[svn] Introduce non-strict comment parsing.

NEWS

@@ -19,7 +19,7 @@ data.
 
 ** Download speed shown by the progress bar is based on the data
 recently read, rather than the average speed of the entire download.
-The ETA is still based on the average speed, though.
+The ETA projection is still based on the overall average.
 
 ** It is now possible to connect to FTP servers through FWTK
 firewalls.  Set ftp_proxy to an FTP URL, and Wget will automatically
@@ -39,6 +39,17 @@ characters such as space.  You can use the new option
 --restrict-file-names to relax or strengthen these rules, which can be
 useful if you dislike the default or if you're downloading to
 non-native partitions.
+
+** Handling of HTML comments has been dumbed down to conform to what
+users expect and other browsers do: instead of being treated as SGML
+declaration, a comment is terminated at the first occurrence of "-->".
+Use `--strict-comments' to revert to the old behavior.
+
+** Wget now correctly handles relative URIs that begin with "//", such
+as "//img.foo.com/foo.jpg".
+
+** Boolean options in `.wgetrc' and on the command line now accept
+values "yes" and "no" along with the traditional "on" and "off".
 
 * Wget 1.8.2 is a bugfix release with no user-visible changes.
 

doc/wget.texi

@@ -1365,6 +1365,40 @@ To finish off this topic, it's worth knowing that Wget's idea of an
 external document link is any URL specified in an @code{<A>} tag, an
 @code{<AREA>} tag, or a @code{<LINK>} tag other than @code{<LINK
 REL="stylesheet">}.
+
+@cindex HTML comments
+@cindex comments, HTML
+@item --strict-comments
+Turn on strict parsing of HTML comments.  The default is to terminate
+comments at the first occurrence of @samp{-->}.
+
+According to specifications, HTML comments are expressed as SGML
+@dfn{declarations}.  Declaration is special markup that begins with
+@samp{<!} and ends with @samp{>}, such as @samp{<!DOCTYPE ...>}, that
+may contain comments between a pair of @samp{--} delimiters.  HTML
+comments are ``empty declarations'', SGML declarations without any
+non-comment text.  Therefore, @samp{<!--foo-->} is a valid comment, and
+so is @samp{<!--one-- --two-->}, but @samp{<!--1--2-->} is not.
+
+On the other hand, most HTML writers don't perceive comments as anything
+other than text delimited with @samp{<!--} and @samp{-->}, which is not
+quite the same.  For example, something like @samp{<!------------>}
+works as a valid comment as long as the number of dashes is a multiple
+of four (!).  If not, the comment technically lasts until the next
+@samp{--}, which may be at the other end of the document.  Because of
+this, many popular browsers completely ignore the specification and
+implement what users have come to expect: comments delimited with
+@samp{<!--} and @samp{-->}.
+
+Until version 1.9, Wget interpreted comments strictly, which resulted in
+missing links in many web pages that displayed fine in browsers, but had
+the misfortune of containing non-compliant comments.  Beginning with
+version 1.9, Wget has joined the ranks of clients that implements
+``naive'' comments, terminating each comment at the first occurrence of
+@samp{-->}.
+
+If, for whatever reason, you want strict comment parsing, use this
+option to turn it on.
 @end table
 
 @node Recursive Accept/Reject Options,  , Recursive Retrieval Options, Invoking
@@ -2306,6 +2340,9 @@ responses---the same as @samp{-S}.
 @item span_hosts = on/off
 Same as @samp{-H}.
 
+@item strict_comments = on/off
+Same as @samp{--strict-comments}.
+
 @item timeout = @var{n}
 Set timeout value---the same as @samp{-T}.
 

src/ChangeLog

@@ -1,3 +1,12 @@
+2003-09-19  Hrvoje Niksic  <hniksic@xemacs.org>
+
+	* main.c (main): New option --strict-comments.
+
+	* html-parse.c (find_comment_end): New function: simple BM search
+	for "-->".
+	(map_html_tags): Use it if looking at a comment and not in strict
+	comments mode.
+
 2003-09-17  Aurelien Marchand  <artaxerxes@users.sf.net>
 
 	* ftp.h: Added OS400 system in enum

src/html-parse.c

@@ -1,5 +1,5 @@
 /* HTML parser for Wget.
-   Copyright (C) 1998, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1998, 2000, 2003 Free Software Foundation, Inc.
 
 This file is part of GNU Wget.
 
@@ -344,7 +344,7 @@ array_allowed (const char **array, const char *beg, const char *end)
   return 1;
 }
 
-/* Originally we used to adhere to RFC1866 here, and allowed only
+/* Originally we used to adhere to rfc 1866 here, and allowed only
    letters, digits, periods, and hyphens as names (of tags or
    attributes).  However, this broke too many pages which used
    proprietary or strange attributes, e.g. <img src="a.gif"
@@ -362,29 +362,13 @@ array_allowed (const char **array, const char *beg, const char *end)
 #define NAME_CHAR_P(x) ((x) > 32 && (x) < 127				\
 			&& (x) != '=' && (x) != '>' && (x) != '/')
 
-/* States while advancing through comments. */
-#define AC_S_DONE	0
-#define AC_S_BACKOUT	1
-#define AC_S_BANG	2
-#define AC_S_DEFAULT	3
-#define AC_S_DCLNAME	4
-#define AC_S_DASH1	5
-#define AC_S_DASH2	6
-#define AC_S_COMMENT	7
-#define AC_S_DASH3	8
-#define AC_S_DASH4	9
-#define AC_S_QUOTE1	10
-#define AC_S_IN_QUOTE	11
-#define AC_S_QUOTE2	12
-
 #ifdef STANDALONE
 static int comment_backout_count;
 #endif
 
-/* Advance over an SGML declaration (the <!...> forms you find in HTML
+/* Advance over an SGML declaration, such as <!DOCTYPE ...>.  In
-   documents).  The function returns the location after the
+   strict comments mode, this is used for skipping over comments as
-   declaration.  The reason we need this is that HTML comments are
+   well.
-   expressed as comments in so-called "empty declarations".
 
    To recap: any SGML declaration may have comments associated with
    it, e.g.
@@ -398,17 +382,31 @@ static int comment_backout_count;
        <!-- have -- -- fun -->
 
    Whitespace is allowed between and after the comments, but not
-   before the first comment.
+   before the first comment.  Additionally, this function attempts to
+   handle double quotes in SGML declarations correctly.  */
 
-   Additionally, this function attempts to handle double quotes in
-   SGML declarations correctly.  */
 static const char *
 advance_declaration (const char *beg, const char *end)
 {
   const char *p = beg;
   char quote_char = '\0';	/* shut up, gcc! */
   char ch;
-  int state = AC_S_BANG;
+
+  enum {
+    AC_S_DONE,
+    AC_S_BACKOUT,
+    AC_S_BANG,
+    AC_S_DEFAULT,
+    AC_S_DCLNAME,
+    AC_S_DASH1,
+    AC_S_DASH2,
+    AC_S_COMMENT,
+    AC_S_DASH3,
+    AC_S_DASH4,
+    AC_S_QUOTE1,
+    AC_S_IN_QUOTE,
+    AC_S_QUOTE2,
+  } state = AC_S_BANG;
 
   if (beg == end)
     return beg;
@@ -547,6 +545,55 @@ advance_declaration (const char *beg, const char *end)
     }
   return p;
 }
+
+/* Find the first occurrence of the substring "-->" in [BEG, END) and
+   return the pointer to the character after the substring.  If the
+   substring is not found, return NULL.  */
+
+static const char *
+find_comment_end (const char *beg, const char *end)
+{
+  /* Open-coded Boyer-Moore search for "-->".  Examine the third char;
+     if it's not '>' or '-', advance by three characters.  Otherwise,
+     look at the preceding characters and try to find a match.  */
+
+  const char *p = beg - 1;
+
+  while ((p += 3) < end)
+    switch (p[0])
+      {
+      case '>':
+	if (p[-1] == '-' && p[-2] == '-')
+	  return p + 1;
+	break;
+      case '-':
+      at_dash:
+	if (p[-1] == '-')
+	  {
+	  at_dash_dash:
+	    if (++p == end) return NULL;
+	    switch (p[0])
+	      {
+	      case '>': return p + 1;
+	      case '-': goto at_dash_dash;
+	      }
+	  }
+	else
+	  {
+	    if ((p += 2) >= end) return NULL;
+	    switch (p[0])
+	      {
+	      case '>':
+		if (p[-1] == '-')
+		  return p + 1;
+		break;
+	      case '-':
+		goto at_dash;
+	      }
+	  }
+      }
+  return NULL;
+}
 
 /* Advance P (a char pointer), with the explicit intent of being able
    to read the next character.  If this is not possible, go to finish.  */
@@ -638,8 +685,26 @@ map_html_tags (const char *text, int size,
        declaration).  */
     if (*p == '!')
       {
-	/* This is an SGML declaration -- just skip it.  */
+	if (!opt.strict_comments
+	    && p < end + 3 && p[1] == '-' && p[2] == '-')
+	  {
+	    /* If strict comments are not enforced and if we know
+	       we're looking at a comment, simply look for the
+	       terminating "-->".  Non-strict is the default because
+	       it works in other browsers and most HTML writers can't
+	       be bothered with getting the comments right.  */
+	    const char *comment_end = find_comment_end (p + 3, end);
+	    if (comment_end)
+	      p = comment_end;
+	  }
+	else
+	  {
+	    /* Either in strict comment mode or looking at a non-empty
+	       declaration.  Real declarations are much less likely to
+	       be misused the way comments are, so advance over them
+	       properly regardless of strictness.  */
 	    p = advance_declaration (p, end);
+	  }
 	if (p == end)
 	  goto finish;
 	goto look_for_tag;

src/init.c

@@ -207,6 +207,7 @@ static struct {
   { "sslcheckcert",	&opt.sslcheckcert,	cmd_number },
   { "sslprotocol",	&opt.sslprotocol,	cmd_number },
 #endif /* HAVE_SSL */
+  { "strictcomments",	&opt.strict_comments,	cmd_boolean },
   { "timeout",		&opt.timeout,		cmd_time },
   { "timestamping",	&opt.timestamping,	cmd_boolean },
   { "tries",		&opt.ntry,		cmd_number_inf },

src/main.c

@@ -239,6 +239,7 @@ Recursive retrieval:\n\
   -K,  --backup-converted   before converting file X, back up as X.orig.\n\
   -m,  --mirror             shortcut option equivalent to -r -N -l inf -nr.\n\
   -p,  --page-requisites    get all images, etc. needed to display HTML page.\n\
+       --strict-comments    turn on strict (SGML) handling of HTML comments.\n\
 \n"), stdout);
   fputs (_("\
 Recursive accept/reject:\n\
@@ -302,6 +303,7 @@ main (int argc, char *const *argv)
     { "server-response", no_argument, NULL, 'S' },
     { "span-hosts", no_argument, NULL, 'H' },
     { "spider", no_argument, NULL, 132 },
+    { "strict-comments", no_argument, NULL, 177 },
     { "timestamping", no_argument, NULL, 'N' },
     { "verbose", no_argument, NULL, 'v' },
     { "version", no_argument, NULL, 'V' },
@@ -524,6 +526,9 @@ GNU General Public License for more details.\n"));
 	case 174:
 	  setval ("retryconnrefused", "on");
 	  break;
+	case 177:
+	  setval ("strictcomments", "on");
+	  break;
 
 	  /* Options accepting an argument: */
 	case 129:

src/options.h

@@ -192,6 +192,9 @@ struct options
   int restrict_files_ctrl;	/* non-zero if control chars in URLs
 				   are restricted from appearing in
 				   generated file names. */
+
+  int strict_comments;		/* whether strict SGML comments are
+				   enforced.  */
 };
 
 extern struct options opt;