mirror of https://github.com/CIRCL/PyCIRCLean
366 lines
12 KiB
Python
366 lines
12 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""
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Contains the base objects for use when creating a sanitizer using
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PyCIRCLean. Subclass or import from FileBase/KittenGroomerBase and implement
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your desired behavior.
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"""
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import os
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import hashlib
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import shutil
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import argparse
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import stat
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import magic
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class FileBase(object):
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"""
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Base object for individual files in the source directory.
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Contains file attributes and various helper methods.
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"""
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def __init__(self, src_path, dst_path):
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"""
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Initialized with the source path and expected destination path.
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Create various properties and determine the file's mimetype.
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"""
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self.src_path = src_path
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self.dst_dir = os.path.dirname(dst_path)
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self.filename = os.path.basename(src_path)
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self.size = self._get_size(src_path)
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self.is_dangerous = False
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self.copied = False
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self.symlink_path = None
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self._description_string = [] # array of descriptions to be joined
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self._errors = {}
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self._user_defined = {}
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self.should_copy = True
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self.mimetype = self._determine_mimetype(src_path)
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@property
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def dst_path(self):
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return os.path.join(self.dst_dir, self.filename)
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@property
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def extension(self):
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_, ext = os.path.splitext(self.filename)
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if ext == '':
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return None
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else:
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return ext.lower()
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@property
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def maintype(self):
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main, _ = self._split_mimetype(self.mimetype)
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return main
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@property
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def subtype(self):
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_, sub = self._split_mimetype(self.mimetype)
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return sub
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@property
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def has_mimetype(self):
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"""True if file has a main and sub mimetype, else False."""
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if not self.maintype or not self.subtype:
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return False
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else:
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return True
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@property
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def has_extension(self):
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"""True if self.extension is set, else False."""
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if self.extension is None:
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return False
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else:
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return True
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@property
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def is_symlink(self):
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"""True if file is a symlink, else False."""
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if self.symlink_path is None:
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return False
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else:
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return True
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@property
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def description_string(self):
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if len(self._description_string) == 0:
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return 'No description'
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elif len(self._description_string) == 1:
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return self._description_string[0]
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else:
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ret_string = ', '.join(self._description_string)
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return ret_string.strip(', ')
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@description_string.setter
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def description_string(self, value):
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if hasattr(self, 'description_string'):
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if isinstance(value, str):
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if value not in self._description_string:
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self._description_string.append(value)
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else:
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raise TypeError("Description_string can only include strings")
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else:
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self._description_string = value
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def set_property(self, prop_string, value):
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"""
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Take a property and a value and add them to the file's stored props.
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If `prop_string` is part of the file property API, set it to `value`.
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Otherwise, add `prop_string`: `value` to `user_defined` properties.
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TODO: rewrite docstring
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"""
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if hasattr(self, prop_string):
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setattr(self, prop_string, value)
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else:
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self._user_defined[prop_string] = value
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def get_property(self, prop_string):
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"""
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Get the value for a property stored on the file.
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Returns `None` if `prop_string` cannot be found on the file.
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"""
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try:
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return getattr(self, prop_string)
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except AttributeError:
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return self._user_defined.get(prop_string, None)
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def get_all_props(self):
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"""Return a dict containing all stored properties of this file."""
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# Maybe move this onto the logger? I think that makes more sense
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props_dict = {
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'filepath': self.src_path,
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'filename': self.filename,
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'file_size': self.size,
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'mimetype': self.mimetype,
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'maintype': self.maintype,
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'subtype': self.subtype,
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'extension': self.extension,
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'is_dangerous': self.is_dangerous,
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'is_symlink': self.is_symlink,
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'symlink_path': self.symlink_path,
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'copied': self.copied,
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'description_string': self.description_string,
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'errors': self._errors,
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'user_defined': self._user_defined
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}
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return props_dict
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def add_error(self, error, info_string):
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"""Add an `error`: `info_string` pair to the file."""
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self._errors.update({error: info_string})
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def add_description(self, description_string):
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"""
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Add a description string to the file.
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If `description_string` is already present, will prevent duplicates.
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"""
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self.set_property('description_string', description_string)
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def make_dangerous(self, reason_string=None):
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"""
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Mark file as dangerous.
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Prepend and append DANGEROUS to the destination file name
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to help prevent double-click of death.
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"""
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if not self.is_dangerous:
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self.set_property('is_dangerous', True)
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self.filename = 'DANGEROUS_{}_DANGEROUS'.format(self.filename)
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if reason_string:
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self.add_description(reason_string)
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def safe_copy(self, src=None, dst=None):
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"""
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Copy file and create destination directories if needed.
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Sets all exec bits to '0'.
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"""
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if src is None:
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src = self.src_path
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if dst is None:
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dst = self.dst_path
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try:
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os.makedirs(self.dst_dir, exist_ok=True)
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shutil.copy(src, dst)
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current_perms = self._get_file_permissions(dst)
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only_exec_bits = 0o0111
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perms_no_exec = current_perms & (~only_exec_bits)
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os.chmod(dst, perms_no_exec)
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except IOError as e:
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# Probably means we can't write in the dest dir
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self.add_error(e, '')
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def force_ext(self, extension):
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"""If dst_path does not end in `extension`, append .ext to it."""
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new_ext = self._check_leading_dot(extension)
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if not self.filename.endswith(new_ext):
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# TODO: log that the extension was changed
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self.filename += new_ext
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if not self.get_property('extension') == new_ext:
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self.set_property('extension', new_ext)
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def create_metadata_file(self, extension):
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# TODO: this method name is confusing
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"""
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Create a separate file to hold extracted metadata.
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The string `extension` will be used as the extension for the file.
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"""
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ext = self._check_leading_dot(extension)
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try:
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# Prevent using the same path as another file from src_path
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if os.path.exists(self.src_path + ext):
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raise KittenGroomerError(
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"Could not create metadata file for \"" +
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self.filename +
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"\": a file with that path exists.")
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else:
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os.makedirs(self.dst_dir, exist_ok=True)
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# TODO: shouldn't mutate state and also return something
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self.metadata_file_path = self.dst_path + ext
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return self.metadata_file_path
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# TODO: can probably let this exception bubble up
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except KittenGroomerError as e:
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self.add_error(e, '')
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return False
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def _check_leading_dot(self, ext):
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# TODO: this method name is confusing
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if len(ext) > 0:
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if not ext.startswith('.'):
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return '.' + ext
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return ext
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def _determine_mimetype(self, file_path):
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if os.path.islink(file_path):
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# libmagic will throw an IOError on a broken symlink
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mimetype = 'inode/symlink'
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self.set_property('symlink_path', os.readlink(file_path))
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else:
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try:
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mt = magic.from_file(file_path, mime=True)
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# libmagic always returns something, even if it's just 'data'
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except UnicodeEncodeError as e:
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self.add_error(e, '')
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mt = None
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try:
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mimetype = mt.decode("utf-8")
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except:
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# FIXME: what should the exception be if mimetype isn't utf-8?
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mimetype = mt
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return mimetype
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def _split_mimetype(self, mimetype):
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if mimetype and '/' in mimetype:
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main_type, sub_type = mimetype.split('/')
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else:
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main_type, sub_type = None, None
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return main_type, sub_type
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def _get_size(self, file_path):
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"""Filesize in bytes as an int, 0 if file does not exist."""
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try:
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size = os.path.getsize(file_path)
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except FileNotFoundError:
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size = 0
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return size
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def _remove_exec_bit(self, file_path):
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current_perms = self._get_file_permissions(file_path)
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perms_no_exec = current_perms & (~stat.S_IEXEC)
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os.chmod(file_path, perms_no_exec)
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def _get_file_permissions(self, file_path):
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full_mode = os.stat(file_path, follow_symlinks=False).st_mode
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return stat.S_IMODE(full_mode)
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class Logging(object):
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@staticmethod
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def computehash(path):
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"""Return the sha256 hash of a file at a given path."""
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s = hashlib.sha256()
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with open(path, 'rb') as f:
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while True:
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buf = f.read(0x100000)
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if not buf:
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break
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s.update(buf)
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return s.hexdigest()
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class KittenGroomerBase(object):
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"""Base object responsible for copy/sanitization process."""
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def __init__(self, src_root_path, dst_root_path):
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"""Initialized with path to source and dest directories."""
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self.src_root_path = os.path.abspath(src_root_path)
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self.dst_root_path = os.path.abspath(dst_root_path)
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def safe_rmtree(self, directory_path):
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"""Remove a directory tree if it exists."""
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if os.path.exists(directory_path):
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shutil.rmtree(directory_path)
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def safe_remove(self, file_path):
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"""Remove file at file_path if it exists."""
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if os.path.exists(file_path):
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os.remove(file_path)
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def safe_mkdir(self, directory_path):
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"""Make a directory if it does not exist."""
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if not os.path.exists(directory_path):
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os.makedirs(directory_path)
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def list_all_files(self, directory_path):
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"""Generator yielding path to all of the files in a directory tree."""
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for root, dirs, files in os.walk(directory_path):
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for filename in files:
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filepath = os.path.join(root, filename)
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yield filepath
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#######################
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def processdir(self, src_dir, dst_dir):
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"""Implement this function to define file processing behavior."""
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raise ImplementationRequired('Please implement processdir.')
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class KittenGroomerError(Exception):
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"""Base KittenGroomer exception handler."""
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def __init__(self, message):
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super(KittenGroomerError, self).__init__(message)
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self.message = message
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class ImplementationRequired(KittenGroomerError):
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"""Implementation required error."""
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pass
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def main(
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kg_implementation,
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description=("Call a KittenGroomer implementation to process files "
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"present in the source directory and copy them to the "
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"destination directory.")):
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print(description)
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parser = argparse.ArgumentParser(prog='KittenGroomer', description=description)
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parser.add_argument('-s', '--source', type=str, help='Source directory')
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parser.add_argument('-d', '--destination', type=str, help='Destination directory')
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args = parser.parse_args()
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kg = kg_implementation(args.source, args.destination)
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kg.processdir()
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