# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Helper methods to deal with images.

This is essentially a copy from nova.virt.images.py
Some slight modifications, but at some point
we should look at maybe pushing this up to Oslo
"""

import contextlib
import errno
import io
import math
import os
import re
import tempfile
from typing import ContextManager, Generator, Optional

import cryptography
from cursive import exception as cursive_exception
from cursive import signature_utils
from eventlet import tpool
from oslo_concurrency import processutils
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import fileutils
from oslo_utils import imageutils
from oslo_utils import timeutils
from oslo_utils import units
import psutil

from cinder import context
from cinder import exception
from cinder.i18n import _
from cinder.image import accelerator
from cinder.image import glance
import cinder.privsep.format_inspector
from cinder import utils
from cinder.volume import throttling
from cinder.volume import volume_utils

LOG = logging.getLogger(__name__)

image_opts = [
    cfg.StrOpt('image_conversion_dir',
               default='$state_path/conversion',
               help='Directory used for temporary storage '
               'during image conversion'),
    cfg.BoolOpt('image_compress_on_upload',
                default=True,
                help='When possible, compress images uploaded '
                'to the image service'),
    cfg.IntOpt('image_conversion_cpu_limit',
               default=60,
               help='CPU time limit in seconds to convert the image'),
    cfg.IntOpt('image_conversion_address_space_limit',
               default=1,
               help='Address space limit in gigabytes to convert the image'),
    cfg.BoolOpt('image_conversion_disable',
                default=False,
                help='Disallow image conversion when creating a volume from '
                'an image and when uploading a volume as an image. Image '
                'conversion consumes a large amount of system resources and '
                'can cause performance problems on the cinder-volume node. '
                'When set True, this option disables image conversion.'),
    cfg.ListOpt('vmdk_allowed_types',
                default=['streamOptimized', 'monolithicSparse'],
                help='A list of strings describing the VMDK createType '
                'subformats that are allowed.  We recommend that you only '
                'include single-file-with-sparse-header variants to avoid '
                'potential host file exposure when processing named extents '
                'when an image is converted to raw format as it is written '
                'to a volume.  If this list is empty, no VMDK images are '
                'allowed.'),
    cfg.ListOpt('reserved_image_namespaces',
                help='List of reserved image namespaces that should be '
                     'filtered out when uploading a volume as an image back '
                     'to Glance. When a volume is created from an image, '
                     'Cinder stores the image properties as volume '
                     'image metadata, and if the volume is later uploaded as '
                     'an image, Cinder will add these properties when it '
                     'creates the image in Glance. This can cause problems '
                     'for image metadata that are in namespaces that glance '
                     'reserves for itself, or when properties (such as an '
                     'image signature) cannot apply to the new image, or when '
                     'an operator has configured glance property protections '
                     'to make some image properties read-only. Cinder will '
                     '*always* filter out image metadata in the namespaces '
                     '`os_glance`, `img_signature` and `signature_verified`; '
                     'this configuration option allows operators to specify '
                     '*additional* namespaces to be excluded.',
                default=[]),
]

CONF = cfg.CONF
CONF.register_opts(image_opts)

QEMU_IMG_LIMITS = processutils.ProcessLimits(
    cpu_time=CONF.image_conversion_cpu_limit,
    address_space=CONF.image_conversion_address_space_limit * units.Gi)


QEMU_IMG_FORMAT_MAP = {
    # Convert formats of Glance images to how they are processed with qemu-img.
    'iso': 'raw',
    'vhd': 'vpc',
    'ploop': 'parallels',
}
QEMU_IMG_FORMAT_MAP_INV = {v: k for k, v in QEMU_IMG_FORMAT_MAP.items()}

QEMU_IMG_VERSION = None

COMPRESSIBLE_IMAGE_FORMATS = ('qcow2',)

GLANCE_RESERVED_NAMESPACES = ["os_glance", "img_signature",
                              "signature_verified"]


def validate_stores_id(context: context.RequestContext,
                       image_service_store_id: str) -> None:
    image_service = glance.get_default_image_service()
    stores_info = image_service.get_stores(context)['stores']
    for info in stores_info:
        if image_service_store_id == info['id']:
            if info.get('read-only') == "true":
                raise exception.GlanceStoreReadOnly(
                    store_id=image_service_store_id)
            return

    raise exception.GlanceStoreNotFound(store_id=image_service_store_id)


def fixup_disk_format(disk_format: str) -> str:
    """Return the format to be provided to qemu-img convert."""

    return QEMU_IMG_FORMAT_MAP.get(disk_format, disk_format)


def from_qemu_img_disk_format(disk_format: str) -> str:
    """Return the conventional format derived from qemu-img format."""

    return QEMU_IMG_FORMAT_MAP_INV.get(disk_format, disk_format)


def qemu_img_info(
        path: str,
        run_as_root: bool = True,
        force_share: bool = False,
        allow_qcow2_backing_file: bool = False) -> imageutils.QemuImgInfo:
    """Return an object containing the parsed output from qemu-img info."""

    format_name = cinder.privsep.format_inspector.get_format_if_safe(
        path=path,
        allow_qcow2_backing_file=allow_qcow2_backing_file)
    if format_name is None:
        LOG.warning('Image/Volume %s failed safety check', path)
        # NOTE(danms): This is the same exception as would be raised
        # by qemu_img_info() if the disk format was unreadable or
        # otherwise unsuitable.
        raise exception.Invalid(
            reason=_('Image/Volume failed safety check'))

    cmd = ['env', 'LC_ALL=C', 'qemu-img', 'info',
           '-f', format_name, '--output=json']
    if force_share:
        cmd.append('--force-share')
    cmd.append(path)

    if os.name == 'nt':
        cmd = cmd[2:]
    out, _err = utils.execute(*cmd, run_as_root=run_as_root,
                              prlimit=QEMU_IMG_LIMITS)
    info = imageutils.QemuImgInfo(out, format='json')

    # FIXME: figure out a more elegant way to do this
    if info.file_format == 'raw':
        # The format_inspector will detect a luks image as 'raw', and then when
        # we call qemu-img info -f raw above, we don't get any of the luks
        # format-specific info (some of which is used in the create_volume
        # flow).  So we need to check if this is really a luks container.
        # (We didn't have to do this in the past because we called
        # qemu-img info without -f.)
        cmd = ['env', 'LC_ALL=C', 'qemu-img', 'info',
               '-f', 'luks', '--output=json']
        if force_share:
            cmd.append('--force-share')
        cmd.append(path)
        if os.name == 'nt':
            cmd = cmd[2:]
        try:
            out, _err = utils.execute(*cmd, run_as_root=run_as_root,
                                      prlimit=QEMU_IMG_LIMITS)
            info = imageutils.QemuImgInfo(out, format='json')
        except processutils.ProcessExecutionError:
            # we'll just use the info object we already got earlier
            pass

    # From Cinder's point of view, any 'luks' formatted images
    # should be treated as 'raw'.  (This changes the file_format, but
    # not any of the format-specific information.)
    if info.file_format == 'luks':
        info.file_format = 'raw'

    return info


def get_qemu_img_version() -> Optional[list[int]]:
    """The qemu-img version will be cached until the process is restarted."""

    global QEMU_IMG_VERSION
    if QEMU_IMG_VERSION is not None:
        return QEMU_IMG_VERSION

    info = utils.execute('qemu-img', '--version', check_exit_code=False)[0]
    pattern = r"qemu-img version ([0-9\.]*)"
    version = re.match(pattern, info)
    if not version:
        LOG.warning("qemu-img is not installed.")
        return None
    QEMU_IMG_VERSION = _get_version_from_string(version.groups()[0])
    return QEMU_IMG_VERSION


def _get_qemu_convert_luks_cmd(src: str,
                               dest: str,
                               out_format: str,
                               src_format: Optional[str] = None,
                               out_subformat: Optional[str] = None,
                               cache_mode: Optional[str] = None,
                               prefix: Optional[tuple] = None,
                               cipher_spec: Optional[dict] = None,
                               passphrase_file: Optional[str] = None,
                               src_passphrase_file: Optional[str] = None,
                               disable_sparse: bool = False) -> list[str]:
    cmd = ['qemu-img', 'convert']

    if prefix:
        cmd = list(prefix) + cmd

    if cache_mode:
        cmd += ('-t', cache_mode)

    if disable_sparse:
        cmd += ('-S', '0')

    obj1 = ['--object',
            'secret,id=sec1,format=raw,file=%s' % src_passphrase_file]
    obj2 = ['--object',
            'secret,id=sec2,format=raw,file=%s' % passphrase_file]

    src_opts = 'encrypt.format=luks,encrypt.key-secret=sec1,' \
               'file.filename=%s' % src

    image_opts = ['--image-opts', src_opts]
    output_opts = ['-O', 'luks', '-o', 'key-secret=sec2', dest]

    command = cmd + obj1 + obj2 + image_opts + output_opts
    return command


def _get_qemu_convert_cmd(src: str,
                          dest: str,
                          out_format: str,
                          src_format: Optional[str] = None,
                          out_subformat: Optional[str] = None,
                          cache_mode: Optional[str] = None,
                          prefix: Optional[tuple] = None,
                          cipher_spec: Optional[dict] = None,
                          passphrase_file: Optional[str] = None,
                          compress: bool = False,
                          src_passphrase_file: Optional[str] = None,
                          disable_sparse: bool = False) -> list[str]:
    if src_passphrase_file is not None:
        if passphrase_file is None:
            message = _("Can't create unencrypted volume %(format)s "
                        "from an encrypted source volume."
                        ) % {'format': out_format}
            LOG.error(message)
            # TODO(enriquetaso): handle encrypted->unencrypted
            raise exception.NotSupportedOperation(operation=message)
        return _get_qemu_convert_luks_cmd(
            src,
            dest,
            out_format,
            src_format=src_format,
            out_subformat=out_subformat,
            cache_mode=cache_mode,
            prefix=None,
            cipher_spec=cipher_spec,
            passphrase_file=passphrase_file,
            src_passphrase_file=src_passphrase_file,
            disable_sparse=disable_sparse)

    if out_format == 'vhd':
        # qemu-img still uses the legacy vpc name
        out_format = 'vpc'

    cmd = ['qemu-img', 'convert', '-O', out_format]

    if prefix:
        cmd = list(prefix) + cmd

    if cache_mode:
        cmd += ('-t', cache_mode)

    if disable_sparse:
        cmd += ('-S', '0')

    if CONF.image_compress_on_upload and compress:
        if out_format in COMPRESSIBLE_IMAGE_FORMATS:
            cmd += ('-c',)

    if out_subformat:
        cmd += ('-o', 'subformat=%s' % out_subformat)

    # AMI images can be raw or qcow2 but qemu-img doesn't accept "ami" as
    # an image format, so we use automatic detection.
    # TODO(geguileo): This fixes unencrypted AMI image case, but we need to
    # fix the encrypted case.

    if (src_format or '').lower() not in ('', 'ami'):
        assert src_format is not None
        cmd += ['-f', src_format]  # prevent detection of format

    # NOTE(lyarwood): When converting to LUKS add the cipher spec if present
    # and create a secret for the passphrase, written to a temp file
    if out_format == 'luks':
        if cipher_spec:
            cmd += ('-o', 'cipher-alg=%s,cipher-mode=%s,ivgen-alg=%s' %
                    (cipher_spec['cipher_alg'], cipher_spec['cipher_mode'],
                     cipher_spec['ivgen_alg']))
        cmd += ('--object',
                'secret,id=luks_sec,format=raw,file=%s' % passphrase_file,
                '-o', 'key-secret=luks_sec')

    cmd += [src, dest]

    return cmd


def _get_version_from_string(version_string: str) -> list[int]:
    return [int(x) for x in version_string.split('.')]


def check_qemu_img_version(minimum_version: str) -> None:
    qemu_version = get_qemu_img_version()
    if (qemu_version is None
       or qemu_version < _get_version_from_string(minimum_version)):
        current_version: Optional[str]
        if qemu_version:
            current_version = '.'.join((str(element)
                                       for element in qemu_version))
        else:
            current_version = None

        _msg = _('qemu-img %(minimum_version)s or later is required by '
                 'this volume driver. Current qemu-img version: '
                 '%(current_version)s') % {'minimum_version': minimum_version,
                                           'current_version': current_version}
        raise exception.VolumeBackendAPIException(data=_msg)


def _convert_image(
        prefix: tuple,
        source: str,
        dest: str,
        out_format: str,
        out_subformat: Optional[str] = None,
        src_format: Optional[str] = None,
        run_as_root: bool = True,
        cipher_spec: Optional[dict] = None,
        passphrase_file: Optional[str] = None,
        compress: bool = False,
        src_passphrase_file: Optional[str] = None,
        disable_sparse: bool = False,
        src_img_info: Optional[imageutils.QemuImgInfo] = None) -> None:
    """Convert image to other format.

    NOTE: If the qemu-img convert command fails and this function raises an
    exception, a non-empty dest file may be left in the filesystem.
    It is the responsibility of the caller to decide what to do with this file.

    :param prefix: command prefix, i.e. cgexec for throttling
    :param source: source filename
    :param dest: destination filename
    :param out_format: output image format of qemu-img
    :param out_subformat: output image subformat
    :param src_format: source image format
    :param run_as_root: run qemu-img as root
    :param cipher_spec: encryption details
    :param passphrase_file: filename containing luks passphrase
    :param compress: compress w/ qemu-img when possible (best effort)
    :param src_passphrase_file: filename containing source volume's
                                luks passphrase
    :param src_img_info: a imageutils.QemuImgInfo object from this image,
                            or None
    """

    # Check whether O_DIRECT is supported and set '-t none' if it is
    # This is needed to ensure that all data hit the device before
    # it gets unmapped remotely from the host for some backends
    # Reference Bug: #1363016

    # NOTE(jdg): In the case of file devices qemu does the
    # flush properly and more efficiently than would be done
    # setting O_DIRECT, so check for that and skip the
    # setting for non BLK devs
    cache_mode: Optional[str]
    if (utils.is_blk_device(dest) and
            volume_utils.check_for_odirect_support(source,
                                                   dest,
                                                   'oflag=direct')):
        cache_mode = 'none'
    else:
        # use default
        cache_mode = None

    cmd = _get_qemu_convert_cmd(source, dest,
                                out_format=out_format,
                                src_format=src_format,
                                out_subformat=out_subformat,
                                cache_mode=cache_mode,
                                prefix=prefix,
                                cipher_spec=cipher_spec,
                                passphrase_file=passphrase_file,
                                compress=compress,
                                src_passphrase_file=src_passphrase_file,
                                disable_sparse=disable_sparse)

    start_time = timeutils.utcnow()

    # If there is not enough space on the conversion partition, include
    # the partitions's name in the error message.
    try:
        utils.execute(*cmd, run_as_root=run_as_root)
    except processutils.ProcessExecutionError as ex:
        if "No space left" in ex.stderr and CONF.image_conversion_dir in dest:
            conversion_dir = CONF.image_conversion_dir
            while not os.path.ismount(conversion_dir):
                conversion_dir = os.path.dirname(conversion_dir)

            message = _("Insufficient free space on %(location)s for image "
                        "conversion.") % {'location': conversion_dir}
            LOG.error(message)

        raise
    duration = timeutils.delta_seconds(start_time, timeutils.utcnow())

    # NOTE(jdg): use a default of 1, mostly for unit test, but in
    # some incredible event this is 0 (cirros image?) don't barf
    if duration < 1:
        duration = 1

    image_info = src_img_info
    if not image_info:
        try:
            image_info = qemu_img_info(source, run_as_root=run_as_root)
        except Exception:
            # NOTE: at this point, the image conversion has already
            # happened, and all that's left is some performance logging.
            # So ignoring an exception from qemu_img_info here is not a
            # security risk.  I'm afraid that if we are too strict here
            # we will cause a regression, given that the converted image
            # source could be cinder glance_store, Glance, or one of
            # cinder's own backend drivers.  The nfs driver knows
            # to pass in a src_img_info object, but others may not.
            #
            # We are catching the most general Exception here for a
            # similar reason: the image conversion has already happened.
            # If the conversion raised a ProcessExecutionError, we would
            # never have reached this point.  But a PEE now is meaningless,
            # so we ignore it.
            pass
    if not image_info or image_info.virtual_size is None:
        msg = ("The image was successfully converted, but image size "
               "is unavailable. src %(src)s, dest %(dest)s")
        LOG.info(msg, {"src": source, "dest": dest})
        return

    image_size = image_info.virtual_size
    fsz_mb = image_size / units.Mi
    mbps = (fsz_mb / duration)
    msg = ("Image conversion details: src %(src)s, size %(sz).2f MB, "
           "duration %(duration).2f sec, destination %(dest)s")
    LOG.debug(msg, {"src": source,
                    "sz": fsz_mb,
                    "duration": duration,
                    "dest": dest})

    msg = "Converted %(sz).2f MB image at %(mbps).2f MB/s"
    LOG.info(msg, {"sz": fsz_mb, "mbps": mbps})


def convert_image(source: str,
                  dest: str,
                  out_format: str,
                  out_subformat: Optional[str] = None,
                  src_format: Optional[str] = None,
                  run_as_root: bool = True,
                  throttle=None,
                  cipher_spec: Optional[dict] = None,
                  passphrase_file: Optional[str] = None,
                  compress: bool = False,
                  src_passphrase_file: Optional[str] = None,
                  image_id: Optional[str] = None,
                  data: Optional[imageutils.QemuImgInfo] = None,
                  disable_sparse: bool = False) -> None:
    """Convert image to other format.

    NOTE: If the qemu-img convert command fails and this function raises an
    exception, a non-empty dest file may be left in the filesystem.
    It is the responsibility of the caller to decide what to do with this file.

    :param source: source filename
    :param dest: destination filename
    :param out_format: output image format of qemu-img
    :param out_subformat: output image subformat
    :param src_format: source image format (use image_utils.fixup_disk_format()
           to translate from a Glance format to one recognizable by qemu_img)
    :param run_as_root: run qemu-img as root
    :param throttle: a cinder.throttling.Throttle object, or None
    :param cipher_spec: encryption details
    :param passphrase_file: filename containing luks passphrase
    :param compress: compress w/ qemu-img when possible (best effort)
    :param src_passphrase_file: filename containing source volume's
                                luks passphrase
    :param image_id: the image ID if this is a Glance image, or None
    :param data: a imageutils.QemuImgInfo object from this image, or None
    :raises ImageUnacceptable: when the image fails some format checks
    :raises ProcessExecutionError: when something goes wrong during conversion
    """
    check_image_format(source, src_format, image_id, data, run_as_root)

    if not throttle:
        throttle = throttling.Throttle.get_default()
    with throttle.subcommand(source, dest) as throttle_cmd:
        _convert_image(tuple(throttle_cmd['prefix']),
                       source, dest,
                       out_format,
                       out_subformat=out_subformat,
                       src_format=src_format,
                       run_as_root=run_as_root,
                       cipher_spec=cipher_spec,
                       passphrase_file=passphrase_file,
                       compress=compress,
                       src_passphrase_file=src_passphrase_file,
                       disable_sparse=disable_sparse,
                       src_img_info=data)


def resize_image(source: str,
                 size: int,
                 run_as_root: bool = False,
                 file_format: Optional[str] = None) -> None:
    """Changes the virtual size of the image."""
    cmd: tuple[str, ...]
    if file_format:
        cmd = ('qemu-img', 'resize', '-f', file_format, source, '%sG' % size)
    else:
        cmd = ('qemu-img', 'resize', source, '%sG' % size)
    utils.execute(*cmd, run_as_root=run_as_root)


def _verify_image(img_file: io.RawIOBase, verifier) -> None:
    # This methods must be called from a native thread, as the file I/O may
    # not yield to other greenthread in some cases, and since the update and
    # verify operations are CPU bound there would not be any yielding either,
    # which could lead to thread starvation.
    while True:
        chunk = img_file.read(1024)
        if not chunk:
            break
        verifier.update(chunk)
    verifier.verify()


def verify_glance_image_signature(context: context.RequestContext,
                                  image_service: glance.GlanceImageService,
                                  image_id: str,
                                  path: str) -> bool:
    verifier = None
    image_meta = image_service.show(context, image_id)
    image_properties = image_meta.get('properties', {})
    img_signature = image_properties.get('img_signature')
    img_sig_hash_method = image_properties.get('img_signature_hash_method')
    img_sig_cert_uuid = image_properties.get('img_signature_certificate_uuid')
    img_sig_key_type = image_properties.get('img_signature_key_type')
    if all(m is None for m in [img_signature,
                               img_sig_cert_uuid,
                               img_sig_hash_method,
                               img_sig_key_type]):
        # NOTE(tommylikehu): We won't verify the image signature
        # if none of the signature metadata presents.
        return False
    if any(m is None for m in [img_signature,
                               img_sig_cert_uuid,
                               img_sig_hash_method,
                               img_sig_key_type]):
        LOG.error('Image signature metadata for image %s is '
                  'incomplete.', image_id)
        raise exception.InvalidSignatureImage(image_id=image_id)

    try:
        verifier = signature_utils.get_verifier(
            context=context,
            img_signature_certificate_uuid=img_sig_cert_uuid,
            img_signature_hash_method=img_sig_hash_method,
            img_signature=img_signature,
            img_signature_key_type=img_sig_key_type,
        )
    except cursive_exception.SignatureVerificationError:
        message = _('Failed to get verifier for image: %s') % image_id
        LOG.error(message)
        raise exception.ImageSignatureVerificationException(
            reason=message)
    if verifier:
        with fileutils.remove_path_on_error(path):
            with open(path, "rb") as tem_file:
                try:
                    tpool.execute(_verify_image, tem_file, verifier)
                    LOG.info('Image signature verification succeeded '
                             'for image: %s', image_id)
                    return True
                except cryptography.exceptions.InvalidSignature:
                    message = _('Image signature verification '
                                'failed for image: %s') % image_id
                    LOG.error(message)
                    raise exception.ImageSignatureVerificationException(
                        reason=message)
                except Exception as ex:
                    message = _('Failed to verify signature for '
                                'image: %(image)s due to '
                                'error: %(error)s ') % {'image': image_id,
                                                        'error': ex}
                    LOG.error(message)
                    raise exception.ImageSignatureVerificationException(
                        reason=message)
    return False


def fetch(context: context.RequestContext,
          image_service: glance.GlanceImageService,
          image_id: str,
          path: str,
          _user_id,
          _project_id) -> None:
    # TODO(vish): Improve context handling and add owner and auth data
    #             when it is added to glance.  Right now there is no
    #             auth checking in glance, so we assume that access was
    #             checked before we got here.
    start_time = timeutils.utcnow()
    with fileutils.remove_path_on_error(path):
        with open(path, "wb") as image_file:
            try:
                image_service.download(context, image_id,
                                       tpool.Proxy(image_file))
            except IOError as e:
                if e.errno == errno.ENOSPC:
                    params = {'path': os.path.dirname(path),
                              'image': image_id}
                    reason = _("No space left in image_conversion_dir "
                               "path (%(path)s) while fetching "
                               "image %(image)s.") % params
                    LOG.exception(reason)
                    raise exception.ImageTooBig(image_id=image_id,
                                                reason=reason)

                reason = ("IOError: %(errno)s %(strerror)s" %
                          {'errno': e.errno, 'strerror': e.strerror})
                LOG.error(reason)
                raise exception.ImageDownloadFailed(image_href=image_id,
                                                    reason=reason)

    duration = timeutils.delta_seconds(start_time, timeutils.utcnow())

    # NOTE(jdg): use a default of 1, mostly for unit test, but in
    # some incredible event this is 0 (cirros image?) don't barf
    if duration < 1:
        duration = 1
    fsz_mb = os.stat(image_file.name).st_size / units.Mi
    mbps = (fsz_mb / duration)
    msg = ("Image fetch details: dest %(dest)s, size %(sz).2f MB, "
           "duration %(duration).2f sec")
    LOG.debug(msg, {"dest": image_file.name,
                    "sz": fsz_mb,
                    "duration": duration})
    msg = "Image download %(sz).2f MB at %(mbps).2f MB/s"
    LOG.info(msg, {"sz": fsz_mb, "mbps": mbps})


def get_qemu_data(image_id: str,
                  has_meta: bool,
                  disk_format_raw: bool,
                  dest: str,
                  run_as_root: bool,
                  force_share: bool = False) -> imageutils.QemuImgInfo:
    # We may be on a system that doesn't have qemu-img installed.  That
    # is ok if we are working with a RAW image.  This logic checks to see
    # if qemu-img is installed.  If not we make sure the image is RAW and
    # throw an exception if not.  Otherwise we stop before needing
    # qemu-img.  Systems with qemu-img will always progress through the
    # whole function.
    try:
        # Use the empty tmp file to make sure qemu_img_info works.
        data = qemu_img_info(dest,
                             run_as_root=run_as_root,
                             force_share=force_share)
    # There are a lot of cases that can cause a process execution
    # error, but until we do more work to separate out the various
    # cases we'll keep the general catch here
    except processutils.ProcessExecutionError:
        data = None
        if has_meta:
            if not disk_format_raw:
                raise exception.ImageUnacceptable(
                    reason=_("qemu-img is not installed and image is not of "
                             "type RAW.  Only RAW images can be used if "
                             "qemu-img is not installed."),
                    image_id=image_id)
        else:
            raise exception.ImageUnacceptable(
                reason=_("qemu-img is not installed and the disk "
                         "format is not specified.  Only RAW images "
                         "can be used if qemu-img is not installed."),
                image_id=image_id)
    return data


def check_qcow2_image(image_id: str, data: imageutils.QemuImgInfo) -> None:
    """Check some rules about qcow2 images.

    Does not check for a backing_file, because cinder has some legitimate
    use cases for qcow2 backing files.

    Makes sure the image:

    - does not have a data_file

    :param image_id: the image id
    :param data: an imageutils.QemuImgInfo object
    :raises ImageUnacceptable: when the image fails the check
    """
    try:
        data_file = data.format_specific['data'].get('data-file')
    except (KeyError, TypeError):
        LOG.debug('Unexpected response from qemu-img info when processing '
                  'image %s: missing format-specific info for a qcow2 image',
                  image_id)
        msg = _('Cannot determine format-specific information')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)
    if data_file:
        LOG.warning("Refusing to process qcow2 file with data-file '%s'",
                    data_file)
        msg = _('A qcow2 format image is not allowed to have a data file')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)


def check_vmdk_image(image_id: str, data: imageutils.QemuImgInfo) -> None:
    """Check some rules about VMDK images.

    Make sure the VMDK subformat (the "createType" in vmware docs)
    is one that we allow as determined by the 'vmdk_allowed_types'
    configuration option.  The default set includes only types that
    do not reference files outside the VMDK file, which can otherwise
    be used in exploits to expose host information.

    :param image_id: the image id
    :param data: an imageutils.QemuImgInfo object
    :raises ImageUnacceptable: when the VMDK createType is not in the
                               allowed list
    """
    allowed_types = CONF.vmdk_allowed_types

    if not len(allowed_types):
        msg = _('Image is a VMDK, but no VMDK createType is allowed')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)

    try:
        create_type = data.format_specific['data']['create-type']
    except KeyError:
        msg = _('Unable to determine VMDK createType')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)
    except TypeError:
        msg = _('Unable to determine VMDK createType as no format-specific '
                'information is available')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)

    if create_type not in allowed_types:
        LOG.warning('Refusing to process VMDK file with createType of %r '
                    'which is not in allowed set of: %s', create_type,
                    ','.join(allowed_types))
        msg = _('Invalid VMDK create-type specified')
        raise exception.ImageUnacceptable(image_id=image_id, reason=msg)


def check_image_format(source: str,
                       src_format: Optional[str] = None,
                       image_id: Optional[str] = None,
                       data: Optional[imageutils.QemuImgInfo] = None,
                       run_as_root: bool = True) -> None:
    """Do some image format checks.

    Verifies that the src_format matches what qemu-img thinks the image
    format is, and does some vmdk subformat checks.  See Bug #1996188.

    - Does not check for a qcow2 backing file.
    - Will make a call out to qemu_img if data is None.

    :param source: filename of the image to check
    :param src_format: source image format recognized by qemu_img, or None
    :param image_id: the image ID if this is a Glance image, or None
    :param data: a imageutils.QemuImgInfo object from this image, or None
    :param run_as_root: when 'data' is None, call 'qemu-img info' as root
    :raises ImageUnacceptable: when the image fails some format checks
    :raises ProcessExecutionError: if 'qemu-img info' fails
    """
    if image_id is None:
        image_id = 'internal image'
    if data is None:
        data = qemu_img_info(source, run_as_root=run_as_root)

    if data.file_format is None:
        raise exception.ImageUnacceptable(
            reason=_("'qemu-img info' parsing failed."),
            image_id=image_id)

    if src_format is not None:
        if src_format.lower() == 'ami':
            # qemu-img doesn't recognize AMI format; see change Icde4c0f936ce.
            # We also use lower() here (though nowhere else) to be consistent
            # with that change.
            pass
        elif data.file_format != src_format:
            LOG.debug("Rejecting image %(image_id)s due to format mismatch. "
                      "src_format: '%(src)s', but qemu-img info reports: "
                      "'%(qemu)s'",
                      {'image_id': image_id,
                       'src': src_format,
                       'qemu': data.file_format})
            msg = _("The image format was claimed to be '%(src)s' but the "
                    "image data appears to be in a different format.")
            raise exception.ImageUnacceptable(
                image_id=image_id,
                reason=(msg % {'src': src_format}))

    if data.file_format == 'vmdk':
        check_vmdk_image(image_id, data)
    if data.file_format == 'qcow2':
        check_qcow2_image(image_id, data)


def fetch_verify_image(context: context.RequestContext,
                       image_service: glance.GlanceImageService,
                       image_id: str,
                       dest: str) -> None:
    fetch(context, image_service, image_id, dest,
          None, None)
    image_meta = image_service.show(context, image_id)

    with fileutils.remove_path_on_error(dest):
        has_meta = False if not image_meta else True
        try:
            format_raw = True if image_meta['disk_format'] == 'raw' else False
        except TypeError:
            format_raw = False
        data = get_qemu_data(image_id, has_meta, format_raw,
                             dest, True)
        # We can only really do verification of the image if we have
        # qemu data to use.
        # NOTE: We won't have data if qemu_img is not installed *and* the
        # disk_format recorded in Glance is raw (otherwise an ImageUnacceptable
        # would have been raised already).  So this isn't as bad as it looks.
        if data is not None:
            fmt = data.file_format
            if fmt is None:
                raise exception.ImageUnacceptable(
                    reason=_("'qemu-img info' parsing failed."),
                    image_id=image_id)

            backing_file = data.backing_file
            if backing_file is not None:
                raise exception.ImageUnacceptable(
                    image_id=image_id,
                    reason=(_("fmt=%(fmt)s backed by: %(backing_file)s") %
                            {'fmt': fmt, 'backing_file': backing_file}))

            # a VMDK can have a backing file, but we have to check for
            # it differently
            if fmt == 'vmdk':
                check_vmdk_image(image_id, data)

            # Bug #2059809: a qcow2 can have a data file that's similar
            # to a backing file and is also unacceptable
            if fmt == 'qcow2':
                check_qcow2_image(image_id, data)


def fetch_to_vhd(context: context.RequestContext,
                 image_service: glance.GlanceImageService,
                 image_id: str,
                 dest: str,
                 blocksize: int,
                 volume_subformat: Optional[str] = None,
                 user_id: Optional[str] = None,
                 project_id: Optional[str] = None,
                 run_as_root: bool = True,
                 disable_sparse: bool = False) -> None:
    fetch_to_volume_format(context, image_service, image_id, dest, 'vpc',
                           blocksize, volume_subformat=volume_subformat,
                           user_id=user_id, project_id=project_id,
                           run_as_root=run_as_root,
                           disable_sparse=disable_sparse)


def fetch_to_raw(context: context.RequestContext,
                 image_service: glance.GlanceImageService,
                 image_id: str,
                 dest: str,
                 blocksize: int,
                 user_id: Optional[str] = None,
                 project_id: Optional[str] = None,
                 size: Optional[int] = None,
                 run_as_root: bool = True,
                 disable_sparse: bool = False) -> None:
    fetch_to_volume_format(context, image_service, image_id, dest, 'raw',
                           blocksize, user_id=user_id, project_id=project_id,
                           size=size, run_as_root=run_as_root,
                           disable_sparse=disable_sparse)


def check_image_conversion_disable(disk_format, volume_format, image_id,
                                   upload=False):
    if CONF.image_conversion_disable and disk_format != volume_format:
        if upload:
            msg = _("Image conversion is disabled. The image disk_format "
                    "you have requested is '%(disk_format)s', but your "
                    "volume can only be uploaded in the format "
                    "'%(volume_format)s'.")
        else:
            msg = _("Image conversion is disabled. The volume type you have "
                    "requested requires that the image it is being created "
                    "from be in '%(volume_format)s' format, but the image "
                    "you are using has the disk_format property "
                    "'%(disk_format)s'. You must use an image with the "
                    "disk_format property '%(volume_format)s' to create a "
                    "volume of this type.")
        raise exception.ImageConversionNotAllowed(
            reason=msg % {'disk_format': disk_format,
                          'volume_format': volume_format},
            image_id=image_id)


def fetch_to_volume_format(context: context.RequestContext,
                           image_service: glance.GlanceImageService,
                           image_id: str,
                           dest: str,
                           volume_format: str,
                           blocksize: int,
                           volume_subformat: Optional[str] = None,
                           user_id: Optional[str] = None,
                           project_id: Optional[str] = None,
                           size: Optional[int] = None,
                           run_as_root: bool = True,
                           disable_sparse: bool = False) -> None:
    qemu_img = True
    image_meta = image_service.show(context, image_id)

    check_image_conversion_disable(
        image_meta['disk_format'], volume_format, image_id, upload=False)

    allow_image_compression = CONF.allow_compression_on_image_upload
    if image_meta and (image_meta.get('container_format') == 'compressed'):
        if allow_image_compression is False:
            compression_param = {'container_format':
                                 image_meta.get('container_format')}
            raise exception.ImageUnacceptable(
                image_id=image_id,
                reason=_("Image compression disallowed, "
                         "but container_format is "
                         "%(container_format)s.") % compression_param)

    # NOTE(avishay): I'm not crazy about creating temp files which may be
    # large and cause disk full errors which would confuse users.
    # Unfortunately it seems that you can't pipe to 'qemu-img convert' because
    # it seeks. Maybe we can think of something for a future version.
    with temporary_file(prefix='image_download_%s_' % image_id) as tmp:
        has_meta = False if not image_meta else True
        try:
            format_raw = True if image_meta['disk_format'] == 'raw' else False
        except TypeError:
            format_raw = False

        # Probe using the empty tmp file to see if qemu-img is available.
        # If it's not, and the disk_format recorded in Glance is not 'raw',
        # this will raise ImageUnacceptable
        data = get_qemu_data(image_id, has_meta, format_raw,
                             tmp, run_as_root)
        if data is None:
            qemu_img = False

        tmp_images = TemporaryImages.for_image_service(image_service)
        tmp_image = tmp_images.get(context, image_id)
        if tmp_image:
            tmp = tmp_image
        else:
            fetch(context, image_service, image_id, tmp, user_id, project_id)

        # NOTE(ZhengMa): This is used to do image decompression on image
        # downloading with 'compressed' container_format. It is a
        # transparent level between original image downloaded from
        # Glance and Cinder image service. So the source file path is
        # the same with destination file path.
        if image_meta.get('container_format') == 'compressed':
            LOG.debug("Found image with compressed container format")
            if not accelerator.is_gzip_compressed(tmp):
                raise exception.ImageUnacceptable(
                    image_id=image_id,
                    reason=_("Unsupported compressed image format found. "
                             "Only gzip is supported currently"))
            accel = accelerator.ImageAccel(tmp, tmp)
            accel.decompress_img(run_as_root=run_as_root)

        if is_xenserver_format(image_meta):
            replace_xenserver_image_with_coalesced_vhd(tmp)

        if not qemu_img:
            # qemu-img is not installed but we do have a RAW image.  As a
            # result we only need to copy the image to the destination and then
            # return.
            LOG.debug('Copying image from %(tmp)s to volume %(dest)s - '
                      'size: %(size)s', {'tmp': tmp, 'dest': dest,
                                         'size': image_meta['size']})
            image_size_m = math.ceil(float(image_meta['size']) / units.Mi)
            volume_utils.copy_volume(tmp, dest, image_size_m, blocksize)
            return

        data = qemu_img_info(tmp, run_as_root=run_as_root)

        # NOTE(xqueralt): If the image virtual size doesn't fit in the
        # requested volume there is no point on resizing it because it will
        # generate an unusable image.
        if size is not None:
            check_virtual_size(data.virtual_size, size, image_id)

        fmt = data.file_format
        if fmt is None:
            raise exception.ImageUnacceptable(
                reason=_("'qemu-img info' parsing failed."),
                image_id=image_id)

        backing_file = data.backing_file
        if backing_file is not None:
            raise exception.ImageUnacceptable(
                image_id=image_id,
                reason=_("fmt=%(fmt)s backed by:%(backing_file)s")
                % {'fmt': fmt, 'backing_file': backing_file, })

        # NOTE(jdg): I'm using qemu-img convert to write
        # to the volume regardless if it *needs* conversion or not
        # TODO(avishay): We can speed this up by checking if the image is raw
        # and if so, writing directly to the device. However, we need to keep
        # check via 'qemu-img info' that what we copied was in fact a raw
        # image and not a different format with a backing file, which may be
        # malicious.
        # FIXME: revisit the above 2 comments.  We already have an exception
        # above for RAW format images when qemu-img is not available, and I'm
        # pretty sure that the backing file exploit only happens when
        # converting from some format that supports a backing file TO raw ...
        # a bit-for-bit copy of a qcow2 with backing file will copy the backing
        # file *reference* but not its *content*.
        disk_format = fixup_disk_format(image_meta['disk_format'])
        LOG.debug("%s was %s, converting to %s", image_id, fmt, volume_format)

        convert_image(tmp, dest, volume_format,
                      out_subformat=volume_subformat,
                      src_format=disk_format,
                      run_as_root=run_as_root,
                      image_id=image_id,
                      data=data,
                      disable_sparse=disable_sparse)


@contextlib.contextmanager
def chown_if_needed(volume_path: str) -> Generator[None, None, None]:
    if os.name == 'nt' or os.access(volume_path, os.R_OK):
        yield
    else:
        with utils.temporary_chown(volume_path):
            yield


def upload_volume(context: context.RequestContext,
                  image_service: glance.GlanceImageService,
                  image_meta: dict,
                  volume_path: str,
                  volume_fd = None,
                  volume_format: str = 'raw',
                  run_as_root: bool = True,
                  compress: bool = True,
                  store_id: Optional[str] = None,
                  base_image_ref: Optional[str] = None) -> None:
    # NOTE: You probably want to use volume_utils.upload_volume(),
    # not this function.
    image_id = image_meta['id']

    check_image_conversion_disable(
        image_meta['disk_format'], volume_format, image_id, upload=True)

    if image_meta.get('container_format') != 'compressed':
        if (image_meta['disk_format'] == volume_format):
            LOG.debug("%s was %s, no need to convert to %s",
                      image_id, volume_format, image_meta['disk_format'])
            if volume_fd is not None:
                image_service.update(context, image_id, {},
                                     tpool.Proxy(volume_fd),
                                     store_id=store_id,
                                     base_image_ref=base_image_ref)
            else:
                with chown_if_needed(volume_path):
                    with open(volume_path, 'rb') as image_file:
                        image_service.update(context, image_id, {},
                                             tpool.Proxy(image_file),
                                             store_id=store_id,
                                             base_image_ref=base_image_ref)
            return

    with temporary_file(prefix='vol_upload_') as tmp:
        LOG.debug("%s was %s, converting to %s",
                  image_id, volume_format, image_meta['disk_format'])

        data = qemu_img_info(volume_path, run_as_root=run_as_root)
        backing_file = data.backing_file
        fmt = data.file_format
        if backing_file is not None:
            # Disallow backing files as a security measure.
            # This prevents a user from writing an image header into a raw
            # volume with a backing file pointing to data they wish to
            # access.
            raise exception.ImageUnacceptable(
                image_id=image_id,
                reason=_("fmt=%(fmt)s backed by:%(backing_file)s")
                % {'fmt': fmt, 'backing_file': backing_file})

        out_format = fixup_disk_format(image_meta['disk_format'])
        convert_image(volume_path, tmp, out_format,
                      run_as_root=run_as_root,
                      compress=compress,
                      image_id=image_id,
                      data=data)

        data = qemu_img_info(tmp, run_as_root=run_as_root)
        if data.file_format != out_format:
            raise exception.ImageUnacceptable(
                image_id=image_id,
                reason=_("Converted to %(f1)s, but format is now %(f2)s") %
                {'f1': out_format, 'f2': data.file_format})

        # NOTE(ZhengMa): This is used to do image compression on image
        # uploading with 'compressed' container_format.
        # Compress file 'tmp' in-place
        if image_meta.get('container_format') == 'compressed':
            LOG.debug("Container_format set to 'compressed', compressing "
                      "image before uploading.")
            accel = accelerator.ImageAccel(tmp, tmp)
            accel.compress_img(run_as_root=run_as_root)
        with open(tmp, 'rb') as image_file:
            image_service.update(context, image_id, {},
                                 tpool.Proxy(image_file),
                                 store_id=store_id,
                                 base_image_ref=base_image_ref)


def check_virtual_size(virtual_size: float,
                       volume_size: int,
                       image_id: str) -> int:
    virtual_size = int(math.ceil(float(virtual_size) / units.Gi))

    if virtual_size > volume_size:
        params = {'image_size': virtual_size,
                  'volume_size': volume_size}
        reason = _("Image virtual size is %(image_size)dGB"
                   " and doesn't fit in a volume of size"
                   " %(volume_size)dGB.") % params
        raise exception.ImageUnacceptable(image_id=image_id,
                                          reason=reason)
    return virtual_size


def check_available_space(dest: str, image_size: int, image_id: str) -> None:
    # TODO(e0ne): replace psutil with shutil.disk_usage when we drop
    # Python 2.7 support.
    if not os.path.isdir(dest):
        dest = os.path.dirname(dest)

    free_space = psutil.disk_usage(dest).free
    if free_space <= image_size:
        msg = ('There is no space on %(dest_dir)s to convert image. '
               'Requested: %(image_size)s, available: %(free_space)s.'
               ) % {'dest_dir': dest,
                    'image_size': image_size,
                    'free_space': free_space}
        raise exception.ImageTooBig(image_id=image_id, reason=msg)


def is_xenserver_format(image_meta: dict) -> bool:
    return (
        image_meta['disk_format'] == 'vhd'
        and image_meta['container_format'] == 'ovf'
    )


def set_vhd_parent(vhd_path: str, parentpath: str) -> None:
    utils.execute('vhd-util', 'modify', '-n', vhd_path, '-p', parentpath)


def extract_targz(archive_name: str, target: str) -> None:
    utils.execute('tar', '-xzf', archive_name, '-C', target)


def fix_vhd_chain(vhd_chain: list[str]) -> None:
    for child, parent in zip(vhd_chain[:-1], vhd_chain[1:]):
        set_vhd_parent(child, parent)


def get_vhd_size(vhd_path: str) -> int:
    out, _err = utils.execute('vhd-util', 'query', '-n', vhd_path, '-v')
    return int(out)


def resize_vhd(vhd_path: str, size: int, journal: str) -> None:
    utils.execute(
        'vhd-util', 'resize', '-n', vhd_path, '-s', '%d' % size, '-j', journal)


def coalesce_vhd(vhd_path: str) -> None:
    utils.execute(
        'vhd-util', 'coalesce', '-n', vhd_path)


def create_temporary_file(*args: str, **kwargs: str) -> str:
    fileutils.ensure_tree(CONF.image_conversion_dir)

    fd, tmp = tempfile.mkstemp(dir=CONF.image_conversion_dir,
                               *args, **kwargs)  # type: ignore
    os.close(fd)
    return tmp


def cleanup_temporary_file(backend_name: str) -> None:
    temp_dir = CONF.image_conversion_dir
    if (not temp_dir or not os.path.exists(temp_dir)):
        LOG.debug("Configuration image_conversion_dir is None or the path "
                  "doesn't exist.")
        return
    try:
        # TODO(wanghao): Consider using os.scandir for better performance in
        # future when cinder only supports Python version 3.5+.
        files = os.listdir(CONF.image_conversion_dir)
        # NOTE(wanghao): For multi-backend case, if one backend was slow
        # starting but another backend is up and doing an image conversion,
        # init_host should only clean the tmp files which belongs to its
        # backend.
        for tmp_file in files:
            if tmp_file.endswith(backend_name):
                path = os.path.join(temp_dir, tmp_file)
                os.remove(path)
    except OSError as e:
        LOG.warning("Exception caught while clearing temporary image "
                    "files: %s", e)


@contextlib.contextmanager
def temporary_file(*args: str, **kwargs) -> Generator[str, None, None]:
    tmp = None
    try:
        tmp = create_temporary_file(*args, **kwargs)
        yield tmp
    finally:
        if tmp:
            fileutils.delete_if_exists(tmp)


def temporary_dir() -> ContextManager[str]:
    fileutils.ensure_tree(CONF.image_conversion_dir)

    return utils.tempdir(dir=CONF.image_conversion_dir)


def coalesce_chain(vhd_chain: list[str]) -> str:
    for child, parent in zip(vhd_chain[:-1], vhd_chain[1:]):
        with temporary_dir() as directory_for_journal:
            size = get_vhd_size(child)
            journal_file = os.path.join(
                directory_for_journal, 'vhd-util-resize-journal')
            resize_vhd(parent, size, journal_file)
            coalesce_vhd(child)

    return vhd_chain[-1]


def discover_vhd_chain(directory: str) -> list[str]:
    counter = 0
    chain = []

    while True:
        fpath = os.path.join(directory, '%d.vhd' % counter)
        if os.path.exists(fpath):
            chain.append(fpath)
        else:
            break
        counter += 1

    return chain


def replace_xenserver_image_with_coalesced_vhd(image_file: str) -> None:
    with temporary_dir() as tempdir:
        extract_targz(image_file, tempdir)
        chain = discover_vhd_chain(tempdir)
        fix_vhd_chain(chain)
        coalesced = coalesce_chain(chain)
        fileutils.delete_if_exists(image_file)
        os.rename(coalesced, image_file)


def decode_cipher(cipher_spec: str, key_size: int) -> dict[str, str]:
    """Decode a dm-crypt style cipher specification string

       The assumed format being cipher-chainmode-ivmode, similar to that
       documented under
       linux/Documentation/admin-guide/device-mapper/dm-crypt.txt in the
       kernel source tree.  Cinder does not support the [:keycount] or
       [:ivopts] options.
    """
    try:
        cipher_alg, cipher_mode, ivgen_alg = cipher_spec.split('-')
    except ValueError:
        raise exception.InvalidVolumeType(
            reason="Invalid cipher field in encryption type")

    cipher_alg = cipher_alg + '-' + str(key_size)

    return {'cipher_alg': cipher_alg,
            'cipher_mode': cipher_mode,
            'ivgen_alg': ivgen_alg}


class TemporaryImages(object):
    """Manage temporarily downloaded images to avoid downloading it twice.

    In the 'with TemporaryImages.fetch(image_service, ctx, image_id) as tmp'
    clause, 'tmp' can be used as the downloaded image path. In addition,
    image_utils.fetch() will use the pre-fetched image by the TemporaryImages.
    This is useful to inspect image contents before conversion.
    """

    def __init__(self, image_service: glance.GlanceImageService):
        self.temporary_images: dict[str, dict] = {}
        self.image_service = image_service
        image_service.temp_images = self

    @staticmethod
    def for_image_service(
            image_service: glance.GlanceImageService) -> 'TemporaryImages':
        instance = image_service.temp_images
        if instance:
            return instance
        return TemporaryImages(image_service)

    @classmethod
    @contextlib.contextmanager
    def fetch(cls,
              image_service: glance.GlanceImageService,
              context: context.RequestContext,
              image_id: str,
              suffix: Optional[str] = '') -> Generator[str, None, None]:
        tmp_images = cls.for_image_service(image_service).temporary_images
        with temporary_file(prefix='image_fetch_%s_' % image_id,
                            suffix=suffix) as tmp:
            fetch_verify_image(context, image_service, image_id, tmp)
            user = context.user_id
            if not tmp_images.get(user):
                tmp_images[user] = {}
            tmp_images[user][image_id] = tmp
            LOG.debug("Temporary image %(id)s is fetched for user %(user)s.",
                      {'id': image_id, 'user': user})
            yield tmp
            del tmp_images[user][image_id]
        LOG.debug("Temporary image %(id)s for user %(user)s is deleted.",
                  {'id': image_id, 'user': user})

    def get(self, context: context.RequestContext, image_id: str):
        user = context.user_id
        if not self.temporary_images.get(user):
            return None
        return self.temporary_images[user].get(image_id)


def _filter_out_metadata(metadata, filter_keys):
    new_metadata = {}
    for k, v in metadata.items():
        if any(k.startswith(filter_key)
               for filter_key in filter_keys):
            continue
        new_metadata[k] = v
    return new_metadata


def filter_out_reserved_namespaces_metadata(
        metadata: Optional[dict[str, str]]) -> dict[str, str]:

    reserved_name_spaces = GLANCE_RESERVED_NAMESPACES.copy()
    if CONF.reserved_image_namespaces:
        for image_namespace in CONF.reserved_image_namespaces:
            if image_namespace not in reserved_name_spaces:
                reserved_name_spaces.append(image_namespace)

    if not metadata:
        LOG.debug("No metadata to be filtered.")
        return {}

    new_metadata = _filter_out_metadata(metadata, reserved_name_spaces)
    # NOTE(ganso): handle adjustment of metadata structure performed by
    # the cinder.volume.api.API._merge_volume_image_meta() method
    if 'properties' in new_metadata:
        new_metadata['properties'] = _filter_out_metadata(
            metadata['properties'], reserved_name_spaces)

    LOG.debug("The metadata set [%s] was filtered using the reserved name "
              "spaces [%s], and the result is [%s].", metadata,
              reserved_name_spaces, new_metadata)
    return new_metadata
