# This file is part of cloud-init. See LICENSE file for license information.
from cloudinit import log as logging
from cloudinit import subp
from cloudinit.util import is_container, is_FreeBSD

from collections import namedtuple
import os

LOG = logging.getLogger(__name__)

# Path for DMI Data
DMI_SYS_PATH = "/sys/class/dmi/id"

kdmi = namedtuple('KernelNames', ['linux', 'freebsd'])
kdmi.__new__.defaults__ = (None, None)

# FreeBSD's kenv(1) and Linux /sys/class/dmi/id/* both use different names from
# dmidecode. The values are the same, and ultimately what we're interested in.
# These tools offer a "cheaper" way to access those values over dmidecode.
# This is our canonical translation table. If we add more tools on other
# platforms to find dmidecode's values, their keys need to be put in here.
DMIDECODE_TO_KERNEL = {
    'baseboard-asset-tag': kdmi('board_asset_tag', 'smbios.planar.tag'),
    'baseboard-manufacturer': kdmi('board_vendor', 'smbios.planar.maker'),
    'baseboard-product-name': kdmi('board_name', 'smbios.planar.product'),
    'baseboard-serial-number': kdmi('board_serial', 'smbios.planar.serial'),
    'baseboard-version': kdmi('board_version', 'smbios.planar.version'),
    'bios-release-date': kdmi('bios_date', 'smbios.bios.reldate'),
    'bios-vendor': kdmi('bios_vendor', 'smbios.bios.vendor'),
    'bios-version': kdmi('bios_version', 'smbios.bios.version'),
    'chassis-asset-tag': kdmi('chassis_asset_tag', 'smbios.chassis.tag'),
    'chassis-manufacturer': kdmi('chassis_vendor', 'smbios.chassis.maker'),
    'chassis-serial-number': kdmi('chassis_serial', 'smbios.chassis.serial'),
    'chassis-version': kdmi('chassis_version', 'smbios.chassis.version'),
    'system-manufacturer': kdmi('sys_vendor', 'smbios.system.maker'),
    'system-product-name': kdmi('product_name', 'smbios.system.product'),
    'system-serial-number': kdmi('product_serial', 'smbios.system.serial'),
    'system-uuid': kdmi('product_uuid', 'smbios.system.uuid'),
    'system-version': kdmi('product_version', 'smbios.system.version'),
}


def _read_dmi_syspath(key):
    """
    Reads dmi data from /sys/class/dmi/id
    """
    kmap = DMIDECODE_TO_KERNEL.get(key)
    if kmap is None or kmap.linux is None:
        return None
    dmi_key_path = "{0}/{1}".format(DMI_SYS_PATH, kmap.linux)
    LOG.debug("querying dmi data %s", dmi_key_path)
    if not os.path.exists(dmi_key_path):
        LOG.debug("did not find %s", dmi_key_path)
        return None

    try:
        with open(dmi_key_path, "rb") as fp:
            key_data = fp.read()
    except PermissionError:
        LOG.debug("Could not read %s", dmi_key_path)
        return None

    # uninitialized dmi values show as all \xff and /sys appends a '\n'.
    # in that event, return empty string.
    if key_data == b'\xff' * (len(key_data) - 1) + b'\n':
        key_data = b""

    try:
        return key_data.decode('utf8').strip()
    except UnicodeDecodeError as e:
        LOG.error("utf-8 decode of content (%s) in %s failed: %s",
                  dmi_key_path, key_data, e)

    return None


def _read_kenv(key):
    """
    Reads dmi data from FreeBSD's kenv(1)
    """
    kmap = DMIDECODE_TO_KERNEL.get(key)
    if kmap is None or kmap.freebsd is None:
        return None

    LOG.debug("querying dmi data %s", kmap.freebsd)

    try:
        cmd = ["kenv", "-q", kmap.freebsd]
        (result, _err) = subp.subp(cmd)
        result = result.strip()
        LOG.debug("kenv returned '%s' for '%s'", result, kmap.freebsd)
        return result
    except subp.ProcessExecutionError as e:
        LOG.debug('failed kenv cmd: %s\n%s', cmd, e)
        return None

    return None


def _call_dmidecode(key, dmidecode_path):
    """
    Calls out to dmidecode to get the data out. This is mostly for supporting
    OS's without /sys/class/dmi/id support.
    """
    try:
        cmd = [dmidecode_path, "--string", key]
        (result, _err) = subp.subp(cmd)
        result = result.strip()
        LOG.debug("dmidecode returned '%s' for '%s'", result, key)
        if result.replace(".", "") == "":
            return ""
        return result
    except subp.ProcessExecutionError as e:
        LOG.debug('failed dmidecode cmd: %s\n%s', cmd, e)
        return None


def read_dmi_data(key):
    """
    Wrapper for reading DMI data.

    If running in a container return None.  This is because DMI data is
    assumed to be not useful in a container as it does not represent the
    container but rather the host.

    This will do the following (returning the first that produces a
    result):
        1) Use a mapping to translate `key` from dmidecode naming to
           sysfs naming and look in /sys/class/dmi/... for a value.
        2) Use `key` as a sysfs key directly and look in /sys/class/dmi/...
        3) Fall-back to passing `key` to `dmidecode --string`.

    If all of the above fail to find a value, None will be returned.
    """

    if is_container():
        return None

    if is_FreeBSD():
        return _read_kenv(key)

    syspath_value = _read_dmi_syspath(key)
    if syspath_value is not None:
        return syspath_value

    def is_x86(arch):
        return (arch == 'x86_64' or (arch[0] == 'i' and arch[2:] == '86'))

    # running dmidecode can be problematic on some arches (LP: #1243287)
    uname_arch = os.uname()[4]
    if not (is_x86(uname_arch) or uname_arch in ('aarch64', 'amd64')):
        LOG.debug("dmidata is not supported on %s", uname_arch)
        return None

    dmidecode_path = subp.which('dmidecode')
    if dmidecode_path:
        return _call_dmidecode(key, dmidecode_path)

    LOG.warning("did not find either path %s or dmidecode command",
                DMI_SYS_PATH)
    return None

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