mirror of https://github.com/Shizmob/smol
154 lines
3.6 KiB
Python
154 lines
3.6 KiB
Python
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# stolen from the contrib folder in https://github.com/blackle/LZMA-Vizualizer
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# (i.e. I'm stealing it from myself)
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# custom elf parser because a standard one wouldn't be trustable because the
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# ELFs we're parsing will be a bit wonky anyway
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from struct import unpack
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from typing import *
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ELFCLASS32 = 1
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ELFCLASS64 = 2
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EM_386 = 3
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EM_X86_64 = 62
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PT_NULL = 0
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PT_LOAD = 1
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PT_DYNAMIC = 2
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PT_INTERP = 3
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DT_NULL = 0
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DT_NEEDED = 1
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DT_STRTAB = 5
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DT_SYMTAB = 6
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class Phdr(NamedTuple):
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ptype: int
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off : int
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vaddr: int
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paddr: int
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filesz: int
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memsz: int
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flags: int
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align: int
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class Dyn(NamedTuple):
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tag: int
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val: int
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class ELF(NamedTuple):
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data : bytes
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ident : bytes
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eclass: int
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mach : int
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entry : int
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phdrs : Sequence[Phdr]
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dyn : Sequence[Dyn]
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is32bit: bool
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# yeah, there's some code duplication here
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# idgaf
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def parse_phdr32(data: bytes, phoff:int, phentsz:int, phnum:int) -> Sequence[Phdr]:
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ps = []
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for off in range(phoff, phoff+phentsz*phnum, phentsz):
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ptype, off, vaddr, paddr, filesz, memsz, flags, align = \
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unpack('<IIIIIIII', data[off:off+8*4])
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p = Phdr(ptype, off, vaddr, paddr, filesz, memsz, flags, align)
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ps.append(p)
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return ps
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def parse_dyn32(data: bytes, dynp: Phdr) -> Dyn:
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ds = []
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off = dynp.off
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while True:
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tag, val = unpack('<II', data[off:off+2*4])
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ds.append(Dyn(tag, val))
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if tag == DT_NULL: break
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off = off + 2*4
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return ds
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def parse_32(data: bytes) -> ELF:
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ident = data[:16]
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eclass = data[4]
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mach = unpack('<H', data[18:18+2])[0]
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entry = unpack('<I', data[24:24+4])[0]
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phoff = unpack('<I', data[28:28+4])[0]
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phentsz = unpack('<H', data[42:42+2])[0]
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phnum = unpack('<H', data[44:44+2])[0]
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phdrs = parse_phdr32(data, phoff, phentsz, phnum)
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dyn = None
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for p in phdrs:
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if p.ptype == PT_DYNAMIC:
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dyn = parse_dyn32(data, p)
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break
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return ELF(data, ident, eclass, mach, entry, phdrs, dyn, True)
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def parse_phdr64(data: bytes, phoff:int, phentsz:int, phnum:int) -> Sequence[Phdr]:
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ps = []
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for off in range(phoff, phoff+phentsz*phnum, phentsz):
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# TODO
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ptype, flags, off, vaddr, paddr, filesz, memsz, align = \
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unpack('<IIQQQQQQ', data[off:off+2*4+6*8])
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p = Phdr(ptype, off, vaddr, paddr, filesz, memsz, flags, align)
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ps.append(p)
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return ps
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def parse_dyn64(data: bytes, dynp: Phdr) -> Dyn:
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ds = []
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off = dynp.off
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while True:
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tag, val = unpack('<QQ', data[off:off+2*8])
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ds.append(Dyn(tag, val))
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if tag == DT_NULL: break
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off = off + 2*8
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return ds
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def parse_64(data: bytes) -> ELF:
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ident = data[:16]
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eclass = data[4]
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mach = unpack('<H', data[18:18+2])[0]
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entry = unpack('<Q', data[24:24+8])[0]
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phoff = unpack('<Q', data[32:32+8])[0]
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phentsz = unpack('<H', data[54:54+2])[0]
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phnum = unpack('<H', data[56:56+2])[0]
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phdrs = parse_phdr64(data, phoff, phentsz, phnum)
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dyn = None
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for p in phdrs:
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if p.ptype == PT_DYNAMIC:
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dyn = parse_dyn64(data, p)
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break
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return ELF(data, ident, eclass, mach, entry, phdrs, dyn, False)
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def parse(data: bytes) -> ELF:
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assert data[:4] == b'\x7FELF', "Not a valid ELF file" # good enough
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ecls = data[4]
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if ecls == ELFCLASS32: return parse_32(data)
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elif ecls == ELFCLASS64: return parse_64(data)
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else:
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emch = unpack('<H', data[18:18+2])[0]
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if emch == EM_386: return parse_32(data)
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elif emch == EM_X86_64: return parse_64(data)
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assert False, "bad E_CLASS %d" % ecls
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