mirror of
https://github.com/AsahiLinux/m1n1
synced 2024-11-26 00:10:18 +00:00
macho.py: Support loading and importing symbol files
Signed-off-by: Hector Martin <marcan@marcan.st>
This commit is contained in:
Hector Martin
parent
db9acba268
commit
90872f460e
2 changed files with 140 additions and 25 deletions
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@ -1,13 +1,26 @@
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#!/usr/bin/env python3
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from io import BytesIO, SEEK_END, SEEK_SET
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import bisect
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from tgtypes import *
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from utils import *
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class MachO:
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def __init__(self, data):
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self.data = data
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self.obj = MachOFile.parse(data)
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if isinstance(data, bytes):
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self.io = BytesIO(data)
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else:
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self.io = data
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self.off = self.io.tell()
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self.io.seek(0, SEEK_END)
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self.end = self.io.tell()
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self.size = self.end - self.off
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self.io.seek(self.off, SEEK_SET)
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self.obj = MachOFile.parse_stream(self.io)
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self.symbols = {}
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self.load_info()
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self.load_fileset()
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def load_info(self):
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self.vmin, self.vmax = (1 << 64), 0
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@ -24,27 +37,105 @@ class MachO:
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image = bytearray(memory_size)
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for cmdi, cmd in enumerate(self.obj.cmds):
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is_m1n1 = None
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if cmd.cmd == MachOLoadCmdType.SEGMENT_64:
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if is_m1n1 is None:
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is_m1n1 = cmd.args.segname == "_HDR"
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dest = cmd.args.vmaddr - self.vmin
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end = min(len(self.data), cmd.args.fileoff + cmd.args.filesize)
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size = end - cmd.args.fileoff
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print(f"LOAD: {cmd.args.segname} {size} bytes from {cmd.args.fileoff:x} to {dest:x}")
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data = self.data[cmd.args.fileoff:end]
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if load_hook is not None:
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data = load_hook(data, cmd.args.segname, size, cmd.args.fileoff, dest)
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image[dest:dest + size] = data
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if cmd.args.vmsize > size:
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clearsize = cmd.args.vmsize - size
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if cmd.args.segname == "PYLD":
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print("SKIP: %d bytes from 0x%x to 0x%x" % (clearsize, dest + size, dest + size + clearsize))
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memory_size -= clearsize - 4 # leave a payload end marker
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image = image[:memory_size]
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else:
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print("ZERO: %d bytes from 0x%x to 0x%x" % (clearsize, dest + size, dest + size + clearsize))
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image[dest + size:dest + cmd.args.vmsize] = bytes(clearsize)
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for cmd in self.get_cmds(MachOLoadCmdType.SEGMENT_64):
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dest = cmd.args.vmaddr - self.vmin
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end = min(self.size, cmd.args.fileoff + cmd.args.filesize)
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size = end - cmd.args.fileoff
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print(f"LOAD: {cmd.args.segname} {size} bytes from {cmd.args.fileoff:x} to {dest:x}")
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self.io.seek(self.off + cmd.args.fileoff)
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data = self.io.read(size)
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if load_hook is not None:
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data = load_hook(data, cmd.args.segname, size, cmd.args.fileoff, dest)
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image[dest:dest + size] = data
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if cmd.args.vmsize > size:
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clearsize = cmd.args.vmsize - size
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if cmd.args.segname == "PYLD":
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print("SKIP: %d bytes from 0x%x to 0x%x" % (clearsize, dest + size, dest + size + clearsize))
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memory_size -= clearsize - 4 # leave a payload end marker
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image = image[:memory_size]
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else:
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print("ZERO: %d bytes from 0x%x to 0x%x" % (clearsize, dest + size, dest + size + clearsize))
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image[dest + size:dest + cmd.args.vmsize] = bytes(clearsize)
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return image
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def get_cmds(self, cmdtype):
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for cmd in self.obj.cmds:
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if cmd.cmd == cmdtype:
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yield cmd
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def get_cmd(self, cmdtype):
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cmds = list(self.get_cmds(cmdtype))
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if len(cmds) == 0:
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raise Exception(f"No commands of type {cmdtype}")
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if len(cmds) > 1:
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raise Exception(f"More than one commands of type {cmdtype} (found {len(cmd)})")
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return cmds[0]
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def load_fileset(self):
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self.subfiles = {}
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for fe in self.get_cmds(MachOLoadCmdType.FILESET_ENTRY):
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self.io.seek(self.off + fe.args.offset)
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subfile = MachO(self.io)
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self.subfiles[fe.args.name] = subfile
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for seg in subfile.get_cmds(MachOLoadCmdType.SEGMENT_64):
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self.symbols[f"{fe.args.name}:{seg.args.segname}"] = seg.args.vmaddr
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def add_symbols(self, filename, syms):
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try:
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subfile = self.subfiles[filename]
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except KeyError:
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raise Exception(f"No fileset entry for {filename}")
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sym_segs = {}
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for sym_seg in syms.get_cmds(MachOLoadCmdType.SEGMENT_64):
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sym_segs[sym_seg.args.segname] = sym_seg
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syms.load_symbols()
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symtab = [(v, k) for (k, v) in syms.symbols.items()]
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symtab.sort()
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for seg in subfile.get_cmds(MachOLoadCmdType.SEGMENT_64):
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if seg.args.segname not in sym_segs:
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continue
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sym_seg = sym_segs[seg.args.segname]
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start = bisect.bisect_left(symtab, (sym_seg.args.vmaddr, ""))
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end = bisect.bisect_left(symtab, (sym_seg.args.vmaddr + sym_seg.args.vmsize, ""))
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for addr, sym in symtab[start:end]:
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sname = f"{filename}:{sym}"
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self.symbols[sname] = addr - sym_seg.args.vmaddr + seg.args.vmaddr
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def load_symbols(self):
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self.symbols = {}
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cmd = self.get_cmd(MachOLoadCmdType.SYMTAB)
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nsyms = cmd.args.nsyms
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length = NList.sizeof() * nsyms
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self.io.seek(self.off + cmd.args.symoff)
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symdata = self.io.read(length)
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symbols = Array(nsyms, NList).parse(symdata)
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for i in symbols:
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off = cmd.args.stroff + i.n_strx
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self.io.seek(self.off + off)
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name = self.io.read(1024).split(b"\x00")[0].decode("ascii")
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self.symbols[name] = i.n_value
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if __name__ == "__main__":
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import sys
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macho = MachO(open(sys.argv[1], "rb").read())
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if len(sys.argv) > 2:
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syms = MachO(open(sys.argv[2], "rb").read())
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macho.add_symbols("com.apple.kernel", syms)
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symtab = [(v, k) for (k, v) in macho.symbols.items()]
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symtab.sort()
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for addr, name in symtab:
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print(f"0x{addr:x} {name}")
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@ -28,6 +28,7 @@ BootArgs = Struct(
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)
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MachOLoadCmdType = "LoadCmdType" / Enum(Int32ul,
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SYMTAB = 0x02,
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UNIXTHREAD = 0x05,
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SEGMENT_64 = 0x19,
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UUID = 0x1b,
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@ -57,6 +58,13 @@ MachOVmProt = FlagsEnum(Int32sl,
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PROT_EXECUTE = 0x04,
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)
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MachOCmdSymTab = Struct(
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"symoff" / Hex(Int32ul),
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"nsyms" / Int32ul,
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"stroff" / Hex(Int32ul),
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"strsize" / Hex(Int32ul),
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)
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MachOCmdUnixThread = GreedyRange(Struct(
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"flavor" / MachOArmThreadStateFlavor,
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"data" / Prefixed(ExprAdapter(Int32ul, obj_ * 4, obj_ / 4), Switch(this.flavor, {
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@ -72,6 +80,13 @@ MachOCmdUnixThread = GreedyRange(Struct(
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})),
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))
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NList = Struct(
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"n_strx" / Hex(Int32ul),
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"n_type" / Hex(Int8ul),
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"n_sect" / Hex(Int8ul),
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"n_desc" / Hex(Int16sl),
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"n_value" / Hex(Int64ul),
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)
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MachOCmdSegment64 = Struct(
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"segname" / PaddedString(16, "ascii"),
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@ -99,17 +114,26 @@ MachOCmdSegment64 = Struct(
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)),
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)
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MachOFilesetEntry = Struct(
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"addr" / Hex(Int64ul),
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"offset" / Hex(Int64ul),
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"entryid" / Hex(Int32ul),
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"reserved" / Hex(Int32ul),
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"name" / CString("ascii"),
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)
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MachOCmd = Struct(
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"cmd" / Hex(MachOLoadCmdType),
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"args" / Prefixed(ExprAdapter(Int32ul, obj_ - 8, obj_ + 8), Switch(this.cmd, {
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MachOLoadCmdType.SYMTAB: MachOCmdSymTab,
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MachOLoadCmdType.UNIXTHREAD: MachOCmdUnixThread,
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MachOLoadCmdType.SEGMENT_64: MachOCmdSegment64,
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MachOLoadCmdType.UUID: Hex(Bytes(16)),
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MachOLoadCmdType.FILESET_ENTRY: MachOFilesetEntry,
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}, default=GreedyBytes)),
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)
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MachOFile = Struct(
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"header" / MachOHeader,
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"cmds" / Array(this.header.ncmds, MachOCmd),
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"extradata" / GreedyBytes,
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)
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