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Fix significant memory leak in contrib/xml2 functions.

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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.
REL8_2_STABLE
Tom Lane 15 years ago
parent eaf0766d74
commit cfb6ac6ba2
1 changed files with 90 additions and 72 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 162
      contrib/xml2/xpath.c

162
contrib/xml2/xpath.c
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@ -35,6 +35,15 @@ 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,...);
@ -48,7 +57,10 @@ 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 */
@ -292,25 +304,22 @@ 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);
@ -328,23 +337,21 @@ 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);
@ -359,13 +366,13 @@ 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;
@ -376,13 +383,16 @@ 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);
@ -397,21 +407,17 @@ 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)
@ -419,6 +425,8 @@ xpath_number(PG_FUNCTION_ARGS)
fRes = xmlXPathCastToNumber(res);
cleanup_workspace(&workspace);
if (xmlXPathIsNaN(fRes))
PG_RETURN_NULL();
@ -431,21 +439,17 @@ 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)
@ -453,6 +457,8 @@ xpath_bool(PG_FUNCTION_ARGS)
bRes = xmlXPathCastToBoolean(res);
cleanup_workspace(&workspace);
PG_RETURN_BOOL(bRes);
}
@ -461,48 +467,60 @@ 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,

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