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Fix: Tidy nov99 segfaults on some htmls

From: Victor Wagner <vitus@ice.ru>
Date: Mon, 29 Nov 1999 17:47:27 +0300 (MSK)
To: html-tidy@w3.org
Message-ID: <Pine.LNX.4.10L0.9911291744470.6631-100000@zinc.fe.msk.ru>
On Mon, 29 Nov 1999, Victor Wagner wrote:

> From: Victor Wagner <vitus@ice.ru>
> Subject: Tidy nov99 segfaults on some htmls
> 
> Dear sir,
> 
> I've downloaded latest version of html-tidy to use as preprocessor in
> our web-based publishing system, but found out that it segfaults
> on some ill-formed html. Particular piece of html was produced by
> RTF::Parser perl module ver 1.07, but I suspect that other converters
> from office formats would give simular results.
> 

Investigation shows that sometimes after DiscardElement call lexer->token
still point to the element which was just freed.

When then GetToken tries to access lexer->token->type at line 1195,
various weird things happen.
 
Following patch seems to fix problem
diff -ru tidy24nov99/lexer.c tidy-fixed/lexer.c
--- tidy24nov99/lexer.c	Wed Nov 24 17:49:34 1999
+++ tidy-fixed/lexer.c	Mon Nov 29 15:01:20 1999
@@ -1189,7 +1188,7 @@
     Bool isempty;
     AttVal *attributes;
 
-    if (lexer->pushed)
+    if (lexer->pushed && lexer->token)
     {
         /* duplicate inlines in preference to pushed text nodes when appropriate */
         if (lexer->token->type != TextNode || (!lexer->insert && !lexer->inode))
diff -ru tidy24nov99/parser.c tidy-fixed/parser.c
--- tidy24nov99/parser.c	Wed Nov 24 17:49:34 1999
+++ tidy-fixed/parser.c	Mon Nov 29 15:01:01 1999
@@ -185,6 +185,9 @@
             ReportWarning(lexer, element, null, TRIM_EMPTY_ELEMENT);
 
         DiscardElement(element);
+	if (element == lexer->token) {
+               lexer->token = NULL;
+	}     
     }
 }
 
@@ -793,6 +796,9 @@
         {
             ReportWarning(lexer, element->parent, element, DISCARDING_UNEXPECTED);
             DiscardElement(element);
+	    if (element==lexer->token) {
+		 lexer->token = NULL;
+            }		 
             return;
         }
     }
@@ -829,7 +835,9 @@
                 PopInline(lexer, node);
 
             FreeNode(node);
-
+            if (node==lexer->token) {
+                lexer->token=NULL;
+            } 		
             if (!(mode & Preformatted))
                 TrimTrailingSpace(lexer, element->last);
 
@@ -2608,6 +2616,9 @@
         /* discard unexpected tags */
         ReportWarning(lexer, body, node, DISCARDING_UNEXPECTED);
         FreeNode(node);
+	if (lexer->token == node) {
+	    lexer->token = NULL;
+	}    
     }
 }
 
--------------------------------------------------
Victor Wagner			vitus@ice.ru
Programmer			Office:7-(095)-203-50-60
Institute for Commerce 		Home: 7-(095)-135-46-61
Engineering                     http://www.ice.ru/~vitus
Received on Monday, 29 November 1999 09:47:33 GMT

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