep)
     438             : {
     439             :     xmlChar    *xpresstr;
     440             :     text       *xpres;
     441             : 
     442           2 :     if (res == NULL)
     443           2 :         return NULL;
     444             : 
     445           0 :     switch (res->type)
     446             :     {
     447           0 :         case XPATH_NODESET:
     448           0 :             xpresstr = pgxmlNodeSetToText(res->nodesetval,
     449             :                                           toptag,
     450             :                                           septag, plainsep);
     451           0 :             break;
     452             : 
     453           0 :         case XPATH_STRING:
     454           0 :             xpresstr = xmlStrdup(res->stringval);
     455           0 :             break;
     456             : 
     457           0 :         default:
     458           0 :             elog(NOTICE, "unsupported XQuery result: %d", res->type);
     459           0 :             xpresstr = xmlStrdup((const xmlChar *) "<unsupported/>");
     460             :     }
     461             : 
     462             :     /* Now convert this result back to text */
     463           0 :     xpres = cstring_to_text((char *) xpresstr);
     464             : 
     465             :     /* Free various storage */
     466           0 :     xmlFree(xpresstr);
     467             : 
     468           0 :     return xpres;
     469             : }
     470             : 
     471             : /*
     472             :  * xpath_table is a table function. It needs some tidying (as do the
     473             :  * other functions here!
     474             :  */
     475           4 : PG_FUNCTION_INFO_V1(xpath_table);
     476             : 
     477             : Datum
     478          10 : xpath_table(PG_FUNCTION_ARGS)
     479             : {
     480             :     /* Function parameters */
     481          10 :     char       *pkeyfield = text_to_cstring(PG_GETARG_TEXT_PP(0));
     482          10 :     char       *xmlfield = text_to_cstring(PG_GETARG_TEXT_PP(1));
     483          10 :     char       *relname = text_to_cstring(PG_GETARG_TEXT_PP(2));
     484          10 :     char       *xpathset = text_to_cstring(PG_GETARG_TEXT_PP(3));
     485          10 :     char       *condition = text_to_cstring(PG_GETARG_TEXT_PP(4));
     486             : 
     487             :     /* SPI (input tuple) support */
     488             :     SPITupleTable *tuptable;
     489             :     HeapTuple   spi_tuple;
     490             :     TupleDesc   spi_tupdesc;
     491             : 
     492             : 
     493          10 :     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
     494             :     AttInMetadata *attinmeta;
     495             : 
     496             :     char      **values;
     497             :     xmlChar   **xpaths;
     498             :     char       *pos;
     499          10 :     const char *pathsep = "|";
     500             : 
     501             :     int         numpaths;
     502             :     int         ret;
     503             :     uint64      proc;
     504             :     int         j;
     505             :     int         rownr;          /* For issuing multiple rows from one original
     506             :                                  * document */
     507             :     bool        had_values;     /* To determine end of nodeset results */
     508             :     StringInfoData query_buf;
     509             :     PgXmlErrorContext *xmlerrcxt;
     510          10 :     volatile xmlDocPtr doctree = NULL;
     511             : 
     512          10 :     InitMaterializedSRF(fcinfo, MAT_SRF_USE_EXPECTED_DESC);
     513             : 
     514             :     /* must have at least one output column (for the pkey) */
     515          10 :     if (rsinfo->setDesc->natts < 1)
     516           0 :         ereport(ERROR,
     517             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     518             :                  errmsg("xpath_table must have at least one output column")));
     519             : 
     520             :     /*
     521             :      * At the moment we assume that the returned attributes make sense for the
     522             :      * XPath specified (i.e. we trust the caller). It's not fatal if they get
     523             :      * it wrong - the input function for the column type will raise an error
     524             :      * if the path result can't be converted into the correct binary
     525             :      * representation.
     526             :      */
     527             : 
     528          10 :     attinmeta = TupleDescGetAttInMetadata(rsinfo->setDesc);
     529             : 
     530          10 :     values = (char **) palloc(rsinfo->setDesc->natts * sizeof(char *));
     531          10 :     xpaths = (xmlChar **) palloc(rsinfo->setDesc->natts * sizeof(xmlChar *));
     532             : 
     533             :     /*
     534             :      * Split XPaths. xpathset is a writable CString.
     535             :      *
     536             :      * Note that we stop splitting once we've done all needed for tupdesc
     537             :      */
     538          10 :     numpaths = 0;
     539          10 :     pos = xpathset;
     540          14 :     while (numpaths < (rsinfo->setDesc->natts - 1))
     541             :     {
     542          10 :         xpaths[numpaths++] = (xmlChar *) pos;
     543          10 :         pos = strstr(pos, pathsep);
     544          10 :         if (pos != NULL)
     545             :         {
     546           4 :             *pos = '\0';
     547           4 :             pos++;
     548             :         }
     549             :         else
     550           6 :             break;
     551             :     }
     552             : 
     553             :     /* Now build query */
     554          10 :     initStringInfo(&query_buf);
     555             : 
     556             :     /* Build initial sql statement */
     557          10 :     appendStringInfo(&query_buf, "SELECT %s, %s FROM %s WHERE %s",
     558             :                      pkeyfield,
     559             :                      xmlfield,
     560             :                      relname,
     561             :                      condition);
     562             : 
     563          10 :     if ((ret = SPI_connect()) < 0)
     564           0 :         elog(ERROR, "xpath_table: SPI_connect returned %d", ret);
     565             : 
     566          10 :     if ((ret = SPI_exec(query_buf.data, 0)) != SPI_OK_SELECT)
     567           0 :         elog(ERROR, "xpath_table: SPI execution failed for query %s",
     568             :              query_buf.data);
     569             : 
     570          10 :     proc = SPI_processed;
     571          10 :     tuptable = SPI_tuptable;
     572          10 :     spi_tupdesc = tuptable->tupdesc;
     573             : 
     574             :     /*
     575             :      * Check that SPI returned correct result. If you put a comma into one of
     576             :      * the function parameters, this will catch it when the SPI query returns
     577             :      * e.g. 3 columns.
     578             :      */
     579          10 :     if (spi_tupdesc->natts != 2)
     580             :     {
     581           0 :         ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     582             :                         errmsg("expression returning multiple columns is not valid in parameter list"),
     583             :                         errdetail("Expected two columns in SPI result, got %d.", spi_tupdesc->natts)));
     584             :     }
     585             : 
     586             :     /*
     587             :      * Setup the parser.  This should happen after we are done evaluating the
     588             :      * query, in case it calls functions that set up libxml differently.
     589             :      */
     590          10 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     591             : 
     592          10 :     PG_TRY();
     593             :     {
     594             :         /* For each row i.e. document returned from SPI */
     595             :         uint64      i;
     596             : 
     597          20 :         for (i = 0; i < proc; i++)
     598             :         {
     599             :             char       *pkey;
     600             :             char       *xmldoc;
     601             :             xmlXPathContextPtr ctxt;
     602             :             xmlXPathObjectPtr res;
     603             :             xmlChar    *resstr;
     604             :             xmlXPathCompExprPtr comppath;
     605             :             HeapTuple   ret_tuple;
     606             : 
     607             :             /* Extract the row data as C Strings */
     608          10 :             spi_tuple = tuptable->vals[i];
     609          10 :             pkey = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
     610          10 :             xmldoc = SPI_getvalue(spi_tuple, spi_tupdesc, 2);
     611             : 
     612             :             /*
     613             :              * Clear the values array, so that not-well-formed documents
     614             :              * return NULL in all columns.  Note that this also means that
     615             :              * spare columns will be NULL.
     616             :              */
     617          30 :             for (j = 0; j < rsinfo->setDesc->natts; j++)
     618          20 :                 values[j] = NULL;
     619             : 
     620             :             /* Insert primary key */
     621          10 :             values[0] = pkey;
     622             : 
     623             :             /* Parse the document */
     624          10 :             if (xmldoc)
     625          10 :                 doctree = xmlReadMemory(xmldoc, strlen(xmldoc),
     626             :                                         NULL, NULL,
     627             :                                         XML_PARSE_NOENT);
     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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