second commit

env/lib/python3.11/site-packages/shellingham/posix/__init__.py

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+import os
+import re
+
+from .._core import SHELL_NAMES, ShellDetectionFailure
+from . import proc, ps
+
+# Based on QEMU docs: https://www.qemu.org/docs/master/user/main.html
+QEMU_BIN_REGEX = re.compile(
+    r"""qemu-
+        (alpha
+        |armeb
+        |arm
+        |m68k
+        |cris
+        |i386
+        |x86_64
+        |microblaze
+        |mips
+        |mipsel
+        |mips64
+        |mips64el
+        |mipsn32
+        |mipsn32el
+        |nios2
+        |ppc64
+        |ppc
+        |sh4eb
+        |sh4
+        |sparc
+        |sparc32plus
+        |sparc64
+    )""",
+    re.VERBOSE,
+)
+
+
+def _iter_process_parents(pid, max_depth=10):
+    """Select a way to obtain process information from the system.
+
+    * `/proc` is used if supported.
+    * The system `ps` utility is used as a fallback option.
+    """
+    for impl in (proc, ps):
+        try:
+            iterator = impl.iter_process_parents(pid, max_depth)
+        except EnvironmentError:
+            continue
+        return iterator
+    raise ShellDetectionFailure("compatible proc fs or ps utility is required")
+
+
+def _get_login_shell(proc_cmd):
+    """Form shell information from SHELL environ if possible."""
+    login_shell = os.environ.get("SHELL", "")
+    if login_shell:
+        proc_cmd = login_shell
+    else:
+        proc_cmd = proc_cmd[1:]
+    return (os.path.basename(proc_cmd).lower(), proc_cmd)
+
+
+_INTERPRETER_SHELL_NAMES = [
+    (re.compile(r"^python(\d+(\.\d+)?)?$"), {"xonsh"}),
+]
+
+
+def _get_interpreter_shell(proc_name, proc_args):
+    """Get shell invoked via an interpreter.
+
+    Some shells are implemented on, and invoked with an interpreter, e.g. xonsh
+    is commonly executed with an executable Python script. This detects what
+    script the interpreter is actually running, and check whether that looks
+    like a shell.
+
+    See sarugaku/shellingham#26 for rational.
+    """
+    for pattern, shell_names in _INTERPRETER_SHELL_NAMES:
+        if not pattern.match(proc_name):
+            continue
+        for arg in proc_args:
+            name = os.path.basename(arg).lower()
+            if os.path.isfile(arg) and name in shell_names:
+                return (name, arg)
+    return None
+
+
+def _get_shell(cmd, *args):
+    if cmd.startswith("-"):  # Login shell! Let's use this.
+        return _get_login_shell(cmd)
+    name = os.path.basename(cmd).lower()
+    if name == "rosetta" or QEMU_BIN_REGEX.fullmatch(name):
+        # If the current process is Rosetta or QEMU, this likely is a
+        # containerized process. Parse out the actual command instead.
+        cmd = args[0]
+        args = args[1:]
+        name = os.path.basename(cmd).lower()
+    if name in SHELL_NAMES:  # Command looks like a shell.
+        return (name, cmd)
+    shell = _get_interpreter_shell(name, args)
+    if shell:
+        return shell
+    return None
+
+
+def get_shell(pid=None, max_depth=10):
+    """Get the shell that the supplied pid or os.getpid() is running in."""
+    pid = str(pid or os.getpid())
+    for proc_args, _, _ in _iter_process_parents(pid, max_depth):
+        shell = _get_shell(*proc_args)
+        if shell:
+            return shell
+    return None

env/lib/python3.11/site-packages/shellingham/posix/_core.py

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+import collections
+
+Process = collections.namedtuple("Process", "args pid ppid")

env/lib/python3.11/site-packages/shellingham/posix/proc.py

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+import io
+import os
+import re
+import sys
+
+from ._core import Process
+
+# FreeBSD: https://www.freebsd.org/cgi/man.cgi?query=procfs
+# NetBSD: https://man.netbsd.org/NetBSD-9.3-STABLE/mount_procfs.8
+# DragonFlyBSD: https://www.dragonflybsd.org/cgi/web-man?command=procfs
+BSD_STAT_PPID = 2
+
+# See https://docs.kernel.org/filesystems/proc.html
+LINUX_STAT_PPID = 3
+
+STAT_PATTERN = re.compile(r"\(.+\)|\S+")
+
+
+def detect_proc():
+    """Detect /proc filesystem style.
+
+    This checks the /proc/{pid} directory for possible formats. Returns one of
+    the following as str:
+
+    * `stat`: Linux-style, i.e. ``/proc/{pid}/stat``.
+    * `status`: BSD-style, i.e. ``/proc/{pid}/status``.
+    """
+    pid = os.getpid()
+    for name in ("stat", "status"):
+        if os.path.exists(os.path.join("/proc", str(pid), name)):
+            return name
+    raise ProcFormatError("unsupported proc format")
+
+
+def _use_bsd_stat_format():
+    try:
+        return os.uname().sysname.lower() in ("freebsd", "netbsd", "dragonfly")
+    except Exception:
+        return False
+
+
+def _get_ppid(pid, name):
+    path = os.path.join("/proc", str(pid), name)
+    with io.open(path, encoding="ascii", errors="replace") as f:
+        parts = STAT_PATTERN.findall(f.read())
+    # We only care about TTY and PPID -- both are numbers.
+    if _use_bsd_stat_format():
+        return parts[BSD_STAT_PPID]
+    return parts[LINUX_STAT_PPID]
+
+
+def _get_cmdline(pid):
+    path = os.path.join("/proc", str(pid), "cmdline")
+    encoding = sys.getfilesystemencoding() or "utf-8"
+    with io.open(path, encoding=encoding, errors="replace") as f:
+        # XXX: Command line arguments can be arbitrary byte sequences, not
+        # necessarily decodable. For Shellingham's purpose, however, we don't
+        # care. (pypa/pipenv#2820)
+        # cmdline appends an extra NULL at the end, hence the [:-1].
+        return tuple(f.read().split("\0")[:-1])
+
+
+class ProcFormatError(EnvironmentError):
+    pass
+
+
+def iter_process_parents(pid, max_depth=10):
+    """Try to look up the process tree via the /proc interface."""
+    stat_name = detect_proc()
+
+    # Inner generator function so we correctly throw an error eagerly if proc
+    # is not supported, rather than on the first call to the iterator. This
+    # allows the call site detects the correct implementation.
+    def _iter_process_parents(pid, max_depth):
+        for _ in range(max_depth):
+            ppid = _get_ppid(pid, stat_name)
+            args = _get_cmdline(pid)
+            yield Process(args=args, pid=pid, ppid=ppid)
+            if ppid == "0":
+                break
+            pid = ppid
+
+    return _iter_process_parents(pid, max_depth)

env/lib/python3.11/site-packages/shellingham/posix/ps.py

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+import errno
+import subprocess
+import sys
+
+from ._core import Process
+
+
+class PsNotAvailable(EnvironmentError):
+    pass
+
+
+def iter_process_parents(pid, max_depth=10):
+    """Try to look up the process tree via the output of `ps`."""
+    try:
+        cmd = ["ps", "-ww", "-o", "pid=", "-o", "ppid=", "-o", "args="]
+        output = subprocess.check_output(cmd)
+    except OSError as e:  # Python 2-compatible FileNotFoundError.
+        if e.errno != errno.ENOENT:
+            raise
+        raise PsNotAvailable("ps not found")
+    except subprocess.CalledProcessError as e:
+        # `ps` can return 1 if the process list is completely empty.
+        # (sarugaku/shellingham#15)
+        if not e.output.strip():
+            return
+        raise
+    if not isinstance(output, str):
+        encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()
+        output = output.decode(encoding)
+
+    processes_mapping = {}
+    for line in output.split("\n"):
+        try:
+            _pid, ppid, args = line.strip().split(None, 2)
+            # XXX: This is not right, but we are really out of options.
+            # ps does not offer a sane way to decode the argument display,
+            # and this is "Good Enough" for obtaining shell names. Hopefully
+            # people don't name their shell with a space, or have something
+            # like "/usr/bin/xonsh is uber". (sarugaku/shellingham#14)
+            args = tuple(a.strip() for a in args.split(" "))
+        except ValueError:
+            continue
+        processes_mapping[_pid] = Process(args=args, pid=_pid, ppid=ppid)
+
+    for _ in range(max_depth):
+        try:
+            process = processes_mapping[pid]
+        except KeyError:
+            return
+        yield process
+        pid = process.ppid