From 35a3def7b218f2264cf34385a8487a36f96e76ec Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 26 Nov 2010 15:21:12 -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 | 166 ++++++++++++++++++++++++------------------- 1 file changed, 92 insertions(+), 74 deletions(-) diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c index 269ca73ce9..5e2a87765e 100644 --- a/contrib/xml2/xpath.c +++ b/contrib/xml2/xpath.c @@ -32,6 +32,15 @@ Datum xpath_table(PG_FUNCTION_ARGS); void elog_error(const char *explain, bool force); void pgxml_parser_init(void); +/* workspace for pgxml_xpath() */ + +typedef struct +{ + xmlDocPtr doctree; + xmlXPathContextPtr ctxt; + xmlXPathObjectPtr res; +} xpath_workspace; + /* local declarations */ static void pgxml_errorHandler(void *ctxt, const char *msg,...); @@ -45,7 +54,10 @@ 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); /* Global variables */ static char *pgxml_errorMsg = NULL; /* overall error message */ @@ -289,25 +301,22 @@ 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 */ - - toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); - septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3)); - - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + 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; xpath = pgxml_texttoxmlchar(xpathsupp); - xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath), - toptag, septag, NULL); + res = pgxml_xpath(document, xpath, &workspace); + + xpres = pgxml_result_to_text(res, toptag, septag, NULL); + + cleanup_workspace(&workspace); pfree(xpath); @@ -325,23 +334,21 @@ 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 */ - - plainsep = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2)); - - pathsize = VARSIZE(xpathsupp) - VARHDRSZ; + 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; xpath = pgxml_texttoxmlchar(xpathsupp); - xpres = pgxml_result_to_text(pgxml_xpath(PG_GETARG_TEXT_P(0), xpath), - NULL, NULL, plainsep); + res = pgxml_xpath(document, xpath, &workspace); + + xpres = pgxml_result_to_text(res, NULL, NULL, plainsep); + + cleanup_workspace(&workspace); pfree(xpath); @@ -356,13 +363,13 @@ 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; @@ -373,13 +380,16 @@ 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); @@ -394,21 +404,17 @@ 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) @@ -416,6 +422,8 @@ xpath_number(PG_FUNCTION_ARGS) fRes = xmlXPathCastToNumber(res); + cleanup_workspace(&workspace); + if (xmlXPathIsNaN(fRes)) PG_RETURN_NULL(); @@ -428,21 +436,17 @@ 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) @@ -450,6 +454,8 @@ xpath_bool(PG_FUNCTION_ARGS) bRes = xmlXPathCastToBoolean(res); + cleanup_workspace(&workspace); + PG_RETURN_BOOL(bRes); } @@ -458,48 +464,60 @@ 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); elog_error("XPath Syntax Error", true); } /* 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,