mirror of
https://github.com/robmcmullen/atrcopy.git
synced 2024-06-06 11:29:29 +00:00
389 lines
13 KiB
Python
389 lines
13 KiB
Python
import hashlib
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import inspect
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import pkg_resources
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import numpy as np
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from . import errors
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from . import style_bits
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from .segment import Segment
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from .utils import to_numpy, to_numpy_list, uuid
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import logging
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log = logging.getLogger(__name__)
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try: # Expensive debugging
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_xd = _expensive_debugging
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except NameError:
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_xd = False
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class Filesystem:
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"""Base class for a "filesystem", which takes a source segment and
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subdivides it into a set of segments where each represents a file. Some
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auxiliary segments include a `VTOC` and a list of 'dirent's that point to
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files.
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"""
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pretty_name = "Filesystem"
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extra_serializable_attributes = []
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def __init__(self, media):
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self.check_media(media)
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self.media = media
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self.boot = self.calc_boot_segment()
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self.vtoc = self.calc_vtoc_segment()
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self.directory = self.calc_directory_segment()
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#### initialization
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def check_media(self):
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"""Subclasses should override this method to verify the media type is
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supported by the filesystem.
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Subclasses should raise IncompatibleMediaError if the filesystem is not
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possible on this media, for instance attempting to use a disk
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filesystem on a cassette media image.
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"""
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pass
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def calc_boot_segment(self):
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"""Subclasses should override this method to create a boot segment if
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the filesystem supports one and it is present.
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If it is present, return a single `Segment` instance comprising the
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entire set of data, and use sub-segments if more detail is present.
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If this feature is not present, return None.
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Subclasses should raise the appropriate FilesystemError if the data is
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incompatible with this filesystem.
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"""
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pass
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def calc_vtoc_segment(self):
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"""Subclasses should override this method to create a VTOC segment if
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the filesystem supports one and it is present.
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If it is present, return a single `Segment` instance comprising the
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entire set of data, and use sub-segments if more detail is present.
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If this feature is not present, return None.
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Subclasses should raise the appropriate FilesystemError if the data is
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incompatible with this filesystem.
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"""
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pass
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def calc_directory_segment(self):
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"""Subclasses should override this method to create a directory segment
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if the filesystem supports one and it is present.
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If it is present, return a single `Segment` instance comprising the
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entire set of data, and use sub-segments if more detail is present.
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If this feature is not present, return None.
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Subclasses should raise the appropriate FilesystemError if the data is
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incompatible with this filesystem.
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"""
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pass
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####
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@property
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def max_file_size(self):
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return len(self.media)
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####
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def iter_segments(self):
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if self.boot is not None:
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yield self.boot
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if self.vtoc is not None:
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yield self.vtoc
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if self.directory is not None:
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yield self.directory
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class Dirent(Segment):
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"""Abstract base class for a directory entry
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"""
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def __init__(self, filesystem, parent, file_num, start, length):
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self.filesystem = filesystem
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self.file_num = file_num
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Segment.__init__(self, parent, start, name=f"Dirent {file_num}", length=length)
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def __eq__(self, other):
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raise errors.NotImplementedError
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@property
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def in_use(self):
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raise errors.NotImplementedError
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def extra_metadata(self, image):
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raise errors.NotImplementedError
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def mark_deleted(self):
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raise errors.NotImplementedError
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def parse_raw_dirent(self, image, bytes):
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raise errors.NotImplementedError
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def encode_dirent(self):
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raise errors.NotImplementedError
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def get_sectors_in_vtoc(self, image):
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raise errors.NotImplementedError
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def start_read(self, image):
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raise errors.NotImplementedError
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def read_sector(self, image):
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raise errors.NotImplementedError
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class Directory(Segment):
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def __init__(self, filesystem):
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self.filesystem = filesystem
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offset, length = self.find_segment_location()
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Segment.__init__(self, filesystem.media, offset, name="Directory", length=length)
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# Each segment is a dirent
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self.segments = self.calc_dirents()
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@property
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def media(self):
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return self.filesystem.media
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def find_segment_location(self):
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raise NotImplementedError("Subclasses must define this to declare where the directory segment is located in the media image")
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def calc_dirents(self):
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raise NotImplementedError("Subclasses must define this to generate a list of Dirent segments")
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def set(self, index, dirent):
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self.segments[index] = dirent
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if _xd: log.debug("set dirent #%d: %s" % (index, dirent))
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def get_free_dirent(self):
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used = set()
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d = list(self.segments.items())
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if d:
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d.sort()
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for i, dirent in d:
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if not dirent.in_use:
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return i
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used.add(i)
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if self.num_dirents > 0 and (len(used) >= self.num_dirents):
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raise errors.NoSpaceInDirectory()
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i += 1
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else:
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i = 0
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used.add(i)
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return i
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def add_dirent(self, filename, filetype):
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index = self.get_free_dirent()
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dirent = self.dirent_class(None)
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dirent.set_values(filename, filetype, index)
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self.set(index, dirent)
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return dirent
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def find_dirent(self, filename):
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if hasattr(filename, "filename"):
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# we've been passed a dirent instead of a filename
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for dirent in list(self.segments.values()):
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if dirent == filename:
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return dirent
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else:
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for dirent in list(self.segments.values()):
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if filename == dirent.filename:
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return dirent
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raise errors.FileNotFound("%s not found on disk" % filename)
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def save_dirent(self, image, dirent, vtoc, sector_list):
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vtoc.assign_sector_numbers(dirent, sector_list)
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dirent.add_metadata_sectors(vtoc, sector_list, image.header)
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dirent.update_sector_info(sector_list)
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self.calc_sectors(image)
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def remove_dirent(self, image, dirent, vtoc, sector_list):
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vtoc.free_sector_list(sector_list)
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dirent.mark_deleted()
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self.calc_sectors(image)
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@property
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def dirent_class(self):
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raise errors.NotImplementedError
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def calc_sectors(self, image):
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self.sectors = []
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self.current_sector = self.get_dirent_sector()
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self.encode_index = 0
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d = list(self.segments.items())
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d.sort()
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# there may be gaps, so fill in missing entries with blanks
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current = 0
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for index, dirent in d:
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for missing in range(current, index):
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if _xd: log.debug("Encoding empty dirent at %d" % missing)
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data = self.encode_empty()
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self.store_encoded(data)
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if _xd: log.debug("Encoding dirent: %s" % dirent)
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data = self.encode_dirent(dirent)
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self.store_encoded(data)
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current = index + 1
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self.finish_encoding(image)
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def get_dirent_sector(self):
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return self.sector_class(self.sector_size)
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def encode_empty(self):
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raise errors.NotImplementedError
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def encode_dirent(self, dirent):
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raise errors.NotImplementedError
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def store_encoded(self, data):
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while True:
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if _xd: log.debug("store_encoded: %d bytes in %s" % (len(data), self.current_sector))
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data = self.current_sector.add_data(data)
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if len(data) > 0:
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self.sectors.append(self.current_sector)
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self.current_sector = self.get_dirent_sector()
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else:
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break
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def finish_encoding(self, image):
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if not self.current_sector.is_empty:
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self.sectors.append(self.current_sector)
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self.set_sector_numbers(image)
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def set_sector_numbers(self, image):
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raise errors.NotImplementedError
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class VTOC(Segment):
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def __init__(self, filesystem):
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self.filesystem = filesystem
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offset, length = self.find_segment_location()
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Segment.__init__(self, filesystem.media, offset, name="VTOC", length=length)
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# sector map: 1 is free, 0 is allocated
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self.sector_map = np.zeros([filesystem.media.num_sectors], dtype=np.uint8)
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self.unpack_vtoc()
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@property
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def media(self):
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return self.filesystem.media
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def find_segment_location(self):
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"""Calculate the location on the media for the VTOC. Return either
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sector number and count, or offset list
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"""
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raise NotImplementedError("Subclasses must define this to declare where the directory segment is located in the media image")
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# def __str__(self):
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# return "%s\n (%d free)" % ("\n".join(["track %02d: %s" % (i, line) for i, line in enumerate(str(self.sector_map[self.header.starting_sector_label:(self.header.tracks_per_disk*self.header.sectors_per_track) + self.header.starting_sector_label].reshape([self.header.tracks_per_disk,self.header.sectors_per_track])).splitlines())]), self.num_free_sectors)
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def unpack_vtoc(self):
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"""Using the bit-encoded data, unpack it into the sector_map array
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"""
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raise NotImplementedError()
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def pack_vtoc(self):
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"""Pack the sector_map array into the segment
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"""
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raise NotImplementedError()
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@property
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def num_free_sectors(self):
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free = np.where(self.sector_map == 1)[0]
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return len(free)
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def iter_free_sectors(self):
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for i, pos, size in self.filesystem.media.iter_sectors():
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if self.sector_map[i] == 1:
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yield i, pos, size
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def assign_sector_numbers(self, dirent, sector_list):
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""" Map out the sectors and link the sectors together
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raises NotEnoughSpaceOnDisk if the whole file won't fit. It will not
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allow partial writes.
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"""
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num = len(sector_list)
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order = self.reserve_space(num)
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if len(order) != num:
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raise errors.InvalidFile("VTOC reserved space for %d sectors. Sectors needed: %d" % (len(order), num))
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file_length = 0
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last_sector = None
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for sector, sector_num in zip(sector_list.sectors, order):
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sector.sector_num = sector_num
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sector.file_num = dirent.file_num
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file_length += sector.used
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if last_sector is not None:
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last_sector.next_sector_num = sector_num
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last_sector = sector
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if last_sector is not None:
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last_sector.next_sector_num = 0
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sector_list.file_length = file_length
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def reserve_space(self, num):
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order = []
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for i in range(num):
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order.append(self.get_next_free_sector())
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if _xd: log.debug("Sectors reserved: %s" % order)
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self.calc_bitmap()
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return order
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def get_next_free_sector(self):
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free = np.nonzero(self.sector_map)[0]
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if len(free) > 0:
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num = free[0]
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if _xd: log.debug("Found sector %d free" % num)
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self.sector_map[num] = 0
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return num
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raise errors.NotEnoughSpaceOnDisk("No space left in VTOC")
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def calc_bitmap(self):
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raise errors.NotImplementedError
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def free_sector_list(self, sector_list):
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for sector in sector_list:
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self.sector_map[sector.sector_num] = 1
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self.calc_bitmap()
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def find_filesystems():
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filesystems = []
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for entry_point in pkg_resources.iter_entry_points('atrcopy.filesystems'):
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mod = entry_point.load()
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log.debug(f"find_filesystems: Found module {entry_point.name}={mod.__name__}")
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for name, obj in inspect.getmembers(mod):
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if inspect.isclass(obj) and Filesystem in obj.__mro__[1:]:
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log.debug(f"find_filesystems: found media_type class {name}")
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filesystems.append(obj)
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return filesystems
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def guess_filesystem(segment, verbose=False):
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for f in find_filesystems():
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if verbose:
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log.info(f"trying filesystem {f}")
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try:
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found = f(segment)
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except errors.FilesystemError as e:
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log.debug(f"found error: {e}")
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continue
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else:
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if verbose:
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log.info(f"found filesystem {f}")
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return found
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log.info(f"No recognized filesystem.")
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return None
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