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104a14781d
Test both .zdebug_* sections and SHF_COMPRESSED .debug_* sections. Signed-off-by: Omar Sandoval <osandov@osandov.com>
279 lines
8.9 KiB
Python
279 lines
8.9 KiB
Python
# Copyright (c) Meta Platforms, Inc. and affiliates.
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# SPDX-License-Identifier: LGPL-2.1-or-later
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import struct
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from typing import List, NamedTuple, Optional, Sequence
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import zlib
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from tests.elf import ET, PT, SHF, SHN, SHT, STB, STT, STV
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class ElfSection:
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def __init__(
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self,
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data: bytes = b"",
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name: Optional[str] = None,
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sh_type: Optional[SHT] = None,
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p_type: Optional[PT] = None,
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vaddr: int = 0,
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paddr: int = 0,
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memsz: Optional[int] = None,
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p_align: int = 0,
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sh_link: int = 0,
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sh_info: int = 0,
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sh_entsize: int = 0,
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compressed=False,
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):
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self.data = data
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self.name = name
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self.sh_type = sh_type
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self.sh_flags = SHF.COMPRESSED if compressed else 0
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self.p_type = p_type
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self.vaddr = vaddr
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self.paddr = paddr
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self.memsz = memsz
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self.p_align = p_align
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self.sh_link = sh_link
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self.sh_info = sh_info
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self.sh_entsize = sh_entsize
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assert (self.name is not None) or (self.p_type is not None)
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assert (self.name is None) == (self.sh_type is None)
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assert self.p_type is None or not compressed
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class ElfSymbol(NamedTuple):
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name: str
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value: int
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size: int
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type: STT
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binding: STB
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shindex: Optional[int] = None
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visibility: STV = STV.DEFAULT
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def st_info(self) -> int:
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return (self.binding << 4) + (self.type & 0xF)
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def _create_symtab(
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sections: List[ElfSection],
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symbols: Sequence[ElfSymbol],
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little_endian: bool,
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bits: int,
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):
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assert not any(section.name in (".symtab", ".strtab") for section in sections)
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endian = "<" if little_endian else ">"
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if bits == 64:
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symbol_struct = struct.Struct(endian + "IBBHQQ")
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def symbol_fields(sym: ElfSymbol):
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return (
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sym.st_info(),
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sym.visibility,
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SHN.UNDEF if sym.shindex is None else sym.shindex,
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sym.value,
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sym.size,
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)
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else:
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symbol_struct = struct.Struct(endian + "IIIBBH")
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def symbol_fields(sym: ElfSymbol):
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return (
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sym.value,
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sym.size,
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sym.st_info(),
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sym.visibility,
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SHN.UNDEF if sym.shindex is None else sym.shindex,
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)
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symtab_data = bytearray((len(symbols) + 1) * symbol_struct.size)
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strtab_data = bytearray(1)
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sh_info = 1
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for i, sym in enumerate(symbols, 1):
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symbol_struct.pack_into(
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symtab_data, i * symbol_struct.size, len(strtab_data), *symbol_fields(sym)
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)
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strtab_data.extend(sym.name.encode())
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strtab_data.append(0)
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if sym.binding == STB.LOCAL:
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assert sh_info == i, "local symbol after non-local symbol"
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sh_info = i + 1
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sections.append(
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ElfSection(
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name=".symtab",
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sh_type=SHT.SYMTAB,
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data=symtab_data,
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sh_link=sum((1 for section in sections if section.name is not None), 2),
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sh_info=sh_info,
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sh_entsize=symbol_struct.size,
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)
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)
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sections.append(ElfSection(name=".strtab", sh_type=SHT.STRTAB, data=strtab_data))
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def create_elf_file(
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type: ET,
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sections: Sequence[ElfSection],
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symbols: Sequence[ElfSymbol] = (),
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little_endian: bool = True,
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bits: int = 64,
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):
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endian = "<" if little_endian else ">"
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if bits == 64:
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ehdr_struct = struct.Struct(endian + "16BHHIQQQIHHHHHH")
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shdr_struct = struct.Struct(endian + "IIQQQQIIQQ")
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phdr_struct = struct.Struct(endian + "IIQQQQQQ")
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chdr_struct = struct.Struct(endian + "IIQQ")
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e_machine = 62 if little_endian else 43 # EM_X86_64 or EM_SPARCV9
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else:
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assert bits == 32
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ehdr_struct = struct.Struct(endian + "16BHHIIIIIHHHHHH")
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shdr_struct = struct.Struct(endian + "10I")
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phdr_struct = struct.Struct(endian + "8I")
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chdr_struct = struct.Struct(endian + "III")
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e_machine = 3 if little_endian else 8 # EM_386 or EM_MIPS
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sections = list(sections)
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if symbols:
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_create_symtab(sections, symbols, little_endian=little_endian, bits=bits)
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shnum = 0
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phnum = 0
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shstrtab = bytearray(1)
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for section in sections:
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if section.name is not None:
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shstrtab.extend(section.name.encode())
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shstrtab.append(0)
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shnum += 1
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if section.p_type is not None:
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phnum += 1
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if shnum > 0:
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shnum += 2 # One for the SHT_NULL section, one for .shstrtab.
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shstrtab.extend(b".shstrtab\0")
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sections = list(sections)
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sections.append(ElfSection(name=".shstrtab", sh_type=SHT.STRTAB, data=shstrtab))
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shdr_offset = ehdr_struct.size
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phdr_offset = shdr_offset + shdr_struct.size * shnum
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headers_size = phdr_offset + phdr_struct.size * phnum
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buf = bytearray(headers_size)
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ehdr_struct.pack_into(
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buf,
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0,
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0x7F, # ELFMAG0
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ord("E"), # ELFMAG1
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ord("L"), # ELFMAG2
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ord("F"), # ELFMAG3
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2 if bits == 64 else 1, # EI_CLASS = ELFCLASS64 or ELFCLASS32
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1 if little_endian else 2, # EI_DATA = ELFDATA2LSB or ELFDATA2MSB
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1, # EI_VERSION = EV_CURRENT
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0, # EI_OSABI = ELFOSABI_NONE
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0, # EI_ABIVERSION
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0,
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0,
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0,
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0,
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0,
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0,
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0, # EI_PAD
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type, # e_type
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e_machine,
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1, # e_version = EV_CURRENT
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0, # e_entry
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phdr_offset if phnum else 0, # e_phoff
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shdr_offset if shnum else 0, # e_shoff
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0, # e_flags
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ehdr_struct.size, # e_ehsize
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phdr_struct.size, # e_phentsize
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phnum, # e_phnum
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shdr_struct.size, # e_shentsize
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shnum, # e_shnum
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shnum - 1 if shnum else 0, # e_shstrndx
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)
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shdr_offset += shdr_struct.size
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for section in sections:
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ch_addralign = 1 if section.p_type is None else bits // 8
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memsz = len(section.data) if section.memsz is None else section.memsz
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if section.sh_flags & SHF.COMPRESSED:
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sh_addralign = bits // 8
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compressed_data = zlib.compress(section.data)
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sh_size = chdr_struct.size + len(compressed_data)
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else:
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sh_addralign = ch_addralign
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sh_size = memsz
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if section.p_align:
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padding = section.vaddr % section.p_align - len(buf) % section.p_align
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buf.extend(bytes(padding))
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if section.name is not None:
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shdr_struct.pack_into(
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buf,
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shdr_offset,
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shstrtab.index(section.name.encode()), # sh_name
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section.sh_type, # sh_type
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section.sh_flags, # sh_flags
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section.vaddr, # sh_addr
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len(buf), # sh_offset
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sh_size, # sh_size
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section.sh_link, # sh_link
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section.sh_info, # sh_info
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sh_addralign, # sh_addralign
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section.sh_entsize, # sh_entsize
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)
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shdr_offset += shdr_struct.size
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if section.p_type is not None:
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flags = 7 # PF_R | PF_W | PF_X
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if bits == 64:
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phdr_struct.pack_into(
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buf,
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phdr_offset,
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section.p_type, # p_type
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flags, # p_flags
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len(buf), # p_offset
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section.vaddr, # p_vaddr
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section.paddr, # p_paddr
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len(section.data), # p_filesz
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memsz, # p_memsz
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section.p_align, # p_align
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)
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else:
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phdr_struct.pack_into(
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buf,
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phdr_offset,
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section.p_type, # p_type
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len(buf), # p_offset
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section.vaddr, # p_vaddr
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section.paddr, # p_paddr
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len(section.data), # p_filesz
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memsz, # p_memsz
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flags, # p_flags
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section.p_align, # p_align
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)
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phdr_offset += phdr_struct.size
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if section.sh_flags & SHF.COMPRESSED:
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ELFCOMPRESS_ZLIB = 1
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if bits == 64:
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buf.extend(
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chdr_struct.pack(
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ELFCOMPRESS_ZLIB, # ch_type
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0, # ch_reserved
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memsz, # ch_size
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ch_addralign, # ch_addralign
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)
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)
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else:
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buf.extend(
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chdr_struct.pack(
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ELFCOMPRESS_ZLIB, # ch_type
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memsz, # ch_size
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ch_addralign, # ch_addralign
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)
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)
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buf.extend(compressed_data)
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else:
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buf.extend(section.data)
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return buf
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