From c578bbfcfa1e136654a40c1c96d7269a62646a80 Mon Sep 17 00:00:00 2001 From: "Kyle J. McKay" Date: Sun, 14 Mar 2021 20:06:39 -0700 Subject: [PATCH] Markdown.pl: add more comment stripping options With --strip-comments-lax even strictly invalid XML comments will be stripped. With --strip-comments-lax-only only strictly invalid XML comments will be stripped. Allowing strictly invalid XML comments to pass through to the output would produce invalid XML. By default such invalid comments end up having their leading '<' escaped so that they become plain text in the output thereby avoiding making it invalid XML. However, if comments are being stripped out, there's no reason the standard cannot be relaxed a little bit since the output will remain valid XML as the comments will not be passed through to the output in that case. The two new options, --strip-comments-lax and --strip-comments-lax-only provide a choice of behavior, strip all comments including the strictly invalid ones, or just strip the strictly invalid ones. Signed-off-by: Kyle J. McKay --- Markdown.pl | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 105 insertions(+), 4 deletions(-) diff --git a/Markdown.pl b/Markdown.pl index 53a8f12..c6ef02b 100755 --- a/Markdown.pl +++ b/Markdown.pl @@ -609,7 +609,12 @@ sub _main { 'validate-xml' => sub {$cli_opts{'validate-xml'} = 1}, 'validate-xml-internal' => sub {$cli_opts{'validate-xml'} = 2}, 'no-validate-xml' => sub {$cli_opts{'validate-xml'} = 0}, - 'stripcomments|strip-comments' => \$cli_opts{'stripcomments'}, + 'stripcomments|strip-comments' => sub + {!$cli_opts{'stripcomments'} and $cli_opts{'stripcomments'} = 1}, + 'stripcommentslax|stripcomments-lax|strip-comments-lax' => + sub {$cli_opts{'stripcomments'} = 2}, + 'stripcommentslaxonly|stripcomments-laxonly|stripcomments-lax-only|strip-comments-lax-only' => + sub {$cli_opts{'stripcomments'} = 3}, 'no-stripcomments|no-strip-comments' => sub {$cli_opts{'stripcomments'} = 0}, 'keepabs|keep-abs|k' => \$cli_opts{'keepabs'}, 'absroot|a=s' => \$cli_opts{'absroot'}, @@ -990,6 +995,13 @@ sub ProcessRaw { # which gets turned into "

" which then
 #               no longer validates).
 #   stripcomments => any-false-value (no action), any-true-value (strip).
+#                 => 1 (strip), 2 (strip-lax), 3 (strip-lax-only)
+#               a non-integer true value will be forced to 1.
+#               an integer value < 0 will be forced to 1.
+#               an integer value > 3 will be forced to 3.
+#               1, 2, and 3 correspond to the command line options
+#               --strip-comments, --strip-comments-lax and
+#               --strip-comments-lax-only respectively.
 #               since the strip comments mechanism is a function of the
 #               sanitizer, if stripcomments is set to any-true-value then
 #               tag attributes will also always be sanitized.
@@ -1160,6 +1172,10 @@ sub _SanitizeOpts {
     $o->{keep_named_character_entities} = 0 unless
 	defined($o->{keep_named_character_entities}) && $o->{keep_named_character_entities} eq "1";
     $o->{xmlcheck} = looks_like_number($o->{xmlcheck}) && $o->{xmlcheck} == 0 ? 0 : 2;
+    !looks_like_number($o->{stripcomments}) and $o->{stripcomments} = $o->{stripcomments} ? 1 : 0;
+    $o->{stripcomments} && $o->{stripcomments} < 2 and $o->{stripcomments} = 1;
+    $o->{stripcomments} = int($o->{stripcomments});
+    $o->{stripcomments} > 3 and $o->{stripcomments} = 3;
     $o->{sanitize} = 1 if $o->{stripcomments} && !$o->{sanitize};
     $o->{sanitize} = 1 if $o->{xmlcheck} && !$o->{sanitize};
     $o->{sanitize} = 1 if ref($o->{urlfunc}) eq 'CODE' && !$o->{sanitize};
@@ -1626,6 +1642,7 @@ sub _HashHTMLBlocks {
 	    }eigx;
 
     # Special case for standalone XML comments:
+    $opt{stripcomments} != 2 &&
     $text =~ s{
 		(?:
 		    (?<=\n\n)	    # Starting after a blank line
@@ -1651,7 +1668,39 @@ sub _HashHTMLBlocks {
 	    }{
 		my $key = block_id($1);
 		push(@g_xml_comments, $key)
-			if $opt{stripcomments} && !exists($g_html_blocks{$key});
+			if $opt{stripcomments} && $opt{stripcomments} < 3 &&
+			   !exists($g_html_blocks{$key});
+		$g_html_blocks{$key} = $1;
+		"\n\n" . $key . "\n\n";
+	    }egx;
+
+    # Special case for standalone XML-like comments:
+    $opt{stripcomments} >= 2 &&
+    $text =~ s{
+		(?:
+		    (?<=\n\n)	    # Starting after a blank line
+		    |		    # or
+		    \A\n?	    # the beginning of the doc
+		)
+		(		    # save in $1
+		    [ ]{0,$less_than_indent}
+		    (?s:
+			
+			(?:
+			    (?:[ \t]*\n[ \t]*)?
+			    
+			)*
+		    )
+		    [ ]*
+		    (?=\n{1,}|\Z)   # followed by end of line or end of document
+		)
+	    }{
+		my $key = block_id($1);
+		push(@g_xml_comments, $key) unless exists($g_html_blocks{$key});
 		$g_html_blocks{$key} = $1;
 		"\n\n" . $key . "\n\n";
 	    }egx;
@@ -3508,9 +3557,10 @@ sub _SanitizeTags {
 	    next;
 	}
 	my $tstart = pos($text);
-	if ($text =~ /\G()/gc) {
+	if ($opt{stripcomments} != 2 &&
+	    $text =~ /\G()/gc) {
 	    # pass "comments" through unless stripping them
-	    if ($opt{stripcomments}) {
+	    if ($opt{stripcomments} && $opt{stripcomments} < 3) {
 		# strip any trailing whitespace + \n after comment if present
 		$text =~ /\G[ \t]*\n/gc;
 	    } else {
@@ -3519,6 +3569,12 @@ sub _SanitizeTags {
 	    }
 	    next;
 	}
+	if ($opt{stripcomments} >= 2 &&
+	    $text =~ /\G()/gc) {
+	    # strip any trailing whitespace + \n after lax comment if present
+	    $text =~ /\G[ \t]*\n/gc;
+	    next;
+	}
 	if ($text =~ /\G(<[^>]*>)/gc) {
 	    my $tag = $1;
 	    my $tt;
@@ -4378,6 +4434,8 @@ B [B<--help>] [B<--html4tags>] [B<--htmlroot>=I]
    --validate-xml-internal              fast basic check if output is valid XML
    --no-validate-xml                    do not check output for valid XML
    --strip-comments                     remove XML comments from output
+   --strip-comments-lax                 remove XML-like comments from output
+   --strip-comments-lax-only            remove only invalid XML-like comments
    --no-strip-comments                  do not remove XML comments (default)
    --tabwidth=num                       expand tabs to num instead of 8
    --auto-number                        automatically number h1-h6 headers
@@ -4612,6 +4670,49 @@ invalid XML comments.
 What this means is that the B<--strip-comments> option I remove
 invalid XML comments (such as S >>>)!
 
+But see the B<--strip-comments-lax> option for a solution.
+
+
+=item B<--strip-comments-lax>
+
+Strip XML-like comments from the output.  Any XML-like comments encountered
+will be omitted from the output if this option is given.  Supersedes the
+B<--strip-comments> option if both are given.
+
+While the syntax of XML comments cannot be relaxed (that would require
+altering the XML standard), if they are being stripped out anyway, then the
+standard isn't quite so relevant since they will not be present in the output.
+
+The B<--strip-comments-lax> option acts just like the B<--strip-comments>
+option EXCEPT that the content between the starting comment tag S>>
+and then ending comment tag S >>> is I restricted since it will be
+stripped out of the final result which will therefore remain XML compliant.
+
+The only restriction, of course, is that the content between the XML comment
+start tag and the XML comment end tag cannot contain the XML comment end tag
+itself.
+
+With the B<--strip-comments-lax> option, strictly invalid XML comments
+(such as S >>>) I be stripped as well as all
+strictly valid XML comments.
+
+
+=item B<--strip-comments-lax-only>
+
+This is a compromise option.  It works just like B<--strip-comments-lax>, but
+I on strictly invalid XML-like comments.  Supersedes the
+B<--strip-comments> option if both are given.
+
+In other words, if a strictly valid XML comment is present, it will be retained
+in the output.  If a strictly invalid XML comment is present which would have
+been stripped by B<--strip-comments-lax> but would have had its leading C<< < >>
+escaped automatically by the default B<--no-strip-comments> mode (because it's
+not a strictly valid XML comment), then it will be stripped by this mode.
+
+This option avoids ugly invalid XML comments from slipping through into the
+output as escaped plain text while still passing through valid XML comments
+without stripping them.
+
 
 =item B<--no-strip-comments>