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818d0f8cf1
The auto-patchelf python script assembles a list of library (so=shared object) file names and their paths. This helps speed up the discovery of library files later when patching elf files. As further optimization, if a symlink points to a library file, the script uses the resolved path and file name. However, this produces a broken list entry if the symlink's target name doesn't match the symlink's name. A symptom of the bug, affecting the `tsm-client` package, is fixed in https://github.com/NixOS/nixpkgs/pull/172372 . The commit at hand stops resolving symlinks if the target name differs from the symlink's name. The commit has been authored by layus (Guillaume Maudoux <layus.on@gmail.com>) in pull request comment https://github.com/NixOS/nixpkgs/pull/172372#issuecomment-1194687183
346 lines
12 KiB
Python
346 lines
12 KiB
Python
#!/usr/bin/env python3
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import argparse
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import os
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import pprint
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import subprocess
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import sys
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from fnmatch import fnmatch
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from collections import defaultdict
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from contextlib import contextmanager
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from dataclasses import dataclass
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from itertools import chain
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from pathlib import Path, PurePath
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from typing import DefaultDict, Iterator, List, Optional, Set, Tuple
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from elftools.common.exceptions import ELFError # type: ignore
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from elftools.elf.dynamic import DynamicSection # type: ignore
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from elftools.elf.elffile import ELFFile # type: ignore
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from elftools.elf.enums import ENUM_E_TYPE, ENUM_EI_OSABI # type: ignore
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@contextmanager
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def open_elf(path: Path) -> Iterator[ELFFile]:
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with path.open('rb') as stream:
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yield ELFFile(stream)
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def is_static_executable(elf: ELFFile) -> bool:
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# Statically linked executables have an ELF type of EXEC but no INTERP.
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return (elf.header["e_type"] == 'ET_EXEC'
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and not elf.get_section_by_name(".interp"))
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def is_dynamic_executable(elf: ELFFile) -> bool:
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# We do not require an ELF type of EXEC. This also catches
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# position-independent executables, as they typically have an INTERP
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# section but their ELF type is DYN.
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return bool(elf.get_section_by_name(".interp"))
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def get_dependencies(elf: ELFFile) -> List[str]:
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dependencies = []
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# This convoluted code is here on purpose. For some reason, using
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# elf.get_section_by_name(".dynamic") does not always return an
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# instance of DynamicSection, but that is required to call iter_tags
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for section in elf.iter_sections():
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if isinstance(section, DynamicSection):
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for tag in section.iter_tags('DT_NEEDED'):
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dependencies.append(tag.needed)
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break # There is only one dynamic section
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return dependencies
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def get_rpath(elf: ELFFile) -> List[str]:
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# This convoluted code is here on purpose. For some reason, using
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# elf.get_section_by_name(".dynamic") does not always return an
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# instance of DynamicSection, but that is required to call iter_tags
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for section in elf.iter_sections():
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if isinstance(section, DynamicSection):
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for tag in section.iter_tags('DT_RUNPATH'):
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return tag.runpath.split(':')
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for tag in section.iter_tags('DT_RPATH'):
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return tag.rpath.split(':')
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break # There is only one dynamic section
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return []
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def get_arch(elf: ELFFile) -> str:
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return elf.get_machine_arch()
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def get_osabi(elf: ELFFile) -> str:
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return elf.header["e_ident"]["EI_OSABI"]
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def osabi_are_compatible(wanted: str, got: str) -> bool:
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"""
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Tests whether two OS ABIs are compatible, taking into account the
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generally accepted compatibility of SVR4 ABI with other ABIs.
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"""
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if not wanted or not got:
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# One of the types couldn't be detected, so as a fallback we'll
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# assume they're compatible.
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return True
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# Generally speaking, the base ABI (0x00), which is represented by
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# readelf(1) as "UNIX - System V", indicates broad compatibility
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# with other ABIs.
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#
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# TODO: This isn't always true. For example, some OSes embed ABI
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# compatibility into SHT_NOTE sections like .note.tag and
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# .note.ABI-tag. It would be prudent to add these to the detection
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# logic to produce better ABI information.
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if wanted == 'ELFOSABI_SYSV':
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return True
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# Similarly here, we should be able to link against a superset of
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# features, so even if the target has another ABI, this should be
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# fine.
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if got == 'ELFOSABI_SYSV':
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return True
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# Otherwise, we simply return whether the ABIs are identical.
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return wanted == got
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def glob(path: Path, pattern: str, recursive: bool) -> Iterator[Path]:
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return path.rglob(pattern) if recursive else path.glob(pattern)
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cached_paths: Set[Path] = set()
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soname_cache: DefaultDict[Tuple[str, str], List[Tuple[Path, str]]] = defaultdict(list)
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def populate_cache(initial: List[Path], recursive: bool =False) -> None:
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lib_dirs = list(initial)
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while lib_dirs:
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lib_dir = lib_dirs.pop(0)
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if lib_dir in cached_paths:
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continue
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cached_paths.add(lib_dir)
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for path in glob(lib_dir, "*.so*", recursive):
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if not path.is_file():
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continue
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# As an optimisation, resolve the symlinks here, as the target is unique
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# XXX: (layus, 2022-07-25) is this really an optimisation in all cases ?
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# It could make the rpath bigger or break the fragile precedence of $out.
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resolved = path.resolve()
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# Do not use resolved paths when names do not match
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if resolved.name != path.name:
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resolved = path
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try:
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with open_elf(path) as elf:
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osabi = get_osabi(elf)
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arch = get_arch(elf)
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rpath = [Path(p) for p in get_rpath(elf)
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if p and '$ORIGIN' not in p]
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lib_dirs += rpath
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soname_cache[(path.name, arch)].append((resolved.parent, osabi))
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except ELFError:
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# Not an ELF file in the right format
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pass
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def find_dependency(soname: str, soarch: str, soabi: str) -> Optional[Path]:
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for lib, libabi in soname_cache[(soname, soarch)]:
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if osabi_are_compatible(soabi, libabi):
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return lib
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return None
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@dataclass
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class Dependency:
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file: Path # The file that contains the dependency
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name: Path # The name of the dependency
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found: bool = False # Whether it was found somewhere
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def auto_patchelf_file(path: Path, runtime_deps: list[Path]) -> list[Dependency]:
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try:
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with open_elf(path) as elf:
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if is_static_executable(elf):
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# No point patching these
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print(f"skipping {path} because it is statically linked")
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return []
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if elf.num_segments() == 0:
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# no segment (e.g. object file)
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print(f"skipping {path} because it contains no segment")
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return []
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file_arch = get_arch(elf)
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if interpreter_arch != file_arch:
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# Our target architecture is different than this file's
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# architecture, so skip it.
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print(f"skipping {path} because its architecture ({file_arch})"
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f" differs from target ({interpreter_arch})")
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return []
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file_osabi = get_osabi(elf)
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if not osabi_are_compatible(interpreter_osabi, file_osabi):
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print(f"skipping {path} because its OS ABI ({file_osabi}) is"
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f" not compatible with target ({interpreter_osabi})")
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return []
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file_is_dynamic_executable = is_dynamic_executable(elf)
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file_dependencies = map(Path, get_dependencies(elf))
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except ELFError:
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return []
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rpath = []
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if file_is_dynamic_executable:
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print("setting interpreter of", path)
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subprocess.run(
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["patchelf", "--set-interpreter", interpreter_path.as_posix(), path.as_posix()],
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check=True)
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rpath += runtime_deps
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print("searching for dependencies of", path)
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dependencies = []
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# Be sure to get the output of all missing dependencies instead of
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# failing at the first one, because it's more useful when working
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# on a new package where you don't yet know the dependencies.
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for dep in file_dependencies:
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if dep.is_absolute() and dep.is_file():
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# This is an absolute path. If it exists, just use it.
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# Otherwise, we probably want this to produce an error when
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# checked (because just updating the rpath won't satisfy
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# it).
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continue
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elif (libc_lib / dep).is_file():
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# This library exists in libc, and will be correctly
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# resolved by the linker.
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continue
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if found_dependency := find_dependency(dep.name, file_arch, file_osabi):
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rpath.append(found_dependency)
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dependencies.append(Dependency(path, dep, True))
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print(f" {dep} -> found: {found_dependency}")
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else:
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dependencies.append(Dependency(path, dep, False))
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print(f" {dep} -> not found!")
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# Dedup the rpath
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rpath_str = ":".join(dict.fromkeys(map(Path.as_posix, rpath)))
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if rpath:
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print("setting RPATH to:", rpath_str)
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subprocess.run(
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["patchelf", "--set-rpath", rpath_str, path.as_posix()],
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check=True)
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return dependencies
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def auto_patchelf(
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paths_to_patch: List[Path],
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lib_dirs: List[Path],
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runtime_deps: List[Path],
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recursive: bool =True,
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ignore_missing: List[str] = []) -> None:
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if not paths_to_patch:
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sys.exit("No paths to patch, stopping.")
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# Add all shared objects of the current output path to the cache,
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# before lib_dirs, so that they are chosen first in find_dependency.
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populate_cache(paths_to_patch, recursive)
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populate_cache(lib_dirs)
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dependencies = []
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for path in chain.from_iterable(glob(p, '*', recursive) for p in paths_to_patch):
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if not path.is_symlink() and path.is_file():
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dependencies += auto_patchelf_file(path, runtime_deps)
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missing = [dep for dep in dependencies if not dep.found]
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# Print a summary of the missing dependencies at the end
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print(f"auto-patchelf: {len(missing)} dependencies could not be satisfied")
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failure = False
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for dep in missing:
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for pattern in ignore_missing:
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if fnmatch(dep.name.name, pattern):
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print(f"warn: auto-patchelf ignoring missing {dep.name} wanted by {dep.file}")
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break
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else:
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print(f"error: auto-patchelf could not satisfy dependency {dep.name} wanted by {dep.file}")
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failure = True
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if failure:
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sys.exit('auto-patchelf failed to find all the required dependencies.\n'
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'Add the missing dependencies to --libs or use '
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'`--ignore-missing="foo.so.1 bar.so etc.so"`.')
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def main() -> None:
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parser = argparse.ArgumentParser(
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prog="auto-patchelf",
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description='auto-patchelf tries as hard as possible to patch the'
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' provided binary files by looking for compatible'
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'libraries in the provided paths.')
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parser.add_argument(
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"--ignore-missing",
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nargs="*",
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type=str,
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help="Do not fail when some dependencies are not found.")
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parser.add_argument(
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"--no-recurse",
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dest="recursive",
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action="store_false",
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help="Patch only the provided paths, and ignore their children")
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parser.add_argument(
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"--paths", nargs="*", type=Path,
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help="Paths whose content needs to be patched.")
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parser.add_argument(
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"--libs", nargs="*", type=Path,
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help="Paths where libraries are searched for.")
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parser.add_argument(
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"--runtime-dependencies", nargs="*", type=Path,
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help="Paths to prepend to the runtime path of executable binaries.")
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print("automatically fixing dependencies for ELF files")
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args = parser.parse_args()
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pprint.pprint(vars(args))
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auto_patchelf(
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args.paths,
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args.libs,
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args.runtime_dependencies,
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args.recursive,
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args.ignore_missing)
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interpreter_path: Path = None # type: ignore
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interpreter_osabi: str = None # type: ignore
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interpreter_arch: str = None # type: ignore
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libc_lib: Path = None # type: ignore
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if __name__ == "__main__":
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nix_support = Path(os.environ['NIX_BINTOOLS']) / 'nix-support'
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interpreter_path = Path((nix_support / 'dynamic-linker').read_text().strip())
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libc_lib = Path((nix_support / 'orig-libc').read_text().strip()) / 'lib'
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with open_elf(interpreter_path) as interpreter:
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interpreter_osabi = get_osabi(interpreter)
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interpreter_arch = get_arch(interpreter)
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if interpreter_arch and interpreter_osabi and interpreter_path and libc_lib:
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main()
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else:
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sys.exit("Failed to parse dynamic linker (ld) properties.")
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