def __init__(self, fh, offset, size):
self.MH_MAGIC = MH_MAGIC_64
self.mach_header = mach_header_64
self.endian = '<'
self.offset = offset
self.size = size
self.prelink_offset = 0
self.kernel_header = None
self.fh = fileview(fh, offset, size)
def write(self, fileobj):
fileobj = fileview(fileobj, self.offset, self.size)
fileobj.seek(0)
# serialize all the mach-o commands
self.synchronize_size()
self.header.to_fileobj(fileobj)
for lc, cmd, data in self.commands:
lc.to_fileobj(fileobj)
cmd.to_fileobj(fileobj)
if sys.version_info[0] == 2:
if isinstance(data, unicode):
fileobj.write(data.encode(sys.getfilesystemencoding()))
elif isinstance(data, (bytes, str)):
fileobj.write(data)
else:
# segments..
for obj in data:
obj.to_fileobj(fileobj)
else:
if isinstance(data, str):
fileobj.write(data.encode(sys.getfilesystemencoding()))
elif isinstance(data, bytes):
fileobj.write(data)
else:
# segments..
for obj in data:
obj.to_fileobj(fileobj)
# zero out the unused space, doubt this is strictly necessary
# and is generally probably already the case
fileobj.write(b'\x00' * (self.low_offset - fileobj.tell()))
def load(self, fh):
fh = fileview(fh, self.offset, self.size)
fh.seek(0)
self.sizediff = 0
kw = {'_endian_': self.endian}
header = self.mach_header.from_fileobj(fh, **kw)
self.header = header
#print(hex(header.magic)
#if header.magic != self.MH_MAGIC:
# raise ValueError("header has magic %08x, expecting %08x" % (
# header.magic, self.MH_MAGIC))
self.cmd = self.commands = []
self.filetype = self.get_filetype_shortname(header.filetype)
read_bytes = 0
low_offset = sys.maxsize
for i in range(header.ncmds):
# read the load command
cmd_load = load_command.from_fileobj(fh, **kw)
# read the specific command
klass = LC_REGISTRY.get(cmd_load.cmd, None)
# print(klass.__name__
if klass is None:
raise ValueError("Unknown load command: %d" % (cmd_load.cmd, ))
cmd_cmd = klass.from_fileobj(fh, **kw)
#print(LC_NAMES[cmd_load.cmd]
if cmd_load.cmd == LC_ID_DYLIB:
# remember where this command was
if self.id_cmd is not None:
raise ValueError("This dylib already has an id")
self.id_cmd = i
if cmd_load.cmd in (LC_SEGMENT, LC_SEGMENT_64):
# for segment commands, read the list of segments
segs = []
# assert that the size makes sense
if cmd_load.cmd == LC_SEGMENT:
section_cls = section
else: # LC_SEGMENT_64
section_cls = section_64
expected_size = (sizeof(klass) + sizeof(load_command) +
(sizeof(section_cls) * cmd_cmd.nsects))
if cmd_load.cmdsize != expected_size:
raise ValueError("Segment size mismatch")
# this is a zero block or something
# so the beginning is wherever the fileoff of this command is
if cmd_cmd.nsects == 0:
if cmd_cmd.filesize != 0:
self.other_segment_details[cmd_cmd.describe()["segname"]] =\
{"offset":cmd_cmd.describe()["fileoff"], "size":cmd_cmd.describe()["vmsize"]}
low_offset = min(low_offset, cmd_cmd.fileoff)
else:
# this one has multiple segments
for j in range(cmd_cmd.nsects):
# read the segment
seg = section_cls.from_fileobj(fh, **kw)
self.section_details[seg.describe()["segname"] + "," + seg.describe()["sectname"]] =\
{"offset":seg.describe()["offset"], "size":seg.describe()["size"],
"addr":seg.describe()["addr"]}
# if the segment has a size and is not zero filled
# then its beginning is the offset of this segment
not_zerofill = ((seg.flags & S_ZEROFILL) != S_ZEROFILL)
if seg.offset > 0 and seg.size > 0 and not_zerofill:
low_offset = min(low_offset, seg.offset)
if not_zerofill:
c = fh.tell()
fh.seek(seg.offset)
sd = fh.read(seg.size)
seg.add_section_data(sd)
fh.seek(c)
segs.append(seg)
# data is a list of segments
cmd_data = segs
else:
# data is a raw str
#self.other_segment_details[LC_NAMES[cmd_load.cmd]] =
#print(klass
data_size = (cmd_load.cmdsize - sizeof(klass) -
sizeof(load_command))
cmd_data = fh.read(data_size)
self.cmd.append((cmd_load, cmd_cmd, cmd_data))
read_bytes += cmd_load.cmdsize
# make sure the header made sense
if read_bytes != header.sizeofcmds:
raise ValueError("Read %d bytes, header reports %d bytes" %
(read_bytes, header.sizeofcmds))
self.total_size = sizeof(self.mach_header) + read_bytes
self.low_offset = low_offset