venv/lib/python3.11/site-packages/pip/_vendor/packaging/_musllinux.py

   1 """PEP 656 support.
   2
   3 This module implements logic to detect if the currently running Python is
   4 linked against musl, and what musl version is used.
   5 """
   6
   7 import contextlib
   8 import functools
   9 import operator
  10 import os
  11 import re
  12 import struct
  13 import subprocess
  14 import sys
  15 from typing import IO, Iterator, NamedTuple, Optional, Tuple
  16
  17
  18 def _read_unpacked(f: IO[bytes], fmt: str) -> Tuple[int, ...]:
  19     return struct.unpack(fmt, f.read(struct.calcsize(fmt)))
  20
  21
  22 def _parse_ld_musl_from_elf(f: IO[bytes]) -> Optional[str]:
  23     """Detect musl libc location by parsing the Python executable.
  24
  25     Based on: https://gist.github.com/lyssdod/f51579ae8d93c8657a5564aefc2ffbca
  26     ELF header: https://refspecs.linuxfoundation.org/elf/gabi4+/ch4.eheader.html
  27     """
  28     f.seek(0)
  29     try:
  30         ident = _read_unpacked(f, "16B")
  31     except struct.error:
  32         return None
  33     if ident[:4] != tuple(b"\x7fELF"):  # Invalid magic, not ELF.
  34         return None
  35     f.seek(struct.calcsize("HHI"), 1)  # Skip file type, machine, and version.
  36
  37     try:
  38         # e_fmt: Format for program header.
  39         # p_fmt: Format for section header.
  40         # p_idx: Indexes to find p_type, p_offset, and p_filesz.
  41         e_fmt, p_fmt, p_idx = {
  42             1: ("IIIIHHH", "IIIIIIII", (0, 1, 4)),  # 32-bit.
  43             2: ("QQQIHHH", "IIQQQQQQ", (0, 2, 5)),  # 64-bit.
  44         }[ident[4]]
  45     except KeyError:
  46         return None
  47     else:
  48         p_get = operator.itemgetter(*p_idx)
  49
  50     # Find the interpreter section and return its content.
  51     try:
  52         _, e_phoff, _, _, _, e_phentsize, e_phnum = _read_unpacked(f, e_fmt)
  53     except struct.error:
  54         return None
  55     for i in range(e_phnum + 1):
  56         f.seek(e_phoff + e_phentsize * i)
  57         try:
  58             p_type, p_offset, p_filesz = p_get(_read_unpacked(f, p_fmt))
  59         except struct.error:
  60             return None
  61         if p_type != 3:  # Not PT_INTERP.
  62             continue
  63         f.seek(p_offset)
  64         interpreter = os.fsdecode(f.read(p_filesz)).strip("\0")
  65         if "musl" not in interpreter:
  66             return None
  67         return interpreter
  68     return None
  69
  70
  71 class _MuslVersion(NamedTuple):
  72     major: int
  73     minor: int
  74
  75
  76 def _parse_musl_version(output: str) -> Optional[_MuslVersion]:
  77     lines = [n for n in (n.strip() for n in output.splitlines()) if n]
  78     if len(lines) < 2 or lines[0][:4] != "musl":
  79         return None
  80     m = re.match(r"Version (\d+)\.(\d+)", lines[1])
  81     if not m:
  82         return None
  83     return _MuslVersion(major=int(m.group(1)), minor=int(m.group(2)))
  84
  85
  86 @functools.lru_cache()
  87 def _get_musl_version(executable: str) -> Optional[_MuslVersion]:
  88     """Detect currently-running musl runtime version.
  89
  90     This is done by checking the specified executable's dynamic linking
  91     information, and invoking the loader to parse its output for a version
  92     string. If the loader is musl, the output would be something like::
  93
  94         musl libc (x86_64)
  95         Version 1.2.2
  96         Dynamic Program Loader
  97     """
  98     with contextlib.ExitStack() as stack:
  99         try:
 100             f = stack.enter_context(open(executable, "rb"))
 101         except OSError:
 102             return None
 103         ld = _parse_ld_musl_from_elf(f)
 104     if not ld:
 105         return None
 106     proc = subprocess.run([ld], stderr=subprocess.PIPE, universal_newlines=True)
 107     return _parse_musl_version(proc.stderr)
 108
 109
 110 def platform_tags(arch: str) -> Iterator[str]:
 111     """Generate musllinux tags compatible to the current platform.
 112
 113     :param arch: Should be the part of platform tag after the ``linux_``
 114         prefix, e.g. ``x86_64``. The ``linux_`` prefix is assumed as a
 115         prerequisite for the current platform to be musllinux-compatible.
 116
 117     :returns: An iterator of compatible musllinux tags.
 118     """
 119     sys_musl = _get_musl_version(sys.executable)
 120     if sys_musl is None:  # Python not dynamically linked against musl.
 121         return
 122     for minor in range(sys_musl.minor, -1, -1):
 123         yield f"musllinux_{sys_musl.major}_{minor}_{arch}"
 124
 125
 126 if __name__ == "__main__":  # pragma: no cover
 127     import sysconfig
 128
 129     plat = sysconfig.get_platform()
 130     assert plat.startswith("linux-"), "not linux"
 131
 132     print("plat:", plat)
 133     print("musl:", _get_musl_version(sys.executable))
 134     print("tags:", end=" ")
 135     for t in platform_tags(re.sub(r"[.-]", "_", plat.split("-", 1)[-1])):
 136         print(t, end="\n      ")