mirror of https://github.com/postgres/postgres
Fix significant memory leak in contrib/xml2 functions.
Most of the functions that execute XPath queries leaked the data structures created by libxml2. This memory would not be recovered until end of session, so it mounts up pretty quickly in any serious use of the feature. Per report from Pavel Stehule, though this isn't his patch. Back-patch to all supported branches.
This commit is contained in:
Tom Lane
parent
268da29219
commit
35a3def7b2
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@ -32,6 +32,15 @@ Datum xpath_table(PG_FUNCTION_ARGS);
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void elog_error(const char *explain, bool force);
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void pgxml_parser_init(void);
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/* workspace for pgxml_xpath() */
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typedef struct
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{
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xmlDocPtr doctree;
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xmlXPathContextPtr ctxt;
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xmlXPathObjectPtr res;
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} xpath_workspace;
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/* local declarations */
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static void pgxml_errorHandler(void *ctxt, const char *msg,...);
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@ -45,7 +54,10 @@ static text *pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag,
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static xmlChar *pgxml_texttoxmlchar(text *textstring);
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static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath);
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static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath,
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xpath_workspace *workspace);
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static void cleanup_workspace(xpath_workspace *workspace);
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/* Global variables */
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static char *pgxml_errorMsg = NULL; /* overall error message */
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@ -289,25 +301,22 @@ PG_FUNCTION_INFO_V1(xpath_nodeset);
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Datum
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xpath_nodeset(PG_FUNCTION_ARGS)
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{
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xmlChar *xpath,
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*toptag,
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*septag;
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int32 pathsize;
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text *xpathsupp,
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*xpres;
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/* PG_GETARG_TEXT_P(0) is document buffer */
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xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2));
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septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3));
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pathsize = VARSIZE(xpathsupp) - VARHDRSZ;
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text *document = PG_GETARG_TEXT_P(0);
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text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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xmlChar *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2));
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xmlChar *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3));
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xmlChar *xpath;
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
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toptag, septag, NULL);
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, toptag, septag, NULL);
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cleanup_workspace(&workspace);
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pfree(xpath);
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@ -325,23 +334,21 @@ PG_FUNCTION_INFO_V1(xpath_list);
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Datum
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xpath_list(PG_FUNCTION_ARGS)
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{
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xmlChar *xpath,
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*plainsep;
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int32 pathsize;
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text *xpathsupp,
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*xpres;
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/* PG_GETARG_TEXT_P(0) is document buffer */
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xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2));
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pathsize = VARSIZE(xpathsupp) - VARHDRSZ;
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text *document = PG_GETARG_TEXT_P(0);
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text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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xmlChar *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2));
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xmlChar *xpath;
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
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NULL, NULL, plainsep);
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, NULL, NULL, plainsep);
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cleanup_workspace(&workspace);
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pfree(xpath);
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@ -356,13 +363,13 @@ PG_FUNCTION_INFO_V1(xpath_string);
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Datum
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xpath_string(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_P(0);
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text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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xmlChar *xpath;
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int32 pathsize;
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text *xpathsupp,
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*xpres;
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/* PG_GETARG_TEXT_P(0) is document buffer */
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xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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text *xpres;
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xmlXPathObjectPtr res;
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xpath_workspace workspace;
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pathsize = VARSIZE(xpathsupp) - VARHDRSZ;
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@ -373,13 +380,16 @@ xpath_string(PG_FUNCTION_ARGS)
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/* We could try casting to string using the libxml function? */
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xpath = (xmlChar *) palloc(pathsize + 9);
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memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize);
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strncpy((char *) xpath, "string(", 7);
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memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize);
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xpath[pathsize + 7] = ')';
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xpath[pathsize + 8] = '\0';
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xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
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NULL, NULL, NULL);
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res = pgxml_xpath(document, xpath, &workspace);
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xpres = pgxml_result_to_text(res, NULL, NULL, NULL);
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cleanup_workspace(&workspace);
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pfree(xpath);
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@ -394,21 +404,17 @@ PG_FUNCTION_INFO_V1(xpath_number);
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Datum
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xpath_number(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_P(0);
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text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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xmlChar *xpath;
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int32 pathsize;
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text *xpathsupp;
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float4 fRes;
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xmlXPathObjectPtr res;
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/* PG_GETARG_TEXT_P(0) is document buffer */
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xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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pathsize = VARSIZE(xpathsupp) - VARHDRSZ;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(PG_GETARG_TEXT_P(0), xpath);
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res = pgxml_xpath(document, xpath, &workspace);
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pfree(xpath);
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if (res == NULL)
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@ -416,6 +422,8 @@ xpath_number(PG_FUNCTION_ARGS)
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fRes = xmlXPathCastToNumber(res);
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cleanup_workspace(&workspace);
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if (xmlXPathIsNaN(fRes))
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PG_RETURN_NULL();
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@ -428,21 +436,17 @@ PG_FUNCTION_INFO_V1(xpath_bool);
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Datum
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xpath_bool(PG_FUNCTION_ARGS)
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{
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text *document = PG_GETARG_TEXT_P(0);
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text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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xmlChar *xpath;
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int32 pathsize;
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text *xpathsupp;
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int bRes;
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xmlXPathObjectPtr res;
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/* PG_GETARG_TEXT_P(0) is document buffer */
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xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */
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pathsize = VARSIZE(xpathsupp) - VARHDRSZ;
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xpath_workspace workspace;
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xpath = pgxml_texttoxmlchar(xpathsupp);
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res = pgxml_xpath(PG_GETARG_TEXT_P(0), xpath);
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res = pgxml_xpath(document, xpath, &workspace);
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pfree(xpath);
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if (res == NULL)
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@ -450,6 +454,8 @@ xpath_bool(PG_FUNCTION_ARGS)
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bRes = xmlXPathCastToBoolean(res);
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cleanup_workspace(&workspace);
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PG_RETURN_BOOL(bRes);
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}
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@ -458,48 +464,60 @@ xpath_bool(PG_FUNCTION_ARGS)
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/* Core function to evaluate XPath query */
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static xmlXPathObjectPtr
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pgxml_xpath(text *document, xmlChar *xpath)
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pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
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{
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xmlDocPtr doctree;
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xmlXPathContextPtr ctxt;
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int32 docsize = VARSIZE(document) - VARHDRSZ;
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xmlXPathObjectPtr res;
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xmlXPathCompExprPtr comppath;
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int32 docsize;
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docsize = VARSIZE(document) - VARHDRSZ;
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workspace->doctree = NULL;
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workspace->ctxt = NULL;
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workspace->res = NULL;
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pgxml_parser_init();
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doctree = xmlParseMemory((char *) VARDATA(document), docsize);
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if (doctree == NULL)
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workspace->doctree = xmlParseMemory((char *) VARDATA(document), docsize);
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if (workspace->doctree == NULL)
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return NULL; /* not well-formed */
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ctxt = xmlXPathNewContext(doctree);
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ctxt->node = xmlDocGetRootElement(doctree);
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workspace->ctxt = xmlXPathNewContext(workspace->doctree);
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workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);
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/* compile the path */
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comppath = xmlXPathCompile(xpath);
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if (comppath == NULL)
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{
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xmlFreeDoc(doctree);
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cleanup_workspace(workspace);
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elog_error("XPath Syntax Error", true);
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}
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/* Now evaluate the path expression. */
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res = xmlXPathCompiledEval(comppath, ctxt);
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res = xmlXPathCompiledEval(comppath, workspace->ctxt);
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workspace->res = res;
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xmlXPathFreeCompExpr(comppath);
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if (res == NULL)
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{
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xmlXPathFreeContext(ctxt);
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xmlFreeDoc(doctree);
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cleanup_workspace(workspace);
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return NULL;
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}
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/* xmlFreeDoc(doctree); */
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return res;
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}
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/* Clean up after processing the result of pgxml_xpath() */
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static void
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cleanup_workspace(xpath_workspace *workspace)
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{
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if (workspace->res)
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xmlXPathFreeObject(workspace->res);
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workspace->res = NULL;
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if (workspace->ctxt)
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xmlXPathFreeContext(workspace->ctxt);
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workspace->ctxt = NULL;
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if (workspace->doctree)
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xmlFreeDoc(workspace->doctree);
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workspace->doctree = NULL;
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}
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static text *
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pgxml_result_to_text(xmlXPathObjectPtr res,
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xmlChar *toptag,
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