libextractor

GNU libextractor
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extractor_plugins.h (3323B)

      1 /*
      2      This file is part of libextractor.
      3      Copyright (C) 2002, 2003, 2004, 2005, 2006, 2009, 2012 Vidyut Samanta and Christian Grothoff
      4 
      5      libextractor is free software; you can redistribute it and/or modify
      6      it under the terms of the GNU General Public License as published
      7      by the Free Software Foundation; either version 3, or (at your
      8      option) any later version.
      9 
     10      libextractor is distributed in the hope that it will be useful, but
     11      WITHOUT ANY WARRANTY; without even the implied warranty of
     12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13      General Public License for more details.
     14 
     15      You should have received a copy of the GNU General Public License
     16      along with libextractor; see the file COPYING.  If not, write to the
     17      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     18      Boston, MA 02110-1301, USA.
     19  */
     20 /**
     21  * @file main/extractor_plugins.h
     22  * @brief code to load plugins
     23  * @author Christian Grothoff
     24  */
     25 #ifndef EXTRACTOR_PLUGINS_H
     26 #define EXTRACTOR_PLUGINS_H
     27 
     28 #include "platform.h"
     29 #include "extractor.h"
     30 #include <signal.h>
     31 #include <ltdl.h>
     32 
     33 
     34 /**
     35  * Linked list of extractor plugins.  An application builds this list
     36  * by telling libextractor to load various meta data extraction
     37  * plugins.  Plugins can also be unloaded (removed from this list,
     38  * see EXTRACTOR_plugin_remove).
     39  */
     40 struct EXTRACTOR_PluginList
     41 {
     42   /**
     43    * This is a linked list.
     44    */
     45   struct EXTRACTOR_PluginList *next;
     46 
     47   /**
     48    * Pointer to the plugin (as returned by lt_dlopen).
     49    */
     50   void *libraryHandle;
     51 
     52   /**
     53    * Name of the library (i.e., 'libextractor_foo.so')
     54    */
     55   char *libname;
     56 
     57   /**
     58    * Short name of the plugin (i.e., 'foo')
     59    */
     60   char *short_libname;
     61 
     62   /**
     63    * Pointer to the function used for meta data extraction.
     64    */
     65   EXTRACTOR_extract_method extract_method;
     66 
     67   /**
     68    * Options for the plugin.
     69    */
     70   char *plugin_options;
     71 
     72   /**
     73    * Special options for the plugin
     74    * (as returned by the plugin's "options" method;
     75    * typically NULL).
     76    */
     77   const char *specials;
     78 
     79   /**
     80    * Channel to communicate with out-of-process plugin, NULL if not setup.
     81    */
     82   struct EXTRACTOR_Channel *channel;
     83 
     84   /**
     85    * Memory segment shared with the channel of this plugin, NULL for none.
     86    */
     87   struct EXTRACTOR_SharedMemory *shm;
     88 
     89   /**
     90    * A position this plugin wants us to seek to. -1 if it's finished.
     91    * A positive value from the end of the file is used of 'whence' is
     92    * SEEK_END; a postive value from the start is used of 'whence' is
     93    * SEEK_SET.  'SEEK_CUR' is never used.
     94    */
     95   int64_t seek_request;
     96 
     97   /**
     98    * Flags to control how the plugin is executed.
     99    */
    100   enum EXTRACTOR_Options flags;
    101 
    102   /**
    103    * Is this plugin finished extracting for this round?
    104    * 0: no, 1: yes
    105    */
    106   int round_finished;
    107 
    108   /**
    109    * 'whence' value for the seek operation;
    110    * 0 = SEEK_SET, 1 = SEEK_CUR, 2 = SEEK_END.
    111    * Note that 'SEEK_CUR' is never used here.
    112    */
    113   uint16_t seek_whence;
    114 
    115 };
    116 
    117 
    118 /**
    119  * Load a plugin.
    120  *
    121  * @param plugin plugin to load
    122  * @return 0 on success, -1 on error
    123  */
    124 int
    125 EXTRACTOR_plugin_load_ (struct EXTRACTOR_PluginList *plugin);
    126 
    127 #endif /* EXTRACTOR_PLUGINS_H */