mirror of https://github.com/Shizmob/smol
shdr parsing in hackyelf, linkmap parsing bug fixes
This commit is contained in:
parent
6ad8eed5b2
commit
e37a0d8e50
191
smol/hackyelf.py
191
smol/hackyelf.py
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@ -8,6 +8,7 @@
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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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@ -24,6 +25,30 @@ DT_NEEDED = 1
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DT_STRTAB = 5
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DT_SYMTAB = 6
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SHT_NULL = 0
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SHT_PROGBITS = 1
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SHT_SYMTAB = 2
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SHT_STRTAB = 3
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SHT_DYNSYM = 11
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STB_LOCAL = 0
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STB_GLOBAL = 1
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STB_WEAK = 2
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STT_NOTYPE = 0
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STT_OBJECT = 1
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STT_FUNC = 2
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STT_SECTION= 3
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STT_FILE = 4
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STT_COMMON = 5
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STT_TLS = 6
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STT_GNU_IFUNC = 10
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STV_DEFAULT = 0
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STV_INTERNAL = 1
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STV_HIDDEN = 2
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STV_PROTECTED = 3
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class Phdr(NamedTuple):
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ptype: int
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off : int
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@ -38,6 +63,27 @@ class Dyn(NamedTuple):
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tag: int
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val: int
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class Shdr(NamedTuple):
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name: Union[int, str]
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type: int
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flags: int
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addr: int
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offset: int
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size: int
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link: int
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info: int
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addralign: int
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entsize: int
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class Sym(NamedTuple):
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name: str
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value: int
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size: int
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type: int
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binding: int
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visibility: int
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shndx: int
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class ELF(NamedTuple):
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data : bytes
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ident : bytes
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@ -46,8 +92,18 @@ class ELF(NamedTuple):
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entry : int
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phdrs : Sequence[Phdr]
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dyn : Sequence[Dyn]
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shdrs : Sequence[Shdr]
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symtab: Sequence[Sym]
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dynsym: Sequence[Sym]
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is32bit: bool
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def readstr(data: bytes, off: int) -> str:
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strb = bytearray()
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while data[off] != 0 and off < len(data):
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strb.append(data[off])
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off = off + 1
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return strb.decode('utf-8')
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# yeah, there's some code duplication here
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# idgaf
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@ -74,6 +130,46 @@ def parse_dyn32(data: bytes, dynp: Phdr) -> Dyn:
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return ds
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def parse_shdr32(data: bytes, shoff: int, shentsz: int, shnum: int,
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shstrndx: int) -> Sequence[Shdr]:
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if shnum*shentsz+shoff > len(data) or shentsz==0 or shnum==0 or shoff==0:
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print("snum*shentsz+shoff",shnum*shentsz+shoff)
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print("len(data)",len(data))
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print("shentsz",shentsz)
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print("shnum",shnum)
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print("shoff",shoff)
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return []
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ss = []
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for off in range(shoff, shoff+shentsz*shnum, shentsz):
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noff, typ, flags, addr, off, size, link, info, align, entsz = \
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unpack('<IIIIIIIIII', data[off:off+10*4])
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s = Shdr(noff, typ, flags, addr, off, size, link, info, align, entsz)
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ss.append(s)
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if shstrndx < shnum:
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shstr = ss[shstrndx]
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for i in range(len(ss)):
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sname = readstr(data, shstr.offset + ss[i].name) \
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if ss[i].name < shstr.size else None
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ss[i] = Shdr(sname, ss[i].type, ss[i].flags, ss[i].addr,
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ss[i].offset, ss[i].size, ss[i].link, ss[i].info,
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ss[i].addralign, ss[i].entsize)
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return ss
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def parse_sym32(data: bytes, sym: Shdr, strt: Shdr) -> Sequence[Sym]:
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ss = []
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for off in range(sym.offset, sym.offset+sym.size, sym.entsize):
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noff, val, sz, info, other, shndx = \
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unpack('<IIIBBH', data[off:off+3*4+2+2])
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sn = readstr(data, strt.offset + noff) \
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if noff < strt.size else None
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s = Sym(sn, val, sz, (info & 15), (info >> 4), other, shndx)
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ss.append(s)
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return sorted(ss, key=lambda x:x.value)
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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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@ -81,8 +177,12 @@ def parse_32(data: bytes) -> ELF:
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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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shoff = unpack('<I', data[32:32+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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shentsz = unpack('<H', data[46:46+2])[0]
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shnum = unpack('<H', data[48:48+2])[0]
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shstrndx= unpack('<H', data[50:50+2])[0]
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phdrs = parse_phdr32(data, phoff, phentsz, phnum)
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dyn = None
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@ -92,12 +192,37 @@ def parse_32(data: bytes) -> ELF:
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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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shdrs = parse_shdr32(data, shoff, shentsz, shnum, shstrndx)
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#print("shdrs",shdrs)
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symtabsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".symtab"]
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strtabsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".strtab"]
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dynsymsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".dynsym"]
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dynstrsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".dynstr"]
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#print("symtab",symtabsh)
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#print("strtab",strtabsh)
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assert len(symtabsh) < 2
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assert len(strtabsh) < 2
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assert len(dynsymsh) < 2
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assert len(dynstrsh) < 2
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symtab, dynsym = None, None
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if len(symtabsh) and len(strtabsh):
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symtab = parse_sym32(data, symtabsh[0], strtabsh[0]) \
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if len(shdrs) > 0 else []
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if len(dynsymsh) and len(dynstrsh):
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dynsym = parse_sym32(data, symtabsh[0], strtabsh[0]) \
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if len(shdrs) > 0 else []
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return ELF(data, ident, eclass, mach, entry, phdrs, dyn, shdrs,
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symtab, dynsym, 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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# TODO # what is TODO exactly??
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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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@ -118,6 +243,41 @@ def parse_dyn64(data: bytes, dynp: Phdr) -> Dyn:
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return ds
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def parse_shdr64(data: bytes, shoff: int, shentsz: int, shnum: int,
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shstrndx: int) -> Sequence[Shdr]:
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if shnum*shentsz+shoff >= len(data) or shentsz==0 or shnum==0 or shoff==0:
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return []
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ss = []
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for off in range(shoff, shoff+shentsz*shnum, shentsz):
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noff, typ, flags, addr, off, size, link, info, align, entsz = \
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unpack('<IIQQQQIIQQ', data[off:off+4*4+6*8])
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s = Shdr(noff, typ, flags, addr, off, size, link, info, align, entsz)
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ss.append(s)
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if shstrndx < shnum:
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shstr = ss[shstrndx]
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for i in range(len(ss)):
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sname = readstr(data, shstr.offset + ss[i].name) \
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if ss[i].name < shstr.size else None
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ss[i] = Shdr(sname, ss[i].type, ss[i].flags, ss[i].addr,
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ss[i].offset, ss[i].size, ss[i].link, ss[i].info,
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ss[i].addralign, ss[i].entsize)
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return ss
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def parse_sym64(data: bytes, sym: Shdr, strt: Shdr) -> Sequence[Sym]:
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ss = []
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for off in range(sym.offset, sym.offset+sym.size, sym.entsize):
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noff, info, other, shndx, value, sz = \
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unpack('<IBBHQQ', data[off:off+4+2+2+8*2])
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sn = readstr(data, strt.offset + noff) \
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if noff < strt.size else None
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s = Sym(sn, val, sz, (info & 15), (info >> 4), other, shndx)
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ss.append(s)
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return sorted(ss, key=lambda x:x.value)
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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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@ -125,8 +285,12 @@ def parse_64(data: bytes) -> ELF:
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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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shoff = unpack('<Q', data[40:40+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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shentsz = unpack('<H', data[58:58+2])[0]
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shnum = unpack('<H', data[60:60+2])[0]
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shstrndx= unpack('<H', data[62:62+2])[0]
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phdrs = parse_phdr64(data, phoff, phentsz, phnum)
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dyn = None
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@ -136,7 +300,28 @@ def parse_64(data: bytes) -> ELF:
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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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shdrs = parse_shdr64(data, shoff, shentsz, shnum, shstrndx)
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symtabsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".symtab"]
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strtabsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".strtab"]
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dynsymsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".dynsym"]
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dynstrsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".dynstr"]
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assert len(symtabsh) < 2
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assert len(strtabsh) < 2
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assert len(dynsymsh) < 2
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assert len(dynstrsh) < 2
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symtab, dynsym = None, None
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if len(symtabsh) and len(strtabsh):
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symtab = parse_sym64(data, symtabsh[0], strtabsh[0]) \
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if len(shdrs) > 0 else []
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if len(dynsymsh) and len(dynstrsh):
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dynsym = parse_sym64(data, symtabsh[0], strtabsh[0]) \
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if len(shdrs) > 0 else []
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return ELF(data, ident, eclass, mach, entry, phdrs, dyn, shdrs,
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symtab, dynsym, 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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@ -27,6 +27,17 @@ class XRef(NamedTuple):
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name: str
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deff: str
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reff: Sequence[str]
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class ImpObj(NamedTuple):
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ar: str
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obj: str
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class ImpRsnObj(NamedTuple):
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sym: str
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obj: ImpObj
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class ImpRsnSym(NamedTuple):
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sym: str
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class ArImp(NamedTuple):
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impobj: ImpObj
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reason: Union[ImpRsnSym, ImpRsnObj]
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class LinkMap(NamedTuple):
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common : Sequence[CommonSym]
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@ -34,11 +45,13 @@ class LinkMap(NamedTuple):
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memcfg : Sequence[MemCfg]
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mmap : Sequence[MMap]
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xref : Sequence[XRef]
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arimp : Sequence[ArImp]
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def parse_common( ls: Sequence[str]) -> Sequence[CommonSym]: return [] # TODO
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def parse_discard(ls: Sequence[str]) -> Sequence[Discard ]: return [] # TODO
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def parse_memcfg( ls: Sequence[str]) -> Sequence[MemCfg ]: return [] # TODO
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def parse_xref( ls: Sequence[str]) -> Sequence[XRef ]: return [] # TODO
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def parse_arimp( ls: Sequence[str]) -> Sequence[ArImp ]: return [] # TODO
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def parse_mmap(ls: Sequence[str]) -> Sequence[MMap]:
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rrr = []
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@ -55,7 +68,9 @@ def parse_mmap(ls: Sequence[str]) -> Sequence[MMap]:
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#print(repr(l))
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s = l.strip(); w = s.split()
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if s.startswith('LOAD ') or s.startswith('OUTPUT('): continue#break
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if s.startswith('LOAD ') or s.startswith('OUTPUT(') or \
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s.startswith('START GROUP') or s.startswith('END GROUP'):
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continue#break
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if l[0] != ' ':
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bigsect = w[0]
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@ -68,7 +83,7 @@ def parse_mmap(ls: Sequence[str]) -> Sequence[MMap]:
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continue # addr placed on next line for prettyprinting reasons
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#print(repr(l), w[0])
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assert w[0].startswith("0x"), "welp, bad symbol addr"
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assert w[0].startswith("0x"), "welp, bad symbol addr %s"%w[0]
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addr = int(w[0], 16)
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@ -90,10 +105,11 @@ def parse(s: str) -> LinkMap:
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MEMCFG = 2
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MMAP = 3
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XREF = 4
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ARIMP = 5
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curpt = -1
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commonl, discardl, memcfgl, mmapl, xrefl = [], [], [], [], []
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commonl, discardl, memcfgl, mmapl, xrefl, arimpl = [], [], [], [], [], []
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for l in s.split('\n'):
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if len(l.strip()) == 0: continue
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@ -103,15 +119,18 @@ def parse(s: str) -> LinkMap:
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elif ls == "Discarded input sections": curpt = DISCARD
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elif ls == "Memory Configuration": curpt = MEMCFG
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elif ls == "Linker script and memory map": curpt = MMAP
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elif ls == 'Cross Reference Table': curpt = XREF
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elif ls == "Cross Reference Table": curpt = XREF
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elif ls == "Archive member included to satisfy reference by file (symbol)": curpt = ARIMP
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elif curpt == COMMON : commonl.append(l)
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elif curpt == DISCARD: discardl.append(l)
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elif curpt == MEMCFG : memcfgl.append(l)
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elif curpt == MMAP : mmapl.append(l)
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elif curpt == XREF : xrefl.append(l)
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elif curpt == ARIMP : arimpl.append(l)
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else:
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assert False, "bad line %s" % ls
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return LinkMap(parse_common(commonl), parse_discard(discardl), \
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parse_memcfg(memcfgl), parse_mmap(mmapl), parse_xref(xrefl))
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return LinkMap(parse_common(commonl), parse_discard(discardl),
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parse_memcfg(memcfgl), parse_mmap(mmapl), parse_xref(xrefl),
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parse_arimp(arimpl))
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