diff options
Diffstat (limited to 'pkgs/build-support/setup-hooks/auto-patchelf.py')
| -rw-r--r-- | pkgs/build-support/setup-hooks/auto-patchelf.py | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/pkgs/build-support/setup-hooks/auto-patchelf.py b/pkgs/build-support/setup-hooks/auto-patchelf.py new file mode 100644 index 00000000000..26fd623e3da --- /dev/null +++ b/pkgs/build-support/setup-hooks/auto-patchelf.py @@ -0,0 +1,329 @@ +#!/usr/bin/env python3 + +from collections import defaultdict +from contextlib import contextmanager +from dataclasses import dataclass +from elftools.common.exceptions import ELFError # type: ignore +from elftools.elf.dynamic import DynamicSection # type: ignore +from elftools.elf.elffile import ELFFile # type: ignore +from elftools.elf.enums import ENUM_E_TYPE, ENUM_EI_OSABI # type: ignore +from itertools import chain +from pathlib import Path, PurePath + +from typing import Tuple, Optional, Iterator, List, DefaultDict, Set + +import argparse +import os +import pprint +import subprocess +import sys + + + +@contextmanager +def open_elf(path: Path) -> Iterator[ELFFile]: + with path.open('rb') as stream: + yield ELFFile(stream) + + +def is_static_executable(elf: ELFFile) -> bool: + # Statically linked executables have an ELF type of EXEC but no INTERP. + return (elf.header["e_type"] == 'ET_EXEC' + and not elf.get_section_by_name(".interp")) + + +def is_dynamic_executable(elf: ELFFile) -> bool: + # We do not require an ELF type of EXEC. This also catches + # position-independent executables, as they typically have an INTERP + # section but their ELF type is DYN. + return bool(elf.get_section_by_name(".interp")) + + +def get_dependencies(elf: ELFFile) -> List[str]: + dependencies = [] + # This convoluted code is here on purpose. For some reason, using + # elf.get_section_by_name(".dynamic") does not always return an + # instance of DynamicSection, but that is required to call iter_tags + for section in elf.iter_sections(): + if isinstance(section, DynamicSection): + for tag in section.iter_tags('DT_NEEDED'): + dependencies.append(tag.needed) + break # There is only one dynamic section + + return dependencies + + +def get_rpath(elf: ELFFile) -> List[str]: + # This convoluted code is here on purpose. For some reason, using + # elf.get_section_by_name(".dynamic") does not always return an + # instance of DynamicSection, but that is required to call iter_tags + for section in elf.iter_sections(): + if isinstance(section, DynamicSection): + for tag in section.iter_tags('DT_RUNPATH'): + return tag.runpath.split(':') + + for tag in section.iter_tags('DT_RPATH'): + return tag.rpath.split(':') + + break # There is only one dynamic section + + return [] + + +def get_arch(elf: ELFFile) -> str: + return elf.get_machine_arch() + + +def get_osabi(elf: ELFFile) -> str: + return elf.header["e_ident"]["EI_OSABI"] + + +def osabi_are_compatible(wanted: str, got: str) -> bool: + """ + Tests whether two OS ABIs are compatible, taking into account the + generally accepted compatibility of SVR4 ABI with other ABIs. + """ + if not wanted or not got: + # One of the types couldn't be detected, so as a fallback we'll + # assume they're compatible. + return True + + # Generally speaking, the base ABI (0x00), which is represented by + # readelf(1) as "UNIX - System V", indicates broad compatibility + # with other ABIs. + # + # TODO: This isn't always true. For example, some OSes embed ABI + # compatibility into SHT_NOTE sections like .note.tag and + # .note.ABI-tag. It would be prudent to add these to the detection + # logic to produce better ABI information. + if wanted == 'ELFOSABI_SYSV': + return True + + # Similarly here, we should be able to link against a superset of + # features, so even if the target has another ABI, this should be + # fine. + if got == 'ELFOSABI_SYSV': + return True + + # Otherwise, we simply return whether the ABIs are identical. + return wanted == got + + +def glob(path: Path, pattern: str, recursive: bool) -> Iterator[Path]: + return path.rglob(pattern) if recursive else path.glob(pattern) + + +cached_paths: Set[Path] = set() +soname_cache: DefaultDict[Tuple[str, str], List[Tuple[Path, str]]] = defaultdict(list) + + +def populate_cache(initial: List[Path], recursive: bool =False) -> None: + lib_dirs = list(initial) + + while lib_dirs: + lib_dir = lib_dirs.pop(0) + + if lib_dir in cached_paths: + continue + + cached_paths.add(lib_dir) + + for path in glob(lib_dir, "*.so*", recursive): + if not path.is_file(): + continue + + resolved = path.resolve() + try: + with open_elf(path) as elf: + osabi = get_osabi(elf) + arch = get_arch(elf) + rpath = [Path(p) for p in get_rpath(elf) + if p and '$ORIGIN' not in p] + lib_dirs += rpath + soname_cache[(path.name, arch)].append((resolved.parent, osabi)) + + except ELFError: + # Not an ELF file in the right format + pass + + +def find_dependency(soname: str, soarch: str, soabi: str) -> Optional[Path]: + for lib, libabi in soname_cache[(soname, soarch)]: + if osabi_are_compatible(soabi, libabi): + return lib + return None + + +@dataclass +class Dependency: + file: Path # The file that contains the dependency + name: Path # The name of the dependency + found: bool = False # Whether it was found somewhere + + +def auto_patchelf_file(path: Path, runtime_deps: list[Path]) -> list[Dependency]: + try: + with open_elf(path) as elf: + + if is_static_executable(elf): + # No point patching these + print(f"skipping {path} because it is statically linked") + return [] + + if elf.num_segments() == 0: + # no segment (e.g. object file) + print(f"skipping {path} because it contains no segment") + return [] + + file_arch = get_arch(elf) + if interpreter_arch != file_arch: + # Our target architecture is different than this file's + # architecture, so skip it. + print(f"skipping {path} because its architecture ({file_arch})" + f" differs from target ({interpreter_arch})") + return [] + + file_osabi = get_osabi(elf) + if not osabi_are_compatible(interpreter_osabi, file_osabi): + print(f"skipping {path} because its OS ABI ({file_osabi}) is" + f" not compatible with target ({interpreter_osabi})") + return [] + + file_is_dynamic_executable = is_dynamic_executable(elf) + + file_dependencies = map(Path, get_dependencies(elf)) + + except ELFError: + return [] + + rpath = [] + if file_is_dynamic_executable: + print("setting interpreter of", path) + subprocess.run( + ["patchelf", "--set-interpreter", interpreter_path.as_posix(), path.as_posix()], + check=True) + rpath += runtime_deps + + print("searching for dependencies of", path) + dependencies = [] + # Be sure to get the output of all missing dependencies instead of + # failing at the first one, because it's more useful when working + # on a new package where you don't yet know the dependencies. + for dep in file_dependencies: + if dep.is_absolute() and dep.is_file(): + # This is an absolute path. If it exists, just use it. + # Otherwise, we probably want this to produce an error when + # checked (because just updating the rpath won't satisfy + # it). + continue + elif (libc_lib / dep).is_file(): + # This library exists in libc, and will be correctly + # resolved by the linker. + continue + + if found_dependency := find_dependency(dep.name, file_arch, file_osabi): + rpath.append(found_dependency) + dependencies.append(Dependency(path, dep, True)) + print(f" {dep} -> found: {found_dependency}") + else: + dependencies.append(Dependency(path, dep, False)) + print(f" {dep} -> not found!") + + # Dedup the rpath + rpath_str = ":".join(dict.fromkeys(map(Path.as_posix, rpath))) + + if rpath: + print("setting RPATH to:", rpath_str) + subprocess.run( + ["patchelf", "--set-rpath", rpath_str, path.as_posix()], + check=True) + + return dependencies + + +def auto_patchelf( + paths_to_patch: List[Path], + lib_dirs: List[Path], + runtime_deps: List[Path], + recursive: bool =True, + ignore_missing: bool =False) -> None: + + if not paths_to_patch: + sys.exit("No paths to patch, stopping.") + + # Add all shared objects of the current output path to the cache, + # before lib_dirs, so that they are chosen first in find_dependency. + populate_cache(paths_to_patch, recursive) + populate_cache(lib_dirs) + + dependencies = [] + for path in chain.from_iterable(glob(p, '*', recursive) for p in paths_to_patch): + if not path.is_symlink() and path.is_file(): + dependencies += auto_patchelf_file(path, runtime_deps) + + missing = [dep for dep in dependencies if not dep.found] + + # Print a summary of the missing dependencies at the end + for dep in missing: + print(f"auto-patchelf could not satisfy dependency {dep.name} wanted by {dep.file}") + + if missing and not ignore_missing: + sys.exit('auto-patchelf failed to find all the required dependencies.\n' + 'Add the missing dependencies to --libs or use --ignore-missing.') + + +def main() -> None: + parser = argparse.ArgumentParser( + prog="auto-patchelf", + description='auto-patchelf tries as hard as possible to patch the' + ' provided binary files by looking for compatible' + 'libraries in the provided paths.') + parser.add_argument( + "--ignore-missing", + action="store_true", + help="Do not fail when some dependencies are not found.") + parser.add_argument( + "--no-recurse", + dest="recursive", + action="store_false", + help="Patch only the provided paths, and ignore their children") + parser.add_argument( + "--paths", nargs="*", type=Path, + help="Paths whose content needs to be patched.") + parser.add_argument( + "--libs", nargs="*", type=Path, + help="Paths where libraries are searched for.") + parser.add_argument( + "--runtime-dependencies", nargs="*", type=Path, + help="Paths to prepend to the runtime path of executable binaries.") + + print("automatically fixing dependencies for ELF files") + args = parser.parse_args() + pprint.pprint(vars(args)) + + auto_patchelf( + args.paths, + args.libs, + args.runtime_dependencies, + args.recursive, + args.ignore_missing) + + +interpreter_path: Path = None # type: ignore +interpreter_osabi: str = None # type: ignore +interpreter_arch: str = None # type: ignore +libc_lib: Path = None # type: ignore + +if __name__ == "__main__": + nix_support = Path(os.environ['NIX_BINTOOLS']) / 'nix-support' + interpreter_path = Path((nix_support / 'dynamic-linker').read_text().strip()) + libc_lib = Path((nix_support / 'orig-libc').read_text().strip()) / 'lib' + + with open_elf(interpreter_path) as interpreter: + interpreter_osabi = get_osabi(interpreter) + interpreter_arch = get_arch(interpreter) + + if interpreter_arch and interpreter_osabi and interpreter_path and libc_lib: + main() + else: + sys.exit("Failed to parse dynamic linker (ld) properties.") |