mymc/ps2mc.py

#
# ps2mc.py
#
# By Ross Ridge
# Public Domain
#

"""Manipulate PS2 memory card images."""

_SCCS_ID = "@(#) mysc ps2mc.py 1.9 08/08/13 15:31:32\n"

import sys
import array
import struct
from errno import EACCES, ENOENT, EEXIST, ENOTDIR, EISDIR, EROFS, ENOTEMPTY,\
     ENOSPC, EIO, EBUSY
import fnmatch
import traceback

from round import *
from ps2mc_ecc import *
from ps2mc_dir import *
import ps2save

PS2MC_MAGIC = "Sony PS2 Memory Card Format "
PS2MC_FAT_ALLOCATED_BIT = 0x80000000
PS2MC_FAT_CHAIN_END = 0xFFFFFFFF
PS2MC_FAT_CHAIN_END_UNALLOC = 0x7FFFFFFF
PS2MC_FAT_CLUSTER_MASK = 0x7FFFFFFF
PS2MC_MAX_INDIRECT_FAT_CLUSTERS = 32
PS2MC_CLUSTER_SIZE = 1024
PS2MC_INDIRECT_FAT_OFFSET = 0x2000

PS2MC_STANDARD_PAGE_SIZE = 512
PS2MC_STANDARD_PAGES_PER_CARD = 16384
PS2MC_STANDARD_PAGES_PER_ERASE_BLOCK = 16

class error(Exception):
	pass

class io_error(error, IOError):
	def __init__(self, *args, **kwargs):
		IOError.__init__(self, *args, **kwargs)

	def __str__(self):
		if getattr(self, "strerror", None) == None:
			return str(self.args)
		if getattr(self, "filename", None) != None:
			return self.filename + ": " + self.strerror
		return self.strerror
	
class path_not_found(io_error):
	def __init__(self, filename):
		io_error.__init__(self, ENOENT, "path not found", filename)

class file_not_found(io_error):
	def __init__(self, filename):
		io_error.__init__(self, ENOENT, "file not found", filename)

class dir_not_found(io_error):
	def __init__(self, filename):
		io_error.__init__(self, ENOENT, "directory not found",
				  filename)

class corrupt(io_error):
	def __init__(self, msg, f = None):
		filename = None
		if f != None:
			filename = getattr(f, "name")
		io_error.__init__(self, EIO, msg, filename)
		
class ecc_error(corrupt):
	def __init__(self, msg, filename = None):
		corrupt.__init__(self, msg, filename)

if sys.byteorder == "big":
	def unpack_32bit_array(s):
		a = array.array('I', s)
		a.byteswap()

	def pack_32bit_array(a):
		a = a[:]
		a.byteswap()
		return a.tostring()
else:
	def unpack_32bit_array(s):
		#if isinstance(s, str):
		#	a = array.array('L')
		#	a.fromstring(s)
		#	return a
		return array.array('I', s)

	def pack_32bit_array(a):
		return a.tostring()
	
def unpack_superblock(s):
	sb = struct.unpack("<28s12sHHHHLLLLLL8x128s128sbbxx", s)
	sb = list(sb)
	sb[12] = unpack_32bit_array(sb[12])
	sb[13] = unpack_32bit_array(sb[13])
	return sb

def pack_superblock(sb):
	sb = list(sb)
	sb[12] = pack_32bit_array(sb[12])
	sb[13] = pack_32bit_array(sb[13])
	return struct.pack("<28s12sHHHHLLLLLL8x128s128sbbxx", *sb)

unpack_fat = unpack_32bit_array
pack_fat = pack_32bit_array

class lru_cache(object):
	def __init__(self, length):
		self._lru_list = [[i - 1, None, None, i + 1]
				  for i in range(length + 1)]
		self._index_map = {}

	def dump(self):
		lru_list = self._lru_list
		i = 0
		while i != len(self._lru_list):
			print "%d: %s, " % (i, str(lru_list[i][1])), 
			i = lru_list[i][3]
		print
		print self._index_map
			
	def _move_to_front(self, i):
		lru_list = self._lru_list
		first = lru_list[0]
		i2 = first[3]
		if i != i2:
			elt = lru_list[i]
			prev = lru_list[elt[0]]
			next = lru_list[elt[3]]
			prev[3] = elt[3]
			next[0] = elt[0]
			elt[0] = 0
			elt[3] = i2
			lru_list[i2][0] = i
			first[3] = i
		
	def add(self, key, value):
		lru_list = self._lru_list
		index_map = self._index_map
		ret = None
		if key in index_map:
			i = index_map[key]
			# print "add hit ", key, i
			elt = lru_list[i]
		else:
			# print "add miss", key
			i = lru_list[-1][0]
			elt = lru_list[i]
			old_key = elt[1]
			if old_key != None:
				del index_map[old_key]
				ret = (old_key, elt[2])
			index_map[key] = i
			elt[1] = key
		elt[2] = value
		self._move_to_front(i)

		return ret
		
	def get(self, key, default = None):
		i = self._index_map.get(key)
		if i == None:
			# print "get miss", key
			return default
		# print "get hit ", key, i
		ret = self._lru_list[i][2]
		self._move_to_front(i)
		return ret

	def items(self):
		return [(elt[1], elt[2])
			for elt in self._lru_list[1 : -1]
			if elt[2] != None]
		
class fat_chain(object):
	"""A class for accessing a file's FAT entries as a simple sequence."""
	
	def __init__(self, lookup_fat, first):
		self.lookup_fat = lookup_fat
		self._first = first
		self.offset = 0
		self._prev = None
		self._cur = first

	def __getitem__(self, i):
		# not iterable
		offset = self.offset
		if i == offset:
			# print "@@@ fat_chain[] cur:", i, self._cur
			return self._cur
		elif i == offset - 1:
			assert self._prev != None
			# print "@@@ fat_chain[] prev:", i, self._prev
			return self._prev
		if i < offset:
			if i == 0:
				# print "@@@ fat_chain[] first", i, self._first
				return self._first
			offset = 0
			prev = None
			cur = self._first
		else:
			prev = self._prev
			cur = self._cur
		# print "@@@ fat_chain[] distance", i - offset
		while offset != i:
			next = self.lookup_fat(cur)
			if next == PS2MC_FAT_CHAIN_END:
				break;
			if next & PS2MC_FAT_ALLOCATED_BIT:
				next &= ~PS2MC_FAT_ALLOCATED_BIT
			else:
				# corrupt
				next = PS2MC_FAT_CHAIN_END
				break

			offset += 1
			prev = cur
			cur = next
		self.offset = offset
		self._prev = prev
		self._cur = cur
		# print "@@@ offset, prev, cur:", offset, prev, cur
		# print "@@@ fat_chain[]", i, next
		return next

	def __len__(self):
		old_prev = self._prev
		old_cur = self._cur
		old_offset = self.offset
		i = self.offset
		while self[i] != PS2MC_FAT_CHAIN_END:
			i += 1
		self._prev = old_prev
		self._cur = old_cur
		self.offset = old_offset
		return i
		
class ps2mc_file(object):
	"""A file-like object for accessing a file in memory card image."""
	
	def __init__(self, mc, dirloc, first_cluster, length, mode,
		     name = None):
		# print "ps2mc_file.__init__", name, self
		self.mc = mc
		self.length = length
		self.first_cluster = first_cluster
		self.dirloc = dirloc
		self.fat_chain = None
		self._pos = 0
		self.buffer = None
		self.buffer_cluster = None
		self.softspace = 0
		if name == None:
			self.name = "<ps2mc_file>"
		else:
			self.name = name
		self.closed = False

		if mode == None or len(mode) == 0:
			mode = "rb"
		self.mode = mode
		self._append = False
		self._write = False
		if mode[0] == "a":
			self._append = True
		elif mode[0] != "w" or ("+" not in self.mode):
			self._write = True

	def _find_file_cluster(self, n):
		if self.fat_chain == None:
			self.fat_chain = self.mc.fat_chain(self.first_cluster)
		return self.fat_chain[n]
		
	def read_file_cluster(self, n):
		if n == self.buffer_cluster:
			return self.buffer
		cluster = self._find_file_cluster(n)
		# print "@@@ read_file_cluster", self.dirloc, n, cluster, repr(self.name)
		if cluster == PS2MC_FAT_CHAIN_END:
			return None
		self.buffer = self.mc.read_allocatable_cluster(cluster)
		self.buffer_cluster = n
		return self.buffer 

	def _extend_file(self, n):
		mc = self.mc
		cluster = mc.allocate_cluster()
		# print "@@@ extending file", n, cluster
		if cluster == None:
			return None
		if n == 0:
			self.first_cluster = cluster
			self.fat_chain = None
			# print "@@@ linking", self.dirloc, "->", cluster
			mc.update_dirent(self.dirloc, self, cluster,
					 None, False)
		else:
			prev = self.fat_chain[n - 1]
			# print "@@@ linking", prev, "->", cluster
			mc.set_fat(prev, cluster | PS2MC_FAT_ALLOCATED_BIT)
		return cluster
	
	def write_file_cluster(self, n, buf):
		mc = self.mc
		cluster = self._find_file_cluster(n)
		if cluster != PS2MC_FAT_CHAIN_END:
			mc.write_allocatable_cluster(cluster, buf)
			self.buffer = buf
			self.buffer_cluster = n
			return True

		cluster_size = mc.cluster_size
		file_cluster_end = div_round_up(self.length, cluster_size)

		if (cluster < file_cluster_end
		    or len(self.fat_chain) != file_cluster_end):
			raise corrupt, ("file length doesn't match cluster"
					" chain length", mc.f)

		for i in range(file_cluster_end, n):
			cluster = self._extend_file(i)
			if cluster == None:
				if i != file_cluster_end:
					self.length = (i - 1) * cluster_size
					mc.update_dirent(self.dirloc, self,
							 None, self.length,
							 True)
				return False
			mc.write_allocatable_cluster(cluster,
						     ["\0"] * cluster_size)
		
		cluster = self._extend_file(n)
		if cluster == None:
			return False

		mc.write_allocatable_cluster(cluster, buf)
		self.buffer = buf
		self.buffer_cluster = n
		return True
	
	def update_notify(self, first_cluster, length):
		if self.first_cluster != first_cluster:
			self.first_cluster = first_cluster
			self.fat_chain = None
		self.length = length
		self.buffer = None
		self.buffer_cluster = None
		
	def read(self, size = None, eol = None):
		if self.closed:
			raise ValueError, "file is closed"

		pos = self._pos
		cluster_size = self.mc.cluster_size
		if size == None:
			size = self.length
		size = max(min(self.length - pos, size), 0)
		ret = ""
		while size > 0:
			off = pos % cluster_size
			l = min(cluster_size - off, size)
			buf = self.read_file_cluster(pos / cluster_size)
			if buf == None:
				break
			if eol != None:
				i = buf.find(eol, off, off + l)
				if i != -1:
					l = off - i + 1
					size = l
			pos += l
			self._pos = pos
			ret += buf[off : off + l]
			size -= l
		return ret

	def write(self, out, _set_modified = True):
		if self.closed:
			raise ValueError, "file is closed"
	
		cluster_size = self.mc.cluster_size
		pos = self._pos
		if self._append: 
			pos = self.length
		elif not self._write:
			raise io_error, (EACCES, "file not opened for writing",
					 self.name)

		size = len(out)
		# print "@@@ write", pos, size
		i = 0
		while size > 0:
			cluster = pos / cluster_size
			off = pos % cluster_size
			l = min(cluster_size - off, size)
			s = out[i : i + l]
			pos += l
			if l == cluster_size:
				buf = s
			else:
				buf = self.read_file_cluster(cluster)
				if buf == None:
					buf = "\0" * cluster_size
				buf = buf[:off] + s + buf[off + l:]
			if not self.write_file_cluster(cluster, buf):
				raise io_error, (ENOSPC,
						 "out of space on image",
						 self.name)
			self._pos = pos
			# print "@@@ pos", pos
			new_length = None
			if pos > self.length:
				new_length = self.length = pos
			self.mc.update_dirent(self.dirloc, self, None,
					      new_length, _set_modified)

			i += l
			size -= l

	def close(self):
		# print "ps2mc_file.close", self.name, self
		if self.mc != None:
			self.mc.notify_closed(self.dirloc, self)
			self.mc = None
		self.fat_chain = None
		self.buffer = None

	def next(self):
		r = self.readline()
		if r == "":
			raise StopIteration
		return r

	def readline(self, size = None):
		return self.read(size, "\n")
		
	def readlines(self, sizehint):
		return [line for line in self]

	def seek(self, offset, whence = 0):
		if self.closed:
			raise ValueError, "file is closed"

		if whence == 1:
			base = self._pos
		elif whence == 2:
			base = self.length
		else:
			base = 0
		pos = max(base + offset, 0)
		self._pos = pos

	def tell(self):
		if self.closed:
			raise ValueError, "file is closed"
		return self._pos

	def __enter__(self):
		return

	def __exit__(self, a, b, c):
		self.close()
		return
	
	# def __del__(self):
	#	# print "ps2mc_file.__del__", self
	#	if self.mc != None:
	#		self.mc.notify_closed(self.dirloc, self)
	#		self.mc = None
	#	self.fat_chain = None
		
class ps2mc_directory(object):
	"""A sequence and iterator object for directories."""
	
	def __init__(self, mc, dirloc, first_cluster, length,
		     mode = "rb", name = None):
		self.f = ps2mc_file(mc, dirloc, first_cluster,
				    length * PS2MC_DIRENT_LENGTH, mode, name)

	def __iter__(self):
		start = self.tell()
		if start != 0:
			start -= 1
			self.seek(start)
		self._iter_end = start
		return self

	def write_raw_ent(self, index, ent, set_modified):
		# print "@@@ write_raw_ent", index
		self.seek(index)
		self.f.write(pack_dirent(ent),
			     _set_modified = set_modified)

	def next(self):
		# print "@@@ next", self.tell(), self.f.name
		dirent = self.f.read(PS2MC_DIRENT_LENGTH)
		if dirent == "":
			if 0 == self._iter_end:
				raise StopIteration
			self.seek(0)
			dirent = self.f.read(PS2MC_DIRENT_LENGTH)
		elif self.tell() == self._iter_end:
			raise StopIteration
		return unpack_dirent(dirent)

	def seek(self, offset, whence = 0):
		self.f.seek(offset * PS2MC_DIRENT_LENGTH, whence)

	def tell(self):
		return self.f.tell() / PS2MC_DIRENT_LENGTH

	def __len__(self):
		return self.f.length / PS2MC_DIRENT_LENGTH
	
	def __getitem__(self, index):
		# print "@@@ getitem", index, self.f.name
		self.seek(index)
		dirent = self.f.read(PS2MC_DIRENT_LENGTH)
		if dirent == "":
			raise IndexError
		return unpack_dirent(dirent)

	def __setitem__(self, index, new_ent):
		ent = self[index]
		mode = ent[0]
		if (mode & DF_EXISTS) == 0:
			return
		if new_ent[0] != None:
			mode = ((new_ent[0] & ~(DF_FILE | DF_DIR | DF_EXISTS))
				| (mode & (DF_FILE | DF_DIR | DF_EXISTS)))
			ent[0] = mode
		if new_ent[1] != None:
			ent[1] = new_ent[1]
		if new_ent[3] != None:
			ent[3] = new_ent[3]
		if new_ent[6] != None:
			ent[6] = new_ent[6]
		if new_ent[7] != None:
			ent[7] = new_ent[7]
		self.write_raw_ent(index, ent, False)

	def close(self):
		# print "ps2mc_directory.close", self
		self.f.close()
		self.f = None

	def __del__(self):
		# print "ps2mc_directory.__del__", self
		if self.f != None:
			self.f.close()
			self.f = None
			
class _root_directory(ps2mc_directory):
	"""Wrapper for the cached root directory object.

	The close() method is disabled so the cached object can be reused."""
	
	def __init__(self, mc, dirloc, first_cluster, length,
		     mode = "r+b", name = "/"):
		ps2mc_directory.__init__(self, mc, dirloc, first_cluster,
					 length, mode, name)

	def close(self):
		pass

	def real_close(self):
		ps2mc_directory.close(self)
		
class ps2mc(object):
	"""A PlayStation 2 memory card filesystem implementation.

	The close() method must be called when the object is no longer needed,
	otherwise cycles that can't be collected by the garbage collector
	will remain."""
	
	open_files = None
	fat_cache = None
	
	def _calculate_derived(self):
		self.spare_size = div_round_up(self.page_size, 128) * 4
		self.raw_page_size = self.page_size + self.spare_size
		self.cluster_size = self.page_size * self.pages_per_cluster
		self.entries_per_cluster = (self.page_size
					    * self.pages_per_cluster / 4)

		limit = (min(self.good_block2, self.good_block1)
			 * self.pages_per_erase_block
			 / self.pages_per_cluster
			 - self.allocatable_cluster_offset)
		self.allocatable_cluster_limit = limit

	def __init__(self, f, ignore_ecc = False, params = None):
		self.open_files = {}
		self.fat_cache = lru_cache(12)
		self.alloc_cluster_cache = lru_cache(64)
		self.modified = False
		self.f = None
		self.rootdir = None
		
		f.seek(0)
		s = f.read(0x154)
		if len(s) != 0x154 or not s.startswith(PS2MC_MAGIC):
			if (params == None):
				raise corrupt, ("Not a PS2 memory card image",
						f)
			self.f = f
			self.format(params)
		else:
			sb = unpack_superblock(s)
			self.version = sb[1]
			self.page_size = sb[2]
			self.pages_per_cluster = sb[3]
			self.pages_per_erase_block = sb[4]
			self.clusters_per_card = sb[6]
			self.allocatable_cluster_offset = sb[7]
			self.allocatable_cluster_end = sb[8]
			self.rootdir_fat_cluster = sb[9]
			self.good_block1 = sb[10]
			self.good_block2 = sb[11]
			self.indirect_fat_cluster_list = sb[12]
			self.bad_erase_block_list = sb[13]
			self._calculate_derived()
		
		self.f = f

		self.ignore_ecc = False
		try:
			self.read_page(0)
			self.ignore_ecc = ignore_ecc
		except ecc_error:
			# the error might be due the fact the file image
			# doesn't contain ECC data
			self.spare_size = 0
			self.raw_page_size = self.page_size
			ignore_ecc = True

		# sanity check
		root = self._directory(None, 0, 1)
		dot = root[0]
		dotdot = root[1]
		root.close()
		if (dot[8] != "." or dotdot[8] != ".."
		    or not mode_is_dir(dot[0]) or not mode_is_dir(dotdot[0])):
			raise corrupt, "Root directory damaged."
		
		self.fat_cursor = 0
		self.curdir = (0, 0)

	def write_superblock(self):
		s = pack_superblock((PS2MC_MAGIC,
				     self.version,
				     self.page_size,
				     self.pages_per_cluster,
				     self.pages_per_erase_block,
				     0xFF00,
				     self.clusters_per_card,
				     self.allocatable_cluster_offset,
				     self.allocatable_cluster_end,
				     self.rootdir_fat_cluster,
				     self.good_block1,
				     self.good_block2,
				     self.indirect_fat_cluster_list,
				     self.bad_erase_block_list,
				     2,
				     0x2B))
		s += "\x00" * (self.page_size - len(s))
		self.write_page(0, s)

		page = "\xFF" * self.raw_page_size
		self.f.seek(self.good_block2 * self.pages_per_erase_block
			    * self.raw_page_size)
		for i in range(self.pages_per_erase_block):
			self.f.write(page)

		self.modified = False
		return
		
	def format(self, params):
		"""Create (format) a new memory card image."""
		
		(with_ecc, page_size,
		 pages_per_erase_block, param_pages_per_card) = params

		if pages_per_erase_block < 1:
			raise error, ("invalid pages per erase block (%d)"
				      % page_size)
			
		pages_per_card = round_down(param_pages_per_card,
					    pages_per_erase_block)
		cluster_size = PS2MC_CLUSTER_SIZE
		pages_per_cluster = cluster_size / page_size
		clusters_per_erase_block = (pages_per_erase_block
					    / pages_per_cluster)
		erase_blocks_per_card = pages_per_card / pages_per_erase_block
		clusters_per_card = pages_per_card / pages_per_cluster
		epc = cluster_size / 4

		if (page_size < PS2MC_DIRENT_LENGTH
		    or pages_per_cluster < 1
		    or pages_per_cluster * page_size != cluster_size):
			raise error, "invalid page size (%d)" % page_size
		
		good_block1 = erase_blocks_per_card - 1
		good_block2 = erase_blocks_per_card - 2
		first_ifc = div_round_up(PS2MC_INDIRECT_FAT_OFFSET,
					 cluster_size)

		allocatable_clusters = clusters_per_card - (first_ifc + 2)
		fat_clusters = div_round_up(allocatable_clusters, epc)
		indirect_fat_clusters = div_round_up(fat_clusters, epc)
		if indirect_fat_clusters > PS2MC_MAX_INDIRECT_FAT_CLUSTERS:
			indirect_fat_clusters = PS2MC_MAX_INDIRECT_FAT_CLUSTERS
			fat_clusters = indirect_fat_clusters * epc
		allocatable_clusters = fat_clusters * epc

		allocatable_cluster_offset = (first_ifc
					      + indirect_fat_clusters
					      + fat_clusters)
		allocatable_cluster_end = (good_block2
					   * clusters_per_erase_block
					   - allocatable_cluster_offset)
		if allocatable_cluster_end < 1:
			raise error, ("memory card image too small"
				      " to be formatted")

		ifc_list = unpack_fat("\0\0\0\0"
				      * PS2MC_MAX_INDIRECT_FAT_CLUSTERS)
		for i in range(indirect_fat_clusters):
			ifc_list[i] = first_ifc + i

		self.version = "1.2.0.0"
		self.page_size = page_size
		self.pages_per_cluster = pages_per_cluster
		self.pages_per_erase_block = pages_per_erase_block
		self.clusters_per_card = clusters_per_card
		self.allocatable_cluster_offset = allocatable_cluster_offset
		self.allocatable_cluster_end = allocatable_clusters
		self.rootdir_fat_cluster = 0
		self.good_block1 = good_block1
		self.good_block2 = good_block2
		self.indirect_fat_cluster_list = ifc_list
		bebl = "\xFF\xFF\xFF\xFF" * 32		
		self.bad_erase_block_list = unpack_32bit_array(bebl)
		
		self._calculate_derived()

		self.ignore_ecc = not with_ecc
		erased = "\0" * page_size
		if not with_ecc:
			self.spare_size = 0
		else:
			ecc = "".join(["".join(map(chr, s))
				       for s in ecc_calculate_page(erased)])
			erased += ecc + "\0" * (self.spare_size - len(ecc))

		self.f.seek(0)
		for page in range(pages_per_card):
			self.f.write(erased)

		self.modified = True
		
		first_fat_cluster = first_ifc + indirect_fat_clusters
		remainder = fat_clusters % epc
		for i in range(indirect_fat_clusters):
			base = first_fat_cluster + i * epc
			buf = unpack_fat(range(base, base + epc))
			if (i == indirect_fat_clusters - 1
			    and remainder != 0):
				del buf[remainder:]
				buf.fromlist([0xFFFFFFFF] * (epc - remainder))
			self._write_fat_cluster(ifc_list[i], buf)

		
		# go through the fat backwards for better cache usage
		for i in range(allocatable_clusters - 1,
			       allocatable_cluster_end - 1, -1):
			self.set_fat(i, PS2MC_FAT_CHAIN_END)
		for i in range(allocatable_cluster_end - 1, 0, -1):
			self.set_fat(i, PS2MC_FAT_CLUSTER_MASK)
		self.set_fat(0, PS2MC_FAT_CHAIN_END)

		self.allocatable_cluster_end = allocatable_cluster_end
		
		now = tod_now()
		s = pack_dirent((DF_RWX | DF_DIR | DF_0400 | DF_EXISTS,
				 0, 2, now,
				 0, 0, now, 0, "."))
		s += "\0" * (cluster_size - len(s))
		self.write_allocatable_cluster(0, s)
		dir = self._directory((0, 0), 0, 2, "wb", "/")
		dir.write_raw_ent(1, (DF_WRITE | DF_EXECUTE | DF_DIR | DF_0400
				      | DF_HIDDEN | DF_EXISTS,
				      0, 0, now,
				      0, 0, now, 0, ".."), False)
		dir.close()

		self.flush()

	def read_page(self, n):
		# print "@@@ page", n
		f = self.f
		f.seek(self.raw_page_size * n)
		page = f.read(self.page_size)
		if len(page) != self.page_size:
			raise corrupt, ("attempted to read past EOF"
					" (page %05X)" % n, f)
		if self.ignore_ecc:
			return page
		spare = f.read(self.spare_size)
		if len(spare) != self.spare_size:
			raise corrupt, ("attempted to read past EOF"
					" (page %05X)" % n, f)
		(status, page, spare) = ecc_check_page(page, spare)
		if status == ECC_CHECK_FAILED:
			raise ecc_error, ("Unrecoverable ECC error (page %d)"
					  % n)
		return page

	def write_page(self, n, buf):
		f = self.f
		f.seek(self.raw_page_size * n)
		self.modified = True
		if len(buf) != self.page_size:
			raise error, ("internal error: write_page:"
				      " %d != %d" % (len(buf), self.page_size))
		f.write(buf)
		if self.spare_size != 0:
			a = array.array('B')
			for s in ecc_calculate_page(buf):
				a.fromlist(s)
			a.tofile(f)
			f.write("\0" * (self.spare_size - len(a)))
			
	def read_cluster(self, n):
		pages_per_cluster = self.pages_per_cluster
		cluster_size = self.cluster_size
		if self.spare_size == 0:
			self.f.seek(cluster_size * n)
			return self.f.read(cluster_size)
		n *= pages_per_cluster
		if pages_per_cluster == 2:
			return self.read_page(n) + self.read_page(n + 1)
		return "".join(map(self.read_page,
				   range(n, n + pages_per_cluster)))

	def write_cluster(self, n, buf):
		pages_per_cluster = self.pages_per_cluster
		cluster_size = self.cluster_size
		if self.spare_size == 0:
			self.f.seek(cluster_size * n)
			return self.f.write(cluster_size, buf)
		n *= pages_per_cluster
		pgsize = self.page_size
		for i in range(pages_per_cluster):
			self.write_page(n + i, buf[i * pgsize
						   : i * pgsize + pgsize])


	def _add_fat_cluster_to_cache(self, n, fat, dirty):
		old = self.fat_cache.add(n, [fat, dirty])
		if old != None:
			(n, [fat, dirty]) = old
			if dirty:
				self.write_cluster(n, pack_fat(fat))

	def _read_fat_cluster(self, n):
		v = self.fat_cache.get(n)
		if v != None:
			# print "@@@ fat hit", n
			return v[0]
		# print "@@@ fat miss", n
		fat = unpack_fat(self.read_cluster(n))
		self._add_fat_cluster_to_cache(n, fat, False)
		return fat

	def _write_fat_cluster(self, n, fat):
		self._add_fat_cluster_to_cache(n, fat, True)

	def flush_fat_cache(self):
		if self.fat_cache == None:
			return
		for (n, v) in self.fat_cache.items():
			[fat, dirty] = v
			if dirty:
				self.write_cluster(n, pack_fat(fat))
				v[1] = False

	def _add_alloc_cluster_to_cache(self, n, buf, dirty):
		old = self.alloc_cluster_cache.add(n, [buf, dirty])
		if old != None:
			(n, [buf, dirty]) = old
			if dirty:
				n += self.allocatable_cluster_offset
				self.write_cluster(n, buf)
		
	def read_allocatable_cluster(self, n):
		a = self.alloc_cluster_cache.get(n)
		if a != None:
			# print "@@@ cache hit", n
			return a[0]
		# print "@@@ cache miss", n
		buf = self.read_cluster(n + self.allocatable_cluster_offset)
		self._add_alloc_cluster_to_cache(n, buf, False)
		return buf
		
	def write_allocatable_cluster(self, n, buf):
		self._add_alloc_cluster_to_cache(n, buf, True)

	def flush_alloc_cluster_cache(self):
		if self.alloc_cluster_cache == None:
			return
		for (n, a) in self.alloc_cluster_cache.items():
			[buf, dirty] = a
			if dirty:
				n += self.allocatable_cluster_offset
				self.write_cluster(n, buf)
				a[1] = False

	def read_fat_cluster(self, n):
		indirect_offset = n % self.entries_per_cluster
		dbl_offset = n / self.entries_per_cluster
		indirect_cluster = self.indirect_fat_cluster_list[dbl_offset]
		indirect_fat = self._read_fat_cluster(indirect_cluster)
		cluster = indirect_fat[indirect_offset]
		return (self._read_fat_cluster(cluster), cluster)
					      
	def read_fat(self, n):
		if n < 0 or n >= self.allocatable_cluster_end:
			raise io_error, (EIO,
					 "FAT cluster index out of range"
					 " (%d)" % n)
		offset = n % self.entries_per_cluster
		fat_cluster = n / self.entries_per_cluster
		(fat, cluster) = self.read_fat_cluster(fat_cluster)
		return (fat, offset, cluster)

	def lookup_fat(self, n):
		(fat, offset, cluster) = self.read_fat(n)
		return fat[offset]

	def set_fat(self, n, value):
		(fat, offset, cluster) = self.read_fat(n)
		fat[offset] = value
		self._write_fat_cluster(cluster, fat)
		
	def allocate_cluster(self):
		epc = self.entries_per_cluster
		allocatable_cluster_limit = self.allocatable_cluster_limit
		
		end = div_round_up(allocatable_cluster_limit, epc)
		remainder = allocatable_cluster_limit % epc
			
		while self.fat_cursor < end:
			(fat, cluster) = self.read_fat_cluster(self.fat_cursor)
			if (self.fat_cursor == end - 1
			    and remainder != 0):
				n = min(fat[:remainder])
			else: 
				n = min(fat)
			if (n & PS2MC_FAT_ALLOCATED_BIT) == 0:
				offset = fat.index(n)
				fat[offset] = PS2MC_FAT_CHAIN_END
				self._write_fat_cluster(cluster, fat)
				ret = self.fat_cursor * epc + offset
				# print "@@@ allocated", ret
				return ret
			self.fat_cursor += 1
		return None
	
	def fat_chain(self, first_cluster):
		return fat_chain(self.lookup_fat, first_cluster)

	def file(self, dirloc, first_cluster, length, mode, name = None):
		"""Create a new file-like object for a file."""
		
		f = ps2mc_file(self, dirloc, first_cluster, length, mode, name)
		if dirloc == None:
			return
		open_files = self.open_files
		if dirloc not in open_files:
			open_files[dirloc] = [None, set([f])]
		else:
			open_files[dirloc][1].add(f)
		return f

	def directory(self, dirloc, first_cluster, length,
		      mode = None, name = None):
		return ps2mc_directory(self, dirloc, first_cluster, length,
				       mode, name)
	
	def _directory(self, dirloc, first_cluster, length,
		       mode = None, name = None):
		# print "@@@ _directory", dirloc, first_cluster, length
		if first_cluster != 0:
			return self.directory(dirloc, first_cluster, length,
					      mode, name)
		if dirloc == None:
			dirloc = (0, 0)
		assert dirloc == (0, 0)
		if self.rootdir != None:
			return self.rootdir
		dir = _root_directory(self, dirloc, 0, length, "r+b", "/")
		l = dir[0][2]
		if l != length:
			dir.real_close()
			dir = _root_directory(self, dirloc, 0, l, "r+b", "/")
		self.rootdir = dir
		return dir

	def _get_parent_dirloc(self, dirloc):
		"""Get the dirloc of the parent directory of the
		file or directory refered to by dirloc"""
		
		cluster = self.read_allocatable_cluster(dirloc[0])
		ent = unpack_dirent(cluster[:PS2MC_DIRENT_LENGTH])
		return (ent[4], ent[5])

	def _dirloc_to_ent(self, dirloc):
		"""Get the directory entry of the file or directory
		refered to by dirloc"""
		
		dir = self._directory(None, dirloc[0], dirloc[1] + 1,
				      name = "_dirloc_to_ent temp")
		ent = dir[dirloc[1]]
		dir.close()
		return ent

	def _opendir_dirloc(self, dirloc, mode = "rb"):
		"""Open the directory that is refered to by dirloc"""
		
		ent = self._dirloc_to_ent(dirloc)
		return self._directory(dirloc, ent[4], ent[2],
				       name = "_opendir_dirloc temp")

	def _opendir_parent_dirloc(self, dirloc, mode = "rb"):
		"""Open the directory that contains the file or directory
		refered to by dirloc"""
		
		return self._opendir_dirloc(self._get_parent_dirloc(dirloc),
					    mode)
		
	def update_dirent_all(self, dirloc, thisf, new_ent):
		# print "@@@ update_dirent", dirloc
		# print "@@@ new_ent", new_ent
		opened = self.open_files.get(dirloc, None)
		if opened == None:
			files = []
			dir = None
		else:
			dir, files = opened
		if dir == None:
			dir = self._opendir_parent_dirloc(dirloc, "r+b")
			if opened != None:
				opened[0] = dir
		
		ent = dir[dirloc[1]]
		# print "@@@ old_ent", ent
		
		is_dir = ent[0] & DF_DIR

		if is_dir and thisf != None and new_ent[2] != None:
			new_ent = list(new_ent)
			new_ent[2] /= PS2MC_DIRENT_LENGTH
			
		# print "len: ", ent[2], new_ent[2]

		modified = changed = notify = False
		for i in range(len(ent)):
			new = new_ent[i]
			if new != None:
				if new != ent[i]:
					ent[i] = new
					changed = True
					if i == 6:
						modified = True
					if i in [2, 4]:
						notify = True
						
		# Modifying a file causes the modification time of
		# both the file and the file's directory to updated,
		# however modifying a directory never updates the
		# modification time of the directory's parent.
		if changed:
			dir.write_raw_ent(dirloc[1], ent,
					  (modified and not is_dir))

		
		if notify:
			for f in files:
				if f != thisf:
					f.update_notfiy(ent[4], ent[2])
		if opened == None:
			dir.close()

	def update_dirent(self, dirloc, thisf, first_cluster, length,
			  modified):
		if modified:
			modified = tod_now()
		else:
			if first_cluster == None and length == None:
				return
			modified = None
		self.update_dirent_all(dirloc, thisf,
				       (None, None, length, None,
					first_cluster, None, modified, None,
					None))
			
	def notify_closed(self, dirloc, thisf):
		if self.open_files == None or dirloc == None:
			return
		a  = self.open_files.get(dirloc, None)
		if a == None:
			return
		self.flush()
		dir, files = a
		files.discard(thisf)
		if len(files) == 0:
			# print "@@@ notify_closed", dir
			if dir != None:
				dir.close()
			del self.open_files[dirloc]
			
	def search_directory(self, dir, name):
		"""Search dir for name."""

		# start the search where the last search ended.
		start = dir.tell() - 1
		if start == -1:
			start = 0
		for i in range(start, len(dir)) + range(0, start):
			ent = dir[i]
			if ent[8] == name and (ent[0] & DF_EXISTS):
				return (i, ent)
		return (None, None)

	def create_dir_entry(self, parent_dirloc, name, mode):
		"""Create a new directory entry in a directory."""
		
		# print "@@@ create_dir_ent", parent_dirloc, name
		dir_ent = self._dirloc_to_ent(parent_dirloc)
		dir = self._directory(parent_dirloc, dir_ent[4], dir_ent[2],
				      "r+b")
		l = len(dir)
		# print "@@@ len", l
		assert l >= 2
		for i in range(l):
			ent = dir[i]
			if (ent[0] & DF_EXISTS) == 0:
				break
		else:
			i = l
			
		dirloc = (dir_ent[4], i)
		# print "@@@ dirloc", dirloc
		now = tod_now()
		if mode & DF_DIR:
			mode &= ~DF_FILE
			cluster = self.allocate_cluster()
			length = 1
		else:
			mode |= DF_FILE
			mode &= ~DF_DIR
			cluster = PS2MC_FAT_CHAIN_END
			length = 0
		ent[0] = mode | DF_EXISTS
		ent[1] = 0
		ent[2] = length
		ent[3] = now
		ent[4] = cluster
		ent[5] = 0
		ent[6] = now
		ent[7] = 0
		ent[8] = name[:32]
		dir.write_raw_ent(i, ent, True)
		dir.close()

		if mode & DF_FILE:
			# print "@@@ ret", dirloc, ent
			return (dirloc, ent)

		dirent = pack_dirent((DF_RWX | DF_0400 | DF_DIR | DF_EXISTS,
				      0, 0, now, dirloc[0], dirloc[1],
				      now, 0, "."))
		dirent += "\0" * (self.cluster_size - PS2MC_DIRENT_LENGTH)
		self.write_allocatable_cluster(cluster, dirent)
		dir = self._directory(dirloc, cluster, 1, "wb",
				      name = "<create_dir_entry temp>")
		dir.write_raw_ent(1, (DF_RWX | DF_0400 | DF_DIR | DF_EXISTS,
				      0, 0, now,
				      0, 0,
				      now, 0, ".."), False)
		dir.close()
		ent[2] = 2
		# print "@@@ ret", dirloc, ent
		return (dirloc, ent)

	def delete_dirloc(self, dirloc, truncate, name):
		"""Delete or truncate the file or directory given by dirloc."""
		
		if dirloc == (0, 0):
			raise io_error, (EACCES,
					 "cannot remove root directory",
					 name)
		if dirloc[1] in [0, 1]:
			raise io_error, (EACCES,
					 'cannot remove "." or ".." entries',
					 name)

		if dirloc in self.open_files:
			raise io_error, (EBUSY,
					 "cannot remove open file", filename)

		epc = self.entries_per_cluster

		ent = self._dirloc_to_ent(dirloc)
		cluster = ent[4]
		if truncate:
			ent[2] = 0
			ent[4] = PS2MC_FAT_CHAIN_END
			ent[6] = tod_now()
		else:
			ent[0] &= ~DF_EXISTS
		self.update_dirent_all(dirloc, None, ent)
		
		while cluster != PS2MC_FAT_CHAIN_END:
			if cluster / epc < self.fat_cursor:
				self.fat_cursor = cluster / epc
			next_cluster = self.lookup_fat(cluster)
			if next_cluster & PS2MC_FAT_ALLOCATED_BIT == 0:
				# corrupted
				break
			next_cluster &= ~PS2MC_FAT_ALLOCATED_BIT
			self.set_fat(cluster, next_cluster)
			if next_cluster == PS2MC_FAT_CHAIN_END_UNALLOC:
				break
			cluster = next_cluster
			
	def path_search(self, pathname):
		"""Parse and resolve a pathname.

		Return a tuple containing a tuple containing three
		values.  The first is either the dirloc of the file or
		directory, if it exists, otherwise it's the dirloc the
		pathname's parent directory, if that exists otherwise
		it's None.  The second component is directory entry
		for pathname if it exists, otherwise None.  The third
		is a boolean value that's true if the pathname refers
		a directory."""
		
		components = pathname.split("/")
		if len(components) < 1:
			# could return curdir
			return (None, None, False)

		dirloc = self.curdir
		if components[0] == "":
			dirloc = (0, 0)
		if dirloc == (0, 0):
			rootent = self.read_allocatable_cluster(0)
			ent = unpack_dirent(rootent[:PS2MC_DIRENT_LENGTH])
			dir_cluster = 0
			dir = self._directory(dirloc, dir_cluster, ent[2],
					      name = "<path_search temp>")
		else:
			ent = self._dirloc_to_ent(dirloc)
			dir = self._directory(dirloc, ent[4], ent[2],
					      name = "<path_search temp>")

		for s in components:
			# print "@@@", dirloc, repr(s), dir == None, ent
			if s == "":
				continue
			
			if dir == None:
				# tried to traverse a file or a
				# non-existent directory
				return (None, None, False)
			
			if s == "" or s == ".":
				continue
			if s == "..":
				dotent = dir[0]
				dir.close()
				dirloc = (dotent[4], dotent[5])
				ent = self._dirloc_to_ent(dirloc)
				dir = self._directory(dirloc, ent[4], ent[2],
						      name
						      = "<path_search temp>")
				continue

			dir_cluster = ent[4]
			(i, ent) = self.search_directory(dir, s)
			dir.close()
			dir = None

			if ent == None:
				continue
			
			dirloc = (dir_cluster, i)
			if ent[0] & DF_DIR:
				dir = self._directory(dirloc, ent[4], ent[2],
						      name
						      = "<path_search temp>")

		if dir != None:
			dir.close()
			
		return (dirloc, ent, dir != None)

	def open(self, filename, mode = "r"):
		"""Open a file, returning a new file-like object for it."""
		
		(dirloc, ent, is_dir) = self.path_search(filename)
		# print "@@@ open", (dirloc, ent)
		if dirloc == None or (ent == None and is_dir):
			raise path_not_found, filename
		if is_dir:
			raise io_error, (EISDIR, "not a regular file",
					 filename)
		if ent == None:
			if mode[0] not in "wa":
				raise file_not_found, filename
			name = filename.split("/")[-1]
			(dirloc, ent) = self.create_dir_entry(dirloc, name,
							      DF_FILE | DF_RWX
							      | DF_0400);
			self.flush()
		elif mode[0] == "w":
			self.delete_dirloc(dirloc, True, filename)
			ent[4] = PS2MC_FAT_CHAIN_END
			ent[2] = 0
		return self.file(dirloc, ent[4], ent[2], mode, filename)

	def dir_open(self, filename, mode = "rb"):
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent == None:
			raise dir_not_found, filename
		if not is_dir:
			raise io_error, (ENOTDIR, "not a directory", filename)
		return self.directory(dirloc, ent[4], ent[2], mode, filename)

	def mkdir(self, filename):
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent != None:
			raise io_error, (EEXIST, "directory exists", filename)
		a = filename.split("/")
		name = a.pop()
		while name == "":
			name = a.pop()
		self.create_dir_entry(dirloc, name, DF_DIR | DF_RWX | DF_0400)
		self.flush()

	def _is_empty(self, dirloc, ent, filename):
		"""Check if a directory is empty."""
		
		dir = self._directory(dirloc, ent[4], ent[2], "rb",
				      filename)
		try:
			for i in range(2, len(dir)):
				if dir[i][0] & DF_EXISTS:
					return False
		finally:
			dir.close()
		return True
		
	def remove(self, filename):
		"""Remove a file or empty directory."""
		
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent == None:
			raise file_not_found, filename
		if is_dir:
			if ent[4] == 0:
				raise io_error, (EACCES,
						 "cannot remove"
						 " root directory")
			if not self._is_empty(dirloc, ent, filename):
				raise io_error, (ENOTEMPTY,
						 "directory not empty",
						 filename)
		self.delete_dirloc(dirloc, False, filename)
		self.flush()

	def chdir(self, filename):
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent == None:
			raise dir_not_found, filename
		if not is_dir:
			raise io_error, (ENOTDIR, "not a directory", filename)
		self.curdir = dirloc

	def get_mode(self, filename):
		"""Get mode bits of a file.

		Returns None if the filename doesn't exist, rather than
		throwing a error."""
		
		(dirloc, ent, is_dir) = self.path_search(filename)
		if ent == None:
			return None
		return ent[0]
	
	def get_dirent(self, filename):
		"""Get the raw directory entry tuple for a file."""
		
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent == None:
			raise file_not_found, filename
		return ent

	def set_dirent(self, filename, new_ent):
		"""Set various directory entry fields of a file.

		Not all fields can be changed.  If a field in new_ent
		is set to None then is not changed."""
		
		(dirloc, ent, is_dir) = self.path_search(filename)
		if dirloc == None:
			raise path_not_found, filename
		if ent == None:
			raise file_not_found, filename
		dir = self._opendir_parent_dirloc(dirloc)
		try:
			dir[dirloc[1]] = new_ent
		finally:
			dir.close()
		self.flush()
		return ent

	def import_save_file(self, sf, ignore_existing, dirname = None):
		"""Copy the contents a ps2_save_file object to a directory.

		If ingore_existing is true and the directory being imported
		to already exists then False is returned instead of raising
		an error.  If dirname is given then the save file is copied
		to that directory instead of the directory specified by
		the save file.
		"""
		
		dir_ent = sf.get_directory()
		if dirname == None:
			dir_ent_name = dir_ent[8]
			dirname = "/" + dir_ent[8]
		else:
			if dirname == "":
				raise path_not_found, dirname
			
			# remove trailing slashes
			dirname = dirname.rstrip("/")
			if dirname == "":
				dirname = "/"
			dir_ent_name = dirname.split("/")[0]

		(root_dirloc, ent, is_dir) = self.path_search(dirname)
		if root_dirloc == None:
			raise path_not_found, dirname
		if ent != None:
			if ignore_existing:
				return False
			raise io_error, (EEXIST, "directory exists", dirname)
		mode = DF_DIR | (dir_ent[0] & ~DF_FILE)

		(dir_dirloc, ent) = self.create_dir_entry(root_dirloc,
							  dir_ent_name,
							  mode)
		try:
			assert dirname != "/"
			dirname = dirname + "/"
			for i in range(dir_ent[2]):
				(ent, data) = sf.get_file(i)
				mode = DF_FILE | (ent[0] & ~DF_DIR)
				(dirloc, ent) \
					= self.create_dir_entry(dir_dirloc,
								ent[8], mode)
				# print "@@@ file", dirloc, ent[4], ent[2]
				f = self.file(dirloc, ent[4], ent[2], "wb",
					      dirname + ent[8])
				try:
					f.write(data)
				finally:
					f.close()
		except EnvironmentError:
			type, what, where = sys.exc_info()
			try:
				try:
					for i in range(dir_ent[2]):
						(ent, data) = sf.get_file(i)
						# print "@@@ remove", ent[8]
						self.remove(dirname + ent[8])
				except EnvironmentError, why:
					# print "@@@ failed", why
					pass
			
				try:
					# print "@@@ remove dir", dirname
					self.remove(dirname)
				except EnvironmentError, why:
					# print "@@@ failed", why
					pass
				raise type, what, where
			finally:
				del where

		# set modes and timestamps to those of the save file
		
		dir = self._opendir_dirloc(dir_dirloc, "r+b")
		try:
			for i in range(dir_ent[2]):
				dir[i + 2] = sf.get_file(i)[0]
		finally:
			dir.close()
			
		dir = self._opendir_dirloc(root_dirloc, "r+b")
		try:
			dir[dir_dirloc[1]] = dir_ent
		finally:
			dir.close()

		self.flush()
		return True

	def export_save_file(self, filename):
		(dir_dirloc, dirent, is_dir) = self.path_search(filename)
		if dir_dirloc == None:
			raise path_not_found, filename
		if dirent == None:
			raise dir_not_found, filename
		if not is_dir:
			raise io_error, (ENOTDIR, "not a directory", filename)
		if dir_dirloc == (0, 0):
			raise io_error, (EACCES, "can't export root directory",
					 filename)
		sf = ps2save.ps2_save_file()
		files = []
		f = None
		dir = self._directory(dir_dirloc, dirent[4], dirent[2],
				      "rb", filename)
		try:
			for i in range(2, dirent[2]):
				ent = dir[i]
				if not mode_is_file(ent[0]):
					print ("warning: %s/%s is not a file,"
					       " ingored."
					       % (dirent[8], ent[8]))
					continue
				f = self.file((dirent[4], i), ent[4], ent[2],
					      "rb")
				data = f.read(ent[2])
				f.close()
				assert len(data) == ent[2]
				files.append((ent, data))
		finally:
			if f != None:
				f.close()
			dir.close()
		dirent[2] = len(files)
		sf.set_directory(dirent)
		for (i, (ent, data)) in enumerate(files):
			sf.set_file(i, ent, data)
		return sf

	def _remove_dir(self, dirloc, ent, dirname):
		"""Recurse over a directory tree to remove it.
		If not "", dirname must end with a slash (/)."""

		first_cluster = ent[4]
		length = ent[2]
		dir = self._directory(dirloc, first_cluster, length,
				      "rb", dirname)
		try:
			ents = list(enumerate(dir))
		finally:
			dir.close()
		for (i, ent) in ents[2:]:
			mode = ent[0]
			if not (mode & DF_EXISTS):
				continue
			if mode & DF_DIR:
				self._remove_dir((first_cluster, i), ent,
						 dirname + ent[8] + "/")
			else:
				# print "deleting", dirname + ent[8]
				self.delete_dirloc((first_cluster, i), False,
						   dirname + ent[8])
		self.delete_dirloc(dirloc, False, dirname)
		
	def rmdir(self, dirname):
		"""Recursively delete a directory."""
		
		(dirloc, ent, is_dir) = self.path_search(dirname)
		if dirloc == None:
			raise path_not_found, dirname
		if ent == None:
			raise dir_not_found, dirname
		if not is_dir:
			raise io_error, (ENOTDIR, "not a directory", dirname)
		if dirloc == (0, 0):
			raise io_error, (EACCES, "can't delete root directory",
					 dirname)

		if dirname != "" and dirname[-1] != "/":
			dirname += "/"
		self._remove_dir(dirloc, ent, dirname)

	def get_free_space(self):
		"""Returns the amount of free space in bytes."""
		
		free = 0
		for i in xrange(self.allocatable_cluster_end):
			if (self.lookup_fat(i) & PS2MC_FAT_ALLOCATED_BIT) == 0:
				free += 1
		return free * self.cluster_size

	def get_allocatable_space(self):
		"""Returns the total amount of allocatable space in bytes."""
		return self.allocatable_cluster_limit * self.cluster_size
	
	def _check_file(self, fat, first_cluster, length):
		cluster = first_cluster
		i = 0
		while cluster != PS2MC_FAT_CHAIN_END:
			if cluster < 0 or cluster >= len(fat):
				return "invalid cluster in chain"
			if fat[cluster]:
				return "cross linked chain"
			i += 1
			# print cluster,
			fat[cluster] = 1
			next = self.lookup_fat(cluster)
			if next == PS2MC_FAT_CHAIN_END:
				break
			if (next & PS2MC_FAT_ALLOCATED_BIT) == 0:
				return "unallocated cluster in chain"
			cluster = next & ~PS2MC_FAT_ALLOCATED_BIT
		file_cluster_end = div_round_up(length, self.cluster_size)
		if i < file_cluster_end:
			return "chain ends before end of file"
		elif i > file_cluster_end:
			return "chain continues after end of file"
		return None

	def _check_dir(self, fat, dirloc, dirname, ent):
		why = self._check_file(fat, ent[4],
				       ent[2] * PS2MC_DIRENT_LENGTH)
		if why != None:
			print "bad directory:", dirname + ":", why
			return False
		ret = True
		first_cluster = ent[4]
		length = ent[2]
		dir = self._directory(dirloc, first_cluster, length,
				      "rb", dirname)
		dot_ent = dir[0]
		if dot_ent[8] != ".":
			print "bad directory:", dirname + ': missing "." entry'
			ret = False
		if (dot_ent[4], dot_ent[5]) != dirloc:
			print "bad directory:", dirname + ': bad "." entry'
			ret = False
		if dir[1][8] != "..":
			print "bad directory:", (dirname
						 + ': missing ".." entry')
			ret = False
		for i in xrange(2, length):
			ent = dir[i]
			mode = ent[0]
			if not (mode & DF_EXISTS):
				continue
			if mode & DF_DIR:
				if not self._check_dir(fat, (first_cluster, i),
						       dirname + ent[8] + "/",
						       ent):
					ret = False
			else:
				why = self._check_file(fat, ent[4], ent[2])
				if why != None:
					print "bad file:", (dirname + ent[8]
							    + ":"), why
					ret = False
				
		dir.close()
		return ret
		
	def check(self):
		"""Run a simple file system check.

		Any problems found are reported to stdout."""
		
		ret = True

		fat_len = int(str(self.allocatable_cluster_end)) 
		if not isinstance(fat_len, int):
			raise error, "Memory card image too big to check."

		fat = array.array('B', [0]) * fat_len

		cluster = self.read_allocatable_cluster(0)
		ent = unpack_dirent(cluster[:PS2MC_DIRENT_LENGTH])
		ret = self._check_dir(fat, (0, 0), "/", ent)

		lost_clusters = 0
		for i in xrange(self.allocatable_cluster_end):
			a = self.lookup_fat(i)
			if (a & PS2MC_FAT_ALLOCATED_BIT) and not fat[i]:
				print i,
				lost_clusters += 1
		if lost_clusters > 0:
			print
			print "found", lost_clusters, "lost clusters"
			ret = False
			
		return ret

	def _glob(self, dirname, components):
		pattern = components[0]
		if len(components) == 1:
			if pattern == "":
				return [dirname]
			dir = self.dir_open(dirname)
			try:
				return [dirname + ent[8]
					for ent in dir
					if ((ent[0] & DF_EXISTS)
					    and (ent[8] not in [".", ".."]
						 or ent[8] == pattern)
					    and fnmatch.fnmatchcase(ent[8],
								    pattern))]
			finally:
				dir.close()
		if pattern == "":
			return self._glob(dirname + "/", components[1:])
		if dirname == "":
			dir = self.dir_open(".")
		else:
			dir = self.dir_open(dirname)
		try:
			ret = []
			for ent in dir:
				name = ent[8]
				if ((ent[0] & DF_EXISTS) == 0
				    or (ent[0] & DF_DIR) == 0):
					continue
				if name == "." or name == "..":
					if pattern != name:
						continue
				elif not fnmatch.fnmatchcase(name, pattern):
					continue
				ret += self._glob(dirname + name + "/",
						  components[1:])
		finally:
			dir.close()
		return ret
		
	def glob(self, pattern):
		if pattern == "":
			return []
		ret = self._glob("", pattern.split("/"))
		# print pattern, "->", ret
		return self._glob("", pattern.split("/"))

	def get_icon_sys(self, dirname):
		"""Get contents of a directory's icon.sys file, if it exits."""

		icon_sys = dirname + "/icon.sys"
		mode = self.get_mode(icon_sys)
		if mode == None or not mode_is_file(mode):
			return None
		f = self.open(icon_sys, "rb")
		s = f.read(964)
		f.close()
		if len(s) == 964 and s[0:4] == "PS2D":
			return s;
		return None

	def dir_size(self, dirname):
		"""Calculate the total size of the contents of a directory."""

		dir = self.dir_open(dirname)
		try:
			length = round_up(len(dir) * PS2MC_DIRENT_LENGTH,
					  self.cluster_size)
			for ent in dir:
				if mode_is_file(ent[0]):
					length += round_up(ent[2],
							   self.cluster_size)
				elif (mode_is_dir(ent[0])
				      and ent[8] not in [".", ".."]):
					length += self._dir_size(dirname + "/"
								 + ent[8])
		finally:
			dir.close()
		return length
			
	def flush(self):
		self.flush_alloc_cluster_cache()
		self.flush_fat_cache()
		if self.modified:
			self.write_superblock()
		self.f.flush()
		
	def close(self):
		"""Close all open files.

		Disconnects, but doesn't close the file object used
		access the raw image.  After this method has been
		called on a ps2mc object, it can no longer be used."""
		
		# print "ps2mc.close"
		try:
			f = self.f
			if f == None or getattr(f, "closed", False):
				# print "closed"
				return
			open_files = self.open_files
			# print "open_files", open_files
			if open_files != None:
				# this is complicated by the fact as
				# files are closed they will remove
				# themselves from the list of open files
				for (dir, files) in open_files.values():
					for f in list(files):
						f.close()
				while len(open_files) > 0:
					(k, v) = open_files.popitem()
					(dir, files) = v
					if dir != None:
						dir.close()
			if self.rootdir != None:
				self.rootdir.close()
			if self.fat_cache != None:
				self.flush()
		finally:
			self.open_files = None
			self.fat_cache = None
			self.f = None
			self.rootdir = None

	def __del__(self):
		# print "ps2mc.__del__"
		try:
			self.close()
		except:
			sys.stderr.write("ps2mc.__del__: \n")
			traceback.print_exc()