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297 lines
10 KiB

import struct
import tree
import sys
voldesc_fmt = "B" "5s" "B" "2041x"
# all these fields are common between the pri and sec voldescs
privoldesc_fmt = "B" "5s" "B" "x" "32s" "32s" "8x" "8s" "32x" "4s" "4s" "4s" "8s" "4s4s" "4s4s" "34s" "128s" \
"128s" "128s" "128s" "37s" "37s" "37s" "17s" "17s" "17s" "17s" "B" "x" "512s" "653x"
# the fields unique to the sec_vol_desc
secvoldesc_fmt = "x" "5x" "x" "B" "32x" "32x" "8x" "8x" "32s" "4x" "4x" "4x" "8x" "4x4x" "4x4x" "34x" "128x" \
"128x" "128x" "128x" "37x" "37x" "37x" "17x" "17x" "17x" "17x" "x" "x" "512x" "653x"
dirrecord_fmt = "B" "B" "8s" "8s" "7s" "B" "B" "B" "4s" "B" # + file identifier, padding field and SU area
pathrecord_fmt = "B" "B" "4s" "2s" # + directory identifier and padding field
def read_bb(str, le, be):
val1, = struct.unpack(le, str)
val2, = struct.unpack(be, str)
if val1 != val2:
print "val1=%d, val2=%d" % (val1, val2)
raise AssertionError, "values are not equal in dual byte-order field"
return val1
def read_bb4(str):
return read_bb(str, "<I4x", ">4xI")
def read_bb2(str):
return read_bb(str, "<H2x", ">2xH")
def read_lsb4(str):
return struct.unpack("<I", str)[0]
def read_lsb2(str):
return struct.unpack("<H", str)[0]
def read_msb4(str):
return struct.unpack(">I", str)[0]
def read_msb2(str):
return struct.unpack(">H", str)[0]
class VolDesc(object):
def __init__(self, data):
print "fmt len=%d, data len=%d" % ( struct.calcsize(voldesc_fmt), len(data) )
self.vol_desc_type, self.standard_id, self.vol_desc_version = struct.unpack(voldesc_fmt, data)
class PriVolDesc(VolDesc):
def __init__(self, data):
self.vol_desc_type, \
self.standard_id, \
self.vol_desc_version, \
self.system_id, \
self.volume_id, \
self.vol_space_size, \
self.vol_set_size, \
self.vol_seq_num, \
self.block_size, \
self.path_table_size, \
self.l_table_pos, \
self.l_table2_pos, \
self.m_table_pos, \
self.m_table2_pos, \
self.root_record, \
self.volset_id, \
self.publisher_id, \
self.preparer_id, \
self.application_id, \
self.copyright_file, \
self.abstract_file, \
self.bibliographic_file, \
self.creation_timestamp, \
self.modification_timestamp, \
self.expiration_timestamp, \
self.effective_timestamp, \
self.file_struct_version, \
self.application_use = struct.unpack(privoldesc_fmt, data)
# take care of reading the integer types
self.vol_space_size = read_bb4(self.vol_space_size)
self.vol_set_size = read_bb2(self.vol_set_size)
self.vol_seq_num = read_bb2(self.vol_seq_num)
self.block_size = read_bb2(self.block_size)
self.path_table_size = read_bb4(self.path_table_size)
self.l_table_pos = read_lsb4(self.l_table_pos)
self.l_table2_pos = read_lsb4(self.l_table2_pos)
self.m_table_pos = read_msb4(self.m_table_pos)
self.m_table2_pos = read_msb4(self.m_table2_pos)
# parse the root directory record
self.root_record = DirRecord(self.root_record)
def readPathTables(self, file):
file.seek( self.block_size * self.l_table_pos )
self.l_table = PathTable( file.read(self.path_table_size), 0 )
file.seek( self.block_size * self.m_table_pos )
self.m_table = PathTable( file.read(self.path_table_size), 1 )
if self.l_table2_pos:
file.seek( self.block_size * self.l_table2_pos )
self.l_table2 = PathTable( file.read(self.path_table_size), 0 )
else:
self.l_table2 = None
if self.m_table2_pos:
file.seek( self.block_size * self.m_table2_pos )
self.m_table2 = PathTable( file.read(self.path_table_size), 1 )
else:
self.m_table2 = None
def toTree(self, isofile):
ret = tree.Tree(isofile=isofile.name)
ret.root = self.root_record.toTreeNode(parent=None, isofile=isofile)
return ret
class SecVolDesc(PriVolDesc):
def __init__(self, data):
super(SecVolDesc,self).__init__(data)
self.flags, self.escape_sequences = struct.unpack(secvoldesc_fmt, data)
# return a single volume descriptor of the appropriate type
def readVolDesc(data):
desc = VolDesc(data)
if desc.standard_id != "CD001":
print "Unexpected standard_id " +desc.standard_id
return None
if desc.vol_desc_type == 1:
return PriVolDesc(data)
elif desc.vol_desc_type == 2:
return SecVolDesc(data)
elif desc.vol_desc_type == 3:
print "I don't know about partitions yet!"
return None
elif desc.vol_desc_type == 255:
return desc
else:
print "Unknown volume descriptor type %d" % (desc.vol_desc_type,)
return None
def readVolDescSet(file):
ret = [ readVolDesc(file.read(2048)) ]
while ret[-1].vol_desc_type != 255:
ret.append( readVolDesc(file.read(2048)) )
for vol in ret:
if vol.vol_desc_type == 1 or vol.vol_desc_type == 2:
vol.readPathTables(file)
return ret
class DirRecord:
def __init__(self, data):
self.len_dr, \
self.len_xa, \
self.block, \
self.len_data, \
self.timestamp, \
self.flags, \
self.unit_size, \
self.gap_size, \
self.vol_seq_number, \
self.len_fi = struct.unpack(dirrecord_fmt, data[:33])
self.children = []
if self.len_dr > len(data):
raise AssertionError, "Error: not enough data to read in DirRecord()"
elif self.len_dr < 34:
raise AssertionError, "Error: directory record too short"
fmt = str(self.len_fi) + "s"
if self.len_fi % 2 == 0:
fmt += "1x"
len_su = self.len_dr - (33 + self.len_fi + 1 - (self.len_fi % 2))
fmt += str(len_su) + "s"
if len(data) >= self.len_dr:
self.file_id, self.su = struct.unpack(fmt, data[33 : self.len_dr])
else:
print "Error: couldn't read file_id: not enough data"
self.file_id = "BLANK"
self.su = ""
# convert to integers
self.block = read_bb4(self.block)
self.len_data = read_bb4(self.len_data)
self.vol_seq_number = read_bb2(self.vol_seq_number)
def toTreeNode(self, parent, isofile, path=""):
ret = tree.TreeNode(parent=parent, isofile=isofile.name)
if len(path) > 0:
path += "/"
path += self.file_id
ret.path = path
if self.flags & 2: # we are a directory, recurse
isofile.seek( 2048 * self.block )
data = isofile.read( self.len_data )
pos = 0
while pos < self.len_data:
try:
child = DirRecord( data[pos:] )
pos += child.len_dr
if child.len_fi == 1 and (child.file_id == "\x00" or child.file_id == "\x01"):
continue
print "read child named " +child.file_id
self.children.append( child )
ret.children.append( child.toTreeNode(ret, isofile, path) )
except AssertionError:
print "Couldn't read child of directory %s, position is %d, len is %d" % \
(path, pos, self.len_data)
raise
return ret
class PathTableRecord:
def __init__(self, data, readint2, readint4):
self.len_di, self.len_xa, self.block, self.parent_number = struct.unpack(pathrecord_fmt, data[:8])
if len(data) < self.len_di + 8:
raise AssertionError, "Error: not enough data to read path table record"
fmt = str(self.len_di) + "s"
self.dir_id, = struct.unpack(fmt, data[8:8+self.len_di])
self.block = readint4(self.block)
self.parent_number = readint2(self.parent_number)
class PathTable:
def __init__(self, data, m_type):
if m_type:
readint2 = read_msb2
readint4 = read_msb4
else:
readint2 = read_lsb2
readint4 = read_lsb4
pos = 0
self.records = []
while pos < len(data):
try:
self.records.append( PathTableRecord(data[pos:], readint2, readint4) )
print "Read path record %d: dir_id %s, block %d, parent_number %d" %\
(len(self.records), self.records[-1].dir_id, self.records[-1].block, self.records[-1].parent_number)
pos += self.records[-1].len_di + 8
pos += pos % 2
except AssertionError:
print "Last successfully read path table record had dir_id %s, block %d, parent_number %d" % \
(self.records[-1].dir_id, self.records[-1].block, self.records[-1].parent_number)
print "Error was near offset %x" % (pos,)
raise
def findRecord(self, dir_id, block, parent_number):
number=1
for record in self.records:
if record.dir_id == dir_id and record.block == block and record.parent_number == parent_number:
return number, record
number += 1
return None, None
# check this path table for consistency against the actual directory heirarchy
def crossCheckDirRecords(self, root, parent_number=1):
number, rec = self.findRecord(root.file_id, root.block, parent_number)
if not rec:
print "Error: directory record parent_number %d, dir_id %s, block %d doesn't match a path table record" % \
(parent_number, root.file_id, root.block)
parent = self.records[parent_number]
print "Parent has parent_number %d, dir_id %s, block %d" % (parent.parent_number, parent.dir_id, parent.block)
return 0
for child in root.children:
if child.flags & 2:
self.crossCheckDirRecords(child, number)
if len(sys.argv) != 2:
print "Please enter the name of the .iso file to open"
sys.exit(1)
f = file(sys.argv[1])
f.seek(2048 * 16) # system area
volumes = readVolDescSet(f)
vol = volumes[0]
t = vol.toTree(f)
vol.l_table.crossCheckDirRecords(vol.root_record)
vol.m_table.crossCheckDirRecords(vol.root_record)
vol = volumes[1]
try:
t = vol.toTree(f)
vol.l_table.crossCheckDirRecords(vol.root_record)
vol.m_table.crossCheckDirRecords(vol.root_record)
except AttributeError:
pass