From e6fa73e87a3f3aeb4694ad3d20a179fb76e12ce1 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 26 Nov 2010 15:20:55 -0500 Subject: [PATCH] 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. --- contrib/xml2/xpath.c | 162 ++++++++++++++++++++++++++++----------------------- 1 file changed, 90 insertions(+), 72 deletions(-) diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c index dbf0b76f92..853dd1f8b3 100644 --- a/contrib/xml2/xpath.c +++ b/contrib/xml2/xpath.c @@ -40,6 +40,15 @@ Datum xpath_table(PG_FUNCTION_ARGS); void pgxml_parser_init(void); +/* workspace for pgxml_xpath() */ + +typedef struct +{ + xmlDocPtr doctree; + xmlXPathContextPtr ctxt; + xmlXPathObjectPtr res; +} xpath_workspace; + /* local declarations */ static xmlChar *pgxmlNodeSetToText(xmlNodeSetPtr nodeset, @@ -51,7 +60,10 @@ static text *pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag, static xmlChar *pgxml_texttoxmlchar(text *textstring); -static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath); +static xmlXPathObjectPtr pgxml_xpath(text *document, xmlChar *xpath, + xpath_workspace *workspace); + +static void cleanup_workspace(xpath_workspace *workspace); /* @@ -214,25 +226,22 @@ PG_FUNCTION_INFO_V1(xpath_nodeset); Datum xpath_nodeset(PG_FUNCTION_ARGS) { - xmlChar *xpath, - *toptag, - *septag; - int32 pathsize; - text *xpathsupp, - *xpres; - - /* PG_GETARG_TEXT_P(0) is document buffer */ - xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ + text *document = PG_GETARG_TEXT_P(0); + text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ + xmlChar *toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); + xmlChar *septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3)); + xmlChar *xpath; + text *xpres; + xmlXPathObjectPtr res; + xpath_workspace workspace; - toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); - septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3)); + xpath = pgxml_texttoxmlchar(xpathsupp); - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + res = pgxml_xpath(document, xpath, &workspace); - xpath = pgxml_texttoxmlchar(xpathsupp); + xpres = pgxml_result_to_text(res, toptag, septag, NULL); - xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath), - toptag, septag, NULL); + cleanup_workspace(&workspace); pfree(xpath); @@ -250,23 +259,21 @@ PG_FUNCTION_INFO_V1(xpath_list); Datum xpath_list(PG_FUNCTION_ARGS) { - xmlChar *xpath, - *plainsep; - int32 pathsize; - text *xpathsupp, - *xpres; - - /* PG_GETARG_TEXT_P(0) is document buffer */ - xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ + text *document = PG_GETARG_TEXT_P(0); + text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ + xmlChar *plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); + xmlChar *xpath; + text *xpres; + xmlXPathObjectPtr res; + xpath_workspace workspace; - plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); + xpath = pgxml_texttoxmlchar(xpathsupp); - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + res = pgxml_xpath(document, xpath, &workspace); - xpath = pgxml_texttoxmlchar(xpathsupp); + xpres = pgxml_result_to_text(res, NULL, NULL, plainsep); - xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath), - NULL, NULL, plainsep); + cleanup_workspace(&workspace); pfree(xpath); @@ -281,13 +288,13 @@ PG_FUNCTION_INFO_V1(xpath_string); Datum xpath_string(PG_FUNCTION_ARGS) { + text *document = PG_GETARG_TEXT_P(0); + text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ xmlChar *xpath; int32 pathsize; - text *xpathsupp, - *xpres; - - /* PG_GETARG_TEXT_P(0) is document buffer */ - xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ + text *xpres; + xmlXPathObjectPtr res; + xpath_workspace workspace; pathsize = VARSIZE(xpathsupp) - VARHDRSZ; @@ -298,13 +305,16 @@ xpath_string(PG_FUNCTION_ARGS) /* We could try casting to string using the libxml function? */ xpath = (xmlChar *) palloc(pathsize + 9); - memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize); strncpy((char *) xpath, "string(", 7); + memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize); xpath[pathsize + 7] = ')'; xpath[pathsize + 8] = '\0'; - xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath), - NULL, NULL, NULL); + res = pgxml_xpath(document, xpath, &workspace); + + xpres = pgxml_result_to_text(res, NULL, NULL, NULL); + + cleanup_workspace(&workspace); pfree(xpath); @@ -319,21 +329,17 @@ PG_FUNCTION_INFO_V1(xpath_number); Datum xpath_number(PG_FUNCTION_ARGS) { + text *document = PG_GETARG_TEXT_P(0); + text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ xmlChar *xpath; - int32 pathsize; - text *xpathsupp; float4 fRes; - xmlXPathObjectPtr res; - - /* PG_GETARG_TEXT_P(0) is document buffer */ - xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ - - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + xpath_workspace workspace; xpath = pgxml_texttoxmlchar(xpathsupp); - res = pgxml_xpath(PG_GETARG_TEXT_P(0), xpath); + res = pgxml_xpath(document, xpath, &workspace); + pfree(xpath); if (res == NULL) @@ -341,6 +347,8 @@ xpath_number(PG_FUNCTION_ARGS) fRes = xmlXPathCastToNumber(res); + cleanup_workspace(&workspace); + if (xmlXPathIsNaN(fRes)) PG_RETURN_NULL(); @@ -353,21 +361,17 @@ PG_FUNCTION_INFO_V1(xpath_bool); Datum xpath_bool(PG_FUNCTION_ARGS) { + text *document = PG_GETARG_TEXT_P(0); + text *xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ xmlChar *xpath; - int32 pathsize; - text *xpathsupp; int bRes; - xmlXPathObjectPtr res; - - /* PG_GETARG_TEXT_P(0) is document buffer */ - xpathsupp = PG_GETARG_TEXT_P(1); /* XPath expression */ - - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + xpath_workspace workspace; xpath = pgxml_texttoxmlchar(xpathsupp); - res = pgxml_xpath(PG_GETARG_TEXT_P(0), xpath); + res = pgxml_xpath(document, xpath, &workspace); + pfree(xpath); if (res == NULL) @@ -375,6 +379,8 @@ xpath_bool(PG_FUNCTION_ARGS) bRes = xmlXPathCastToBoolean(res); + cleanup_workspace(&workspace); + PG_RETURN_BOOL(bRes); } @@ -383,49 +389,61 @@ xpath_bool(PG_FUNCTION_ARGS) /* Core function to evaluate XPath query */ static xmlXPathObjectPtr -pgxml_xpath(text *document, xmlChar *xpath) +pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace) { - xmlDocPtr doctree; - xmlXPathContextPtr ctxt; + int32 docsize = VARSIZE(document) - VARHDRSZ; xmlXPathObjectPtr res; xmlXPathCompExprPtr comppath; - int32 docsize; - docsize = VARSIZE(document) - VARHDRSZ; + workspace->doctree = NULL; + workspace->ctxt = NULL; + workspace->res = NULL; pgxml_parser_init(); - doctree = xmlParseMemory((char *) VARDATA(document), docsize); - if (doctree == NULL) + workspace->doctree = xmlParseMemory((char *) VARDATA(document), docsize); + if (workspace->doctree == NULL) return NULL; /* not well-formed */ - ctxt = xmlXPathNewContext(doctree); - ctxt->node = xmlDocGetRootElement(doctree); + workspace->ctxt = xmlXPathNewContext(workspace->doctree); + workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree); /* compile the path */ comppath = xmlXPathCompile(xpath); if (comppath == NULL) { - xmlFreeDoc(doctree); + cleanup_workspace(workspace); xml_ereport(ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION, "XPath Syntax Error"); } /* Now evaluate the path expression. */ - res = xmlXPathCompiledEval(comppath, ctxt); + res = xmlXPathCompiledEval(comppath, workspace->ctxt); + workspace->res = res; + xmlXPathFreeCompExpr(comppath); if (res == NULL) - { - xmlXPathFreeContext(ctxt); - xmlFreeDoc(doctree); + cleanup_workspace(workspace); - return NULL; - } - /* xmlFreeDoc(doctree); */ return res; } +/* Clean up after processing the result of pgxml_xpath() */ +static void +cleanup_workspace(xpath_workspace *workspace) +{ + if (workspace->res) + xmlXPathFreeObject(workspace->res); + workspace->res = NULL; + if (workspace->ctxt) + xmlXPathFreeContext(workspace->ctxt); + workspace->ctxt = NULL; + if (workspace->doctree) + xmlFreeDoc(workspace->doctree); + workspace->doctree = NULL; +} + static text * pgxml_result_to_text(xmlXPathObjectPtr res, xmlChar *toptag, -- 2.11.0