PyCIRCLean/kittengroomer/helpers.py

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