def _read_and_validate_fs_info(self):
self.scan_info("Validating FS INFO sector...")
fs_info_bytes = self._sector_slice(self._fs_info_sector)
try:
validate_fs_info(fs_info_bytes)
except ValueError:
if self._print_scan_info:
print("Incorrect format of FS Info sector, "
"FAT32 validation failed.")
self.valid = False
else:
raise FATReaderError("Incorrect format of FS Info sector, "
"image either corrupted or it's not FAT32")
else:
self.scan_info("FS INFO sector is valid.")
parser = BytesParser(fs_info_bytes)
self._free_clusters = \
parser.parse_int_unsigned(0x1e8, 4, byteorder='little')
if self._free_clusters == 0xFFFFFFFF:
self._free_clusters = -1
self._first_free_cluster = \
parser.parse_int_unsigned(0x1ec, 4, byteorder='little')
if self._first_free_cluster == 0xFFFFFFFF:
self._first_free_cluster = -1
def test_parse_int_end(self):
parser = BytesParser(b'\xf4\x43\xff\x57\xa3\x55')
self.assertEqual(0x55, parser.parse_int_unsigned(5, 1))
def test_parse_int_middle(self):
parser = BytesParser(b'\xf4\x43\xff\x57\xa3\x55')
self.assertEqual(0x57ff, parser.parse_int_unsigned(2, 2))
def test_parse_int_start(self):
parser = BytesParser(b'\xf4\x43\xff\x57\xa3\x55')
self.assertEqual(0xff43f4, parser.parse_int_unsigned(0, 3))
def test_parse_int_little_big_endian(self):
parser = BytesParser(b'\xf4\xa3\xff')
self.assertEqual(0xffa3f4, parser.parse_int_unsigned(0, 3))
def test_parse_int_simple(self):
parser = BytesParser(b'\x5f')
self.assertEqual(0x5f, parser.parse_int_unsigned(0, 1))
def _parse_dir_files(self, data, directory):
files = list()
long_file_name_buffer = ""
lfn_checksum_buffer = -1
for start in range(0, len(data) - BYTES_PER_DIR_ENTRY,
BYTES_PER_DIR_ENTRY):
debug('long_file_name_buffer = "' + long_file_name_buffer + '"')
debug('lfn_checksum_buffer = ' + str(lfn_checksum_buffer))
entry_bytes = data[start:start + BYTES_PER_DIR_ENTRY]
if entry_bytes[0] == 0x00:
# directory has no more entries
break
if entry_bytes[0] == 0xE5:
# unused entry
continue
if entry_bytes[0] == 0x05:
entry_bytes = b'\xe5' + entry_bytes[1:]
entry_parser = BytesParser(entry_bytes)
attributes = entry_parser.parse_int_unsigned(11, 1)
if attributes == fsobjects.LFN: # Long file name entry
lfn_part, lfn_checksum = get_lfn_part(entry_bytes)
long_file_name_buffer = lfn_part + \
long_file_name_buffer
if 0 <= lfn_checksum_buffer != lfn_checksum:
debug("Warning: checksum changed from {:d} to"
" {:d} during lfn sequence"
.format(lfn_checksum_buffer, lfn_checksum))
lfn_checksum_buffer = lfn_checksum
elif attributes & fsobjects.VOLUME_ID:
pass
else:
try:
file = self._parse_file_entry(entry_parser,
long_file_name_buffer,
lfn_checksum_buffer)
requires_size_check = self.repair_file_size_mode and \
not file.is_directory
requires_cluster_usage_logging = \
self.log_clusters_usage \
or self.log_clusters_usage_adv
if requires_cluster_usage_logging or \
requires_size_check:
cluster_size = self.get_cluster_size()
cluster_seq_num = start // cluster_size
entry_start_in_cluster = start % cluster_size
chain = self._get_cluster_chain(
directory._start_cluster)
cluster_num = \
chain[
cluster_seq_num]
start_bytes, _ = \
self._get_cluster_start_end_relative_to_data_start(
cluster_num)
entry_start = start_bytes + entry_start_in_cluster + self._data_area_start
if requires_cluster_usage_logging:
self._log_file_clusters_usage(file=file,
entry_start=entry_start)
except ValueError:
debug('Entry is "dot" entry, ignoring...')
continue
if requires_size_check:
self._repair_file_size(file, entry_start)
file.parent = directory
files.append(file)
long_file_name_buffer = ""
lfn_checksum_buffer = -1
debug(file.get_attributes_str())
return files
