"""PEP 656 support.
This module implements logic to detect if the currently running Python is
linked against musl, and what musl version is used.
"""
from __future__ import annotations
import functools
import re
import subprocess
import sys
from typing import Iterator, NamedTuple, Sequence
from ._elffile import ELFFile
class _MuslVersion(NamedTuple):
major: int
minor: int
def _parse_musl_version(output: str) -> _MuslVersion | None:
lines = [n for n in (n.strip() for n in output.splitlines()) if n]
if len(lines) < 2 or lines[0][:4] != "musl":
return None
m = re.match(r"Version (\d+)\.(\d+)", lines[1])
if not m:
return None
return _MuslVersion(major=int(m.group(1)), minor=int(m.group(2)))
@functools.lru_cache
def _get_musl_version(executable: str) -> _MuslVersion | None:
"""Detect currently-running musl runtime version.
This is done by checking the specified executable's dynamic linking
information, and invoking the loader to parse its output for a version
string. If the loader is musl, the output would be something like::
musl libc (x86_64)
Version 1.2.2
Dynamic Program Loader
"""
try:
with open(executable, "rb") as f:
ld = ELFFile(f).interpreter
except (OSError, TypeError, ValueError):
return None
if ld is None or "musl" not in ld:
return None
proc = subprocess.run([ld], check=False, stderr=subprocess.PIPE, text=True)
return _parse_musl_version(proc.stderr)
def platform_tags(archs: Sequence[str]) -> Iterator[str]:
"""Generate musllinux tags compatible to the current platform.
:param archs: Sequence of compatible architectures.
The first one shall be the closest to the actual architecture and be the part of
platform tag after the ``linux_`` prefix, e.g. ``x86_64``.
The ``linux_`` prefix is assumed as a prerequisite for the current platform to
be musllinux-compatible.
:returns: An iterator of compatible musllinux tags.
"""
sys_musl = _get_musl_version(sys.executable)
if sys_musl is None: # Python not dynamically linked against musl.
return
for arch in archs:
for minor in range(sys_musl.minor, -1, -1):
yield f"musllinux_{sys_musl.major}_{minor}_{arch}"
if __name__ == "__main__": # pragma: no cover
import sysconfig
plat = sysconfig.get_platform()
assert plat.startswith("linux-"), "not linux"
print("plat:", plat)
print("musl:", _get_musl_version(sys.executable))
print("tags:", end=" ")
for t in platform_tags(re.sub(r"[.-]", "_", plat.split("-", 1)[-1])):
print(t, end="\n ")
|