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# This file is part of PeachPy package and is licensed under the Simplified BSD license.
# See license.rst for the full text of the license.
from enum import IntEnum
class MemoryProtection(IntEnum):
read = 0x01
write = 0x02
execute = 0x04
default = 0x07
class Segment:
def __init__(self, name):
self.name = name
self.sections = list()
self.flags = 0
def add_section(self, section):
assert isinstance(section, Section)
assert section.segment_name == self.name
self.sections.append(section)
def get_command_size(self, abi):
from peachpy.abi import ABI
assert isinstance(abi, ABI)
assert abi.pointer_size in [4, 8]
return {4: 56, 8: 72}[abi.pointer_size] + \
sum(section.get_command_size(abi) for section in self.sections)
def encode_command(self, encoder, section_offset_map, section_address_map, section_relocations_map):
import peachpy.encoder
assert isinstance(encoder, peachpy.encoder.Encoder)
offset = section_offset_map[self.sections[0]]
memory_size = section_address_map[self.sections[-1]] + self.sections[-1].content_size
file_size = sum(section.content_size for section in self.sections)
address = 0
if self.sections:
address = section_address_map[self.sections[0]]
# TODO: combine the two cases
if encoder.bitness == 32:
command_id = 0x1
command_size = 56 + len(self.sections) * 68
command = encoder.uint32(command_id) + \
encoder.uint32(command_size) + \
encoder.fixed_string(self.name, 16) + \
encoder.uint32(address) + \
encoder.uint32(memory_size) + \
encoder.uint32(offset) + \
encoder.uint32(file_size) + \
encoder.uint32(MemoryProtection.default) + \
encoder.uint32(MemoryProtection.default) + \
encoder.uint32(len(self.sections)) + \
encoder.uint32(self.flags)
else:
command_id = 0x19
command_size = 72 + len(self.sections) * 80
command = encoder.uint32(command_id) + \
encoder.uint32(command_size) + \
encoder.fixed_string(self.name, 16) + \
encoder.uint64(address) + \
encoder.uint64(memory_size) + \
encoder.uint64(offset) + \
encoder.uint64(file_size) + \
encoder.uint32(MemoryProtection.default) + \
encoder.uint32(MemoryProtection.default) + \
encoder.uint32(len(self.sections)) + \
encoder.uint32(self.flags)
for section in self.sections:
command += section.encode_command(encoder,
section_offset_map[section],
section_address_map[section],
section_relocations_map.get(section))
from peachpy.x86_64.abi import system_v_x86_64_abi
return command
class SectionIndex(IntEnum):
no_section = 0
class SectionType(IntEnum):
regular = 0x00
zero_fill = 0x01
gb_zero_fill = 0x0C
cstring_literals = 0x02
four_byte_literals = 0x03
eight_byte_literals = 0x04
sixteen_byte_literals = 0x0E
literal_pointers = 0x05
non_lazy_symbol_pointers = 0x06
lazy_symbol_pointers = 0x07
symbol_stubs = 0x08
module_init_function_pointers = 0x09
module_terminate_function_pointers = 0x0A
coalesced_symbols = 0x0B
interposing = 0x0D
dtrace_object_format = 0x0F
lazy_dylib_symbol_pointers = 0x10
thread_local_regular = 0x11
thread_local_zero_fill = 0x12
thread_local_variable_descriptors = 0x13
thread_local_variable_pointers = 0x14
thread_local_function_pointers = 0x15
class SectionAttributes(IntEnum):
only_instructions = 0x80000000
coalesced_symbols = 0x40000000
strip_static_symbols = 0x20000000
no_dead_stripping = 0x10000000
live_support = 0x08000000
self_modifying_code = 0x04000000
debug = 0x02000000
some_instructions = 0x00000400
external_relocations = 0x00000200
local_relocations = 0x00000100
class Section(object):
def __init__(self, type, segment_name, section_name):
self.type = type
self.segment_name = segment_name
self.section_name = section_name
self.attributes = 0
self._alignment = 1
self.relocations = []
self.content = bytearray()
@property
def alignment(self):
return self._alignment
@alignment.setter
def alignment(self, alignment):
from peachpy.util import is_uint32
if not is_uint32(alignment):
raise TypeError("Section alignment %s is not representable as a 32-bit unsigned integer" % str(alignment))
if alignment & (alignment - 1) != 0:
raise ValueError("Section alignment %d is not a power of 2" % alignment)
if alignment == 0:
alignment = 1
self._alignment = alignment
@property
def log2_alignment(self):
from peachpy.util import ilog2
return ilog2(self._alignment)
@property
def relocations_count(self):
return len(self.relocations)
@property
def content_size(self):
return len(self.content)
@staticmethod
def get_command_size(abi):
from peachpy.abi import ABI
assert isinstance(abi, ABI)
assert abi.pointer_size in [4, 8]
return {4: 68, 8: 80}[abi.pointer_size]
def encode_command(self, encoder, offset, address, relocations_offset):
import peachpy.encoder
assert isinstance(encoder, peachpy.encoder.Encoder)
if len(self.relocations) == 0:
relocations_offset = 0
if encoder.bitness == 32:
return encoder.fixed_string(self.section_name, 16) + \
encoder.fixed_string(self.segment_name, 16) + \
encoder.uint32(address) + \
encoder.uint32(self.content_size) + \
encoder.uint32(offset) + \
encoder.uint32(self.log2_alignment) + \
encoder.uint32(relocations_offset) + \
encoder.uint32(self.relocations_count) + \
encoder.uint32(self.type | self.attributes) + \
bytearray(8)
else:
return encoder.fixed_string(self.section_name, 16) + \
encoder.fixed_string(self.segment_name, 16) + \
encoder.uint64(address) + \
encoder.uint64(self.content_size) + \
encoder.uint32(offset) + \
encoder.uint32(self.log2_alignment) + \
encoder.uint32(relocations_offset) + \
encoder.uint32(self.relocations_count) + \
encoder.uint32(self.type | self.attributes) + \
bytearray(12)
class RegularSection(Section):
def __init__(self, segment_name, section_name):
super(RegularSection, self).__init__(SectionType.regular, segment_name, section_name)
def align(self, alignment):
import peachpy.util
ilog2_alignment = peachpy.util.ilog2(alignment)
self.alignment = max(self.alignment, ilog2_alignment)
if len(self.content) % alignment != 0:
padding_length = alignment - len(self.content) % alignment
self.content += bytearray(padding_length)
class TextSection(RegularSection):
def __init__(self):
super(TextSection, self).__init__("__TEXT", "__text")
self.attributes = SectionAttributes.only_instructions | SectionAttributes.some_instructions
class ConstSection(RegularSection):
def __init__(self):
super(ConstSection, self).__init__("__TEXT", "__const")
class SymbolTable:
command_size = 24
def __init__(self, string_table):
assert isinstance(string_table, StringTable)
self.symbols = list()
self.string_table = string_table
def add_symbol(self, symbol):
from peachpy.formats.macho.symbol import Symbol
assert isinstance(symbol, Symbol)
self.symbols.append(symbol)
self.string_table.add(symbol.name)
def encode_command(self, encoder, symbol_offset_map, string_offset):
import peachpy.encoder
assert isinstance(encoder, peachpy.encoder.Encoder)
command_id = 0x2
symbols_offset = 0
if self.symbols:
symbols_offset = symbol_offset_map[self.symbols[0]]
return encoder.uint32(command_id) + \
encoder.uint32(SymbolTable.command_size) + \
encoder.uint32(symbols_offset) + \
encoder.uint32(len(self.symbols)) + \
encoder.uint32(string_offset) + \
encoder.uint32(self.string_table.size)
class StringTable:
def __init__(self):
self.string_index_map = dict()
self.size = 0
def add(self, string):
import codecs
if string is None or len(string) == 0:
return 0
if string in self.string_index_map:
return self.string_index_map[string]
else:
content_size = self.size
if content_size == 0:
content_size = 1
string_index = content_size
self.string_index_map[string] = string_index
bytestring = codecs.encode(string, "utf-8")
content_size += len(bytestring) + 1
self.size = content_size
def encode(self):
import codecs
if self.size != 0:
bytestring = b"\x00"
for string in sorted(self.string_index_map, key=self.string_index_map.get):
bytestring += codecs.encode(string, "utf8") + b"\x00"
return bytestring
else:
return bytearray()
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