# Copyright 2010-2024 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

__all__ = ["fetch"]

import errno
import functools
import glob
import itertools
import json
import logging
import random
import re
import shlex
import stat
import sys
import tempfile
import time

from collections import OrderedDict
from urllib.parse import urlparse
from urllib.parse import quote as urlquote

import portage

portage.proxy.lazyimport.lazyimport(
    globals(),
    "portage.package.ebuild.config:check_config_instance,config",
    "portage.package.ebuild.doebuild:doebuild_environment," + "_doebuild_spawn",
    "portage.package.ebuild.prepare_build_dirs:prepare_build_dirs",
    "portage.util:atomic_ofstream",
    "portage.util.configparser:SafeConfigParser,read_configs," + "ConfigParserError",
    "portage.util.install_mask:_raise_exc",
    "portage.util._urlopen:urlopen",
)

from portage import (
    os,
    selinux,
    shutil,
    _encodings,
    _movefile,
    _unicode_encode,
)
from portage.checksum import (
    get_valid_checksum_keys,
    perform_md5,
    verify_all,
    _filter_unaccelarated_hashes,
    _hash_filter,
    _apply_hash_filter,
    checksum_str,
)
from portage.const import BASH_BINARY, CUSTOM_MIRRORS_FILE, GLOBAL_CONFIG_PATH
from portage.data import portage_gid, portage_uid, userpriv_groups
from portage.exception import (
    FileNotFound,
    OperationNotPermitted,
    PortageException,
    TryAgain,
)
from portage.localization import _
from portage.locks import lockfile, unlockfile
from portage.output import colorize, EOutput
from portage.util import (
    apply_recursive_permissions,
    apply_secpass_permissions,
    ensure_dirs,
    grabdict,
    varexpand,
    writemsg,
    writemsg_level,
    writemsg_stdout,
)
from portage.util.futures import asyncio
from portage.process import spawn

_download_suffix = ".__download__"

_userpriv_spawn_kwargs = (
    ("uid", portage_uid),
    ("gid", portage_gid),
    ("groups", userpriv_groups),
    ("umask", 0o02),
)


def _hide_url_passwd(url):
    return re.sub(r"//([^:\s]+):[^@\s]+@", r"//\1:*password*@", url)


def _want_userfetch(settings):
    """
    Check if it's desirable to drop privileges for userfetch.

    @param settings: portage config
    @type settings: portage.package.ebuild.config.config
    @return: True if desirable, False otherwise
    """
    return (
        "userfetch" in settings.features
        and portage.data.secpass >= 2
        and os.getuid() == 0
    )


def _drop_privs_userfetch(settings):
    """
    Drop privileges for userfetch, and update portage.data.secpass
    to correspond to the new privilege level.
    """
    spawn_kwargs = dict(_userpriv_spawn_kwargs)
    try:
        asyncio.run(_ensure_distdir(settings, settings["DISTDIR"]))
    except PortageException:
        if not os.path.isdir(settings["DISTDIR"]):
            raise
    os.setgid(int(spawn_kwargs["gid"]))
    os.setgroups(spawn_kwargs["groups"])
    os.setuid(int(spawn_kwargs["uid"]))
    os.umask(spawn_kwargs["umask"])
    portage.data.secpass = 1


def _spawn_fetch(settings, args, **kwargs):
    """
    Spawn a process with appropriate settings for fetching, including
    userfetch and selinux support.
    """

    global _userpriv_spawn_kwargs

    # Redirect all output to stdout since some fetchers like
    # wget pollute stderr (if portage detects a problem then it
    # can send it's own message to stderr).
    if "fd_pipes" not in kwargs:
        kwargs["fd_pipes"] = {
            0: portage._get_stdin().fileno(),
            1: sys.__stdout__.fileno(),
            2: sys.__stdout__.fileno(),
        }

    logname = None
    if (
        "userfetch" in settings.features
        and os.getuid() == 0
        and portage_gid
        and portage_uid
        and hasattr(os, "setgroups")
    ):
        kwargs.update(_userpriv_spawn_kwargs)
        logname = portage.data._portage_username

    spawn_func = spawn

    if settings.selinux_enabled():
        spawn_func = selinux.spawn_wrapper(spawn_func, settings["PORTAGE_FETCH_T"])

        # bash is an allowed entrypoint, while most binaries are not
        if args[0] != BASH_BINARY:
            args = [BASH_BINARY, "-c", 'exec "$@"', args[0]] + args

    # Ensure that EBUILD_PHASE is set to fetch, so that config.environ()
    # does not filter the calling environment (which may contain needed
    # proxy variables, as in bug #315421).
    phase_backup = settings.get("EBUILD_PHASE")
    settings["EBUILD_PHASE"] = "fetch"
    env = settings.environ()
    if logname is not None:
        env["LOGNAME"] = logname
    try:
        rval = spawn_func(args, env=env, **kwargs)
    finally:
        if phase_backup is None:
            settings.pop("EBUILD_PHASE", None)
        else:
            settings["EBUILD_PHASE"] = phase_backup

    return rval


# Instrumentation hooks for use by unit tests.
_async_spawn_fetch_pre_wait = None
_async_spawn_fetch_post_terminate = None


async def _async_spawn_fetch(settings, args, **kwargs):
    kwargs["returnproc"] = True
    proc = _spawn_fetch(settings, args, **kwargs)
    try:
        if _async_spawn_fetch_pre_wait is not None:
            _async_spawn_fetch_pre_wait(proc)
        return await proc.wait()
    except asyncio.CancelledError:
        proc.terminate()
        if _async_spawn_fetch_post_terminate is not None:
            _async_spawn_fetch_post_terminate(proc)
        raise


_async_spawn_fetch.__doc__ = _spawn_fetch.__doc__
_async_spawn_fetch.__doc__ += """
    This function is a coroutine.
"""

_userpriv_test_write_file_cache = {}
_userpriv_test_write_cmd_script = (
    ">> %(file_path)s 2>/dev/null ; rval=$? ; " + "rm -f  %(file_path)s ; exit $rval"
)


async def _userpriv_test_write_file(settings, file_path):
    """
    Drop privileges and try to open a file for writing. The file may or
    may not exist, and the parent directory is assumed to exist. The file
    is removed before returning.

    @param settings: A config instance which is passed to _spawn_fetch()
    @param file_path: A file path to open and write.
    @return: True if write succeeds, False otherwise.
    """

    global _userpriv_test_write_file_cache, _userpriv_test_write_cmd_script
    rval = _userpriv_test_write_file_cache.get(file_path)
    if rval is not None:
        return rval

    # Optimize away the spawn when privileges do not need to be dropped.
    if not _want_userfetch(settings):
        rval = os.access(os.path.dirname(file_path), os.W_OK)
        _userpriv_test_write_file_cache[file_path] = rval
        return rval

    args = [
        BASH_BINARY,
        "-c",
        _userpriv_test_write_cmd_script % {"file_path": shlex.quote(file_path)},
    ]

    returncode = await _async_spawn_fetch(settings, args)

    rval = returncode == os.EX_OK
    _userpriv_test_write_file_cache[file_path] = rval
    return rval


async def _ensure_distdir(settings, distdir):
    """
    Ensure that DISTDIR exists with appropriate permissions.

    @param settings: portage config
    @type settings: portage.package.ebuild.config.config
    @param distdir: DISTDIR path
    @type distdir: str
    @raise PortageException: portage.exception wrapper exception
    """
    global _userpriv_test_write_file_cache
    dirmode = 0o070
    filemode = 0o60
    modemask = 0o2
    dir_gid = portage_gid
    if "FAKED_MODE" in settings:
        # When inside fakeroot, directories with portage's gid appear
        # to have root's gid. Therefore, use root's gid instead of
        # portage's gid to avoid spurious permissions adjustments
        # when inside fakeroot.
        dir_gid = 0

    userfetch = portage.data.secpass >= 2 and "userfetch" in settings.features
    userpriv = portage.data.secpass >= 2 and "userpriv" in settings.features
    write_test_file = os.path.join(distdir, ".__portage_test_write__")

    if await _userpriv_test_write_file(settings, write_test_file):
        return

    _userpriv_test_write_file_cache.pop(write_test_file, None)

    already_exists = os.path.isdir(distdir)

    if ensure_dirs(distdir, gid=dir_gid, mode=dirmode, mask=modemask):
        if not already_exists:
            # The directory has just been created
            # and therefore it must be empty.
            return
        writemsg(
            _("Adjusting permissions recursively: '%s'\n") % distdir, noiselevel=-1
        )
        if not apply_recursive_permissions(
            distdir,
            gid=dir_gid,
            dirmode=dirmode,
            dirmask=modemask,
            filemode=filemode,
            filemask=modemask,
            onerror=_raise_exc,
        ):
            raise OperationNotPermitted(
                _("Failed to apply recursive permissions for the portage group.")
            )


def _checksum_failure_temp_file(settings, distdir, basename):
    """
    First try to find a duplicate temp file with the same checksum and return
    that filename if available. Otherwise, use mkstemp to create a new unique
    filename._checksum_failure_.$RANDOM, rename the given file, and return the
    new filename. In any case, filename will be renamed or removed before this
    function returns a temp filename.
    """

    filename = os.path.join(distdir, basename)
    if basename.endswith(_download_suffix):
        normal_basename = basename[: -len(_download_suffix)]
    else:
        normal_basename = basename
    size = os.stat(filename).st_size
    checksum = None
    tempfile_re = re.compile(re.escape(normal_basename) + r"\._checksum_failure_\..*")
    for temp_filename in os.listdir(distdir):
        if not tempfile_re.match(temp_filename):
            continue
        temp_filename = os.path.join(distdir, temp_filename)
        try:
            if size != os.stat(temp_filename).st_size:
                continue
        except OSError:
            continue
        try:
            temp_checksum = perform_md5(temp_filename)
        except FileNotFound:
            # Apparently the temp file disappeared. Let it go.
            continue
        if checksum is None:
            checksum = perform_md5(filename)
        if checksum == temp_checksum:
            os.unlink(filename)
            return temp_filename

    fd, temp_filename = tempfile.mkstemp(
        "", normal_basename + "._checksum_failure_.", distdir
    )
    os.close(fd)
    _movefile(filename, temp_filename, mysettings=settings)
    return temp_filename


def _check_digests(filename, digests, show_errors=1):
    """
    Check digests and display a message if an error occurs.
    @return True if all digests match, False otherwise.
    """
    verified_ok, reason = verify_all(filename, digests)
    if not verified_ok:
        if show_errors:
            writemsg(
                _("!!! Previously fetched" " file: '%s'\n") % filename, noiselevel=-1
            )
            writemsg(_("!!! Reason: %s\n") % reason[0], noiselevel=-1)
            writemsg(
                _("!!! Got:      %s\n" "!!! Expected: %s\n") % (reason[1], reason[2]),
                noiselevel=-1,
            )
        return False
    return True


def _check_distfile(filename, digests, eout, show_errors=1, hash_filter=None):
    """
    @return a tuple of (match, stat_obj) where match is True if filename
    matches all given digests (if any) and stat_obj is a stat result, or
    None if the file does not exist.
    """
    if digests is None:
        digests = {}
    size = digests.get("size")
    if size is not None and len(digests) == 1:
        digests = None

    try:
        st = os.stat(filename)
    except OSError:
        return (False, None)
    if size is not None and size != st.st_size:
        return (False, st)
    if not digests:
        if size is not None:
            eout.ebegin(_("%s size ;-)") % os.path.basename(filename))
            eout.eend(0)
        elif st.st_size == 0:
            # Zero-byte distfiles are always invalid.
            return (False, st)
    else:
        digests = _filter_unaccelarated_hashes(digests)
        if hash_filter is not None:
            digests = _apply_hash_filter(digests, hash_filter)
        if _check_digests(filename, digests, show_errors=show_errors):
            eout.ebegin(f"{os.path.basename(filename)} {' '.join(sorted(digests))} ;-)")
            eout.eend(0)
        else:
            return (False, st)
    return (True, st)


_fetch_resume_size_re = re.compile(r"(^[\d]+)([KMGTPEZY]?$)")

_size_suffix_map = {
    "": 0,
    "K": 10,
    "M": 20,
    "G": 30,
    "T": 40,
    "P": 50,
    "E": 60,
    "Z": 70,
    "Y": 80,
}


class DistfileName(str):
    """
    The DistfileName type represents a distfile name and associated
    content digests, used by MirrorLayoutConfig and related layout
    implementations.

    The path of a distfile within a layout must be dependent on
    nothing more than the distfile name and its associated content
    digests. For filename-hash layout, path is dependent on distfile
    name alone, and the get_filenames implementation yields strings
    corresponding to distfile names. For content-hash layout, path is
    dependent on content digest alone, and the get_filenames
    implementation yields DistfileName instances whose names are equal
    to content digest values. The content-hash layout simply lacks
    the filename-hash layout's innate ability to translate a distfile
    path to a distfile name, and instead caries an innate ability
    to translate a distfile path to a content digest.

    In order to prepare for a migration from filename-hash to
    content-hash layout, all consumers of the layout get_filenames
    method need to be updated to work with content digests as a
    substitute for distfile names. For example, emirrordist requires
    the --content-db option when working with a content-hash layout,
    which serves as a means to associate distfile names
    with content digest values yielded by the content-hash get_filenames
    implementation.
    """

    def __new__(cls, s, digests=None):
        return str.__new__(cls, s)

    def __init__(self, s, digests=None):
        super().__init__()
        self.digests = {} if digests is None else digests

    def digests_equal(self, other):
        """
        Test if digests compare equal to those of another instance.
        """
        if not isinstance(other, DistfileName):
            return False
        matches = []
        for algo, digest in self.digests.items():
            other_digest = other.digests.get(algo)
            if other_digest is not None:
                if other_digest == digest:
                    matches.append(algo)
                else:
                    return False
        return bool(matches)


class FlatLayout:
    def get_path(self, filename):
        return filename

    def get_filenames(self, distdir):
        for dirpath, dirnames, filenames in os.walk(distdir, onerror=_raise_exc):
            for filename in filenames:
                try:
                    yield portage._unicode_decode(filename, errors="strict")
                except UnicodeDecodeError:
                    # Ignore it. Distfiles names must have valid UTF8 encoding.
                    pass
            return

    @staticmethod
    def verify_args(args):
        return len(args) == 1


class FilenameHashLayout:
    def __init__(self, algo, cutoffs):
        self.algo = algo
        self.cutoffs = [int(x) for x in cutoffs.split(":")]

    def get_path(self, filename):
        fnhash = checksum_str(filename.encode("utf8"), self.algo)
        ret = ""
        for c in self.cutoffs:
            assert c % 4 == 0
            c = c // 4
            ret += fnhash[:c] + "/"
            fnhash = fnhash[c:]
        return ret + filename

    def get_filenames(self, distdir):
        pattern = ""
        for c in self.cutoffs:
            assert c % 4 == 0
            c = c // 4
            pattern += c * "[0-9a-f]" + "/"
        pattern += "*"
        for x in glob.iglob(
            portage._unicode_encode(os.path.join(distdir, pattern), errors="strict")
        ):
            try:
                yield portage._unicode_decode(x, errors="strict").rsplit("/", 1)[1]
            except UnicodeDecodeError:
                # Ignore it. Distfiles names must have valid UTF8 encoding.
                pass

    @staticmethod
    def verify_args(args):
        if len(args) != 3:
            return False
        if args[1] not in get_valid_checksum_keys():
            return False
        # argsidate cutoffs
        for c in args[2].split(":"):
            try:
                c = int(c)
            except ValueError:
                break
            else:
                if c % 4 != 0:
                    break
        else:
            return True
        return False


class ContentHashLayout(FilenameHashLayout):
    """
    The content-hash layout is identical to the filename-hash layout,
    except for these three differences:

    1) A content digest is used instead of a filename digest.

    2) The final element of the path returned from the get_path method
    corresponds to the complete content digest. The path is a function
    of the content digest alone.

    3) Because the path is a function of content digest alone, the
    get_filenames implementation cannot derive distfiles names from
    paths, so it instead yields DistfileName instances whose names are
    equal to content digest values. The DistfileName documentation
    discusses resulting implications.

    Motivations to use the content-hash layout instead of the
    filename-hash layout may include:

    1) Since the file path is independent of the file name, file
    name collisions cannot occur. This makes the content-hash
    layout suitable for storage of multiple types of files (not
    only gentoo distfiles). For example, it can be used to store
    distfiles for multiple linux distros within the same tree,
    with automatic deduplication based on content digest. This
    layout can be used to store and distribute practically anything
    (including binary packages for example).

    2) Allows multiple revisions for the same distfiles name. An
    existing distfile can be updated, and if a user still has an
    older copy of an ebuild repository (or an overlay), then a user
    can successfully fetch a desired revision of the distfile as
    long as it has not been purged from the mirror.

    3) File integrity data is integrated into the layout itself,
    making it very simple to verify the integrity of any file that
    it contains. The only tool required is an implementation of
    the chosen hash algorithm.
    """

    def get_path(self, filename):
        """
        For content-hash, the path is a function of the content digest alone.
        The final element of the path returned from the get_path method
        corresponds to the complete content digest.
        """
        fnhash = remaining = filename.digests[self.algo]
        ret = ""
        for c in self.cutoffs:
            assert c % 4 == 0
            c = c // 4
            ret += remaining[:c] + "/"
            remaining = remaining[c:]
        return ret + fnhash

    def get_filenames(self, distdir):
        """
        Yields DistfileName instances each with filename corresponding
        to a digest value for self.algo, and which can be compared to
        other DistfileName instances with their digests_equal method.
        """
        for filename in super().get_filenames(distdir):
            yield DistfileName(filename, digests=dict([(self.algo, filename)]))

    @staticmethod
    def verify_args(args, filename=None):
        """
        If the filename argument is given, then supported hash
        algorithms are constrained by digests available in the filename
        digests attribute.

        @param args: layout.conf entry args
        @param filename: filename with digests attribute
        @return: True if args are valid for available digest algorithms,
                        and False otherwise
        """
        if len(args) != 3:
            return False
        if filename is None:
            supported_algos = get_valid_checksum_keys()
        else:
            supported_algos = filename.digests
        algo = args[1].upper()
        if algo not in supported_algos:
            return False
        return FilenameHashLayout.verify_args(args)


class MirrorLayoutConfig:
    """
    Class to read layout.conf from a mirror.
    """

    def __init__(self):
        self.structure = ()

    def read_from_file(self, f):
        cp = SafeConfigParser()
        read_configs(cp, [f])
        vals = []
        for i in itertools.count():
            try:
                vals.append(tuple(cp.get("structure", "%d" % i).split()))
            except ConfigParserError:
                break
        self.structure = tuple(vals)

    def serialize(self):
        return self.structure

    def deserialize(self, data):
        self.structure = data

    @staticmethod
    def validate_structure(val, filename=None):
        """
        If the filename argument is given, then supported hash
        algorithms are constrained by digests available in the filename
        digests attribute.

        @param val: layout.conf entry args
        @param filename: filename with digests attribute
        @return: True if args are valid for available digest algorithms,
                and False otherwise
        """
        if val[0] == "flat":
            return FlatLayout.verify_args(val)
        elif val[0] == "filename-hash":
            return FilenameHashLayout.verify_args(val)
        elif val[0] == "content-hash":
            return ContentHashLayout.verify_args(val, filename=filename)
        return False

    def get_best_supported_layout(self, filename=None):
        """
        If the filename argument is given, then acceptable hash
        algorithms are constrained by digests available in the filename
        digests attribute.

        @param filename: filename with digests attribute
        """
        for val in self.structure:
            if self.validate_structure(val, filename=filename):
                if val[0] == "flat":
                    return FlatLayout(*val[1:])
                elif val[0] == "filename-hash":
                    return FilenameHashLayout(*val[1:])
                elif val[0] == "content-hash":
                    return ContentHashLayout(*val[1:])
        # fallback
        return FlatLayout()

    def get_all_layouts(self):
        ret = []
        for val in self.structure:
            if not self.validate_structure(val):
                raise ValueError(f"Unsupported structure: {val}")
            if val[0] == "flat":
                ret.append(FlatLayout(*val[1:]))
            elif val[0] == "filename-hash":
                ret.append(FilenameHashLayout(*val[1:]))
            elif val[0] == "content-hash":
                ret.append(ContentHashLayout(*val[1:]))
        if not ret:
            ret.append(FlatLayout())
        return ret


def get_mirror_url(mirror_url, filename, mysettings, cache_path=None):
    """
    Get correct fetch URL for a given file, accounting for mirror
    layout configuration.

    @param mirror_url: Base URL to the mirror (without '/distfiles')
    @param filename: Filename to fetch
    @param cache_path: Path for mirror metadata cache
    @return: Full URL to fetch
    """
    return asyncio.run(
        async_mirror_url(mirror_url, filename, mysettings, cache_path=cache_path)
    )


async def async_mirror_url(mirror_url, filename, mysettings, cache_path=None):
    mirror_conf = MirrorLayoutConfig()

    cache = {}
    if cache_path is not None:
        try:
            with open(cache_path) as f:
                cache = json.load(f)
        except (OSError, ValueError):
            pass

    ts, data = cache.get(mirror_url, (0, None))
    # refresh at least daily
    if ts >= time.time() - 86400:
        mirror_conf.deserialize(data)
    else:
        tmpfile = f".layout.conf.{urlparse(mirror_url).hostname}"
        try:
            if mirror_url[:1] == "/":
                tmpfile = os.path.join(mirror_url, "layout.conf")
                mirror_conf.read_from_file(tmpfile)
            elif await async_fetch(
                {tmpfile: (mirror_url + "/distfiles/layout.conf",)},
                mysettings,
                force=1,
                try_mirrors=0,
            ):
                tmpfile = os.path.join(mysettings["DISTDIR"], tmpfile)
                mirror_conf.read_from_file(tmpfile)
            else:
                raise OSError()
        except (ConfigParserError, OSError, UnicodeDecodeError):
            pass
        else:
            cache[mirror_url] = (time.time(), mirror_conf.serialize())
            if cache_path is not None:
                f = atomic_ofstream(cache_path, "w")
                json.dump(cache, f)
                f.close()

    # For some protocols, urlquote is required for correct behavior,
    # and it must not be used for other protocols like rsync and sftp.
    path = mirror_conf.get_best_supported_layout(filename=filename).get_path(filename)
    if urlparse(mirror_url).scheme in ("ftp", "http", "https"):
        path = urlquote(path)
    if mirror_url[:1] == "/":
        return os.path.join(mirror_url, path)
    else:
        return mirror_url + "/distfiles/" + path


async_mirror_url.__doc__ = get_mirror_url.__doc__
async_mirror_url.__doc__ += """
    This function is a coroutine.
"""


def fetch(
    myuris,
    mysettings,
    listonly=0,
    fetchonly=0,
    locks_in_subdir=".locks",
    use_locks=1,
    try_mirrors=1,
    digests=None,
    allow_missing_digests=True,
    force=False,
):
    """
    Fetch files to DISTDIR and also verify digests if they are available.

    @param myuris: Maps each file name to a tuple of available fetch URIs.
    @type myuris: dict
    @param mysettings: Portage config instance.
    @type mysettings: portage.config
    @param listonly: Only print URIs and do not actually fetch them.
    @type listonly: bool
    @param fetchonly: Do not block for files that are locked by a
            concurrent fetcher process. This means that the function can
            return successfully *before* all files have been successfully
            fetched!
    @type fetchonly: bool
    @param use_locks: Enable locks. This parameter is ineffective if
            FEATURES=distlocks is disabled in the portage config!
    @type use_locks: bool
    @param digests: Maps each file name to a dict of digest types and values.
    @type digests: dict
    @param allow_missing_digests: Enable fetch even if there are no digests
            available for verification.
    @type allow_missing_digests: bool
    @param force: Force download, even when a file already exists in
            DISTDIR. This is most useful when there are no digests available,
            since otherwise download will be automatically forced if the
            existing file does not match the available digests. Also, this
            avoids the need to remove the existing file in advance, which
            makes it possible to atomically replace the file and avoid
            interference with concurrent processes.
    @type force: bool
    @rtype: int
    @return: 1 if successful, 0 otherwise.
    """
    return asyncio.run(
        async_fetch(
            myuris,
            mysettings,
            listonly=listonly,
            fetchonly=fetchonly,
            locks_in_subdir=locks_in_subdir,
            use_locks=use_locks,
            try_mirrors=try_mirrors,
            digests=digests,
            allow_missing_digests=allow_missing_digests,
            force=force,
        )
    )


async def async_fetch(
    myuris,
    mysettings,
    listonly=0,
    fetchonly=0,
    locks_in_subdir=".locks",
    use_locks=1,
    try_mirrors=1,
    digests=None,
    allow_missing_digests=True,
    force=False,
):

    if force and digests:
        # Since the force parameter can trigger unnecessary fetch when the
        # digests match, do not allow force=True when digests are provided.
        raise PortageException(
            _("fetch: force=True is not allowed when digests are provided")
        )

    if not myuris:
        return 1

    features = mysettings.features
    restrict = mysettings.get("PORTAGE_RESTRICT", "").split()
    userfetch = portage.data.secpass >= 2 and "userfetch" in features

    # 'nomirror' is bad/negative logic. You Restrict mirroring, not no-mirroring.
    restrict_mirror = "mirror" in restrict or "nomirror" in restrict
    if restrict_mirror:
        if ("mirror" in features) and ("lmirror" not in features):
            # lmirror should allow you to bypass mirror restrictions.
            # XXX: This is not a good thing, and is temporary at best.
            print(
                _(
                    '>>> "mirror" mode desired and "mirror" restriction found; skipping fetch.'
                )
            )
            return 1

    # Generally, downloading the same file repeatedly from
    # every single available mirror is a waste of bandwidth
    # and time, so there needs to be a cap.
    checksum_failure_max_tries = 5
    v = checksum_failure_max_tries
    try:
        v = int(
            mysettings.get(
                "PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS", checksum_failure_max_tries
            )
        )
    except (ValueError, OverflowError):
        writemsg(
            _(
                "!!! Variable PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS"
                " contains non-integer value: '%s'\n"
            )
            % mysettings["PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS"],
            noiselevel=-1,
        )
        writemsg(
            _("!!! Using PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS " "default value: %s\n")
            % checksum_failure_max_tries,
            noiselevel=-1,
        )
        v = checksum_failure_max_tries
    if v < 1:
        writemsg(
            _(
                "!!! Variable PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS"
                " contains value less than 1: '%s'\n"
            )
            % v,
            noiselevel=-1,
        )
        writemsg(
            _("!!! Using PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS " "default value: %s\n")
            % checksum_failure_max_tries,
            noiselevel=-1,
        )
        v = checksum_failure_max_tries
    checksum_failure_max_tries = v
    del v

    fetch_resume_size_default = "350K"
    fetch_resume_size = mysettings.get("PORTAGE_FETCH_RESUME_MIN_SIZE")
    if fetch_resume_size is not None:
        fetch_resume_size = "".join(fetch_resume_size.split())
        if not fetch_resume_size:
            # If it's undefined or empty, silently use the default.
            fetch_resume_size = fetch_resume_size_default
        match = _fetch_resume_size_re.match(fetch_resume_size)
        if match is None or (match.group(2).upper() not in _size_suffix_map):
            writemsg(
                _(
                    "!!! Variable PORTAGE_FETCH_RESUME_MIN_SIZE"
                    " contains an unrecognized format: '%s'\n"
                )
                % mysettings["PORTAGE_FETCH_RESUME_MIN_SIZE"],
                noiselevel=-1,
            )
            writemsg(
                _("!!! Using PORTAGE_FETCH_RESUME_MIN_SIZE " "default value: %s\n")
                % fetch_resume_size_default,
                noiselevel=-1,
            )
            fetch_resume_size = None
    if fetch_resume_size is None:
        fetch_resume_size = fetch_resume_size_default
        match = _fetch_resume_size_re.match(fetch_resume_size)
    fetch_resume_size = (
        int(match.group(1)) * 2 ** _size_suffix_map[match.group(2).upper()]
    )

    # Behave like the package has RESTRICT="primaryuri" after a
    # couple of checksum failures, to increase the probablility
    # of success before checksum_failure_max_tries is reached.
    checksum_failure_primaryuri = 2
    thirdpartymirrors = mysettings.thirdpartymirrors()

    # In the background parallel-fetch process, it's safe to skip checksum
    # verification of pre-existing files in $DISTDIR that have the correct
    # file size. The parent process will verify their checksums prior to
    # the unpack phase.

    parallel_fetchonly = "PORTAGE_PARALLEL_FETCHONLY" in mysettings
    if parallel_fetchonly:
        fetchonly = 1

    check_config_instance(mysettings)

    custommirrors = grabdict(
        os.path.join(mysettings["PORTAGE_CONFIGROOT"], CUSTOM_MIRRORS_FILE), recursive=1
    )

    if listonly or ("distlocks" not in features):
        use_locks = 0

    distdir_writable = os.access(mysettings["DISTDIR"], os.W_OK)
    fetch_to_ro = 0
    if "skiprocheck" in features:
        fetch_to_ro = 1

    if not distdir_writable and fetch_to_ro:
        if use_locks:
            writemsg(
                colorize(
                    "BAD",
                    _(
                        "!!! For fetching to a read-only filesystem, "
                        "locking should be turned off.\n"
                    ),
                ),
                noiselevel=-1,
            )
            writemsg(
                _(
                    "!!! This can be done by adding -distlocks to "
                    "FEATURES in /etc/portage/make.conf\n"
                ),
                noiselevel=-1,
            )
    # 			use_locks = 0

    local_mirrors = []
    public_mirrors = []
    fsmirrors = []
    if try_mirrors:
        for x in custommirrors.get("local", []):
            if x.startswith("/"):
                fsmirrors.append(x)
            else:
                local_mirrors.append(x)
        for x in mysettings["GENTOO_MIRRORS"].split():
            if not x:
                continue
            if x.startswith("/"):
                fsmirrors.append(x.rstrip("/"))
            else:
                public_mirrors.append(x.rstrip("/"))

    hash_filter = _hash_filter(mysettings.get("PORTAGE_CHECKSUM_FILTER", ""))
    if hash_filter.transparent:
        hash_filter = None
    skip_manifest = mysettings.get("EBUILD_SKIP_MANIFEST") == "1"
    if skip_manifest:
        allow_missing_digests = True
    pkgdir = mysettings.get("O")
    if digests is None and not (pkgdir is None or skip_manifest):
        mydigests = (
            mysettings.repositories.get_repo_for_location(
                os.path.dirname(os.path.dirname(pkgdir))
            )
            .load_manifest(pkgdir, mysettings["DISTDIR"])
            .getTypeDigests("DIST")
        )
    elif digests is None or skip_manifest:
        # no digests because fetch was not called for a specific package
        mydigests = {}
    else:
        mydigests = digests

    ro_distdirs = [
        x
        for x in shlex.split(mysettings.get("PORTAGE_RO_DISTDIRS", ""))
        if os.path.isdir(x)
    ]

    restrict_fetch = "fetch" in restrict
    force_mirror = "force-mirror" in features and not restrict_mirror and try_mirrors

    file_uri_tuples = []
    # Check for 'items' attribute since OrderedDict is not a dict.
    if hasattr(myuris, "items"):
        for myfile, uri_set in myuris.items():
            for myuri in uri_set:
                file_uri_tuples.append(
                    (DistfileName(myfile, digests=mydigests.get(myfile)), myuri)
                )
            if not uri_set:
                file_uri_tuples.append(
                    (DistfileName(myfile, digests=mydigests.get(myfile)), None)
                )
    else:
        for myuri in myuris:
            if urlparse(myuri).scheme:
                file_uri_tuples.append(
                    (
                        DistfileName(
                            os.path.basename(myuri),
                            digests=mydigests.get(os.path.basename(myuri)),
                        ),
                        myuri,
                    )
                )
            else:
                file_uri_tuples.append(
                    (
                        DistfileName(
                            os.path.basename(myuri),
                            digests=mydigests.get(os.path.basename(myuri)),
                        ),
                        None,
                    )
                )

    filedict = OrderedDict()
    primaryuri_dict = {}
    thirdpartymirror_uris = {}
    for myfile, myuri in file_uri_tuples:
        override_mirror = (myuri or "").startswith("mirror+")
        override_fetch = override_mirror or (myuri or "").startswith("fetch+")
        if override_fetch:
            myuri = myuri.partition("+")[2]

        if myfile not in filedict:
            filedict[myfile] = []
            if distdir_writable:
                mirror_cache = os.path.join(mysettings["DISTDIR"], ".mirror-cache.json")
            else:
                mirror_cache = None

            # fetch restriction implies mirror restriction
            # but fetch unrestriction does not grant mirror permission
            file_restrict_mirror = (
                restrict_fetch or restrict_mirror
            ) and not override_mirror

            # With fetch restriction, a normal uri may only be fetched from
            # custom local mirrors (if available).  A mirror:// uri may also
            # be fetched from specific mirrors (effectively overriding fetch
            # restriction, but only for specific mirrors).
            location_lists = [local_mirrors]
            if not file_restrict_mirror:
                location_lists.append(public_mirrors)

            for l in itertools.chain(*location_lists):
                filedict[myfile].append(
                    functools.partial(
                        async_mirror_url, l, myfile, mysettings, mirror_cache
                    )
                )
        if myuri is None:
            continue
        if myuri[:9] == "mirror://":
            eidx = myuri.find("/", 9)
            if eidx != -1:
                mirrorname = myuri[9:eidx]
                path = myuri[eidx + 1 :]

                # Try user-defined mirrors first
                if mirrorname in custommirrors:
                    for cmirr in custommirrors[mirrorname]:
                        filedict[myfile].append(cmirr.rstrip("/") + "/" + path)

                # now try the official mirrors
                if mirrorname in thirdpartymirrors:
                    uris = [
                        locmirr.rstrip("/") + "/" + path
                        for locmirr in thirdpartymirrors[mirrorname]
                    ]
                    random.shuffle(uris)
                    filedict[myfile].extend(uris)
                    thirdpartymirror_uris.setdefault(myfile, []).extend(uris)

                if (
                    mirrorname not in custommirrors
                    and mirrorname not in thirdpartymirrors
                ):
                    writemsg(_("!!! No known mirror by the name: %s\n") % (mirrorname))
            else:
                writemsg(_("Invalid mirror definition in SRC_URI:\n"), noiselevel=-1)
                writemsg(f"  {myuri}\n", noiselevel=-1)
        else:
            if (restrict_fetch and not override_fetch) or force_mirror:
                # Only fetch from specific mirrors is allowed.
                continue
            primaryuris = primaryuri_dict.get(myfile)
            if primaryuris is None:
                primaryuris = []
                primaryuri_dict[myfile] = primaryuris
            primaryuris.append(myuri)

    # Order primaryuri_dict values to match that in SRC_URI.
    for uris in primaryuri_dict.values():
        uris.reverse()

    # Prefer thirdpartymirrors over normal mirrors in cases when
    # the file does not yet exist on the normal mirrors.
    for myfile, uris in thirdpartymirror_uris.items():
        primaryuri_dict.setdefault(myfile, []).extend(uris)

    # Now merge primaryuri values into filedict (includes mirrors
    # explicitly referenced in SRC_URI).
    if "primaryuri" in restrict:
        for myfile, uris in filedict.items():
            filedict[myfile] = primaryuri_dict.get(myfile, []) + uris
    else:
        for myfile in filedict:
            filedict[myfile] += primaryuri_dict.get(myfile, [])

    can_fetch = True

    if listonly:
        can_fetch = False

    if can_fetch and not fetch_to_ro:
        try:
            await _ensure_distdir(mysettings, mysettings["DISTDIR"])
        except PortageException as e:
            if not os.path.isdir(mysettings["DISTDIR"]):
                writemsg(f"!!! {str(e)}\n", noiselevel=-1)
                writemsg(
                    _("!!! Directory Not Found: DISTDIR='%s'\n")
                    % mysettings["DISTDIR"],
                    noiselevel=-1,
                )
                writemsg(_("!!! Fetching will fail!\n"), noiselevel=-1)

    if can_fetch and not fetch_to_ro and not os.access(mysettings["DISTDIR"], os.W_OK):
        writemsg(
            _("!!! No write access to '%s'\n") % mysettings["DISTDIR"], noiselevel=-1
        )
        can_fetch = False

    distdir_writable = can_fetch and not fetch_to_ro
    failed_files = set()
    restrict_fetch_msg = False
    valid_hashes = set(get_valid_checksum_keys())
    valid_hashes.discard("size")

    for myfile in filedict:
        """
        fetched  status
        0        nonexistent
        1        partially downloaded
        2        completely downloaded
        """
        fetched = 0

        orig_digests = mydigests.get(myfile, {})

        if not (allow_missing_digests or listonly):
            verifiable_hash_types = set(orig_digests).intersection(valid_hashes)
            if not verifiable_hash_types:
                expected = " ".join(sorted(valid_hashes))
                got = set(orig_digests)
                got.discard("size")
                got = " ".join(sorted(got))
                reason = (
                    _("Insufficient data for checksum verification"),
                    got,
                    expected,
                )
                writemsg(
                    _("!!! Fetched file: %s VERIFY FAILED!\n") % myfile, noiselevel=-1
                )
                writemsg(_("!!! Reason: %s\n") % reason[0], noiselevel=-1)
                writemsg(
                    _("!!! Got:      %s\n!!! Expected: %s\n") % (reason[1], reason[2]),
                    noiselevel=-1,
                )

                if fetchonly:
                    failed_files.add(myfile)
                    continue
                else:
                    return 0

        size = orig_digests.get("size")
        if size == 0:
            # Zero-byte distfiles are always invalid, so discard their digests.
            del mydigests[myfile]
            orig_digests.clear()
            size = None
        pruned_digests = orig_digests
        if parallel_fetchonly:
            pruned_digests = {}
            if size is not None:
                pruned_digests["size"] = size

        myfile_path = os.path.join(mysettings["DISTDIR"], myfile)
        download_path = myfile_path if fetch_to_ro else myfile_path + _download_suffix
        has_space = True
        has_space_superuser = True
        file_lock = None
        if listonly:
            writemsg_stdout("\n", noiselevel=-1)
        else:
            # check if there is enough space in DISTDIR to completely store myfile
            # overestimate the filesize so we aren't bitten by FS overhead
            vfs_stat = None
            if size is not None and hasattr(os, "statvfs"):
                try:
                    vfs_stat = os.statvfs(mysettings["DISTDIR"])
                except OSError as e:
                    writemsg_level(
                        f"!!! statvfs('{mysettings['DISTDIR']}'): {e}\n",
                        noiselevel=-1,
                        level=logging.ERROR,
                    )
                    del e

            if vfs_stat is not None:
                try:
                    mysize = os.stat(myfile_path).st_size
                except OSError as e:
                    if e.errno not in (errno.ENOENT, errno.ESTALE):
                        raise
                    del e
                    mysize = 0
                if (size - mysize + vfs_stat.f_bsize) >= (
                    vfs_stat.f_bsize * vfs_stat.f_bavail
                ):
                    if (size - mysize + vfs_stat.f_bsize) >= (
                        vfs_stat.f_bsize * vfs_stat.f_bfree
                    ):
                        has_space_superuser = False

                    if not has_space_superuser:
                        has_space = False
                    elif portage.data.secpass < 2:
                        has_space = False
                    elif userfetch:
                        has_space = False

            if distdir_writable and use_locks:
                lock_kwargs = {}
                if fetchonly:
                    lock_kwargs["flags"] = os.O_NONBLOCK

                try:
                    file_lock = lockfile(myfile_path, wantnewlockfile=1, **lock_kwargs)
                except TryAgain:
                    writemsg(
                        _(
                            ">>> File '%s' is already locked by "
                            "another fetcher. Continuing...\n"
                        )
                        % myfile,
                        noiselevel=-1,
                    )
                    continue
        try:
            if not listonly:
                eout = EOutput()
                eout.quiet = mysettings.get("PORTAGE_QUIET") == "1"
                match, mystat = _check_distfile(
                    myfile_path, pruned_digests, eout, hash_filter=hash_filter
                )
                if match and not force:
                    # Skip permission adjustment for symlinks, since we don't
                    # want to modify anything outside of the primary DISTDIR,
                    # and symlinks typically point to PORTAGE_RO_DISTDIRS.
                    if distdir_writable and not os.path.islink(myfile_path):
                        try:
                            apply_secpass_permissions(
                                myfile_path,
                                gid=portage_gid,
                                mode=0o664,
                                mask=0o2,
                                stat_cached=mystat,
                            )
                        except PortageException as e:
                            if not os.access(myfile_path, os.R_OK):
                                writemsg(
                                    _("!!! Failed to adjust permissions:" " %s\n")
                                    % str(e),
                                    noiselevel=-1,
                                )
                            del e
                    continue

                # Remove broken symlinks or symlinks to files which
                # _check_distfile did not match above.
                if distdir_writable and mystat is None or os.path.islink(myfile_path):
                    try:
                        os.unlink(myfile_path)
                    except OSError as e:
                        if e.errno not in (errno.ENOENT, errno.ESTALE):
                            raise
                    mystat = None

                if mystat is not None:
                    if stat.S_ISDIR(mystat.st_mode):
                        writemsg_level(
                            _(
                                "!!! Unable to fetch file since "
                                "a directory is in the way: \n"
                                "!!!   %s\n"
                            )
                            % myfile_path,
                            level=logging.ERROR,
                            noiselevel=-1,
                        )
                        return 0

                    if distdir_writable and not force:
                        # Since _check_distfile did not match above, the file
                        # is either corrupt or its identity has changed since
                        # the last time it was fetched, so rename it.
                        temp_filename = _checksum_failure_temp_file(
                            mysettings, mysettings["DISTDIR"], myfile
                        )
                        writemsg_stdout(
                            _("Refetching... " "File renamed to '%s'\n\n")
                            % temp_filename,
                            noiselevel=-1,
                        )

                # Stat the temporary download file for comparison with
                # fetch_resume_size.
                try:
                    mystat = os.stat(download_path)
                except OSError as e:
                    if e.errno not in (errno.ENOENT, errno.ESTALE):
                        raise
                    mystat = None

                if mystat is not None:
                    if mystat.st_size == 0:
                        if distdir_writable:
                            try:
                                os.unlink(download_path)
                            except OSError:
                                pass
                    elif distdir_writable and size is not None:
                        if mystat.st_size < fetch_resume_size and mystat.st_size < size:
                            # If the file already exists and the size does not
                            # match the existing digests, it may be that the
                            # user is attempting to update the digest. In this
                            # case, the digestgen() function will advise the
                            # user to use `ebuild --force foo.ebuild manifest`
                            # in order to force the old digests to be replaced.
                            # Since the user may want to keep this file, rename
                            # it instead of deleting it.
                            writemsg(
                                _(
                                    ">>> Renaming distfile with size "
                                    "%d (smaller than "
                                    "PORTAGE_FETCH_RESU"
                                    "ME_MIN_SIZE)\n"
                                )
                                % mystat.st_size
                            )
                            temp_filename = _checksum_failure_temp_file(
                                mysettings,
                                mysettings["DISTDIR"],
                                os.path.basename(download_path),
                            )
                            writemsg_stdout(
                                _("Refetching... " "File renamed to '%s'\n\n")
                                % temp_filename,
                                noiselevel=-1,
                            )
                        elif mystat.st_size >= size:
                            temp_filename = _checksum_failure_temp_file(
                                mysettings,
                                mysettings["DISTDIR"],
                                os.path.basename(download_path),
                            )
                            writemsg_stdout(
                                _("Refetching... " "File renamed to '%s'\n\n")
                                % temp_filename,
                                noiselevel=-1,
                            )

                if distdir_writable and ro_distdirs:
                    readonly_file = None
                    for x in ro_distdirs:
                        filename = await async_mirror_url(x, myfile, mysettings)
                        match, mystat = _check_distfile(
                            filename, pruned_digests, eout, hash_filter=hash_filter
                        )
                        if match:
                            readonly_file = filename
                            break
                    if readonly_file is not None:
                        try:
                            os.unlink(myfile_path)
                        except OSError as e:
                            if e.errno not in (errno.ENOENT, errno.ESTALE):
                                raise
                            del e
                        os.symlink(readonly_file, myfile_path)
                        continue

                # this message is shown only after we know that
                # the file is not already fetched
                if not has_space:
                    writemsg(
                        _("!!! Insufficient space to store %s in %s\n")
                        % (myfile, mysettings["DISTDIR"]),
                        noiselevel=-1,
                    )

                    if has_space_superuser:
                        writemsg(
                            _(
                                "!!! Insufficient privileges to use "
                                "remaining space.\n"
                            ),
                            noiselevel=-1,
                        )
                        if userfetch:
                            writemsg(
                                _(
                                    '!!! You may set FEATURES="-userfetch"'
                                    " in /etc/portage/make.conf in order to fetch with\n"
                                    "!!! superuser privileges.\n"
                                ),
                                noiselevel=-1,
                            )

                if fsmirrors and not os.path.exists(myfile_path) and has_space:
                    for mydir in fsmirrors:
                        mirror_file = await async_mirror_url(mydir, myfile, mysettings)
                        try:
                            shutil.copyfile(mirror_file, download_path)
                            writemsg(_("Local mirror has file: %s\n") % myfile)
                            break
                        except OSError as e:
                            if e.errno not in (errno.ENOENT, errno.ESTALE):
                                raise
                            del e

                try:
                    mystat = os.stat(download_path)
                except OSError as e:
                    if e.errno not in (errno.ENOENT, errno.ESTALE):
                        raise
                    del e
                else:
                    # Skip permission adjustment for symlinks, since we don't
                    # want to modify anything outside of the primary DISTDIR,
                    # and symlinks typically point to PORTAGE_RO_DISTDIRS.
                    if not os.path.islink(download_path):
                        try:
                            apply_secpass_permissions(
                                download_path,
                                gid=portage_gid,
                                mode=0o664,
                                mask=0o2,
                                stat_cached=mystat,
                            )
                        except PortageException as e:
                            if not os.access(download_path, os.R_OK):
                                writemsg(
                                    _("!!! Failed to adjust permissions:" " %s\n")
                                    % (e,),
                                    noiselevel=-1,
                                )

                    # If the file is empty then it's obviously invalid. Remove
                    # the empty file and try to download if possible.
                    if mystat.st_size == 0:
                        if distdir_writable:
                            try:
                                os.unlink(download_path)
                            except OSError:
                                pass
                    elif not orig_digests:
                        # We don't have a digest, and the temporary file exists.
                        if not force:
                            # Try to resume this download when full
                            # download has not been explicitly forced.
                            fetched = 1
                    else:
                        if (
                            mydigests[myfile].get("size") is not None
                            and mystat.st_size < mydigests[myfile]["size"]
                            and not restrict_fetch
                        ):
                            fetched = 1  # Try to resume this download.
                        elif (
                            parallel_fetchonly
                            and mystat.st_size == mydigests[myfile]["size"]
                        ):
                            eout = EOutput()
                            eout.quiet = mysettings.get("PORTAGE_QUIET") == "1"
                            eout.ebegin(f"{myfile} size ;-)")
                            eout.eend(0)
                            continue
                        else:
                            digests = _filter_unaccelarated_hashes(mydigests[myfile])
                            if hash_filter is not None:
                                digests = _apply_hash_filter(digests, hash_filter)
                            verified_ok, reason = verify_all(download_path, digests)
                            if not verified_ok:
                                writemsg(
                                    _("!!! Previously fetched" " file: '%s'\n")
                                    % myfile,
                                    noiselevel=-1,
                                )
                                writemsg(
                                    _("!!! Reason: %s\n") % reason[0], noiselevel=-1
                                )
                                writemsg(
                                    _("!!! Got:      %s\n" "!!! Expected: %s\n")
                                    % (reason[1], reason[2]),
                                    noiselevel=-1,
                                )
                                if reason[0] == _(
                                    "Insufficient data for checksum verification"
                                ):
                                    return 0
                                if distdir_writable:
                                    temp_filename = _checksum_failure_temp_file(
                                        mysettings,
                                        mysettings["DISTDIR"],
                                        os.path.basename(download_path),
                                    )
                                    writemsg_stdout(
                                        _("Refetching... " "File renamed to '%s'\n\n")
                                        % temp_filename,
                                        noiselevel=-1,
                                    )
                            else:
                                if not fetch_to_ro:
                                    _movefile(
                                        download_path,
                                        myfile_path,
                                        mysettings=mysettings,
                                    )
                                eout = EOutput()
                                eout.quiet = (
                                    mysettings.get("PORTAGE_QUIET", None) == "1"
                                )
                                if digests:
                                    digests = list(digests)
                                    digests.sort()
                                    eout.ebegin(f"{myfile} {' '.join(digests)} ;-)")
                                    eout.eend(0)
                                continue  # fetch any remaining files

            # Create a reversed list since that is optimal for list.pop().
            uri_list = filedict[myfile][:]
            uri_list.reverse()
            checksum_failure_count = 0
            tried_locations = set()
            while uri_list:
                loc = uri_list.pop()
                if isinstance(loc, functools.partial):
                    loc = await loc()
                # Eliminate duplicates here in case we've switched to
                # "primaryuri" mode on the fly due to a checksum failure.
                if loc in tried_locations:
                    continue
                tried_locations.add(loc)
                if listonly:
                    writemsg_stdout(loc + " ", noiselevel=-1)
                    fetched = 2
                    continue
                # allow different fetchcommands per protocol
                protocol = loc[0 : loc.find("://")]

                global_config_path = GLOBAL_CONFIG_PATH
                if portage.const.EPREFIX:
                    global_config_path = os.path.join(
                        portage.const.EPREFIX, GLOBAL_CONFIG_PATH.lstrip(os.sep)
                    )

                missing_file_param = False
                fetchcommand_var = "FETCHCOMMAND_" + protocol.upper()
                fetchcommand = mysettings.get(fetchcommand_var)
                if fetchcommand is None:
                    fetchcommand_var = "FETCHCOMMAND"
                    fetchcommand = mysettings.get(fetchcommand_var)
                    if fetchcommand is None:
                        writemsg_level(
                            _(
                                "!!! %s is unset. It should "
                                "have been defined in\n!!! %s/make.globals.\n"
                            )
                            % (fetchcommand_var, global_config_path),
                            level=logging.ERROR,
                            noiselevel=-1,
                        )
                        return 0
                if "${FILE}" not in fetchcommand:
                    writemsg_level(
                        _(
                            "!!! %s does not contain the required ${FILE}"
                            " parameter.\n"
                        )
                        % fetchcommand_var,
                        level=logging.ERROR,
                        noiselevel=-1,
                    )
                    missing_file_param = True

                resumecommand_var = "RESUMECOMMAND_" + protocol.upper()
                resumecommand = mysettings.get(resumecommand_var)
                if resumecommand is None:
                    resumecommand_var = "RESUMECOMMAND"
                    resumecommand = mysettings.get(resumecommand_var)
                    if resumecommand is None:
                        writemsg_level(
                            _(
                                "!!! %s is unset. It should "
                                "have been defined in\n!!! %s/make.globals.\n"
                            )
                            % (resumecommand_var, global_config_path),
                            level=logging.ERROR,
                            noiselevel=-1,
                        )
                        return 0
                if "${FILE}" not in resumecommand:
                    writemsg_level(
                        _(
                            "!!! %s does not contain the required ${FILE}"
                            " parameter.\n"
                        )
                        % resumecommand_var,
                        level=logging.ERROR,
                        noiselevel=-1,
                    )
                    missing_file_param = True

                if missing_file_param:
                    writemsg_level(
                        _(
                            "!!! Refer to the make.conf(5) man page for "
                            "information about how to\n!!! correctly specify "
                            "FETCHCOMMAND and RESUMECOMMAND.\n"
                        ),
                        level=logging.ERROR,
                        noiselevel=-1,
                    )
                    if myfile != os.path.basename(loc):
                        return 0

                if not can_fetch:
                    if fetched != 2:
                        try:
                            mysize = os.stat(download_path).st_size
                        except OSError as e:
                            if e.errno not in (errno.ENOENT, errno.ESTALE):
                                raise
                            del e
                            mysize = 0

                        if mysize == 0:
                            writemsg(
                                _("!!! File %s isn't fetched but unable to get it.\n")
                                % myfile,
                                noiselevel=-1,
                            )
                        elif size is None or size > mysize:
                            writemsg(
                                _(
                                    "!!! File %s isn't fully fetched, but unable to complete it\n"
                                )
                                % myfile,
                                noiselevel=-1,
                            )
                        else:
                            writemsg(
                                _(
                                    "!!! File %s is incorrect size, "
                                    "but unable to retry.\n"
                                )
                                % myfile,
                                noiselevel=-1,
                            )
                        return 0
                    continue

                if fetched != 2 and has_space:
                    # we either need to resume or start the download
                    if fetched == 1:
                        try:
                            mystat = os.stat(download_path)
                        except OSError as e:
                            if e.errno not in (errno.ENOENT, errno.ESTALE):
                                raise
                            del e
                            fetched = 0
                        else:
                            if distdir_writable and mystat.st_size < fetch_resume_size:
                                writemsg(
                                    _(
                                        ">>> Deleting distfile with size "
                                        "%d (smaller than "
                                        "PORTAGE_FETCH_RESU"
                                        "ME_MIN_SIZE)\n"
                                    )
                                    % mystat.st_size
                                )
                                try:
                                    os.unlink(download_path)
                                except OSError as e:
                                    if e.errno not in (errno.ENOENT, errno.ESTALE):
                                        raise
                                    del e
                                fetched = 0
                    if fetched == 1:
                        # resume mode:
                        writemsg(_(">>> Resuming download...\n"))
                        locfetch = resumecommand
                        command_var = resumecommand_var
                    else:
                        # normal mode:
                        locfetch = fetchcommand
                        command_var = fetchcommand_var
                    writemsg_stdout(_(">>> Downloading '%s'\n") % _hide_url_passwd(loc))
                    variables = {"URI": loc, "FILE": os.path.basename(download_path)}

                    try:
                        variables["DIGESTS"] = " ".join(
                            [
                                f"{k.lower()}:{v}"
                                for k, v in mydigests[myfile].items()
                                if k != "size"
                            ]
                        )
                    except KeyError:
                        pass

                    for k in ("DISTDIR", "PORTAGE_SSH_OPTS"):
                        v = mysettings.get(k)
                        if v is not None:
                            variables[k] = v

                    myfetch = varexpand(locfetch, mydict=variables)
                    myfetch = shlex.split(myfetch)

                    myret = -1
                    try:
                        myret = await _async_spawn_fetch(mysettings, myfetch)

                    finally:
                        try:
                            apply_secpass_permissions(
                                download_path, gid=portage_gid, mode=0o664, mask=0o2
                            )
                        except FileNotFound:
                            pass
                        except PortageException as e:
                            if not os.access(download_path, os.R_OK):
                                writemsg(
                                    _("!!! Failed to adjust permissions:" " %s\n")
                                    % str(e),
                                    noiselevel=-1,
                                )
                            del e

                    # If the file is empty then it's obviously invalid.  Don't
                    # trust the return value from the fetcher.  Remove the
                    # empty file and try to download again.
                    try:
                        mystat = os.lstat(download_path)
                        if mystat.st_size == 0 or (
                            stat.S_ISLNK(mystat.st_mode)
                            and not os.path.exists(download_path)
                        ):
                            os.unlink(download_path)
                            fetched = 0
                            continue
                    except OSError:
                        pass

                    if mydigests is not None and myfile in mydigests:
                        try:
                            mystat = os.stat(download_path)
                        except OSError as e:
                            if e.errno not in (errno.ENOENT, errno.ESTALE):
                                raise
                            del e
                            fetched = 0
                        else:
                            if stat.S_ISDIR(mystat.st_mode):
                                # This can happen if FETCHCOMMAND erroneously
                                # contains wget's -P option where it should
                                # instead have -O.
                                writemsg_level(
                                    _(
                                        "!!! The command specified in the "
                                        "%s variable appears to have\n!!! "
                                        "created a directory instead of a "
                                        "normal file.\n"
                                    )
                                    % command_var,
                                    level=logging.ERROR,
                                    noiselevel=-1,
                                )
                                writemsg_level(
                                    _(
                                        "!!! Refer to the make.conf(5) "
                                        "man page for information about how "
                                        "to\n!!! correctly specify "
                                        "FETCHCOMMAND and RESUMECOMMAND.\n"
                                    ),
                                    level=logging.ERROR,
                                    noiselevel=-1,
                                )
                                return 0

                            # no exception?  file exists. let digestcheck() report
                            # an appropriately for size or checksum errors

                            # If the fetcher reported success and the file is
                            # too small, it's probably because the digest is
                            # bad (upstream changed the distfile).  In this
                            # case we don't want to attempt to resume. Show a
                            # digest verification failure to that the user gets
                            # a clue about what just happened.
                            if (
                                myret != os.EX_OK
                                and mystat.st_size < mydigests[myfile]["size"]
                            ):
                                # Fetch failed... Try the next one... Kill 404 files though.
                                if (
                                    (mystat[stat.ST_SIZE] < 100000)
                                    and (len(myfile) > 4)
                                    and not (
                                        (myfile[-5:] == ".html")
                                        or (myfile[-4:] == ".htm")
                                    )
                                ):
                                    html404 = re.compile(
                                        "<title>.*(not found|404).*</title>",
                                        re.I | re.M,
                                    )
                                    with open(
                                        _unicode_encode(
                                            download_path,
                                            encoding=_encodings["fs"],
                                            errors="strict",
                                        ),
                                        encoding=_encodings["content"],
                                        errors="replace",
                                    ) as f:
                                        if html404.search(f.read()):
                                            try:
                                                os.unlink(download_path)
                                                writemsg(
                                                    _(
                                                        ">>> Deleting invalid distfile. (Improper 404 redirect from server.)\n"
                                                    )
                                                )
                                                fetched = 0
                                                continue
                                            except OSError:
                                                pass
                                fetched = 1
                                continue
                            if True:
                                # File is the correct size--check the checksums for the fetched
                                # file NOW, for those users who don't have a stable/continuous
                                # net connection. This way we have a chance to try to download
                                # from another mirror...
                                digests = _filter_unaccelarated_hashes(
                                    mydigests[myfile]
                                )
                                if hash_filter is not None:
                                    digests = _apply_hash_filter(digests, hash_filter)
                                verified_ok, reason = verify_all(download_path, digests)
                                if not verified_ok:
                                    writemsg(
                                        _("!!! Fetched file: %s VERIFY FAILED!\n")
                                        % myfile,
                                        noiselevel=-1,
                                    )
                                    writemsg(
                                        _("!!! Reason: %s\n") % reason[0], noiselevel=-1
                                    )
                                    writemsg(
                                        _("!!! Got:      %s\n!!! Expected: %s\n")
                                        % (reason[1], reason[2]),
                                        noiselevel=-1,
                                    )
                                    if reason[0] == _(
                                        "Insufficient data for checksum verification"
                                    ):
                                        return 0
                                    if distdir_writable:
                                        temp_filename = _checksum_failure_temp_file(
                                            mysettings,
                                            mysettings["DISTDIR"],
                                            os.path.basename(download_path),
                                        )
                                        writemsg_stdout(
                                            _(
                                                "Refetching... "
                                                "File renamed to '%s'\n\n"
                                            )
                                            % temp_filename,
                                            noiselevel=-1,
                                        )
                                    fetched = 0
                                    checksum_failure_count += 1
                                    if (
                                        checksum_failure_count
                                        == checksum_failure_primaryuri
                                    ):
                                        # Switch to "primaryuri" mode in order
                                        # to increase the probablility of
                                        # of success.
                                        primaryuris = primaryuri_dict.get(myfile)
                                        if primaryuris:
                                            uri_list.extend(reversed(primaryuris))
                                    if (
                                        checksum_failure_count
                                        >= checksum_failure_max_tries
                                    ):
                                        break
                                else:
                                    if not fetch_to_ro:
                                        _movefile(
                                            download_path,
                                            myfile_path,
                                            mysettings=mysettings,
                                        )
                                    eout = EOutput()
                                    eout.quiet = (
                                        mysettings.get("PORTAGE_QUIET", None) == "1"
                                    )
                                    if digests:
                                        eout.ebegin(
                                            f"{myfile} {' '.join(sorted(digests))} ;-)"
                                        )
                                        eout.eend(0)
                                    fetched = 2
                                    break
                    else:  # no digests available
                        if not myret:
                            if not fetch_to_ro:
                                _movefile(
                                    download_path, myfile_path, mysettings=mysettings
                                )
                            fetched = 2
                            break
                        elif mydigests is not None:
                            writemsg(
                                _("No digest file available and download failed.\n\n"),
                                noiselevel=-1,
                            )
        finally:
            if use_locks and file_lock:
                unlockfile(file_lock)
                file_lock = None

        if listonly:
            writemsg_stdout("\n", noiselevel=-1)
        if fetched != 2:
            if restrict_fetch and not restrict_fetch_msg:
                restrict_fetch_msg = True
                msg = _(
                    "\n!!! %s/%s"
                    " has fetch restriction turned on.\n"
                    "!!! This probably means that this "
                    "ebuild's files must be downloaded\n"
                    "!!! manually.  See the comments in"
                    " the ebuild for more information.\n\n"
                ) % (mysettings["CATEGORY"], mysettings["PF"])
                writemsg_level(msg, level=logging.ERROR, noiselevel=-1)
            elif restrict_fetch:
                pass
            elif listonly:
                pass
            elif not filedict[myfile]:
                writemsg(
                    _("Warning: No mirrors available for file" " '%s'\n") % (myfile),
                    noiselevel=-1,
                )
            else:
                writemsg(
                    _("!!! Couldn't download '%s'. Aborting.\n") % myfile, noiselevel=-1
                )

            if listonly:
                failed_files.add(myfile)
                continue
            elif fetchonly:
                failed_files.add(myfile)
                continue
            return 0
    if failed_files:
        return 0
    return 1


async_fetch.__doc__ = fetch.__doc__
async_fetch.__doc__ += """
    This function is a coroutine.
"""
