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From b20d746fa7cbb74716171bc49d836af99927e41e Mon Sep 17 00:00:00 2001
From: Mike Dalessio <mike.dalessio@gmail.com>
Date: Sun, 11 Oct 2020 14:15:37 -0400
Subject: [PATCH 2/2] use new htmlParseLookupCommentEnd to find comment ends
Note that the caret in error messages generated during comment parsing
may have moved by one byte.
See guidance provided on incorrectly-closed comments here:
https://html.spec.whatwg.org/multipage/parsing.html#parse-error-incorrectly-closed-comment
---
HTMLparser.c | 46 +++++++++++++++++++++++++++++++++++++---------
1 file changed, 37 insertions(+), 9 deletions(-)
diff --git a/HTMLparser.c b/HTMLparser.c
index 4d43479..000dc3d 100644
--- a/HTMLparser.c
+++ b/HTMLparser.c
@@ -5331,6 +5331,39 @@ htmlParseLookupChars(htmlParserCtxtPtr ctxt, const xmlChar * stop,
return (-1);
}
+/**
+ * htmlParseLookupCommentEnd:
+ * @ctxt: an HTML parser context
+ *
+ * Try to find a comment end tag in the input stream
+ * The search includes "-->" as well as WHATWG-recommended incorrectly-closed tags.
+ * (See https://html.spec.whatwg.org/multipage/parsing.html#parse-error-incorrectly-closed-comment)
+ * This function has a side effect of (possibly) incrementing ctxt->checkIndex
+ * to avoid rescanning sequences of bytes, it DOES change the state of the
+ * parser, do not use liberally.
+ * This wraps to htmlParseLookupSequence()
+ *
+ * Returns the index to the current parsing point if the full sequence is available, -1 otherwise.
+ */
+static int
+htmlParseLookupCommentEnd(htmlParserCtxtPtr ctxt)
+{
+ int mark = 0;
+ int cur = CUR_PTR - BASE_PTR;
+
+ while (mark >= 0) {
+ mark = htmlParseLookupSequence(ctxt, '-', '-', 0, 1, 1);
+ if ((mark < 0) ||
+ (NXT(mark+2) == '>') ||
+ ((NXT(mark+2) == '!') && (NXT(mark+3) == '>'))) {
+ return mark;
+ }
+ ctxt->checkIndex = cur + mark + 1;
+ }
+ return mark;
+}
+
+
/**
* htmlParseTryOrFinish:
* @ctxt: an HTML parser context
@@ -5507,8 +5540,7 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
cur = in->cur[0];
if ((cur == '<') && (next == '!') &&
(in->cur[2] == '-') && (in->cur[3] == '-')) {
- if ((!terminate) &&
- (htmlParseLookupSequence(ctxt, '-', '-', '>', 1, 1) < 0))
+ if ((!terminate) && (htmlParseLookupCommentEnd(ctxt) < 0))
goto done;
#ifdef DEBUG_PUSH
xmlGenericError(xmlGenericErrorContext,
@@ -5567,8 +5599,7 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
next = in->cur[1];
if ((cur == '<') && (next == '!') &&
(in->cur[2] == '-') && (in->cur[3] == '-')) {
- if ((!terminate) &&
- (htmlParseLookupSequence(ctxt, '-', '-', '>', 1, 1) < 0))
+ if ((!terminate) && (htmlParseLookupCommentEnd(ctxt) < 0))
goto done;
#ifdef DEBUG_PUSH
xmlGenericError(xmlGenericErrorContext,
@@ -5614,8 +5645,7 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
next = in->cur[1];
if ((cur == '<') && (next == '!') &&
(in->cur[2] == '-') && (in->cur[3] == '-')) {
- if ((!terminate) &&
- (htmlParseLookupSequence(ctxt, '-', '-', '>', 1, 1) < 0))
+ if ((!terminate) && (htmlParseLookupCommentEnd(ctxt) < 0))
goto done;
#ifdef DEBUG_PUSH
xmlGenericError(xmlGenericErrorContext,
@@ -5871,9 +5901,7 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
htmlParseDocTypeDecl(ctxt);
} else if ((cur == '<') && (next == '!') &&
(in->cur[2] == '-') && (in->cur[3] == '-')) {
- if ((!terminate) &&
- (htmlParseLookupSequence(
- ctxt, '-', '-', '>', 1, 1) < 0))
+ if ((!terminate) && (htmlParseLookupCommentEnd(ctxt) < 0))
goto done;
#ifdef DEBUG_PUSH
xmlGenericError(xmlGenericErrorContext,
--
2.25.1
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