libextractor-python

extractor.py (6531B)

---

 # -*- coding: utf-8 -*-
 # Python bindings for GNU libextractor
 #
 # Copyright (C) 2006 Bader Ladjemi <bader@tele2.fr>
 # Copyright (C) 2011 Christian Grothoff <christian@grothoff.org>
 # Copyright (C) 2017, 2018 Nikita Gillmann <nikita@n0.is>
 #
 # This program 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 of the License, or
 # (at your option) any later version.
 #
 # This program 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 this program; see the file COPYING. If not, write to the
 # Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
 # USA.
 
 """
 Python bindings for GNU libextractor
 
 libextractor is a simple library for keyword extraction.  libextractor
 does not support all formats but supports a simple plugging mechanism
 such that you can quickly add extractors for additional formats, even
 without recompiling libextractor. libextractor typically ships with a
 dozen helper-libraries that can be used to obtain keywords from common
 file-types.
 
 libextractor is a part of the GNU project (http://www.gnu.org/).
 """
 from ctypes import *
 from ctypes import CDLL
 from ctypes.util import find_library
 import os
 import logging
 import faulthandler
 
 faulthandler.enable()
 
 # Can be useful:
 # "DYLD_LIBRARY_PATH" in os.environ
 
 # fake cdll import
 # loading shared object file
 try:
     if os.uname()[0] == 'Linux':
         libextractor = CDLL('libextractor.so.3')
     elif os.uname()[0] == 'Linux':
         libextractor = cdll.LoadLibrary(find_library('libextractor.so.3'))
     else:
         libextractor = cdll.extractor
 except:
     raise ImportError("Could not find shared 'libextractor' library.")
 
 
 __all__ = ['Extractor']
 __version__ = "1.7"
 __licence__ = "GNU GPL"
 
 """
 keyword's charset encoding
 """
 KeywordType = c_int
 MetaType = c_int
 
 EXTRACT_CB = CFUNCTYPE(c_int, c_void_p, c_char_p, KeywordType, MetaType, c_char_p, c_void_p, c_size_t)
 
 libextractor.EXTRACTOR_metatype_get_max.restype = KeywordType
 libextractor.EXTRACTOR_metatype_to_description.restype = c_char_p
 libextractor.EXTRACTOR_metatype_to_string.restype = c_char_p
 libextractor.EXTRACTOR_plugin_add_defaults.restype = c_void_p
 libextractor.EXTRACTOR_extract.argtypes = [c_void_p, c_char_p, c_void_p, c_size_t, EXTRACT_CB, c_void_p]
 
 
 EXTRACTOR_METAFORMAT_UNKNOWN = 0
 EXTRACTOR_METAFORMAT_UTF8 = 1
 EXTRACTOR_METAFORMAT_BINARY = 2
 EXTRACTOR_METAFORMAT_C_STRING = 3
 
 
 class Extractor(object):
     """
     Main class for extracting meta-data with GNU libextractor.
 
     You may create multiple instances of Extractor to use
     different sets of library.  Initially each Extractor
     will start with the default set of libraries.
 
     Use the extract method to obtain keywords from a file.
 
     Use the add and remove libraries methods to change the list of
     libraries that should be used.
     """
 
     def __init__(self, defaults=True, libraries=None):
         """
         Initialize Extractor's instance
 
         @param libraries: list of strings that contains extractor's name (supported types)
         @param defaults: load default plugins
         """
         self.extractors = None
         if defaults:
             self.extractors = libextractor.EXTRACTOR_plugin_add_defaults(0)
         if libraries:
             self.extractors = libextractor.EXTRACTOR_plugin_add_config(self.extractors, libraries, 0)
 
     def extract(self, proc, proc_cls, filename=None, data=None, size=0):
         """
         Extract keywords from a file, or from its data.
 
         @param filename: filename string
         @param data: data contents
         @param size: data size
         @param proc: function to call on each value
         @param proc_cls: closure to proc
 
         If you give data, size has to be given as well.
 
         """
         if not filename and not (data and size):
             return None
         else:
             libextractor.EXTRACTOR_extract(self.extractors, filename, data, size, EXTRACT_CB(proc), proc_cls)
 
     def addLibrary(self, library):
         """
         Add given library to the extractor. Invoke with a string with the name
         of the library that should be added.  For example,
 
         'libextractor_filename'
 
         will prepend the extractor that just adds the filename as a
         keyword.
 
         No errors are reported if the library is not
         found.
 
         @param library: library's name
         """
         self.extractors = libextractor.EXTRACTOR_plugin_add(self.extractors, library, NULL, 0)
 
     def removeLibrary(self, library):
         """
         Remove a library.  Pass the name of the library that is to
         be removed.  Only one library can be removed at a time.
         For example,
 
         'libextractor_pdf'
 
         removes the PDF extractor (if added).
         ValueError will be thrown if no library match.
 
         @param library: library's name
         """
 
         self.extractors = libextractor.EXTRACTOR_plugin_remove(self.extractors, library)
 
     def addLibraries(self, libraries):
         """
         Add given libraries.
         Same as addLibary but libraries is a list of library's names.
 
         @param libraries: list of libraries names
         """
 
         self.extractors = libextractor.EXTRACTOR_plugin_add_config(self.extractors, libraries)
 
     def removeAllLibraries(self):
         """
         Remove all libraries.
         """
 
         libextractor.EXTRACTOR_plugin_remove_all(self.extractors)
         self.extractors = None
 
     def keywordTypes(self):
         """
         Returns the list of all keywords types.
         @return: list of all keywords types
         """
         i = 0
         keyword_types = []
 
         while True:
             keyword_type = libextractor.EXTRACTOR_metatype_to_string(i)
             if not keyword_type:
                 break
             keyword_types.append(keyword_type)
             i += 1
 
         return tuple(keyword_types)
 
     def __del__(self):
         """
         >>> extractor = Extractor()
         >>> del extractor
         """
         if self.extractors:
             self.removeAllLibraries()
 
 
 if __name__ == "__main__":
     try:
         import doctest
         doctest.testmod()
     except Exception as e:
         print(e)