libextractor

html_extractor.c (8780B)

---

 /*
      This file is part of libextractor.
      Copyright (C) 2002, 2003, 2004, 2005, 2009, 2012 Vidyut Samanta and Christian Grothoff
 
      libextractor 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 2, or (at your
      option) any later version.
 
      libextractor 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 libextractor; see the file COPYING.  If not, write to the
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
 
  */
 /**
  * @file plugins/html_extractor.c
  * @brief plugin to support HTML files
  * @author Christian Grothoff
  */
 #include "platform.h"
 #include "extractor.h"
 #include <magic.h>
 #if HAVE_TIDY_H
 #include <tidy.h>
 #include <tidybuffio.h>
 #elif HAVE_TIDY_TIDY_H
 #include <tidy/tidy.h>
 #include <tidy/tidybuffio.h>
 #else
 Broken build, fix tidy detection.
 #endif
 
 /**
  * Mapping of HTML META names to LE types.
  */
 static struct
 {
   /**
    * HTML META name.
    */
   const char *name;
 
   /**
    * Corresponding LE type.
    */
   enum EXTRACTOR_MetaType type;
 } tagmap[] = {
   { "author", EXTRACTOR_METATYPE_AUTHOR_NAME },
   { "dc.author", EXTRACTOR_METATYPE_AUTHOR_NAME },
   { "title", EXTRACTOR_METATYPE_TITLE },
   { "dc.title", EXTRACTOR_METATYPE_TITLE},
   { "description", EXTRACTOR_METATYPE_DESCRIPTION },
   { "dc.description", EXTRACTOR_METATYPE_DESCRIPTION },
   { "subject", EXTRACTOR_METATYPE_SUBJECT},
   { "dc.subject", EXTRACTOR_METATYPE_SUBJECT},
   { "date", EXTRACTOR_METATYPE_UNKNOWN_DATE },
   { "dc.date", EXTRACTOR_METATYPE_UNKNOWN_DATE},
   { "publisher", EXTRACTOR_METATYPE_PUBLISHER },
   { "dc.publisher", EXTRACTOR_METATYPE_PUBLISHER},
   { "rights", EXTRACTOR_METATYPE_RIGHTS },
   { "dc.rights", EXTRACTOR_METATYPE_RIGHTS },
   { "copyright", EXTRACTOR_METATYPE_COPYRIGHT },
   { "language", EXTRACTOR_METATYPE_LANGUAGE },
   { "keywords", EXTRACTOR_METATYPE_KEYWORDS },
   { "abstract", EXTRACTOR_METATYPE_ABSTRACT },
   { "formatter", EXTRACTOR_METATYPE_CREATED_BY_SOFTWARE },
   { "dc.creator", EXTRACTOR_METATYPE_CREATOR},
   { "dc.identifier", EXTRACTOR_METATYPE_URI },
   { "dc.format", EXTRACTOR_METATYPE_FORMAT },
   { NULL, EXTRACTOR_METATYPE_RESERVED }
 };
 
 
 /**
  * Global handle to MAGIC data.
  */
 static magic_t magic;
 
 
 /**
  * Map 'meta' tag to LE type.
  *
  * @param tag tag to map
  * @return EXTRACTOR_METATYPE_RESERVED if the type was not found
  */
 static enum EXTRACTOR_MetaType
 tag_to_type (const char *tag)
 {
   unsigned int i;
 
   for (i = 0; NULL != tagmap[i].name; i++)
     if (0 == strcasecmp (tag,
                          tagmap[i].name))
       return tagmap[i].type;
   return EXTRACTOR_METATYPE_RESERVED;
 }
 
 
 /**
  * Function called by libtidy for error reporting.
  *
  * @param doc tidy doc being processed
  * @param lvl report level
  * @param line input line
  * @param col input column
  * @param mssg message
  * @return FALSE (no output)
  */
 static Bool TIDY_CALL
 report_cb (TidyDoc doc,
            TidyReportLevel lvl,
            uint line,
            uint col,
            ctmbstr mssg)
 {
   return 0;
 }
 
 
 /**
  * Input callback: get next byte of input.
  *
  * @param sourceData our 'struct EXTRACTOR_ExtractContext'
  * @return next byte of input, EndOfStream on errors and EOF
  */
 static int TIDY_CALL
 get_byte_cb (void *sourceData)
 {
   struct EXTRACTOR_ExtractContext *ec = sourceData;
   void *data;
 
   if (1 !=
       ec->read (ec->cls,
                 &data, 1))
     return EndOfStream;
   return *(unsigned char*) data;
 }
 
 
 /**
  * Input callback: unget last byte of input.
  *
  * @param sourceData our 'struct EXTRACTOR_ExtractContext'
  * @param bt byte to unget (ignored)
  */
 static void TIDY_CALL
 unget_byte_cb (void *sourceData, byte bt)
 {
   struct EXTRACTOR_ExtractContext *ec = sourceData;
 
   (void) ec->seek (ec->cls, -1, SEEK_CUR);
 }
 
 
 /**
  * Input callback: check for EOF.
  *
  * @param sourceData our 'struct EXTRACTOR_ExtractContext'
  * @return true if we are at the EOF
  */
 static Bool TIDY_CALL
 eof_cb (void *sourceData)
 {
   struct EXTRACTOR_ExtractContext *ec = sourceData;
 
   return ec->seek (ec->cls, 0, SEEK_CUR) == ec->get_size (ec->cls);
 }
 
 
 /**
  * Main entry method for the 'text/html' extraction plugin.
  *
  * @param ec extraction context provided to the plugin
  */
 void
 EXTRACTOR_html_extract_method (struct EXTRACTOR_ExtractContext *ec);
 
 void
 EXTRACTOR_html_extract_method (struct EXTRACTOR_ExtractContext *ec)
 {
   TidyDoc doc;
   TidyNode head;
   TidyNode child;
   TidyNode title;
   TidyInputSource src;
   const char *name;
   TidyBuffer tbuf;
   TidyAttr attr;
   enum EXTRACTOR_MetaType type;
   ssize_t iret;
   void *data;
   const char *mime;
 
   if (-1 == (iret = ec->read (ec->cls,
                               &data,
                               16 * 1024)))
     return;
   if (NULL == (mime = magic_buffer (magic, data, iret)))
     return;
   if (0 != strncmp (mime,
                     "text/html",
                     strlen ("text/html")))
     return; /* not HTML */
 
   if (0 != ec->seek (ec->cls, 0, SEEK_SET))
     return; /* seek failed !? */
 
   tidyInitSource (&src, ec,
                   &get_byte_cb,
                   &unget_byte_cb,
                   &eof_cb);
   if (NULL == (doc = tidyCreate ()))
     return;
   tidySetReportFilter (doc, &report_cb);
   tidySetAppData (doc, ec);
   if (0 > tidyParseSource (doc, &src))
   {
     tidyRelease (doc);
     return;
   }
   if (1 != tidyStatus (doc))
   {
     tidyRelease (doc);
     return;
   }
   if (NULL == (head = tidyGetHead (doc)))
   {
     tidyRelease (doc);
     return;
   }
   for (child = tidyGetChild (head); NULL != child; child = tidyGetNext (child))
   {
     switch (tidyNodeGetType (child))
     {
     case TidyNode_Root:
       break;
     case TidyNode_DocType:
       break;
     case TidyNode_Comment:
       break;
     case TidyNode_ProcIns:
       break;
     case TidyNode_Text:
       break;
     case TidyNode_CDATA:
       break;
     case TidyNode_Section:
       break;
     case TidyNode_Asp:
       break;
     case TidyNode_Jste:
       break;
     case TidyNode_Php:
       break;
     case TidyNode_XmlDecl:
       break;
     case TidyNode_Start:
     case TidyNode_StartEnd:
       name = tidyNodeGetName (child);
       if (NULL == name)
         break;
       if ( (0 == strcasecmp (name, "title")) &&
            (NULL != (title = tidyGetChild (child))) )
       {
         tidyBufInit (&tbuf);
         tidyNodeGetValue (doc, title, &tbuf);
         /* add 0-termination */
         tidyBufPutByte (&tbuf, 0);
         if (0 !=
             ec->proc (ec->cls,
                       "html",
                       EXTRACTOR_METATYPE_TITLE,
                       EXTRACTOR_METAFORMAT_UTF8,
                       "text/plain",
                       (const char *) tbuf.bp,
                       tbuf.size))
         {
           tidyBufFree (&tbuf);
           goto CLEANUP;
         }
         tidyBufFree (&tbuf);
         break;
       }
       if (0 == strcasecmp (name, "meta"))
       {
         if (NULL == (attr = tidyAttrGetById (child,
                                              TidyAttr_NAME)))
           break;
         name = tidyAttrValue (attr);
         if (NULL == name)
           break;
         if (EXTRACTOR_METATYPE_RESERVED ==
             (type = tag_to_type (name)))
           break;
         if (NULL == (attr = tidyAttrGetById (child,
                                              TidyAttr_CONTENT)))
           break;
         name = tidyAttrValue (attr);
         if (NULL == name)
           break;
         if (0 !=
             ec->proc (ec->cls,
                       "html",
                       type,
                       EXTRACTOR_METAFORMAT_UTF8,
                       "text/plain",
                       name,
                       strlen (name) + 1))
           goto CLEANUP;
         break;
       }
       break;
     case TidyNode_End:
       break;
     default:
       break;
     }
   }
 CLEANUP:
   tidyRelease (doc);
 }
 
 
 /**
  * Initialize glib and load magic file.
  */
 void __attribute__ ((constructor))
 html_gobject_init (void);
 
 void __attribute__ ((constructor))
 html_gobject_init ()
 {
   magic = magic_open (MAGIC_MIME_TYPE);
   if (0 != magic_load (magic, NULL))
   {
     /* FIXME: how to deal with errors? */
   }
 }
 
 
 /**
  * Destructor for the library, cleans up.
  */
 void __attribute__ ((destructor))
 html_ltdl_fini (void);
 
 void __attribute__ ((destructor))
 html_ltdl_fini ()
 {
   if (NULL != magic)
   {
     magic_close (magic);
     magic = NULL;
   }
 }
 
 
 /* end of html_extractor.c */