# -*- coding: utf-8 -*-
"""The GUID Partition Table (GPT) file system implementation."""
import pyvsgpt
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import gpt_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import file_system
from dfvfs.vfs import gpt_file_entry
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class GPTFileSystem(file_system.FileSystem):
"""File system that uses pyvsgpt."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_GPT
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def __init__(self, resolver_context, path_spec):
"""Initializes a file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super(GPTFileSystem, self).__init__(resolver_context, path_spec)
self._file_object = None
self._vsgpt_volume = None
def _Close(self):
"""Closes the file system object.
Raises:
IOError: if the close failed.
"""
self._vsgpt_volume.close()
self._vsgpt_volume = None
self._file_object = None
def _Open(self, mode='rb'):
"""Opens the file system object defined by path specification.
Args:
mode (Optional[str]): file access mode. The default is 'rb' which
represents read-only binary.
Raises:
AccessError: if the access to open the file was denied.
IOError: if the file system object could not be opened.
PathSpecError: if the path specification is incorrect.
ValueError: if the path specification is invalid.
"""
if not self._path_spec.HasParent():
raise errors.PathSpecError(
'Unsupported path specification without parent.')
file_object = resolver.Resolver.OpenFileObject(
self._path_spec.parent, resolver_context=self._resolver_context)
vsgpt_volume = pyvsgpt.volume()
vsgpt_volume.open_file_object(file_object)
self._file_object = file_object
self._vsgpt_volume = vsgpt_volume
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def FileEntryExistsByPathSpec(self, path_spec):
"""Determines if a file entry for a path specification exists.
Args:
path_spec (PathSpec): path specification.
Returns:
bool: True if the file entry exists.
"""
entry_index = self.GetEntryIndexByPathSpec(path_spec)
# The virtual root file has no corresponding partition entry index but
# should have a location.
if entry_index is None:
location = getattr(path_spec, 'location', None)
return location is not None and location == self.LOCATION_ROOT
return self._vsgpt_volume.has_partition_with_identifier(entry_index)
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def GetEntryIndexByPathSpec(self, path_spec):
"""Retrieves the entry index for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
int: entry index or None if not available.
"""
entry_index = getattr(path_spec, 'entry_index', None)
if entry_index is not None:
return entry_index
location = getattr(path_spec, 'location', None)
if location is None:
return None
entry_index = None
if location[:5] == '/gpt{' and location[-1] == '}':
for vsgpt_partition in iter(self._vsgpt_volume.partitions):
if vsgpt_partition.identifier == location[5:-1]:
entry_index = vsgpt_partition.entry_index
elif location[:2] == '/p':
try:
entry_index = int(location[2:], 10) - 1
except ValueError:
pass
if entry_index is None or entry_index < 0:
return None
return entry_index
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def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
GPTFileEntry: a file entry or None if not available.
"""
entry_index = self.GetEntryIndexByPathSpec(path_spec)
# The virtual root file has no corresponding partition entry index but
# should have a location.
if entry_index is None:
location = getattr(path_spec, 'location', None)
if location is None or location != self.LOCATION_ROOT:
return None
return gpt_file_entry.GPTFileEntry(
self._resolver_context, self, path_spec, is_root=True,
is_virtual=True)
if not self._vsgpt_volume.has_partition_with_identifier(entry_index):
return None
return gpt_file_entry.GPTFileEntry(
self._resolver_context, self, path_spec, entry_index=entry_index)
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def GetGPTPartitionByPathSpec(self, path_spec):
"""Retrieves a GPT partition for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
pyvsgpt.partition: a GPT partition or None if not available.
"""
entry_index = self.GetEntryIndexByPathSpec(path_spec)
if entry_index is None:
return None
return self._vsgpt_volume.get_partition_by_identifier(entry_index)
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def GetGPTVolume(self):
"""Retrieves the GPT volume.
Returns:
pyvsgpt.volume: a GPT volume.
"""
return self._vsgpt_volume
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def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
GPTFileEntry: root file entry or None if not available.
"""
path_spec = gpt_path_spec.GPTPathSpec(
location=self.LOCATION_ROOT, parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)