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SickRage/lib/hachoir_core/field/padding.py

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from lib.hachoir_core.field import Bits, Bytes
from lib.hachoir_core.tools import makePrintable, humanFilesize
from lib.hachoir_core import config
class PaddingBits(Bits):
"""
Padding bits used, for example, to align address (of next field).
See also NullBits and PaddingBytes types.
Arguments:
* nbits: Size of the field in bits
Optional arguments:
* pattern (int): Content pattern, eg. 0 if all bits are set to 0
"""
static_size = staticmethod(lambda *args, **kw: args[1])
MAX_SIZE = 128
def __init__(self, parent, name, nbits, description="Padding", pattern=None):
Bits.__init__(self, parent, name, nbits, description)
self.pattern = pattern
self._display_pattern = self.checkPattern()
def checkPattern(self):
if not(config.check_padding_pattern):
return False
if self.pattern != 0:
return False
if self.MAX_SIZE < self._size:
value = self._parent.stream.readBits(
self.absolute_address, self.MAX_SIZE, self._parent.endian)
else:
value = self.value
if value != 0:
self.warning("padding contents doesn't look normal (invalid pattern)")
return False
if self.MAX_SIZE < self._size:
self.info("only check first %u bits" % self.MAX_SIZE)
return True
def createDisplay(self):
if self._display_pattern:
return u"<padding pattern=%s>" % self.pattern
else:
return Bits.createDisplay(self)
class PaddingBytes(Bytes):
"""
Padding bytes used, for example, to align address (of next field).
See also NullBytes and PaddingBits types.
Arguments:
* nbytes: Size of the field in bytes
Optional arguments:
* pattern (str): Content pattern, eg. "\0" for nul bytes
"""
static_size = staticmethod(lambda *args, **kw: args[1]*8)
MAX_SIZE = 4096
def __init__(self, parent, name, nbytes,
description="Padding", pattern=None):
""" pattern is None or repeated string """
assert (pattern is None) or (isinstance(pattern, str))
Bytes.__init__(self, parent, name, nbytes, description)
self.pattern = pattern
self._display_pattern = self.checkPattern()
def checkPattern(self):
if not(config.check_padding_pattern):
return False
if self.pattern is None:
return False
if self.MAX_SIZE < self._size/8:
self.info("only check first %s of padding" % humanFilesize(self.MAX_SIZE))
content = self._parent.stream.readBytes(
self.absolute_address, self.MAX_SIZE)
else:
content = self.value
index = 0
pattern_len = len(self.pattern)
while index < len(content):
if content[index:index+pattern_len] != self.pattern:
self.warning(
"padding contents doesn't look normal"
" (invalid pattern at byte %u)!"
% index)
return False
index += pattern_len
return True
def createDisplay(self):
if self._display_pattern:
return u"<padding pattern=%s>" % makePrintable(self.pattern, "ASCII", quote="'")
else:
return Bytes.createDisplay(self)
def createRawDisplay(self):
return Bytes.createDisplay(self)
class NullBits(PaddingBits):
"""
Null padding bits used, for example, to align address (of next field).
See also PaddingBits and NullBytes types.
Arguments:
* nbits: Size of the field in bits
"""
def __init__(self, parent, name, nbits, description=None):
PaddingBits.__init__(self, parent, name, nbits, description, pattern=0)
def createDisplay(self):
if self._display_pattern:
return "<null>"
else:
return Bits.createDisplay(self)
class NullBytes(PaddingBytes):
"""
Null padding bytes used, for example, to align address (of next field).
See also PaddingBytes and NullBits types.
Arguments:
* nbytes: Size of the field in bytes
"""
def __init__(self, parent, name, nbytes, description=None):
PaddingBytes.__init__(self, parent, name, nbytes, description, pattern="\0")
def createDisplay(self):
if self._display_pattern:
return "<null>"
else:
return Bytes.createDisplay(self)