gzip2

dfvfs/file_io/gzip_file_io.py

@@ -1,160 +1,67 @@
 # -*- coding: utf-8 -*-
 """The gzip file-like object."""
 
-import collections
-import os
-
-from dfvfs.file_io import file_io
+from dfvfs.file_io import file_object_io
 from dfvfs.lib import errors
 from dfvfs.lib import gzipfile
 from dfvfs.resolver import resolver
 
 
-class GzipFile(file_io.FileIO):
-  """File input/output (IO) object of a gzip file.
-
-  The gzip file format is defined in RFC1952: http://www.zlib.org/rfc-gzip.html
-
-  Attributes:
-    uncompressed_data_size (int): total size of the decompressed data stored
-        in the gzip file.
-  """
-
-  def __init__(self, resolver_context, path_spec):
-    """Initializes a file input/output (IO) object.
-
-    Args:
-      resolver_context (Context): resolver context.
-      path_spec (PathSpec): a path specification.
-    """
-    super(GzipFile, self).__init__(resolver_context, path_spec)
-    self._compressed_data_size = -1
-    self._current_offset = 0
-    self._gzip_file_object = None
-    self._members_by_end_offset = collections.OrderedDict()
-
-    self.uncompressed_data_size = 0
+class GzipFile(file_object_io.FileObjectIO):
+  """File input/output (IO) object of a gzip file."""
 
   @property
-  def original_filenames(self):
-    """list(str): The original filenames stored in the gzip file."""
-    return [member.original_filename
-            for member in self._members_by_end_offset.values()]
+  def comments(self):
+    """list(str): comments in the gzip file."""
+    return [member.comment for member in self._file_object.members]
 
   @property
   def modification_times(self):
-    """list(int): The modification times stored in the gzip file."""
-    return [member.modification_time
-            for member in self._members_by_end_offset.values()]
+    """list(int): modification times stored in the gzip file."""
+    return [member.modification_time for member in self._file_object.members]
 
   @property
-  def operating_systems(self):
-    """list(int): The operating system values stored in the gzip file."""
-    return [member.operating_system
-            for member in self._members_by_end_offset.values()]
+  def original_filenames(self):
+    """list(str): original filenames stored in the gzip file."""
+    return [member.original_filename for member in self._file_object.members]
 
   @property
-  def comments(self):
-    """list(str): The comments in the gzip file."""
-    return [member.comment
-            for member in self._members_by_end_offset.values()]
-
-  def _GetMemberForOffset(self, offset):
-    """Finds the member whose data includes the provided offset.
-
-    Args:
-      offset (int): offset in the uncompressed data to find the
-          containing member for.
-
-    Returns:
-      gzipfile.GzipMember: gzip file member or None if not available.
-
-    Raises:
-      ValueError: if the provided offset is outside of the bounds of the
-          uncompressed data.
-    """
-    if offset < 0 or offset >= self.uncompressed_data_size:
-      raise ValueError('Offset {0:d} is larger than file size {1:d}.'.format(
-          offset, self.uncompressed_data_size))
-
-    for end_offset, member in self._members_by_end_offset.items():
-      if offset < end_offset:
-        return member
-
-    return None
-
-  def seek(self, offset, whence=os.SEEK_SET):
-    """Seeks to an offset within the file-like object.
-
-    Args:
-      offset (int): offset to seek to.
-      whence (Optional(int)): value that indicates whether offset is an absolute
-          or relative position within the file.
-
-    Raises:
-      IOError: if the seek failed or the file has not been opened.
-      OSError: if the seek failed or the file has not been opened.
-    """
-    if not self._gzip_file_object:
-      raise IOError('Not opened.')
-
-    if whence == os.SEEK_CUR:
-      offset += self._current_offset
-    elif whence == os.SEEK_END:
-      offset += self.uncompressed_data_size
-    elif whence != os.SEEK_SET:
-      raise IOError('Unsupported whence.')
-
-    if offset < 0:
-      raise IOError('Invalid offset value less than zero.')
-
-    self._current_offset = offset
+  def operating_systems(self):
+    """list(int): operating system values stored in the gzip file."""
+    return [member.operating_system for member in self._file_object.members]
 
-  def read(self, size=None):
-    """Reads a byte string from the gzip file at the current offset.
+  @property
+  def uncompressed_data_size(self):
+    """int: uncompressed data size."""
+    return self._file_object.uncompressed_data_size
 
-    The function will read a byte string up to the specified size or
-    all of the remaining data if no size was specified.
+  def _OpenFileObject(self, path_spec):
+    """Opens the file-like object defined by path specification.
 
     Args:
-      size (Optional[int]): number of bytes to read, where None is all
-          remaining data.
+      path_spec (PathSpec): path specification.
 
     Returns:
-      bytes: data read.
+      pyvde.volume: gzip file-like object.
 
     Raises:
-      IOError: if the read failed.
-      OSError: if the read failed.
+      PathSpecError: if the path specification is incorrect.
     """
-    data = b''
-    while ((size and len(data) < size) and
-           self._current_offset < self.uncompressed_data_size):
-      member = self._GetMemberForOffset(self._current_offset)
-      member_offset = self._current_offset - member.uncompressed_data_offset
-
-      data_read = member.ReadAtOffset(member_offset, size)
-      if not data_read:
-        break
-
-      self._current_offset += len(data_read)
-      data = b''.join([data, data_read])
+    if not path_spec.HasParent():
+      raise errors.PathSpecError(
+          'Unsupported path specification without parent.')
 
-    return data
+    file_object = resolver.Resolver.OpenFileObject(
+        path_spec.parent, resolver_context=self._resolver_context)
 
-  def get_offset(self):
-    """Retrieves the current offset into the file-like object.
+    gzip_compressed_stream = gzipfile.GzipCompressedStream()
+    gzip_compressed_stream.Open(file_object)
 
-    Returns:
-      int: current offset into the file-like object.
+    return gzip_compressed_stream
 
-    Raises:
-      IOError: if the file-like object has not been opened.
-      OSError: if the file-like object has not been opened.
-    """
-    if not self._gzip_file_object:
-      raise IOError('Not opened.')
-    return self._current_offset
+  # Note: that the following functions do not follow the style guide
+  # because they are part of the file-like object interface.
+  # pylint: disable=invalid-name
 
   def get_size(self):
     """Retrieves the size of the file-like object.
@@ -166,46 +73,7 @@ def get_size(self):
       IOError: if the file-like object has not been opened.
       OSError: if the file-like object has not been opened.
     """
-    if not self._gzip_file_object:
+    if not self._is_open:
       raise IOError('Not opened.')
-    return self.uncompressed_data_size
-
-  def _Close(self):
-    """Closes the file-like object."""
-    self._members_by_end_offset = []
-    if self._gzip_file_object:
-      self._gzip_file_object.close()
-
-  def _Open(self, mode='rb'):
-    """Opens the file-like object defined by path specification.
-
-    Args:
-      mode (Optional[str]): file access mode.
-
-    Raises:
-      AccessError: if the access to open the file was denied.
-      IOError: if the file-like object could not be opened.
-      OSError: if the file-like object could not be opened.
-      PathSpecError: if the path specification is incorrect.
-    """
-    if not self._path_spec.HasParent():
-      raise errors.PathSpecError(
-          'Unsupported path specification without parent.')
-
-    self._gzip_file_object = resolver.Resolver.OpenFileObject(
-        self._path_spec.parent, resolver_context=self._resolver_context)
-    file_size = self._gzip_file_object.get_size()
-
-    self._gzip_file_object.seek(0, os.SEEK_SET)
-
-    uncompressed_data_offset = 0
-    next_member_offset = 0
 
-    while next_member_offset < file_size:
-      member = gzipfile.GzipMember(
-          self._gzip_file_object, next_member_offset, uncompressed_data_offset)
-      uncompressed_data_offset = (
-          uncompressed_data_offset + member.uncompressed_data_size)
-      self._members_by_end_offset[uncompressed_data_offset] = member
-      self.uncompressed_data_size += member.uncompressed_data_size
-      next_member_offset = member.member_end_offset
+    return self._file_object.uncompressed_data_size