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Postgres FD Implementation
Commit 4a2516a7 authored by Tom Lane's avatar Tom Lane
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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.
parent e6e38b4a
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Inline Side-by-side
Showing with 90 additions and 72 deletions
contrib/xml2/xpath.c
View file @ 4a2516a7
......@@ -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);
/*
......@@ -221,25 +233,22 @@ 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);
......@@ -257,23 +266,21 @@ 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);
......@@ -288,13 +295,13 @@ 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;
......@@ -305,13 +312,16 @@ 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);
......@@ -326,21 +336,17 @@ 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)
......@@ -348,6 +354,8 @@ xpath_number(PG_FUNCTION_ARGS)
fRes = xmlXPathCastToNumber(res);
cleanup_workspace(&workspace);
if (xmlXPathIsNaN(fRes))
PG_RETURN_NULL();
......@@ -360,21 +368,17 @@ 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)
......@@ -382,6 +386,8 @@ xpath_bool(PG_FUNCTION_ARGS)
bRes = xmlXPathCastToBoolean(res);
cleanup_workspace(&workspace);
PG_RETURN_BOOL(bRes);
}
......@@ -390,49 +396,61 @@ 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,
......
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