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# Source code for asdf._asdf

    import copy
    import datetime
    import io
    import os
    import time
    import warnings
    import weakref

    from packaging.version import Version

    from . import _compression as mcompression
    from . import _display as display
    from . import _io, constants, generic_io, lazy_nodes, reference, schema, treeutil, util, versioning, yamlutil
    from . import _node_info as node_info
    from ._block.manager import Manager as BlockManager
    from ._helpers import validate_version
    from .config import config_context, get_config
    from .exceptions import (
        AsdfManifestURIMismatchWarning,
        AsdfPackageVersionWarning,
        AsdfWarning,
    )
    from .extension import Extension, ExtensionProxy, _serialization_context, get_cached_extension_manager
    from .search import AsdfSearchResult
    from .tags.core import AsdfObject, ExtensionMetadata, HistoryEntry, Software
    from .util import NotSet

    class AsdfFile:
        """
        The main class that represents an ASDF file object.
        """

        def __init__(
            self,
            tree=None,
            uri=None,
            extensions=None,
            version=None,
            ignore_unrecognized_tag=False,
            memmap=False,
            lazy_load=True,
            custom_schema=None,
        ):
            """
            Parameters
            ----------
            tree : dict or AsdfFile, optional
                The main tree data in the ASDF file.  Must conform to the
                ASDF schema.

            uri : str, optional
                The URI for this ASDF file.  Used to resolve relative
                references against.  If not provided, will be
                automatically determined from the associated file object,
                if possible and if created from `asdf.open`.

            extensions : object, optional
                Additional extensions to use when reading and writing the file.
                May be an `asdf.extension.Extension` or a `list` of extensions.

            version : str, optional
                The ASDF core schemas version.  If not provided, defaults to the
                configured default version.  See `asdf.config.AsdfConfig.default_version`.

            ignore_unrecognized_tag : bool, optional
                When `True`, do not raise warnings for unrecognized tags. Set to
                `False` by default.

            memmap : bool, optional
                When `True`, when reading files, attempt to memmap underlying data
                arrays when possible. Defaults to ``False``.

            lazy_load : bool, optional
                When `True` and the underlying file handle is seekable, data
                arrays will only be loaded lazily: i.e. when they are accessed
                for the first time. In this case the underlying file must stay
                open during the lifetime of the tree. Setting to False causes
                all data arrays to be loaded up front, which means that they
                can be accessed even after the underlying file is closed.

            custom_schema : str, optional
                Path to a custom schema file that will be used for a secondary
                validation pass. This can be used to ensure that particular ASDF
                files follow custom conventions beyond those enforced by the
                specification.
            """
            # make a new AsdfVersion instance here so files don't share the same instance
            self._file_format_version = versioning.AsdfVersion(versioning._FILE_FORMAT_VERSION)

            # Don't use the version setter here; it tries to access
            # the extensions, which haven't been assigned yet.
            if version is None:
                self._version = versioning.AsdfVersion(get_config().default_version)
            else:
                self._version = versioning.AsdfVersion(validate_version(version))

            self._user_extensions = self._process_user_extensions(extensions)
            self._plugin_extensions = self._process_plugin_extensions()
            self._extension_manager = None

            if custom_schema is not None:
                self._custom_schema = schema._load_schema_cached(custom_schema, True)
            else:
                self._custom_schema = None

            self._ignore_unrecognized_tag = ignore_unrecognized_tag

            # Context of a call to treeutil.walk_and_modify, needed in the AsdfFile
            # in case walk_and_modify is re-entered by extension code (via
            # custom_tree_to_tagged_tree or tagged_tree_to_custom_tree).
            self._tree_modification_context = treeutil._TreeModificationContext()

            # A cache of tagged objects and their converted custom objects used when
            # a file is read with "lazy_tree=True". Used by lazy_nodes.
            self._tagged_object_cache = lazy_nodes._TaggedObjectCache()

            self._fd = None
            self._closed = False
            self._external_asdf_by_uri = {}
            self._blocks = BlockManager(uri=uri, lazy_load=lazy_load, memmap=memmap)
            if tree is None:
                # Bypassing the tree property here, to avoid validating
                # an empty tree.
                self._tree = AsdfObject()
            elif isinstance(tree, AsdfFile):
                if self.extensions != tree.extensions:
                    # TODO(eslavich): Why not?  What if that's the goal
                    # of copying the file?
                    msg = "Can not copy AsdfFile and change active extensions"
                    raise ValueError(msg)
                self._blocks._uri = tree.uri
                # Set directly to self._tree (bypassing property), since
                # we can assume the other AsdfFile is already valid.
                # Call "walk_and_modify" here to use it's logic for
                # creating a "copy" of the other tree. This mimics what was previously
                # a call to find_references (which we longer do in AsdfFile.__init__)
                self._tree = treeutil.walk_and_modify(tree.tree, lambda o: o)
            else:
                self._tree = AsdfObject(tree)

            self._comments = []

        @property
        def version(self):
            """
            Get this AsdfFile's ASDF core schemas version.

            Returns
            -------
            asdf.versioning.AsdfVersion
            """
            return self._version

        @version.setter
        def version(self, value):
            """
            Set this AsdfFile's ASDF core schemas version.

            Parameters
            ----------
            value : str or asdf.versioning.AsdfVersion
            """
            self._version = versioning.AsdfVersion(validate_version(value))
            # The new version may not be compatible with the previous
            # set of extensions, so we need to check them again:
            self._user_extensions = self._process_user_extensions(self._user_extensions)
            self._plugin_extensions = self._process_plugin_extensions()
            self._extension_manager = None

        @property
        def version_string(self):
            """
            Get this AsdfFile's ASDF core schemas version as a string.

            Returns
            -------
            str
            """
            return str(self._version)

        @property
        def extensions(self):
            """
            Get the list of user extensions that are enabled for
            use with this AsdfFile.

            Returns
            -------
            list of asdf.extension.ExtensionProxy
            """
            return self._user_extensions

        @extensions.setter
        def extensions(self, value):
            """
            Set the list of user extensions that are enabled for
            use with this AsdfFile.

            Parameters
            ----------
            value : list of asdf.extension.Extension
            """
            self._user_extensions = self._process_user_extensions(value)
            self._extension_manager = None

        @property
        def extension_manager(self):
            """
            Get the ExtensionManager for this AsdfFile.

            Returns
            -------
            asdf.extension.ExtensionManager
            """
            if self._extension_manager is None:
                self._extension_manager = get_cached_extension_manager(self._user_extensions + self._plugin_extensions)
            return self._extension_manager

        def __enter__(self):
            return self

        def __exit__(self, type_, value, traceback):
            self.close()

        def _check_extensions(self, tree, strict=False):
            """
            Compare the user's installed extensions to metadata in the tree
            and warn when a) an extension is missing or b) an extension is
            present but the file was written with a later version of the
            extension's package.

            Parameters
            ----------
            tree : AsdfObject
                Fully converted tree of custom types.
            strict : bool, optional
                Set to `True` to convert warnings to exceptions.
            """
            if (
                "history" not in tree
                or not isinstance(tree["history"], (dict, lazy_nodes.AsdfDictNode))
                or "extensions" not in tree["history"]
            ):
                return

            for extension in tree["history"]["extensions"]:
                installed = None
                for ext in self._user_extensions + self._plugin_extensions:
                    if (extension.extension_uri is not None and extension.extension_uri == ext.extension_uri) or (
                        extension.extension_uri is None and extension.extension_class in ext.legacy_class_names
                    ):
                        installed = ext
                        break

                filename = f"'{self._fd._uri}'" if (self._fd is not None and self._fd._uri) else ""
                if extension.extension_uri is not None:
                    extension_description = f"URI '{extension.extension_uri}'"
                else:
                    extension_description = f"class '{extension.extension_class}'"
                if extension.software is not None:
                    extension_description += (
                        f" (from package {extension.software['name']}=={extension.software['version']})"
                    )

                if installed is None:
                    msg = (
                        f"File {filename}was created with extension "
                        f"{extension_description}, which is not currently installed"
                    )
                    if strict:
                        raise RuntimeError(msg)

                    warnings.warn(msg, AsdfPackageVersionWarning)

                elif extension.software:
                    # Local extensions may not have a real version.  If the package name changed,
                    # then the version sequence may have been reset.
                    if installed.package_version is None or installed.package_name != extension.software["name"]:
                        continue
                    # Compare version in file metadata with installed version
                    if Version(installed.package_version) < Version(extension.software["version"]):
                        msg = (
                            f"File {filename}was created with extension {extension_description}, "
                            f"but older package ({installed.package_name}=={installed.package_version}) is installed."
                        )
                        if strict:
                            raise RuntimeError(msg)

                        warnings.warn(msg, AsdfPackageVersionWarning)

                # check version of manifest providing package (if one was recorded)
                if "manifest_software" in extension:
                    package_name = extension["manifest_software"]["name"]
                    package_version = Version(extension["manifest_software"]["version"])
                    package_description = f"{package_name}=={package_version}"
                    installed_version = None
                    for mapping in get_config().resource_manager._resource_mappings:
                        if mapping.package_name == package_name:
                            installed_version = Version(mapping.package_version)
                            break
                    msg = None
                    if installed_version is None:
                        msg = (
                            f"File {filename}was created with package {package_description}, "
                            "which is currently not installed"
                        )
                    elif installed_version < package_version:
                        msg = (
                            f"File {filename}was created with package {package_description}, "
                            f"but older package({package_name}=={installed_version}) is installed."
                        )
                    if msg:
                        if strict:
                            raise RuntimeError(msg)
                        warnings.warn(msg, AsdfPackageVersionWarning)

        def _process_plugin_extensions(self):
            """
            Select installed extensions that are compatible with this
            file's ASDF core schemas version.

            Returns
            -------
            list of asdf.extension.ExtensionProxy
            """
            return [e for e in get_config().extensions if self.version_string in e.asdf_standard_requirement]

        def _process_user_extensions(self, extensions):
            """
            Validate a list of extensions requested by the user
            add missing extensions registered with the current `AsdfConfig`.

            Parameters
            ----------
            extensions : object
                May be an `asdf.extension.Extension` or a `list` of extensions.

            Returns
            -------
            list of asdf.extension.ExtensionProxy
            """
            if extensions is None:
                extensions = []
            elif isinstance(extensions, (Extension, ExtensionProxy)):
                extensions = [extensions]

            if not isinstance(extensions, list):
                msg = "The extensions parameter must be an extension or list of extensions"
                raise TypeError(msg)

            extensions = [ExtensionProxy.maybe_wrap(e) for e in extensions]

            result = []
            for extension in extensions:
                if self.version_string not in extension.asdf_standard_requirement:
                    warnings.warn(
                        f"Extension {extension} does not support ASDF Standard {self.version_string}.  "
                        "It has been disabled.",
                        AsdfWarning,
                    )
                else:
                    result.append(extension)

            return result

        def _update_extension_history(self, tree, serialization_context):
            """
            Update the extension metadata on this file's tree to reflect
            extensions used during serialization.

            Parameters
            ----------
            serialization_context : asdf.extension.SerializationContext
                The context that was used to serialize the tree.
            """
            if serialization_context.version < versioning.NEW_HISTORY_FORMAT_MIN_VERSION:
                return

            if "history" not in tree:
                tree["history"] = {"extensions": []}
            # Support clients who are still using the old history format
            elif isinstance(tree["history"], list):
                histlist = tree["history"]
                tree["history"] = {"entries": histlist, "extensions": []}
                warnings.warn(
                    "The ASDF history format has changed in order to "
                    "support metadata about extensions. History entries "
                    "should now be stored under tree['history']['entries'].",
                    AsdfWarning,
                )
            elif "extensions" not in tree["history"]:
                tree["history"]["extensions"] = []

            for extension in serialization_context._extensions_used:
                ext_name = extension.class_name
                ext_meta = ExtensionMetadata(extension_class=ext_name)
                if extension.package_name is not None:
                    ext_meta["software"] = Software(name=extension.package_name, version=extension.package_version)
                if extension.extension_uri is not None:
                    ext_meta["extension_uri"] = extension.extension_uri
                if extension.compressors:
                    ext_meta["supported_compression"] = [comp.label.decode("ascii") for comp in extension.compressors]
                manifest = getattr(extension._delegate, "_manifest", None)
                if manifest is not None:
                    # check if this extension was built from a manifest is a different package
                    resource_mapping = get_config().resource_manager._mappings_by_uri.get(manifest["id"])
                    # if an extension was registered with a manifest uri that does not match the id the
                    # resource_mapping lookup will fail (resource_mapping will be None)
                    if resource_mapping is None:
                        warnings.warn(
                            f"Extension ({extension.extension_uri}) uses a manifest with a uri that "
                            "does not match it's id. Please open an issue with the extension maintainer",
                            AsdfManifestURIMismatchWarning,
                        )
                    elif resource_mapping.package_name != extension.package_name:
                        ext_meta["manifest_software"] = Software(
                            name=resource_mapping.package_name,
                            version=resource_mapping.package_version,
                        )

                for i, entry in enumerate(tree["history"]["extensions"]):
                    # Update metadata about this extension if it already exists
                    if (
                        entry.extension_uri is not None and entry.extension_uri == extension.extension_uri
                    ) or entry.extension_class in extension.legacy_class_names:
                        tree["history"]["extensions"][i] = ext_meta
                        break
                else:
                    tree["history"]["extensions"].append(ext_meta)

        @property
        def file_format_version(self):
            return self._file_format_version

        def close(self):
            """
            Close the file handles associated with the `asdf.AsdfFile`.
            """
            if self._fd and not self._closed:
                # This is ok to always do because GenericFile knows
                # whether it "owns" the file and should close it.
                self._fd.close()
                self._fd = None
                self._closed = True
                # as we're closing the file, also empty out the
                # tree so that references to array data can be released
                self._tree = AsdfObject()
                self._tagged_object_cache.clear()
            for external in self._external_asdf_by_uri.values():
                external.close()
            self._external_asdf_by_uri.clear()
            self._blocks.close()

        def copy(self):
            return self.__class__(
                copy.deepcopy(self._tree),
                self._blocks._uri,
                self._user_extensions,
            )

        __copy__ = __deepcopy__ = copy

        @property
        def uri(self):
            """
            Get the URI associated with the `AsdfFile`.

            In many cases, it is automatically determined from the file
            handle used to read or write the file.
            """
            return self._blocks._uri

        def resolve_uri(self, uri):
            """
            Resolve a (possibly relative) URI against the URI of this ASDF
            file.  May be overridden by base classes to change how URIs
            are resolved.  This does not apply any ``uri_mapping`` that was
            passed to the constructor.

            Parameters
            ----------
            uri : str
                An absolute or relative URI to resolve against the URI of
                this ASDF file.

            Returns
            -------
            uri : str
                The resolved URI.
            """
            return generic_io.resolve_uri(self.uri, uri)

        def open_external(self, uri, **kwargs):
            """
            Open an external ASDF file, from the given (possibly relative)
            URI.  There is a cache (internal to this ASDF file) that ensures
            each external ASDF file is loaded only once.

            Parameters
            ----------
            uri : str
                An absolute or relative URI to resolve against the URI of
                this ASDF file.

            Returns
            -------
            asdffile : AsdfFile
                The external ASDF file.
            """
            # For a cache key, we want to ignore the "fragment" part.
            base_uri = util.get_base_uri(uri)
            resolved_uri = self.resolve_uri(base_uri)

            # A uri like "#" should resolve back to ourself.  In that case,
            # just return `self`.
            if resolved_uri == "" or resolved_uri == self.uri:
                return self

            asdffile = self._external_asdf_by_uri.get(resolved_uri)
            if asdffile is None:
                asdffile = open_asdf(resolved_uri, mode="r", **kwargs)
                self._external_asdf_by_uri[resolved_uri] = asdffile
            return asdffile

        @property
        def tree(self):
            """
            Get/set the tree of data in the ASDF file.

            When set, the tree will be validated against the ASDF schema.
            """
            if self._closed:
                msg = "Cannot access data from closed ASDF file"
                raise OSError(msg)
            return self._tree

        @tree.setter
        def tree(self, tree):
            self._tree = AsdfObject(tree)

        def keys(self):
            return self.tree.keys()

        def __getitem__(self, key):
            return self.tree[key]

        def __setitem__(self, key, value):
            self.tree[key] = value

        def __contains__(self, item):
            return item in self.tree

        @property
        def comments(self):
            """
            Get the comments after the header, before the tree.
            """
            return self._comments

        def _validate(self, tree, reading=False):
            with self._blocks.options_context():
                # If we're validating on read then the tree
                # is already guaranteed to be in tagged form.
                tagged_tree = tree if reading else yamlutil.custom_tree_to_tagged_tree(tree, self)

                schema.validate(tagged_tree, self, reading=reading)

        def validate(self):
            """
            Validate the current state of the tree against the ASDF schema.
            """
            self._validate(self._tree)

        def make_reference(self, path=None):
            """
            Make a new reference to a part of this file's tree, that can be
            assigned as a reference to another tree.

            Parameters
            ----------
            path : list of str and int, optional
                The parts of the path pointing to an item in this tree.
                If omitted, points to the root of the tree.

            Returns
            -------
            reference :
                A reference object.

            Examples
            --------
            For the given AsdfFile ``ff``, add an external reference to the data in
            an external file::

                >>> import asdf
                >>> flat = asdf.open("http://stsci.edu/reference_files/flat.asdf")  # doctest: +SKIP
                >>> ff.tree['flat_field'] = flat.make_reference(['data'])  # doctest: +SKIP
            """
            return reference.make_reference(self, [] if path is None else path)

        def set_array_storage(self, arr, array_storage):
            """
            Set the block type to use for the given array data.

            Parameters
            ----------
            arr : numpy.ndarray
                The array to set.  If multiple views of the array are in
                the tree, only the most recent block type setting will be
                used, since all views share a single block.

            array_storage : str
                Must be one of:

                - ``internal``: The default.  The array data will be
                  stored in a binary block in the same ASDF file.

                - ``external``: Store the data in a binary block in a
                  separate ASDF file.

                - ``inline``: Store the data as YAML inline in the tree.
            """
            self._blocks._set_array_storage(arr, array_storage)

        def get_array_storage(self, arr):
            """
            Get the block type for the given array data.

            Parameters
            ----------
            arr : numpy.ndarray
            """
            return self._blocks._get_array_storage(arr)

        def set_array_compression(self, arr, compression, **compression_kwargs):
            """
            Set the compression to use for the given array data.

            Parameters
            ----------
            arr : numpy.ndarray
                The array to set.  If multiple views of the array are in
                the tree, only the most recent compression setting will be
                used, since all views share a single block.

            compression : str or None
                Must be one of:

                - ``''`` or `None`: no compression

                - ``zlib``: Use zlib compression

                - ``bzp2``: Use bzip2 compression

                - ``lz4``: Use lz4 compression

                - ``input``: Use the same compression as in the file read.
                  If there is no prior file, acts as None.

            """
            self._blocks._set_array_compression(arr, compression, **compression_kwargs)

        def get_array_compression(self, arr):
            """
            Get the compression type for the given array data.

            Parameters
            ----------
            arr : numpy.ndarray

            Returns
            -------
            compression : str or None
            """
            return self._blocks._get_array_compression(arr)

        def get_array_compression_kwargs(self, arr):
            """ """
            return self._blocks._get_array_compression_kwargs(arr)

        def set_array_save_base(self, arr, save_base):
            """
            Set the ``save_base`` option for ``arr``. When ``arr`` is
            written to a file, if ``save_base`` is ``True`` the base array
            for ``arr`` will be saved.

            Note that similar to other array options this setting is linked
            to the base array if ``arr`` is a view.

            Parameters
            ----------
            arr : numpy.ndarray

            save_base : bool or None
                if ``None`` the ``default_array_save_base`` value from asdf
                config will be used
            """
            self._blocks._set_array_save_base(arr, save_base)

        def get_array_save_base(self, arr):
            """
            Returns the ``save_base`` option for ``arr``. When ``arr`` is
            written to a file, if ``save_base`` is ``True`` the base array
            for ``arr`` will be saved.

            Parameters
            ----------
            arr : numpy.ndarray

            Returns
            -------
            save_base : bool or None
            """
            return self._blocks._get_array_save_base(arr)

        def _write_tree(self, tree, fd, pad_blocks):
            fd.write(constants.ASDF_MAGIC)
            fd.write(b" ")
            fd.write(f"{self.file_format_version}".encode("ascii"))
            fd.write(b"\n")

            fd.write(b"#")
            fd.write(constants.ASDF_STANDARD_COMMENT)
            fd.write(b" ")
            fd.write(self.version_string.encode("ascii"))
            fd.write(b"\n")

            if len(tree):
                serialization_context = self._create_serialization_context(_serialization_context.BlockAccess.WRITE)

                for compression in self._blocks.get_output_compressions():
                    # lookup extension
                    compressor = mcompression._get_compressor_from_extensions(compression, return_extension=True)
                    if compressor is not None:
                        # mark it as used
                        serialization_context._mark_extension_used(compressor[1])

                def _tree_finalizer(tagged_tree):
                    """
                    The list of extensions used is not known until after
                    serialization, so we're using a hook provided by
                    yamlutil.dump_tree to update extension metadata
                    after the tree has been converted to tagged objects.
                    """
                    self._update_extension_history(tree, serialization_context)
                    if "history" in tree:
                        tagged_tree["history"] = yamlutil.custom_tree_to_tagged_tree(
                            tree["history"],
                            self,
                            _serialization_context=serialization_context,
                        )
                    else:
                        tagged_tree.pop("history", None)

                yamlutil.dump_tree(
                    tree,
                    fd,
                    self,
                    tree_finalizer=_tree_finalizer,
                    _serialization_context=serialization_context,
                )

            if pad_blocks:
                padding = util.calculate_padding(fd.tell(), pad_blocks, fd.block_size)
                fd.fast_forward(padding)

        def _serial_write(self, fd, pad_blocks, include_block_index):
            with self._blocks.write_context(fd):
                # prep a tree for a writing
                tree = copy.copy(self._tree)
                tree["asdf_library"] = _io.get_asdf_library_info()
                if "history" in self._tree:
                    tree["history"] = copy.deepcopy(self._tree["history"])

                self._write_tree(tree, fd, pad_blocks)
                self._blocks.write(pad_blocks, include_block_index)

        def update(
            self,
            all_array_storage=NotSet,
            all_array_compression=NotSet,
            compression_kwargs=NotSet,
            pad_blocks=False,
            include_block_index=True,
            version=None,
        ):
            """
            Update the file on disk in place.

            Parameters
            ----------
            all_array_storage : string, optional
                If provided, override the array storage type of all blocks
                in the file immediately before writing.  Must be one of:

                - ``internal``: The default.  The array data will be
                  stored in a binary block in the same ASDF file.

                - ``external``: Store the data in a binary block in a
                  separate ASDF file.

                - ``inline``: Store the data as YAML inline in the tree.

            all_array_compression : string, optional
                If provided, set the compression type on all binary blocks
                in the file.  Must be one of:

                - ``''`` or `None`: No compression.

                - ``zlib``: Use zlib compression.

                - ``bzp2``: Use bzip2 compression.

                - ``lz4``: Use lz4 compression.

                - ``input``: Use the same compression as in the file read.
                  If there is no prior file, acts as None

            compression_kwargs : dict, optional
                If provided, set this as the compression keyword arguments
                for all binary blocks in the file.

            pad_blocks : float or bool, optional
                Add extra space between blocks to allow for updating of
                the file.  If `False` (default), add no padding (always
                return 0).  If `True`, add a default amount of padding of
                10% If a float, it is a factor to multiple content_size by
                to get the new total size.

            include_block_index : bool, optional
                If `False`, don't include a block index at the end of the
                file.  (Default: `True`)  A block index is never written
                if the file has a streamed block.

            version : str, optional
                Update the ASDF core schemas version of this AsdfFile before
                writing.
            """

            with config_context() as config:
                if all_array_storage is not NotSet:
                    config.all_array_storage = all_array_storage
                if all_array_compression is not NotSet:
                    config.all_array_compression = all_array_compression
                if compression_kwargs is not NotSet:
                    config.all_array_compression_kwargs = compression_kwargs

                fd = self._fd

                if fd is None:
                    msg = "Can not update, since there is no associated file"
                    raise ValueError(msg)

                if not fd.writable():
                    msg = (
                        "Can not update, since associated file is read-only. Make "
                        "sure that the AsdfFile was opened with mode='rw' and the "
                        "underlying file handle is writable."
                    )
                    raise OSError(msg)

                if not fd.seekable():
                    msg = "Can not update, since associated file is not seekable"
                    raise OSError(msg)

                if version is not None:
                    self.version = version

                # flush all pending memmap writes
                if fd.can_memmap():
                    fd.flush_memmap()

                def rewrite():
                    self._fd.seek(0)
                    self._serial_write(self._fd, pad_blocks, include_block_index)
                    self._fd.truncate()
                    if self._fd.can_memmap():
                        self._fd.close_memmap()

                # if we have no read blocks, we can just call write_to as no internal blocks are reused
                if len(self._blocks.blocks) == 0:
                    rewrite()
                    return

                # if we have all external blocks, we can just call write_to as no internal blocks are reused
                if config.all_array_storage == "external":
                    rewrite()
                    return

                self._tree["asdf_library"] = _io.get_asdf_library_info()

                # prepare block manager for writing
                with self._blocks.write_context(self._fd, copy_options=False):
                    # write out tree to temporary buffer
                    tree_fd = generic_io.get_file(io.BytesIO(), mode="rw")
                    self._write_tree(self._tree, tree_fd, False)
                    new_tree_size = tree_fd.tell()

                    # update blocks
                    self._blocks.update(new_tree_size, pad_blocks, include_block_index)
                    end_of_file = self._fd.tell()

                # now write the tree
                self._fd.seek(0)
                tree_fd.seek(0)
                self._fd.write(tree_fd.read())
                self._fd.flush()

                # close memmap to trigger arrays to reload themselves
                self._fd.seek(end_of_file)
                self._fd.truncate()
                if self._fd.can_memmap():
                    self._fd.close_memmap()

        def write_to(
            self,
            fd,
            all_array_storage=NotSet,
            all_array_compression=NotSet,
            compression_kwargs=NotSet,
            pad_blocks=False,
            include_block_index=True,
            version=None,
        ):
            """
            Write the ASDF file to the given file-like object.

            `write_to` does not change the underlying file descriptor in
            the `asdf.AsdfFile` object, but merely copies the content to a new
            file.

            Parameters
            ----------
            fd : string or file-like object
                May be a string path to a file, or a Python file-like
                object.  If a string path, the file is automatically
                closed after writing.  If not a string path, it is the
                caller's responsibility to close the object.

            all_array_storage : string, optional
                If provided, override the array storage type of all blocks
                in the file immediately before writing.  Must be one of:

                - ``internal``: The default.  The array data will be
                  stored in a binary block in the same ASDF file.

                - ``external``: Store the data in a binary block in a
                  separate ASDF file.

                - ``inline``: Store the data as YAML inline in the tree.

            all_array_compression : string, optional
                If provided, set the compression type on all binary blocks
                in the file.  Must be one of:

                - ``''`` or `None`: No compression.

                - ``zlib``: Use zlib compression.

                - ``bzp2``: Use bzip2 compression.

                - ``lz4``: Use lz4 compression.

                - ``input``: Use the same compression as in the file read.
                  If there is no prior file, acts as None.

            compression_kwargs : dict, optional
                If provided, set this as the compression keyword arguments
                for all binary blocks in the file.

            pad_blocks : float or bool, optional
                Add extra space between blocks to allow for updating of
                the file.  If `False` (default), add no padding (always
                return 0).  If `True`, add a default amount of padding of
                10% If a float, it is a factor to multiple content_size by
                to get the new total size.

            include_block_index : bool, optional
                If `False`, don't include a block index at the end of the
                file.  (Default: `True`)  A block index is never written
                if the file has a streamed block.

            version : str, optional
                Update the ASDF core schemas version of this AsdfFile before
                writing.
            """
            with config_context() as config:
                if all_array_storage is not NotSet:
                    config.all_array_storage = all_array_storage
                if all_array_compression is not NotSet:
                    config.all_array_compression = all_array_compression
                if compression_kwargs is not NotSet:
                    config.all_array_compression_kwargs = compression_kwargs

                if version is not None:
                    previous_version = self.version
                    self.version = version

                try:
                    with generic_io.get_file(fd, mode="w") as fd:
                        self._serial_write(fd, pad_blocks, include_block_index)
                finally:
                    if version is not None:
                        self.version = previous_version

        def find_references(self):
            """
            Finds all external "JSON References" in the tree and converts
            them to ``reference.Reference`` objects.
            """
            # Set directly to self._tree, since it doesn't need to be re-validated.
            self._tree = reference.find_references(self._tree, self)

        def resolve_references(self):
            """
            Finds all external "JSON References" in the tree, loads the
            external content, and places it directly in the tree.  Saving
            a ASDF file after this operation means it will have no
            external references, and will be completely self-contained.
            """
            self._tree = reference.resolve_references(self._tree, self)

        def fill_defaults(self):
            """
            Fill in any values that are missing in the tree using default
            values from the schema.
            """
            tree = yamlutil.custom_tree_to_tagged_tree(self._tree, self)
            schema.fill_defaults(tree, self)
            self._tree = yamlutil.tagged_tree_to_custom_tree(tree, self)

        def remove_defaults(self):
            """
            Remove any values in the tree that are the same as the default
            values in the schema
            """
            tree = yamlutil.custom_tree_to_tagged_tree(self._tree, self)
            schema.remove_defaults(tree, self)
            self._tree = yamlutil.tagged_tree_to_custom_tree(tree, self)

        def add_history_entry(self, description, software=None):
            """
            Add an entry to the history list.

            Parameters
            ----------
            description : str
                A description of the change.

            software : dict or list of dict
                A description of the software used.  It should not include
                asdf itself, as that is automatically notated in the
                ``asdf_library`` entry.

                Each dict must have the following keys:

                - ``name``: The name of the software
                - ``author``: The author or institution that produced the software
                - ``homepage``: A URI to the homepage of the software
                - ``version``: The version of the software
            """
            if isinstance(software, list):
                software = [Software(x) for x in software]
            elif software is not None:
                software = Software(software)

            time_ = datetime.datetime.fromtimestamp(
                int(os.environ.get("SOURCE_DATE_EPOCH", time.time())), datetime.timezone.utc
            )

            entry = HistoryEntry(
                {
                    "description": description,
                    "time": time_,
                },
            )

            if software is not None:
                entry["software"] = software

            if self.version >= versioning.NEW_HISTORY_FORMAT_MIN_VERSION:
                if "history" not in self.tree:
                    self.tree["history"] = {"entries": []}
                elif "entries" not in self.tree["history"]:
                    self.tree["history"]["entries"] = []

                self.tree["history"]["entries"].append(entry)

                try:
                    self.validate()
                except Exception:
                    self.tree["history"]["entries"].pop()
                    raise
            else:
                if "history" not in self.tree:
                    self.tree["history"] = []

                self.tree["history"].append(entry)

                try:
                    self.validate()
                except Exception:
                    self.tree["history"].pop()
                    raise

        def get_history_entries(self):
            """
            Get a list of history entries from the file object.

            Returns
            -------
            entries : list
                A list of history entries.
            """

            if "history" not in self.tree:
                return []

            if isinstance(self.tree["history"], list):
                return self.tree["history"]

            if "entries" in self.tree["history"]:
                return self.tree["history"]["entries"]

            return []

        def schema_info(self, key="description", path=None, preserve_list=True):
            """
            Get a nested dictionary of the schema information for a given key, relative to the path.

            This method will only return unambiguous info. If a property is subject to multiple
            subschemas or contains ambiguous entries (multiple titles) no result will be returned
            for that property.

            Parameters
            ----------
            key : str
                The key to look up.
                Default: "description"
            path : str or asdf.search.AsdfSearchResult
                A dot-separated path to the parameter to find the key information on or
                an `asdf.search.AsdfSearchResult` object.
                Default = None (full dictionary).
            preserve_list : bool
                If True, then lists are preserved. Otherwise, they are turned into dicts.
            """
            if isinstance(path, AsdfSearchResult):
                return path.schema_info(
                    key,
                    preserve_list=preserve_list,
                )

            return node_info.collect_schema_info(
                key,
                path,
                self.tree,
                preserve_list=preserve_list,
                extension_manager=self.extension_manager,
            )

        def info(
            self,
            max_rows=display.DEFAULT_MAX_ROWS,
            max_cols=display.DEFAULT_MAX_COLS,
            show_values=display.DEFAULT_SHOW_VALUES,
        ):
            """
            Print a rendering of this file's tree to stdout.

            Parameters
            ----------
            max_rows : int, tuple, or None, optional
                Maximum number of lines to print.  Nodes that cannot be
                displayed will be elided with a message.
                If int, constrain total number of displayed lines.
                If tuple, constrain lines per node at the depth corresponding \
                    to the tuple index.
                If None, display all lines.

            max_cols : int or None, optional
                Maximum length of line to print.  Nodes that cannot
                be fully displayed will be truncated with a message.
                If int, constrain length of displayed lines.
                If None, line length is unconstrained.

            show_values : bool, optional
                Set to False to disable display of primitive values in
                the rendered tree.
            """
            lines = display.render_tree(
                self.tree,
                max_rows=max_rows,
                max_cols=max_cols,
                show_values=show_values,
                identifier="root",
                extension_manager=self.extension_manager,
            )
            print("\n".join(lines))

        def search(self, key=NotSet, type_=NotSet, value=NotSet, filter_=None):
            """
            Search this file's tree.

            Parameters
            ----------
            key : NotSet, str, or any other object
                Search query that selects nodes by dict key or list index.
                If NotSet, the node key is unconstrained.
                If str, the input is searched among keys/indexes as a regular
                expression pattern.
                If any other object, node's key or index must equal the queried key.

            type_ : NotSet, str, or builtins.type
                Search query that selects nodes by type.
                If NotSet, the node type is unconstrained.
                If str, the input is searched among (fully qualified) node type
                names as a regular expression pattern.
                If builtins.type, the node must be an instance of the input.

            value : NotSet, str, or any other object
                Search query that selects nodes by value.
                If NotSet, the node value is unconstrained.
                If str, the input is searched among values as a regular
                expression pattern.
                If any other object, node's value must equal the queried value.

            filter_ : callable
                Callable that filters nodes by arbitrary criteria.
                The callable accepts one or two arguments:

                - the node
                - the node's list index or dict key (optional)

                and returns True to retain the node, or False to remove it from
                the search results.

            Returns
            -------
            asdf.search.AsdfSearchResult
                the result of the search
            """
            result = AsdfSearchResult(["root"], self.tree)
            return result.search(key=key, type_=type_, value=value, filter_=filter_)

        # This function is called from within yamlutil methods to create
        # a context when one isn't explicitly passed in.
        def _create_serialization_context(self, operation=_serialization_context.BlockAccess.NONE):
            return _serialization_context.create(self, operation)

    def open_asdf(
        fd,
        uri=None,
        mode=None,
        validate_checksums=False,
        extensions=None,
        ignore_unrecognized_tag=False,
        _force_raw_types=False,
        memmap=False,
        lazy_tree=NotSet,
        lazy_load=True,
        custom_schema=None,
        strict_extension_check=False,
        ignore_missing_extensions=False,
    ):
        """
        Open an existing ASDF file.

        Parameters
        ----------
        fd : string or file-like object
            May be a string ``file`` or ``http`` URI, or a Python
            file-like object.

        uri : string, optional
            The URI of the file.  Only required if the URI can not be
            automatically determined from ``fd``.

        mode : string, optional
            The mode to open the file in.  Must be ``r`` (default) or
            ``rw``.

        validate_checksums : bool, optional
            If `True`, validate the blocks against their checksums.
            Requires reading the entire file, so disabled by default.

        extensions : object, optional
            Additional extensions to use when reading and writing the file.
            May be an `asdf.extension.Extension` or a `list` of extensions.

        ignore_unrecognized_tag : bool, optional
            When `True`, do not raise warnings for unrecognized tags. Set to
            `False` by default.

        memmap : bool, optional
            When `True`, when reading files, attempt to memmap underlying data
            arrays when possible. Defaults to ``False``.

        lazy_load : bool, optional
            When `True` and the underlying file handle is seekable, data
            arrays will only be loaded lazily: i.e. when they are accessed
            for the first time. In this case the underlying file must stay
            open during the lifetime of the tree. Setting to False causes
            all data arrays to be loaded up front, which means that they
            can be accessed even after the underlying file is closed.
            Note: even if ``lazy_load`` is `False`, ``memmap`` is still taken
            into account.

        lazy_tree : bool, optional
            When `True` the ASDF tree will not be converted to custom objects
            when the file is loaded. Instead, objects will be "lazily" converted
            only when they are accessed. Note that the tree will not contain dict
            and list instances for containers and instead return instances of classes
            defined in `asdf.lazy_nodes`. Since objects are converted when they
            are accessed, traversing the tree (like is done during `AsdfFile.info`
            and `AsdfFile.search`) will result in nodes being converted.

        custom_schema : str, optional
            Path to a custom schema file that will be used for a secondary
            validation pass. This can be used to ensure that particular ASDF
            files follow custom conventions beyond those enforced by the
            specification.

        strict_extension_check : bool, optional
            When `True`, if the given ASDF file contains metadata about the
            extensions used to create it, and if those extensions are not
            installed, opening the file will fail. When `False`, opening a file
            under such conditions will cause only a warning. Defaults to
            `False`.

        ignore_missing_extensions : bool, optional
            When `True`, do not raise warnings when a file is read that
            contains metadata about extensions that are not available. Defaults
            to `False`.

        Returns
        -------
        asdffile : AsdfFile
            The new AsdfFile object.
        """

        if strict_extension_check and ignore_missing_extensions:
            msg = "'strict_extension_check' and 'ignore_missing_extensions' are incompatible options"
            raise ValueError(msg)

        if lazy_tree is NotSet:
            lazy_tree = get_config().lazy_tree

        instance = AsdfFile(
            ignore_unrecognized_tag=ignore_unrecognized_tag,
            memmap=memmap,
            lazy_load=lazy_load,
            custom_schema=custom_schema,
            extensions=extensions,
        )

        with _io.maybe_close(fd, mode, uri) as generic_file:
            file_format_version, comments, tree, blocks = _io.open_asdf(
                generic_file, uri, mode, lazy_load, memmap, validate_checksums
            )

            instance._blocks = blocks
            instance._mode = generic_file.mode
            instance._fd = generic_file
            instance._file_format_version = file_format_version
            instance._comments = comments

            instance.version = _io.find_asdf_version_in_comments(comments, versioning.AsdfVersion("1.0.0"))

            if tree is None:
                # At this point the tree should be tagged, but we want it to be
                # tagged with the core/asdf version appropriate to this file's
                # ASDF Standard version.  We're using custom_tree_to_tagged_tree
                # to select the correct tag for us.
                tree = yamlutil.custom_tree_to_tagged_tree(AsdfObject(), instance)

            # possibly fill defaults
            if instance.version <= versioning.FILL_DEFAULTS_MAX_VERSION and get_config().legacy_fill_schema_defaults:
                schema.fill_defaults(tree, instance, reading=True)

            # validate
            if get_config().validate_on_read:
                instance._validate(tree, reading=True)

            # lazy tree?
            if lazy_tree and not _force_raw_types:
                obj = AsdfObject()
                obj.data = lazy_nodes.AsdfDictNode(tree, weakref.ref(instance))
                tree = obj
            else:
                tree = yamlutil.tagged_tree_to_custom_tree(tree, instance, _force_raw_types)

            # check extensions
            if not (ignore_missing_extensions or _force_raw_types):
                instance._check_extensions(tree, strict=strict_extension_check)

            instance._tree = tree

        return instance