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✏️ Editing: ssh_py_shim.py

# pylint: disable=resource-leakage
"""
This is a shim that handles checking and updating salt thin and
then invoking thin.

This is not intended to be instantiated as a module, rather it is a
helper script used by salt.client.ssh.Single.  It is here, in a
separate file, for convenience of development.
"""
from __future__ import absolute_import, print_function

import hashlib
import os
import shutil
import stat
import subprocess
import sys
import tarfile
import time

THIN_ARCHIVE = "salt-thin.tgz"
EXT_ARCHIVE = "salt-ext_mods.tgz"

# Keep these in sync with salt/defaults/exitcodes.py
EX_THIN_PYTHON_INVALID = 10
EX_THIN_DEPLOY = 11
EX_THIN_CHECKSUM = 12
EX_MOD_DEPLOY = 13
EX_SCP_NOT_FOUND = 14
EX_CANTCREAT = 73

class OptionsContainer:
    """
    An empty class for holding instance attribute values.
    """

OPTIONS = OptionsContainer()
ARGS = None
# The below line is where OPTIONS can be redefined with internal options
# (rather than cli arguments) when the shim is bundled by
# client.ssh.Single._cmd_str()
#%%OPTS

def get_system_encoding():
    """
    Get system encoding. Most of this code is a part of salt/__init__.py
    """
    # This is the most trustworthy source of the system encoding, though, if
    # salt is being imported after being daemonized, this information is lost
    # and reset to None
    encoding = None

if not sys.platform.startswith("win") and sys.stdin is not None:
        # On linux we can rely on sys.stdin for the encoding since it
        # most commonly matches the filesystem encoding. This however
        # does not apply to windows
        encoding = sys.stdin.encoding

if not encoding:
        # If the system is properly configured this should return a valid
        # encoding. MS Windows has problems with this and reports the wrong
        # encoding
        import locale

try:
            encoding = locale.getencoding()
        except AttributeError:
            # Python < 3.11
            encoding = locale.getpreferredencoding(do_setlocale=True)

# This is now garbage collectable
        del locale

if not encoding:
            # This is most likely ascii which is not the best but we were
            # unable to find a better encoding. If this fails, we fall all
            # the way back to ascii
            encoding = sys.getdefaultencoding()
        if not encoding:
            if sys.platform.startswith("darwin"):
                # Mac OS X uses UTF-8
                encoding = "utf-8"
            elif sys.platform.startswith("win"):
                # Windows uses a configurable encoding; on Windows, Python uses the name "mbcs"
                # to refer to whatever the currently configured encoding is.
                encoding = "mbcs"
            else:
                # On linux default to ascii as a last resort
                encoding = "ascii"
    return encoding

def is_windows():
    """
    Simple function to return if a host is Windows or not
    """
    return sys.platform.startswith("win")

def need_deployment():
    """
    Salt thin needs to be deployed - prep the target directory and emit the
    delimiter and exit code that signals a required deployment.
    """
    if os.path.exists(OPTIONS.saltdir):
        shutil.rmtree(OPTIONS.saltdir)
    old_umask = os.umask(0o077)  # pylint: disable=blacklisted-function
    try:
        os.makedirs(OPTIONS.saltdir)
    finally:
        os.umask(old_umask)  # pylint: disable=blacklisted-function
    # Verify perms on saltdir
    if not is_windows():
        euid = os.geteuid()
        dstat = os.stat(OPTIONS.saltdir)
        if dstat.st_uid != euid:
            # Attack detected, try again
            need_deployment()
        # AIX has non-POSIX bit 0o240700, isolate to 0o40700
        if dstat.st_mode & ~65536 != 16832:
            # Attack detected
            need_deployment()
        # If SUDOing then also give the super user group write permissions
        sudo_gid = os.environ.get("SUDO_GID")
        if sudo_gid:
            try:
                os.chown(OPTIONS.saltdir, -1, int(sudo_gid))
                stt = os.stat(OPTIONS.saltdir)
                os.chmod(
                    OPTIONS.saltdir,
                    stt.st_mode | stat.S_IWGRP | stat.S_IRGRP | stat.S_IXGRP,
                )
            except OSError:
                sys.stdout.write(
                    "\n\nUnable to set permissions on thin directory.\nIf sudo_user is"
                    " set and is not root, be certain the user is in the same group\nas"
                    " the login user"
                )
                sys.exit(1)

# Delimiter emitted on stdout *only* to indicate shim message to master.
    sys.stdout.write("{0}\ndeploy\n".format(OPTIONS.delimiter))
    sys.exit(EX_THIN_DEPLOY)

# Adapted from salt.utils.hashutils.get_hash()
def get_hash(path, form="sha1", chunk_size=4096):
    """
    Generate a hash digest string for a file.
    """
    try:
        hash_type = getattr(hashlib, form)
    except AttributeError:
        raise ValueError("Invalid hash type: {0}".format(form))
    with open(path, "rb") as ifile:
        hash_obj = hash_type()
        # read the file in in chunks, not the entire file
        for chunk in iter(lambda: ifile.read(chunk_size), b""):
            hash_obj.update(chunk)
        return hash_obj.hexdigest()

def unpack_thin(thin_path):
    """
    Unpack the Salt thin archive.
    """
    tfile = tarfile.TarFile.gzopen(thin_path)
    old_umask = os.umask(0o077)  # pylint: disable=blacklisted-function
    tfile.extractall(path=OPTIONS.saltdir)  # nosec
    tfile.close()
    os.umask(old_umask)  # pylint: disable=blacklisted-function
    try:
        os.unlink(thin_path)
    except OSError:
        pass
    reset_time(OPTIONS.saltdir)

def need_ext():
    """
    Signal that external modules need to be deployed.
    """
    sys.stdout.write("{0}\next_mods\n".format(OPTIONS.delimiter))
    sys.exit(EX_MOD_DEPLOY)

def unpack_ext(ext_path):
    """
    Unpack the external modules.
    """
    modcache = os.path.join(
        OPTIONS.saltdir, "running_data", "var", "cache", "salt", "minion", "extmods"
    )
    tfile = tarfile.TarFile.gzopen(ext_path)
    old_umask = os.umask(0o077)  # pylint: disable=blacklisted-function
    tfile.extractall(path=modcache)  # nosec
    tfile.close()
    os.umask(old_umask)  # pylint: disable=blacklisted-function
    os.unlink(ext_path)
    ver_path = os.path.join(modcache, "ext_version")
    ver_dst = os.path.join(OPTIONS.saltdir, "ext_version")
    shutil.move(ver_path, ver_dst)

def reset_time(path=".", amt=None):
    """
    Reset atime/mtime on all files to prevent systemd swipes only part of the files in the /tmp.
    """
    if not amt:
        amt = int(time.time())
    for fname in os.listdir(path):
        fname = os.path.join(path, fname)
        if os.path.isdir(fname):
            reset_time(fname, amt=amt)
        os.utime(
            fname,
            (
                amt,
                amt,
            ),
        )

def get_executable():
    """
    Find executable which matches supported python version in the thin
    """
    pymap = {}
    with open(
        os.path.join(OPTIONS.saltdir, "supported-versions"), encoding="utf-8"
    ) as _fp:
        for line in _fp.readlines():
            ns, v_maj, v_min = line.strip().split(":")
            pymap[ns] = (int(v_maj), int(v_min))

pycmds = (
        sys.executable,
        "python3",
        "python27",
        "python2.7",
        "python26",
        "python2.6",
        "python2",
        "python",
    )
    for py_cmd in pycmds:
        stdout, _ = subprocess.Popen(
            [
                py_cmd,
                "-c",
                "import sys; sys.stdout.write('%s:%s' % (sys.version_info[0], sys.version_info[1]))",
            ],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
        ).communicate()
        if sys.version_info[0] == 2 and sys.version_info[1] < 7:
            stdout = stdout.decode(get_system_encoding(), "replace").strip()
        else:
            stdout = stdout.decode(
                encoding=get_system_encoding(), errors="replace"
            ).strip()
        if not stdout:
            continue
        c_vn = tuple([int(x) for x in stdout.split(":")])
        for ns in pymap:
            if (
                c_vn[0] == pymap[ns][0]
                and c_vn >= pymap[ns]
                and os.path.exists(os.path.join(OPTIONS.saltdir, ns))
            ):
                return py_cmd

sys.exit(EX_THIN_PYTHON_INVALID)

def main(argv):  # pylint: disable=W0613
    """
    Main program body
    """
    thin_path = os.path.join(OPTIONS.saltdir, THIN_ARCHIVE)
    if os.path.isfile(thin_path):
        if OPTIONS.checksum != get_hash(thin_path, OPTIONS.hashfunc):
            need_deployment()
        unpack_thin(thin_path)
        # Salt thin now is available to use
    else:
        if not sys.platform.startswith("win"):
            scpstat = subprocess.Popen(["/bin/sh", "-c", "command -v scp"]).wait()
            if scpstat != 0:
                sys.exit(EX_SCP_NOT_FOUND)

if os.path.exists(OPTIONS.saltdir) and not os.path.isdir(OPTIONS.saltdir):
            sys.stderr.write(
                'ERROR: salt path "{0}" exists but is not a directory\n'.format(
                    OPTIONS.saltdir
                )
            )
            sys.exit(EX_CANTCREAT)

if not os.path.exists(OPTIONS.saltdir):
            need_deployment()

code_checksum_path = os.path.normpath(
            os.path.join(OPTIONS.saltdir, "code-checksum")
        )
        if not os.path.exists(code_checksum_path) or not os.path.isfile(
            code_checksum_path
        ):
            sys.stderr.write(
                "WARNING: Unable to locate current code checksum: {0}.\n".format(
                    code_checksum_path
                )
            )
            need_deployment()
        with open(code_checksum_path, "r", encoding="utf-8") as vpo:
            cur_code_cs = vpo.readline().strip()
        if cur_code_cs != OPTIONS.code_checksum:
            sys.stderr.write(
                "WARNING: current code checksum {0} is different to {1}.\n".format(
                    cur_code_cs, OPTIONS.code_checksum
                )
            )
            need_deployment()
        # Salt thin exists and is up-to-date - fall through and use it

salt_call_path = os.path.join(OPTIONS.saltdir, "salt-call")
    if not os.path.isfile(salt_call_path):
        sys.stderr.write('ERROR: thin is missing "{0}"\n'.format(salt_call_path))
        need_deployment()

with open(os.path.join(OPTIONS.saltdir, "minion"), "w", encoding="utf-8") as config:
        config.write(OPTIONS.config + "\n")
    if OPTIONS.ext_mods:
        ext_path = os.path.join(OPTIONS.saltdir, EXT_ARCHIVE)
        if os.path.exists(ext_path):
            unpack_ext(ext_path)
        else:
            version_path = os.path.join(OPTIONS.saltdir, "ext_version")
            if not os.path.exists(version_path) or not os.path.isfile(version_path):
                need_ext()
            with open(version_path, "r", encoding="utf-8") as vpo:
                cur_version = vpo.readline().strip()
            if cur_version != OPTIONS.ext_mods:
                need_ext()
    # Fix parameter passing issue
    if len(ARGS) == 1:
        argv_prepared = ARGS[0].split()
    else:
        argv_prepared = ARGS

salt_argv = [
        get_executable(),
        salt_call_path,
        "--retcode-passthrough",
        "--local",
        "--metadata",
        "--out",
        "json",
        "-l",
        "quiet",
        "-c",
        OPTIONS.saltdir,
    ]

try:
        if argv_prepared[-1].startswith("--no-parse="):
            salt_argv.append(argv_prepared.pop(-1))
    except (IndexError, TypeError):
        pass

salt_argv.append("--")
    salt_argv.extend(argv_prepared)

sys.stderr.write("SALT_ARGV: {0}\n".format(salt_argv))

# Only emit the delimiter on *both* stdout and stderr when completely successful.
    # Yes, the flush() is necessary.
    sys.stdout.write(OPTIONS.delimiter + "\n")
    sys.stdout.flush()
    if not OPTIONS.tty:
        sys.stderr.write(OPTIONS.delimiter + "\n")
        sys.stderr.flush()
    if OPTIONS.cmd_umask is not None:
        old_umask = os.umask(OPTIONS.cmd_umask)  # pylint: disable=blacklisted-function
    if OPTIONS.tty:
        proc = subprocess.Popen(
            salt_argv, stdout=subprocess.PIPE, stderr=subprocess.PIPE
        )
        # Returns bytes instead of string on python 3
        stdout, _ = proc.communicate()
        sys.stdout.write(
            stdout.decode(encoding=get_system_encoding(), errors="replace")
        )
        sys.stdout.flush()
        retcode = proc.returncode
        if OPTIONS.wipe:
            shutil.rmtree(OPTIONS.saltdir)
    elif OPTIONS.wipe:
        retcode = subprocess.call(salt_argv)
        shutil.rmtree(OPTIONS.saltdir)
    else:
        retcode = subprocess.call(salt_argv)
    if OPTIONS.cmd_umask is not None:
        os.umask(old_umask)  # pylint: disable=blacklisted-function
    return retcode

if __name__ == "__main__":
    sys.exit(main(sys.argv))

MR SKB