New filter: htmlent

* include/mailutils/filter.h (mu_htmlent_filter): New extern.
* libmailutils/filter/Makefile.am: Add htmlent.c
* libmailutils/filter/filter.c (mu_filter_get_list): Register mu_htmlent_filter.
* libmailutils/filter/htmlent.c: New file.
* libmailutils/tests/htmlent.at: New testcase.
* libmailutils/tests/Makefile.am: Add new testcase.
* libmailutils/tests/testsuite.at: Likewise.

@@ -124,6 +124,7 @@ extern mu_filter_record_t mu_linecon_filter;
 extern mu_filter_record_t mu_linelen_filter;
 extern mu_filter_record_t mu_iconv_filter;
 extern mu_filter_record_t mu_c_escape_filter;
+extern mu_filter_record_t mu_htmlent_filter;
   
 enum mu_iconv_fallback_mode
   {

@@ -29,6 +29,7 @@ libfilter_la_SOURCES =\
  fltchain.c\
  fromflt.c\
  header.c\
+ htmlent.c\
  iconvflt.c\
  inline-comment.c\
  linecon.c\

@@ -84,6 +84,7 @@ mu_filter_get_list (mu_list_t *plist)
       mu_list_append (filter_list, mu_linelen_filter);
       mu_list_append (filter_list, mu_iconv_filter);
       mu_list_append (filter_list, mu_c_escape_filter);
+      mu_list_append (filter_list, mu_htmlent_filter);
       /* FIXME: add the default encodings?  */
     }
   *plist = filter_list;

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2014 Free Software Foundation, Inc.
+
+   This library is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <mailutils/errno.h>
+#include <mailutils/filter.h>
+
+/* The "htmlent" filter converts the following special HTML entities:
+
+    Decode       Encode
+   ---------+------------- 
+      <     +     &lt;
+      >     +     &gt;
+      &     +     &amp;
+ */
+
+struct transcode_map
+{
+  const char *ent;
+  size_t len;
+  int ch;
+};
+
+/* Note: entries in this array must be lexicographically sorted by the
+   ent member. */
+static struct transcode_map transcode_map[] = {
+#define S(s) s, sizeof(s) - 1
+  { S("&amp;"), '&' },
+  { S("&gt;"), '>' },
+  { S("&lt;"), '<' },
+#undef S
+  { NULL }
+};
+
+static struct transcode_map *
+ch2ent (int c)
+{
+  struct transcode_map *p;
+
+  for (p = transcode_map; p->ent; p++) 
+    {
+      if (p->ch == c)
+	return p;
+    }
+  return NULL;
+}
+
+struct htmlent_encode_state
+{
+  char buf[6];
+  int idx;
+};
+
+static enum mu_filter_result
+_htmlent_encoder (void *xd,
+		  enum mu_filter_command cmd,
+		  struct mu_filter_io *iobuf)
+{
+  struct htmlent_encode_state *cp = xd;
+  const char *iptr;
+  size_t isize;
+  char *optr;
+  size_t osize;
+
+  switch (cmd)
+    {
+    case mu_filter_init:
+      cp->idx = -1;
+      return mu_filter_ok;
+      
+    case mu_filter_done:
+      return mu_filter_ok;
+      
+    default:
+      break;
+    }
+
+  iptr = iobuf->input;
+  isize = iobuf->isize;
+  optr = iobuf->output;
+  osize = iobuf->osize;
+
+  while (isize && osize)
+    {
+      if (cp->idx > 0)
+	{
+	  *optr++ = cp->buf[--cp->idx];
+	  --osize;
+	}
+      else
+	{
+	  struct transcode_map *p;
+	  int c = *iptr++;
+	  --isize;
+	  
+	  p = ch2ent (c);
+	  if (p)
+	    {
+	      char const *q = p->ent + p->len;
+	      cp->idx = 0;
+	      while (q > p->ent)
+		cp->buf[cp->idx++] = *--q;
+	    }
+	  else
+	    {
+	      *optr++ = c;
+	      --osize;
+	    }
+	}
+    }
+  iobuf->isize -= isize;
+  iobuf->osize -= osize;
+
+  return mu_filter_ok;
+}
+
+enum htmlent_decode_phase
+  {
+    enc_init,
+    enc_map,
+    enc_rollback,
+    enc_finish
+  };
+
+struct htmlent_decode_state
+{
+  enum htmlent_decode_phase phase;
+  struct transcode_map *map;
+  int idx;
+  int pos;
+};
+
+#define DECODE_INIT(s)				\
+  do						\
+    {						\
+      (s)->phase = enc_init;			\
+      (s)->map = transcode_map;			\
+      (s)->idx = 0;				\
+    }						\
+  while (0)
+
+static enum htmlent_decode_phase
+nextchar (struct htmlent_decode_state *s, int c)
+{
+  if (c == s->map->ent[s->idx])
+    {
+      if (++s->idx == s->map->len)
+	s->phase = enc_finish;
+      else
+	s->phase = enc_map;
+    }
+  else
+    {
+      struct transcode_map *map;
+      
+      for (map = s->map; map->ent && c > map->ent[s->idx]; map++)
+	;
+      if (map->ent == NULL || c != map->ent[s->idx])
+	{
+	  if (s->idx != 0)
+	    { 
+	      s->phase = enc_rollback;
+	      s->pos = 0;
+	    }
+	  else
+	    DECODE_INIT (s);
+	}
+      else
+	{
+	  s->map = map;
+	  if (++s->idx == s->map->len)
+	    s->phase = enc_finish;
+	  else
+	    s->phase = enc_map;
+	}
+    }
+  return s->phase;
+}
+
+static enum mu_filter_result
+_htmlent_decoder (void *xd,
+		  enum mu_filter_command cmd,
+		  struct mu_filter_io *iobuf)
+{
+  struct htmlent_decode_state *cp = xd;
+  const char *iptr;
+  size_t isize;
+  char *optr;
+  size_t osize;
+
+  switch (cmd)
+    {
+    case mu_filter_init:
+      DECODE_INIT (cp);
+      return mu_filter_ok;
+      
+    case mu_filter_done:
+      return mu_filter_ok;
+      
+    default:
+      break;
+    }
+
+  iptr = iobuf->input;
+  isize = iobuf->isize;
+  optr = iobuf->output;
+  osize = iobuf->osize;
+
+  while (isize && osize)
+    {
+      switch (cp->phase)
+	{
+	case enc_init:
+	  nextchar (cp, *iptr);
+	  if (cp->phase == enc_init)
+	    {
+	      *optr++ = *iptr;
+	      --osize;
+	    }
+	  ++iptr;
+	  --isize;
+	  break;
+	      
+	case enc_map:
+	  nextchar (cp, *iptr);
+	  if (cp->phase == enc_map || cp->phase == enc_finish)
+	    {
+	      ++iptr;
+	      --isize;
+	    }
+	  else if (cp->phase == enc_init)
+	    {
+	      *optr++ = *iptr++;
+	      --osize;
+	      --isize;
+	    }
+	  break;
+
+	case enc_finish:
+	  *optr++ = cp->map->ch;
+	  --osize;
+	  DECODE_INIT (cp);
+	  break;
+	  
+	case enc_rollback:
+	  *optr++ = cp->map->ent[cp->pos];
+	  --osize;
+	  if (++cp->pos == cp->idx)
+	    DECODE_INIT (cp);
+	  break;
+	}	  
+    }      
+  iobuf->isize -= isize;
+  iobuf->osize -= osize;
+
+  return mu_filter_ok;  
+}
+
+static int
+alloc_state (void **pret, int mode, int argc MU_ARG_UNUSED,
+	     const char **argv MU_ARG_UNUSED)
+{
+  union
+  {
+    struct htmlent_decode_state decode;
+    struct htmlent_encode_state encode;
+  } *cp;
+    
+
+  switch (mode)
+    {
+    case MU_FILTER_ENCODE:
+      cp = malloc (sizeof (cp->encode));
+      if (!cp)
+	return ENOMEM;
+      cp->encode.idx = -1;
+      break;
+
+    case MU_FILTER_DECODE:
+      cp = malloc (sizeof (cp->decode));
+      if (!cp)
+	return ENOMEM;
+      cp->decode.idx = 0;
+      cp->decode.map = transcode_map;
+      break;
+
+    default:
+      abort ();
+    }
+      
+  *pret = cp;
+  return 0;
+}
+
+static struct _mu_filter_record _htmlent_filter = {
+  "htmlent",
+  alloc_state,
+  _htmlent_encoder,
+  _htmlent_decoder,
+};
+
+mu_filter_record_t mu_htmlent_filter = &_htmlent_filter;
+

@@ -89,6 +89,7 @@ TESTSUITE_AT = \
  fsfolder01.at\
  fsfolder02.at\
  hdrflt.at\
+ htmlent.at\
  imapio.at\
  inline-comment.at\
  linecon.at\

+# This file is part of GNU Mailutils. -*- Autotest -*-
+# Copyright (C) 2014 Free Software Foundation, Inc.
+#
+# GNU Mailutils is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 3, or (at
+# your option) any later version.
+#
+# GNU Mailutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([htmlent filter])
+
+AT_KEYWORDS([filter decode encode htmlent])
+
+AT_CHECK([fltst htmlent encode read <<EOT
+<html>
+<head>
+ <title>Foo</title>
+</head>
+<body>
+  Text & more text
+</body>
+</html>
+EOT
+],
+[0],
+[&lt;html&gt;
+&lt;head&gt;
+ &lt;title&gt;Foo&lt;/title&gt;
+&lt;/head&gt;
+&lt;body&gt;
+  Text &amp; more text
+&lt;/body&gt;
+&lt;/html&gt;
+])
+
+AT_CHECK([fltst htmlent decode read <<EOT
+&lt;html&gt;
+&lt;head&gt;
+ &lt;title&gt;Foo&lt;/title&gt;
+&lt;/head&gt;
+&lt;body&gt;
+  Text &amp; more text
+&lt;/body&gt;
+&lt;/html&gt;
+EOT
+],
+[0],
+[<html>
+<head>
+ <title>Foo</title>
+</head>
+<body>
+  Text & more text
+</body>
+</html>
+])
+
+AT_CHECK([fltst htmlent decode read <<EOT
+&lt;&gt;&ampersand&amp;&gter
+EOT
+],
+[0],
+[<>&ampersand&&gter
+])
+
+AT_CLEANUP

@@ -85,6 +85,7 @@ m4_include([fromflt.at])
 m4_include([inline-comment.at])
 m4_include([hdrflt.at])
 m4_include([linecon.at])
+m4_include([htmlent.at])
 
 AT_BANNER(Debug Specification)
 m4_include([debugspec.at])