LCOV - code coverage report
Current view: top level - contrib/xml2 - xpath.c (source / functions) Hit Total Coverage
Test: PostgreSQL 19devel Lines: 234 370 63.2 %
Date: 2025-07-29 03:18:01 Functions: 18 21 85.7 %
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 "utils/builtins.h"
      15             : #include "utils/xml.h"
      16             : 
      17             : /* libxml includes */
      18             : 
      19             : #include <libxml/xpath.h>
      20             : #include <libxml/tree.h>
      21             : #include <libxml/xmlmemory.h>
      22             : #include <libxml/xmlerror.h>
      23             : #include <libxml/parserInternals.h>
      24             : 
      25           2 : PG_MODULE_MAGIC_EXT(
      26             :                     .name = "xml2",
      27             :                     .version = PG_VERSION
      28             : );
      29             : 
      30             : /* exported for use by xslt_proc.c */
      31             : 
      32             : PgXmlErrorContext *pgxml_parser_init(PgXmlStrictness strictness);
      33             : 
      34             : /* workspace for pgxml_xpath() */
      35             : 
      36             : typedef struct
      37             : {
      38             :     xmlDocPtr   doctree;
      39             :     xmlXPathContextPtr ctxt;
      40             :     xmlXPathObjectPtr res;
      41             : } xpath_workspace;
      42             : 
      43             : /* local declarations */
      44             : 
      45             : static xmlChar *pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
      46             :                                    xmlChar *toptagname, xmlChar *septagname,
      47             :                                    xmlChar *plainsep);
      48             : 
      49             : static text *pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag,
      50             :                                   xmlChar *septag, xmlChar *plainsep);
      51             : 
      52             : static xmlChar *pgxml_texttoxmlchar(text *textstring);
      53             : 
      54             : static xpath_workspace *pgxml_xpath(text *document, xmlChar *xpath,
      55             :                                     PgXmlErrorContext *xmlerrcxt);
      56             : 
      57             : static void cleanup_workspace(xpath_workspace *workspace);
      58             : 
      59             : 
      60             : /*
      61             :  * Initialize for xml parsing.
      62             :  *
      63             :  * As with the underlying pg_xml_init function, calls to this MUST be followed
      64             :  * by a PG_TRY block that guarantees that pg_xml_done is called.
      65             :  */
      66             : PgXmlErrorContext *
      67          22 : pgxml_parser_init(PgXmlStrictness strictness)
      68             : {
      69             :     PgXmlErrorContext *xmlerrcxt;
      70             : 
      71             :     /* Set up error handling (we share the core's error handler) */
      72          22 :     xmlerrcxt = pg_xml_init(strictness);
      73             : 
      74             :     /* Note: we're assuming an elog cannot be thrown by the following calls */
      75             : 
      76             :     /* Initialize libxml */
      77          22 :     xmlInitParser();
      78             : 
      79          22 :     return xmlerrcxt;
      80             : }
      81             : 
      82             : 
      83             : /* Encodes special characters (<, >, &, " and \r) as XML entities */
      84             : 
      85           2 : PG_FUNCTION_INFO_V1(xml_encode_special_chars);
      86             : 
      87             : Datum
      88           0 : xml_encode_special_chars(PG_FUNCTION_ARGS)
      89             : {
      90           0 :     text       *tin = PG_GETARG_TEXT_PP(0);
      91           0 :     text       *volatile tout = NULL;
      92           0 :     xmlChar    *volatile tt = NULL;
      93             :     PgXmlErrorContext *xmlerrcxt;
      94             : 
      95           0 :     xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
      96             : 
      97           0 :     PG_TRY();
      98             :     {
      99             :         xmlChar    *ts;
     100             : 
     101           0 :         ts = pgxml_texttoxmlchar(tin);
     102             : 
     103           0 :         tt = xmlEncodeSpecialChars(NULL, ts);
     104           0 :         if (tt == NULL || pg_xml_error_occurred(xmlerrcxt))
     105           0 :             xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
     106             :                         "could not allocate xmlChar");
     107           0 :         pfree(ts);
     108             : 
     109           0 :         tout = cstring_to_text((char *) tt);
     110             :     }
     111           0 :     PG_CATCH();
     112             :     {
     113           0 :         if (tt != NULL)
     114           0 :             xmlFree(tt);
     115             : 
     116           0 :         pg_xml_done(xmlerrcxt, true);
     117             : 
     118           0 :         PG_RE_THROW();
     119             :     }
     120           0 :     PG_END_TRY();
     121             : 
     122           0 :     if (tt != NULL)
     123           0 :         xmlFree(tt);
     124             : 
     125           0 :     pg_xml_done(xmlerrcxt, false);
     126             : 
     127           0 :     PG_RETURN_TEXT_P(tout);
     128             : }
     129             : 
     130             : /*
     131             :  * Function translates a nodeset into a text representation
     132             :  *
     133             :  * iterates over each node in the set and calls xmlNodeDump to write it to
     134             :  * an xmlBuffer -from which an xmlChar * string is returned.
     135             :  *
     136             :  * each representation is surrounded by <tagname> ... </tagname>
     137             :  *
     138             :  * plainsep is an ordinary (not tag) separator - if used, then nodes are
     139             :  * cast to string as output method
     140             :  */
     141             : static xmlChar *
     142          10 : pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
     143             :                    xmlChar *toptagname,
     144             :                    xmlChar *septagname,
     145             :                    xmlChar *plainsep)
     146             : {
     147          10 :     volatile xmlBufferPtr buf = NULL;
     148          10 :     xmlChar    *volatile result = NULL;
     149             :     PgXmlErrorContext *xmlerrcxt;
     150             : 
     151             :     /* spin up some error handling */
     152          10 :     xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
     153             : 
     154          10 :     PG_TRY();
     155             :     {
     156          10 :         buf = xmlBufferCreate();
     157             : 
     158          10 :         if (buf == NULL || pg_xml_error_occurred(xmlerrcxt))
     159           0 :             xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
     160             :                         "could not allocate xmlBuffer");
     161             : 
     162          10 :         if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     163             :         {
     164           2 :             xmlBufferWriteChar(buf, "<");
     165           2 :             xmlBufferWriteCHAR(buf, toptagname);
     166           2 :             xmlBufferWriteChar(buf, ">");
     167             :         }
     168          10 :         if (nodeset != NULL)
     169             :         {
     170          30 :             for (int i = 0; i < nodeset->nodeNr; i++)
     171             :             {
     172          20 :                 if (plainsep != NULL)
     173             :                 {
     174           8 :                     xmlBufferWriteCHAR(buf,
     175           8 :                                        xmlXPathCastNodeToString(nodeset->nodeTab[i]));
     176             : 
     177             :                     /* If this isn't the last entry, write the plain sep. */
     178           8 :                     if (i < (nodeset->nodeNr) - 1)
     179           4 :                         xmlBufferWriteChar(buf, (char *) plainsep);
     180             :                 }
     181             :                 else
     182             :                 {
     183          12 :                     if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     184             :                     {
     185           8 :                         xmlBufferWriteChar(buf, "<");
     186           8 :                         xmlBufferWriteCHAR(buf, septagname);
     187           8 :                         xmlBufferWriteChar(buf, ">");
     188             :                     }
     189          12 :                     xmlNodeDump(buf,
     190          12 :                                 nodeset->nodeTab[i]->doc,
     191          12 :                                 nodeset->nodeTab[i],
     192             :                                 1, 0);
     193             : 
     194          12 :                     if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
     195             :                     {
     196           8 :                         xmlBufferWriteChar(buf, "</");
     197           8 :                         xmlBufferWriteCHAR(buf, septagname);
     198           8 :                         xmlBufferWriteChar(buf, ">");
     199             :                     }
     200             :                 }
     201             :             }
     202             :         }
     203             : 
     204          10 :         if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
     205             :         {
     206           2 :             xmlBufferWriteChar(buf, "</");
     207           2 :             xmlBufferWriteCHAR(buf, toptagname);
     208           2 :             xmlBufferWriteChar(buf, ">");
     209             :         }
     210             : 
     211          10 :         result = xmlStrdup(xmlBufferContent(buf));
     212          10 :         if (result == NULL || pg_xml_error_occurred(xmlerrcxt))
     213           0 :             xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
     214             :                         "could not allocate result");
     215             :     }
     216           0 :     PG_CATCH();
     217             :     {
     218           0 :         if (buf)
     219           0 :             xmlBufferFree(buf);
     220             : 
     221           0 :         pg_xml_done(xmlerrcxt, true);
     222             : 
     223           0 :         PG_RE_THROW();
     224             :     }
     225          10 :     PG_END_TRY();
     226             : 
     227          10 :     xmlBufferFree(buf);
     228          10 :     pg_xml_done(xmlerrcxt, false);
     229             : 
     230          10 :     return result;
     231             : }
     232             : 
     233             : 
     234             : /* Translate a PostgreSQL "varlena" -i.e. a variable length parameter
     235             :  * into the libxml2 representation
     236             :  */
     237             : static xmlChar *
     238          26 : pgxml_texttoxmlchar(text *textstring)
     239             : {
     240          26 :     return (xmlChar *) text_to_cstring(textstring);
     241             : }
     242             : 
     243             : /* Publicly visible XPath functions */
     244             : 
     245             : /*
     246             :  * This is a "raw" xpath function. Check that it returns child elements
     247             :  * properly
     248             :  */
     249           4 : PG_FUNCTION_INFO_V1(xpath_nodeset);
     250             : 
     251             : Datum
     252           6 : xpath_nodeset(PG_FUNCTION_ARGS)
     253             : {
     254           6 :     text       *document = PG_GETARG_TEXT_PP(0);
     255           6 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     256           6 :     xmlChar    *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     257           6 :     xmlChar    *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(3));
     258             :     xmlChar    *xpath;
     259           6 :     text       *volatile xpres = NULL;
     260           6 :     xpath_workspace *volatile workspace = NULL;
     261             :     PgXmlErrorContext *xmlerrcxt;
     262             : 
     263           6 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     264           6 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     265             : 
     266           6 :     PG_TRY();
     267             :     {
     268           6 :         workspace = pgxml_xpath(document, xpath, xmlerrcxt);
     269           6 :         xpres = pgxml_result_to_text(workspace->res, toptag, septag, NULL);
     270             :     }
     271           0 :     PG_CATCH();
     272             :     {
     273           0 :         if (workspace)
     274           0 :             cleanup_workspace(workspace);
     275             : 
     276           0 :         pg_xml_done(xmlerrcxt, true);
     277           0 :         PG_RE_THROW();
     278             :     }
     279           6 :     PG_END_TRY();
     280             : 
     281           6 :     cleanup_workspace(workspace);
     282           6 :     pg_xml_done(xmlerrcxt, false);
     283             : 
     284           6 :     pfree(xpath);
     285             : 
     286           6 :     if (xpres == NULL)
     287           0 :         PG_RETURN_NULL();
     288           6 :     PG_RETURN_TEXT_P(xpres);
     289             : }
     290             : 
     291             : /*
     292             :  * The following function is almost identical, but returns the elements in
     293             :  * a list.
     294             :  */
     295           4 : PG_FUNCTION_INFO_V1(xpath_list);
     296             : 
     297             : Datum
     298           4 : xpath_list(PG_FUNCTION_ARGS)
     299             : {
     300           4 :     text       *document = PG_GETARG_TEXT_PP(0);
     301           4 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     302           4 :     xmlChar    *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_PP(2));
     303             :     xmlChar    *xpath;
     304           4 :     text       *volatile xpres = NULL;
     305           4 :     xpath_workspace *volatile workspace = NULL;
     306             :     PgXmlErrorContext *xmlerrcxt;
     307             : 
     308           4 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     309           4 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     310             : 
     311           4 :     PG_TRY();
     312             :     {
     313           4 :         workspace = pgxml_xpath(document, xpath, xmlerrcxt);
     314           4 :         xpres = pgxml_result_to_text(workspace->res, NULL, NULL, plainsep);
     315             :     }
     316           0 :     PG_CATCH();
     317             :     {
     318           0 :         if (workspace)
     319           0 :             cleanup_workspace(workspace);
     320             : 
     321           0 :         pg_xml_done(xmlerrcxt, true);
     322           0 :         PG_RE_THROW();
     323             :     }
     324           4 :     PG_END_TRY();
     325             : 
     326           4 :     cleanup_workspace(workspace);
     327           4 :     pg_xml_done(xmlerrcxt, false);
     328             : 
     329           4 :     pfree(xpath);
     330             : 
     331           4 :     if (xpres == NULL)
     332           0 :         PG_RETURN_NULL();
     333           4 :     PG_RETURN_TEXT_P(xpres);
     334             : }
     335             : 
     336             : 
     337           4 : PG_FUNCTION_INFO_V1(xpath_string);
     338             : 
     339             : Datum
     340           2 : xpath_string(PG_FUNCTION_ARGS)
     341             : {
     342           2 :     text       *document = PG_GETARG_TEXT_PP(0);
     343           2 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     344             :     xmlChar    *xpath;
     345             :     int32       pathsize;
     346           2 :     text       *volatile xpres = NULL;
     347           2 :     xpath_workspace *volatile workspace = NULL;
     348             :     PgXmlErrorContext *xmlerrcxt;
     349             : 
     350           2 :     pathsize = VARSIZE_ANY_EXHDR(xpathsupp);
     351             : 
     352             :     /*
     353             :      * We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
     354             :      * at end
     355             :      */
     356             :     /* We could try casting to string using the libxml function? */
     357             : 
     358           2 :     xpath = (xmlChar *) palloc(pathsize + 9);
     359           2 :     memcpy(xpath, "string(", 7);
     360           2 :     memcpy(xpath + 7, VARDATA_ANY(xpathsupp), pathsize);
     361           2 :     xpath[pathsize + 7] = ')';
     362           2 :     xpath[pathsize + 8] = '\0';
     363             : 
     364           2 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     365             : 
     366           2 :     PG_TRY();
     367             :     {
     368           2 :         workspace = pgxml_xpath(document, xpath, xmlerrcxt);
     369           2 :         xpres = pgxml_result_to_text(workspace->res, NULL, NULL, NULL);
     370             :     }
     371           0 :     PG_CATCH();
     372             :     {
     373           0 :         if (workspace)
     374           0 :             cleanup_workspace(workspace);
     375             : 
     376           0 :         pg_xml_done(xmlerrcxt, true);
     377           0 :         PG_RE_THROW();
     378             :     }
     379           2 :     PG_END_TRY();
     380             : 
     381           2 :     cleanup_workspace(workspace);
     382           2 :     pg_xml_done(xmlerrcxt, false);
     383             : 
     384           2 :     pfree(xpath);
     385             : 
     386           2 :     if (xpres == NULL)
     387           2 :         PG_RETURN_NULL();
     388           0 :     PG_RETURN_TEXT_P(xpres);
     389             : }
     390             : 
     391             : 
     392           2 : PG_FUNCTION_INFO_V1(xpath_number);
     393             : 
     394             : Datum
     395           0 : xpath_number(PG_FUNCTION_ARGS)
     396             : {
     397           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     398           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     399             :     xmlChar    *xpath;
     400           0 :     volatile float4 fRes = 0.0;
     401           0 :     volatile bool isNull = false;
     402           0 :     xpath_workspace *volatile workspace = NULL;
     403             :     PgXmlErrorContext *xmlerrcxt;
     404             : 
     405           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     406           0 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     407             : 
     408           0 :     PG_TRY();
     409             :     {
     410           0 :         workspace = pgxml_xpath(document, xpath, xmlerrcxt);
     411           0 :         pfree(xpath);
     412             : 
     413           0 :         if (workspace->res == NULL)
     414           0 :             isNull = true;
     415             :         else
     416           0 :             fRes = xmlXPathCastToNumber(workspace->res);
     417             :     }
     418           0 :     PG_CATCH();
     419             :     {
     420           0 :         if (workspace)
     421           0 :             cleanup_workspace(workspace);
     422             : 
     423           0 :         pg_xml_done(xmlerrcxt, true);
     424           0 :         PG_RE_THROW();
     425             :     }
     426           0 :     PG_END_TRY();
     427             : 
     428           0 :     cleanup_workspace(workspace);
     429           0 :     pg_xml_done(xmlerrcxt, false);
     430             : 
     431           0 :     if (isNull || xmlXPathIsNaN(fRes))
     432           0 :         PG_RETURN_NULL();
     433             : 
     434           0 :     PG_RETURN_FLOAT4(fRes);
     435             : }
     436             : 
     437             : 
     438           2 : PG_FUNCTION_INFO_V1(xpath_bool);
     439             : 
     440             : Datum
     441           0 : xpath_bool(PG_FUNCTION_ARGS)
     442             : {
     443           0 :     text       *document = PG_GETARG_TEXT_PP(0);
     444           0 :     text       *xpathsupp = PG_GETARG_TEXT_PP(1);   /* XPath expression */
     445             :     xmlChar    *xpath;
     446           0 :     volatile int bRes = 0;
     447           0 :     xpath_workspace *volatile workspace = NULL;
     448             :     PgXmlErrorContext *xmlerrcxt;
     449             : 
     450           0 :     xpath = pgxml_texttoxmlchar(xpathsupp);
     451           0 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     452             : 
     453           0 :     PG_TRY();
     454             :     {
     455           0 :         workspace = pgxml_xpath(document, xpath, xmlerrcxt);
     456           0 :         pfree(xpath);
     457             : 
     458           0 :         if (workspace->res == NULL)
     459           0 :             bRes = 0;
     460             :         else
     461           0 :             bRes = xmlXPathCastToBoolean(workspace->res);
     462             :     }
     463           0 :     PG_CATCH();
     464             :     {
     465           0 :         if (workspace)
     466           0 :             cleanup_workspace(workspace);
     467             : 
     468           0 :         pg_xml_done(xmlerrcxt, true);
     469           0 :         PG_RE_THROW();
     470             :     }
     471           0 :     PG_END_TRY();
     472             : 
     473           0 :     cleanup_workspace(workspace);
     474           0 :     pg_xml_done(xmlerrcxt, false);
     475             : 
     476           0 :     PG_RETURN_BOOL(bRes);
     477             : }
     478             : 
     479             : 
     480             : 
     481             : /* Core function to evaluate XPath query */
     482             : 
     483             : static xpath_workspace *
     484          12 : pgxml_xpath(text *document, xmlChar *xpath, PgXmlErrorContext *xmlerrcxt)
     485             : {
     486          12 :     int32       docsize = VARSIZE_ANY_EXHDR(document);
     487             :     xmlXPathCompExprPtr comppath;
     488             :     xpath_workspace *workspace = (xpath_workspace *)
     489          12 :         palloc0(sizeof(xpath_workspace));
     490             : 
     491          12 :     workspace->doctree = NULL;
     492          12 :     workspace->ctxt = NULL;
     493          12 :     workspace->res = NULL;
     494             : 
     495          12 :     workspace->doctree = xmlReadMemory((char *) VARDATA_ANY(document),
     496             :                                        docsize, NULL, NULL,
     497             :                                        XML_PARSE_NOENT);
     498          12 :     if (workspace->doctree != NULL)
     499             :     {
     500          10 :         workspace->ctxt = xmlXPathNewContext(workspace->doctree);
     501          10 :         workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);
     502             : 
     503             :         /* compile the path */
     504          10 :         comppath = xmlXPathCtxtCompile(workspace->ctxt, xpath);
     505          10 :         if (comppath == NULL || pg_xml_error_occurred(xmlerrcxt))
     506           0 :             xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
     507             :                         "XPath Syntax Error");
     508             : 
     509             :         /* Now evaluate the path expression. */
     510          10 :         workspace->res = xmlXPathCompiledEval(comppath, workspace->ctxt);
     511             : 
     512          10 :         xmlXPathFreeCompExpr(comppath);
     513             :     }
     514             : 
     515          12 :     return workspace;
     516             : }
     517             : 
     518             : /* Clean up after processing the result of pgxml_xpath() */
     519             : static void
     520          12 : cleanup_workspace(xpath_workspace *workspace)
     521             : {
     522          12 :     if (workspace->res)
     523          10 :         xmlXPathFreeObject(workspace->res);
     524          12 :     workspace->res = NULL;
     525          12 :     if (workspace->ctxt)
     526          10 :         xmlXPathFreeContext(workspace->ctxt);
     527          12 :     workspace->ctxt = NULL;
     528          12 :     if (workspace->doctree)
     529          10 :         xmlFreeDoc(workspace->doctree);
     530          12 :     workspace->doctree = NULL;
     531          12 : }
     532             : 
     533             : static text *
     534          12 : pgxml_result_to_text(xmlXPathObjectPtr res,
     535             :                      xmlChar *toptag,
     536             :                      xmlChar *septag,
     537             :                      xmlChar *plainsep)
     538             : {
     539          12 :     xmlChar    *volatile xpresstr = NULL;
     540          12 :     text       *volatile xpres = NULL;
     541             :     PgXmlErrorContext *xmlerrcxt;
     542             : 
     543          12 :     if (res == NULL)
     544           2 :         return NULL;
     545             : 
     546             :     /* spin some error handling */
     547          10 :     xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
     548             : 
     549          10 :     PG_TRY();
     550             :     {
     551          10 :         switch (res->type)
     552             :         {
     553          10 :             case XPATH_NODESET:
     554          10 :                 xpresstr = pgxmlNodeSetToText(res->nodesetval,
     555             :                                               toptag,
     556             :                                               septag, plainsep);
     557          10 :                 break;
     558             : 
     559           0 :             case XPATH_STRING:
     560           0 :                 xpresstr = xmlStrdup(res->stringval);
     561           0 :                 if (xpresstr == NULL || pg_xml_error_occurred(xmlerrcxt))
     562           0 :                     xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
     563             :                                 "could not allocate result");
     564           0 :                 break;
     565             : 
     566           0 :             default:
     567           0 :                 elog(NOTICE, "unsupported XQuery result: %d", res->type);
     568           0 :                 xpresstr = xmlStrdup((const xmlChar *) "<unsupported/>");
     569           0 :                 if (xpresstr == NULL || pg_xml_error_occurred(xmlerrcxt))
     570           0 :                     xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
     571             :                                 "could not allocate result");
     572             :         }
     573             : 
     574             :         /* Now convert this result back to text */
     575          10 :         xpres = cstring_to_text((char *) xpresstr);
     576             :     }
     577           0 :     PG_CATCH();
     578             :     {
     579           0 :         if (xpresstr != NULL)
     580           0 :             xmlFree(xpresstr);
     581             : 
     582           0 :         pg_xml_done(xmlerrcxt, true);
     583             : 
     584           0 :         PG_RE_THROW();
     585             :     }
     586          10 :     PG_END_TRY();
     587             : 
     588             :     /* Free various storage */
     589          10 :     xmlFree(xpresstr);
     590             : 
     591          10 :     pg_xml_done(xmlerrcxt, false);
     592             : 
     593          10 :     return xpres;
     594             : }
     595             : 
     596             : /*
     597             :  * xpath_table is a table function. It needs some tidying (as do the
     598             :  * other functions here!
     599             :  */
     600           4 : PG_FUNCTION_INFO_V1(xpath_table);
     601             : 
     602             : Datum
     603          10 : xpath_table(PG_FUNCTION_ARGS)
     604             : {
     605             :     /* Function parameters */
     606          10 :     char       *pkeyfield = text_to_cstring(PG_GETARG_TEXT_PP(0));
     607          10 :     char       *xmlfield = text_to_cstring(PG_GETARG_TEXT_PP(1));
     608          10 :     char       *relname = text_to_cstring(PG_GETARG_TEXT_PP(2));
     609          10 :     char       *xpathset = text_to_cstring(PG_GETARG_TEXT_PP(3));
     610          10 :     char       *condition = text_to_cstring(PG_GETARG_TEXT_PP(4));
     611             : 
     612             :     /* SPI (input tuple) support */
     613             :     SPITupleTable *tuptable;
     614             :     HeapTuple   spi_tuple;
     615             :     TupleDesc   spi_tupdesc;
     616             : 
     617             : 
     618          10 :     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
     619             :     AttInMetadata *attinmeta;
     620             : 
     621             :     char      **values;
     622             :     xmlChar   **xpaths;
     623             :     char       *pos;
     624          10 :     const char *pathsep = "|";
     625             : 
     626             :     int         numpaths;
     627             :     int         ret;
     628             :     uint64      proc;
     629             :     int         j;
     630             :     int         rownr;          /* For issuing multiple rows from one original
     631             :                                  * document */
     632             :     bool        had_values;     /* To determine end of nodeset results */
     633             :     StringInfoData query_buf;
     634             :     PgXmlErrorContext *xmlerrcxt;
     635          10 :     volatile xmlDocPtr doctree = NULL;
     636             : 
     637          10 :     InitMaterializedSRF(fcinfo, MAT_SRF_USE_EXPECTED_DESC);
     638             : 
     639             :     /* must have at least one output column (for the pkey) */
     640          10 :     if (rsinfo->setDesc->natts < 1)
     641           0 :         ereport(ERROR,
     642             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     643             :                  errmsg("xpath_table must have at least one output column")));
     644             : 
     645             :     /*
     646             :      * At the moment we assume that the returned attributes make sense for the
     647             :      * XPath specified (i.e. we trust the caller). It's not fatal if they get
     648             :      * it wrong - the input function for the column type will raise an error
     649             :      * if the path result can't be converted into the correct binary
     650             :      * representation.
     651             :      */
     652             : 
     653          10 :     attinmeta = TupleDescGetAttInMetadata(rsinfo->setDesc);
     654             : 
     655          10 :     values = (char **) palloc(rsinfo->setDesc->natts * sizeof(char *));
     656          10 :     xpaths = (xmlChar **) palloc(rsinfo->setDesc->natts * sizeof(xmlChar *));
     657             : 
     658             :     /*
     659             :      * Split XPaths. xpathset is a writable CString.
     660             :      *
     661             :      * Note that we stop splitting once we've done all needed for tupdesc
     662             :      */
     663          10 :     numpaths = 0;
     664          10 :     pos = xpathset;
     665          14 :     while (numpaths < (rsinfo->setDesc->natts - 1))
     666             :     {
     667          10 :         xpaths[numpaths++] = (xmlChar *) pos;
     668          10 :         pos = strstr(pos, pathsep);
     669          10 :         if (pos != NULL)
     670             :         {
     671           4 :             *pos = '\0';
     672           4 :             pos++;
     673             :         }
     674             :         else
     675           6 :             break;
     676             :     }
     677             : 
     678             :     /* Now build query */
     679          10 :     initStringInfo(&query_buf);
     680             : 
     681             :     /* Build initial sql statement */
     682          10 :     appendStringInfo(&query_buf, "SELECT %s, %s FROM %s WHERE %s",
     683             :                      pkeyfield,
     684             :                      xmlfield,
     685             :                      relname,
     686             :                      condition);
     687             : 
     688          10 :     SPI_connect();
     689             : 
     690          10 :     if ((ret = SPI_exec(query_buf.data, 0)) != SPI_OK_SELECT)
     691           0 :         elog(ERROR, "xpath_table: SPI execution failed for query %s",
     692             :              query_buf.data);
     693             : 
     694          10 :     proc = SPI_processed;
     695          10 :     tuptable = SPI_tuptable;
     696          10 :     spi_tupdesc = tuptable->tupdesc;
     697             : 
     698             :     /*
     699             :      * Check that SPI returned correct result. If you put a comma into one of
     700             :      * the function parameters, this will catch it when the SPI query returns
     701             :      * e.g. 3 columns.
     702             :      */
     703          10 :     if (spi_tupdesc->natts != 2)
     704             :     {
     705           0 :         ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     706             :                         errmsg("expression returning multiple columns is not valid in parameter list"),
     707             :                         errdetail("Expected two columns in SPI result, got %d.", spi_tupdesc->natts)));
     708             :     }
     709             : 
     710             :     /*
     711             :      * Setup the parser.  This should happen after we are done evaluating the
     712             :      * query, in case it calls functions that set up libxml differently.
     713             :      */
     714          10 :     xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
     715             : 
     716          10 :     PG_TRY();
     717             :     {
     718             :         /* For each row i.e. document returned from SPI */
     719             :         uint64      i;
     720             : 
     721          20 :         for (i = 0; i < proc; i++)
     722             :         {
     723             :             char       *pkey;
     724             :             char       *xmldoc;
     725             :             xmlXPathContextPtr ctxt;
     726             :             xmlXPathObjectPtr res;
     727             :             xmlChar    *resstr;
     728             :             xmlXPathCompExprPtr comppath;
     729             :             HeapTuple   ret_tuple;
     730             : 
     731             :             /* Extract the row data as C Strings */
     732          10 :             spi_tuple = tuptable->vals[i];
     733          10 :             pkey = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
     734          10 :             xmldoc = SPI_getvalue(spi_tuple, spi_tupdesc, 2);
     735             : 
     736             :             /*
     737             :              * Clear the values array, so that not-well-formed documents
     738             :              * return NULL in all columns.  Note that this also means that
     739             :              * spare columns will be NULL.
     740             :              */
     741          30 :             for (j = 0; j < rsinfo->setDesc->natts; j++)
     742          20 :                 values[j] = NULL;
     743             : 
     744             :             /* Insert primary key */
     745          10 :             values[0] = pkey;
     746             : 
     747             :             /* Parse the document */
     748          10 :             if (xmldoc)
     749          10 :                 doctree = xmlReadMemory(xmldoc, strlen(xmldoc),
     750             :                                         NULL, NULL,
     751             :                                         XML_PARSE_NOENT);
     752             :             else                /* treat NULL as not well-formed */
     753           0 :                 doctree = NULL;
     754             : 
     755          10 :             if (doctree == NULL)
     756             :             {
     757             :                 /* not well-formed, so output all-NULL tuple */
     758           0 :                 ret_tuple = BuildTupleFromCStrings(attinmeta, values);
     759           0 :                 tuplestore_puttuple(rsinfo->setResult, ret_tuple);
     760           0 :                 heap_freetuple(ret_tuple);
     761             :             }
     762             :             else
     763             :             {
     764             :                 /* New loop here - we have to deal with nodeset results */
     765          10 :                 rownr = 0;
     766             : 
     767             :                 do
     768             :                 {
     769             :                     /* Now evaluate the set of xpaths. */
     770          16 :                     had_values = false;
     771          36 :                     for (j = 0; j < numpaths; j++)
     772             :                     {
     773          20 :                         ctxt = xmlXPathNewContext(doctree);
     774          20 :                         if (ctxt == NULL || pg_xml_error_occurred(xmlerrcxt))
     775           0 :                             xml_ereport(xmlerrcxt,
     776             :                                         ERROR, ERRCODE_OUT_OF_MEMORY,
     777             :                                         "could not allocate XPath context");
     778             : 
     779          20 :                         ctxt->node = xmlDocGetRootElement(doctree);
     780             : 
     781             :                         /* compile the path */
     782          20 :                         comppath = xmlXPathCtxtCompile(ctxt, xpaths[j]);
     783          20 :                         if (comppath == NULL || pg_xml_error_occurred(xmlerrcxt))
     784           0 :                             xml_ereport(xmlerrcxt, ERROR,
     785             :                                         ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
     786             :                                         "XPath Syntax Error");
     787             : 
     788             :                         /* Now evaluate the path expression. */
     789          20 :                         res = xmlXPathCompiledEval(comppath, ctxt);
     790          20 :                         xmlXPathFreeCompExpr(comppath);
     791             : 
     792          20 :                         if (res != NULL)
     793             :                         {
     794          20 :                             switch (res->type)
     795             :                             {
     796          20 :                                 case XPATH_NODESET:
     797             :                                     /* We see if this nodeset has enough nodes */
     798          20 :                                     if (res->nodesetval != NULL &&
     799          20 :                                         rownr < res->nodesetval->nodeNr)
     800             :                                     {
     801           8 :                                         resstr = xmlXPathCastNodeToString(res->nodesetval->nodeTab[rownr]);
     802           8 :                                         if (resstr == NULL || pg_xml_error_occurred(xmlerrcxt))
     803           0 :                                             xml_ereport(xmlerrcxt,
     804             :                                                         ERROR, ERRCODE_OUT_OF_MEMORY,
     805             :                                                         "could not allocate result");
     806           8 :                                         had_values = true;
     807             :                                     }
     808             :                                     else
     809          12 :                                         resstr = NULL;
     810             : 
     811          20 :                                     break;
     812             : 
     813           0 :                                 case XPATH_STRING:
     814           0 :                                     resstr = xmlStrdup(res->stringval);
     815           0 :                                     if (resstr == NULL || pg_xml_error_occurred(xmlerrcxt))
     816           0 :                                         xml_ereport(xmlerrcxt,
     817             :                                                     ERROR, ERRCODE_OUT_OF_MEMORY,
     818             :                                                     "could not allocate result");
     819           0 :                                     break;
     820             : 
     821           0 :                                 default:
     822           0 :                                     elog(NOTICE, "unsupported XQuery result: %d", res->type);
     823           0 :                                     resstr = xmlStrdup((const xmlChar *) "<unsupported/>");
     824           0 :                                     if (resstr == NULL || pg_xml_error_occurred(xmlerrcxt))
     825           0 :                                         xml_ereport(xmlerrcxt,
     826             :                                                     ERROR, ERRCODE_OUT_OF_MEMORY,
     827             :                                                     "could not allocate result");
     828             :                             }
     829             : 
     830             :                             /*
     831             :                              * Insert this into the appropriate column in the
     832             :                              * result tuple.
     833             :                              */
     834          20 :                             values[j + 1] = (char *) resstr;
     835             :                         }
     836          20 :                         xmlXPathFreeContext(ctxt);
     837             :                     }
     838             : 
     839             :                     /* Now add the tuple to the output, if there is one. */
     840          16 :                     if (had_values)
     841             :                     {
     842           6 :                         ret_tuple = BuildTupleFromCStrings(attinmeta, values);
     843           6 :                         tuplestore_puttuple(rsinfo->setResult, ret_tuple);
     844           6 :                         heap_freetuple(ret_tuple);
     845             :                     }
     846             : 
     847          16 :                     rownr++;
     848          16 :                 } while (had_values);
     849             :             }
     850             : 
     851          10 :             if (doctree != NULL)
     852          10 :                 xmlFreeDoc(doctree);
     853          10 :             doctree = NULL;
     854             : 
     855          10 :             if (pkey)
     856          10 :                 pfree(pkey);
     857          10 :             if (xmldoc)
     858          10 :                 pfree(xmldoc);
     859             :         }
     860             :     }
     861           0 :     PG_CATCH();
     862             :     {
     863           0 :         if (doctree != NULL)
     864           0 :             xmlFreeDoc(doctree);
     865             : 
     866           0 :         pg_xml_done(xmlerrcxt, true);
     867             : 
     868           0 :         PG_RE_THROW();
     869             :     }
     870          10 :     PG_END_TRY();
     871             : 
     872          10 :     if (doctree != NULL)
     873           0 :         xmlFreeDoc(doctree);
     874             : 
     875          10 :     pg_xml_done(xmlerrcxt, false);
     876             : 
     877          10 :     SPI_finish();
     878             : 
     879             :     /*
     880             :      * SFRM_Materialize mode expects us to return a NULL Datum. The actual
     881             :      * tuples are in our tuplestore and passed back through rsinfo->setResult.
     882             :      * rsinfo->setDesc is set to the tuple description that we actually used
     883             :      * to build our tuples with, so the caller can verify we did what it was
     884             :      * expecting.
     885             :      */
     886          10 :     return (Datum) 0;
     887             : }

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