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Improve buffer allocation scheme

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In most places, we really need the double-it scheme to avoid quadratic
behavior. The hybrid scheme still can cause many reallocations and the
bounded scheme doesn't seem to provide meaningful protection in
xmlreader.c.
This commit is contained in:
Nick Wellnhofer 2022-03-05 21:46:40 +01:00
parent 422176ad29
commit d99ddd9bd5
6 changed files with 23 additions and 10 deletions
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1
parser.c
View File

@ -8068,6 +8068,7 @@ xmlLoadEntityContent(xmlParserCtxtPtr ctxt, xmlEntityPtr entity) {
"xmlLoadEntityContent parameter error");
return(-1);
}
xmlBufferSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
input = xmlNewEntityInputStream(ctxt, entity);
if (input == NULL) {

3
runsuite.c
View File

@ -325,6 +325,7 @@ xsdIncorrectTestCase(xmlNodePtr cur) {
fprintf(stderr, "out of memory !\n");
fatalError();
}
xmlBufferSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlNodeDump(buf, test->doc, test, 0, 0);
pctxt = xmlRelaxNGNewMemParserCtxt((const char *)buf->content, buf->use);
xmlRelaxNGSetParserErrors(pctxt, testErrorHandler, testErrorHandler,
@ -363,6 +364,7 @@ installResources(xmlNodePtr tst, const xmlChar *base) {
fprintf(stderr, "out of memory !\n");
fatalError();
}
xmlBufferSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlNodeDump(buf, tst->doc, tst, 0, 0);
while (tst != NULL) {
@ -458,6 +460,7 @@ xsdTestCase(xmlNodePtr tst) {
fprintf(stderr, "out of memory !\n");
fatalError();
}
xmlBufferSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlNodeDump(buf, test->doc, test, 0, 0);
pctxt = xmlRelaxNGNewMemParserCtxt((const char *)buf->content, buf->use);
xmlRelaxNGSetParserErrors(pctxt, testErrorHandler, testErrorHandler,

7
tree.c
View File

@ -1284,7 +1284,7 @@ xmlStringLenGetNodeList(const xmlDoc *doc, const xmlChar *value, int len) {
buf = xmlBufCreateSize(0);
if (buf == NULL) return(NULL);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_HYBRID);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
q = cur;
while ((cur < end) && (*cur != 0)) {
@ -1505,7 +1505,7 @@ xmlStringGetNodeList(const xmlDoc *doc, const xmlChar *value) {
buf = xmlBufCreateSize(0);
if (buf == NULL) return(NULL);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_HYBRID);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
q = cur;
while (*cur != 0) {
@ -5559,6 +5559,7 @@ xmlNodeGetContent(const xmlNode *cur)
buf = xmlBufCreateSize(64);
if (buf == NULL)
return (NULL);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlBufGetNodeContent(buf, cur);
ret = xmlBufDetach(buf);
xmlBufFree(buf);
@ -5584,6 +5585,7 @@ xmlNodeGetContent(const xmlNode *cur)
buf = xmlBufCreate();
if (buf == NULL)
return (NULL);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlBufGetNodeContent(buf, cur);
@ -5606,6 +5608,7 @@ xmlNodeGetContent(const xmlNode *cur)
buf = xmlBufCreate();
if (buf == NULL)
return (NULL);
xmlBufSetAllocationScheme(buf, XML_BUFFER_ALLOC_DOUBLEIT);
xmlBufGetNodeContent(buf, (xmlNodePtr) cur);

5
xmlIO.c
View File

@ -2389,10 +2389,7 @@ xmlAllocOutputBuffer(xmlCharEncodingHandlerPtr encoder) {
xmlFree(ret);
return(NULL);
}
/* try to avoid a performance problem with Windows realloc() */
if (xmlBufGetAllocationScheme(ret->buffer) == XML_BUFFER_ALLOC_EXACT)
xmlBufSetAllocationScheme(ret->buffer, XML_BUFFER_ALLOC_DOUBLEIT);
xmlBufSetAllocationScheme(ret->buffer, XML_BUFFER_ALLOC_DOUBLEIT);
ret->encoder = encoder;
if (encoder != NULL) {

13
xmlreader.c
View File

@ -1180,6 +1180,7 @@ xmlTextReaderCollectSiblings(xmlNodePtr node)
buffer = xmlBufferCreate();
if (buffer == NULL)
return NULL;
xmlBufferSetAllocationScheme(buffer, XML_BUFFER_ALLOC_DOUBLEIT);
for ( ; node != NULL; node = node->next) {
switch (node->type) {
@ -1633,11 +1634,14 @@ xmlTextReaderReadInnerXml(xmlTextReaderPtr reader ATTRIBUTE_UNUSED)
buff = xmlBufferCreate();
if (buff == NULL)
return NULL;
xmlBufferSetAllocationScheme(buff, XML_BUFFER_ALLOC_DOUBLEIT);
for (cur_node = reader->node->children; cur_node != NULL;
cur_node = cur_node->next) {
/* XXX: Why is the node copied? */
node = xmlDocCopyNode(cur_node, doc, 1);
/* XXX: Why do we need a second buffer? */
buff2 = xmlBufferCreate();
xmlBufferSetAllocationScheme(buff2, XML_BUFFER_ALLOC_DOUBLEIT);
if (xmlNodeDump(buff2, doc, node, 0, 0) == -1) {
xmlFreeNode(node);
xmlBufferFree(buff2);
@ -1687,6 +1691,7 @@ xmlTextReaderReadOuterXml(xmlTextReaderPtr reader ATTRIBUTE_UNUSED)
node = xmlDocCopyNode(node, doc, 1);
}
buff = xmlBufferCreate();
xmlBufferSetAllocationScheme(buff, XML_BUFFER_ALLOC_DOUBLEIT);
if (xmlNodeDump(buff, doc, node, 0, 0) == -1) {
xmlFreeNode(node);
xmlBufferFree(buff);
@ -2017,7 +2022,7 @@ xmlNewTextReader(xmlParserInputBufferPtr input, const char *URI) {
}
/* no operation on a reader should require a huge buffer */
xmlBufSetAllocationScheme(ret->buffer,
XML_BUFFER_ALLOC_BOUNDED);
XML_BUFFER_ALLOC_DOUBLEIT);
ret->sax = (xmlSAXHandler *) xmlMalloc(sizeof(xmlSAXHandler));
if (ret->sax == NULL) {
xmlBufFree(ret->buffer);
@ -3555,7 +3560,7 @@ xmlTextReaderConstValue(xmlTextReaderPtr reader) {
return (NULL);
}
xmlBufSetAllocationScheme(reader->buffer,
XML_BUFFER_ALLOC_BOUNDED);
XML_BUFFER_ALLOC_DOUBLEIT);
} else
xmlBufEmpty(reader->buffer);
xmlBufGetNodeContent(reader->buffer, node);
@ -3565,7 +3570,7 @@ xmlTextReaderConstValue(xmlTextReaderPtr reader) {
xmlBufFree(reader->buffer);
reader->buffer = xmlBufCreateSize(100);
xmlBufSetAllocationScheme(reader->buffer,
XML_BUFFER_ALLOC_BOUNDED);
XML_BUFFER_ALLOC_DOUBLEIT);
ret = BAD_CAST "";
}
return(ret);
@ -5079,7 +5084,7 @@ xmlTextReaderSetup(xmlTextReaderPtr reader,
}
/* no operation on a reader should require a huge buffer */
xmlBufSetAllocationScheme(reader->buffer,
XML_BUFFER_ALLOC_BOUNDED);
XML_BUFFER_ALLOC_DOUBLEIT);
if (reader->sax == NULL)
reader->sax = (xmlSAXHandler *) xmlMalloc(sizeof(xmlSAXHandler));
if (reader->sax == NULL) {

4
xmlsave.c
View File

@ -474,6 +474,7 @@ xmlBufDumpNotationTable(xmlBufPtr buf, xmlNotationTablePtr table) {
*/
return;
}
xmlBufferSetAllocationScheme(buffer, XML_BUFFER_ALLOC_DOUBLEIT);
xmlDumpNotationTable(buffer, table);
xmlBufMergeBuffer(buf, buffer);
}
@ -497,6 +498,7 @@ xmlBufDumpElementDecl(xmlBufPtr buf, xmlElementPtr elem) {
*/
return;
}
xmlBufferSetAllocationScheme(buffer, XML_BUFFER_ALLOC_DOUBLEIT);
xmlDumpElementDecl(buffer, elem);
xmlBufMergeBuffer(buf, buffer);
}
@ -520,6 +522,7 @@ xmlBufDumpAttributeDecl(xmlBufPtr buf, xmlAttributePtr attr) {
*/
return;
}
xmlBufferSetAllocationScheme(buffer, XML_BUFFER_ALLOC_DOUBLEIT);
xmlDumpAttributeDecl(buffer, attr);
xmlBufMergeBuffer(buf, buffer);
}
@ -542,6 +545,7 @@ xmlBufDumpEntityDecl(xmlBufPtr buf, xmlEntityPtr ent) {
*/
return;
}
xmlBufferSetAllocationScheme(buffer, XML_BUFFER_ALLOC_DOUBLEIT);
xmlDumpEntityDecl(buffer, ent);
xmlBufMergeBuffer(buf, buffer);
}