# Copyright (C) 2011 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""Resizefs: cloud-config module which resizes the filesystem"""

import errno
import os
import stat
from textwrap import dedent

from cloudinit import subp, util
from cloudinit.config.schema import get_meta_doc, validate_cloudconfig_schema
from cloudinit.settings import PER_ALWAYS

NOBLOCK = "noblock"

frequency = PER_ALWAYS
distros = ["all"]

meta = {
    "id": "cc_resizefs",
    "name": "Resizefs",
    "title": "Resize filesystem",
    "description": dedent(
        """\
        Resize a filesystem to use all avaliable space on partition. This
        module is useful along with ``cc_growpart`` and will ensure that if the
        root partition has been resized the root filesystem will be resized
        along with it. By default, ``cc_resizefs`` will resize the root
        partition and will block the boot process while the resize command is
        running. Optionally, the resize operation can be performed in the
        background while cloud-init continues running modules. This can be
        enabled by setting ``resize_rootfs`` to ``true``. This module can be
        disabled altogether by setting ``resize_rootfs`` to ``false``."""
    ),
    "distros": distros,
    "examples": [
        "resize_rootfs: false  # disable root filesystem resize operation"
    ],
    "frequency": PER_ALWAYS,
}

schema = {
    "type": "object",
    "properties": {
        "resize_rootfs": {
            "enum": [True, False, NOBLOCK],
            "description": dedent(
                """\
                Whether to resize the root partition. Default: 'true'"""
            ),
        }
    },
}

__doc__ = get_meta_doc(meta, schema)  # Supplement python help()


def _resize_btrfs(mount_point, devpth):
    # If "/" is ro resize will fail. However it should be allowed since resize
    # makes everything bigger and subvolumes that are not ro will benefit.
    # Use a subvolume that is not ro to trick the resize operation to do the
    # "right" thing. The use of ".snapshot" is specific to "snapper" a generic
    # solution would be walk the subvolumes and find a rw mounted subvolume.
    if not util.mount_is_read_write(mount_point) and os.path.isdir(
        "%s/.snapshots" % mount_point
    ):
        return (
            "btrfs",
            "filesystem",
            "resize",
            "max",
            "%s/.snapshots" % mount_point,
        )
    else:
        return ("btrfs", "filesystem", "resize", "max", mount_point)


def _resize_ext(mount_point, devpth):
    return ("resize2fs", devpth)


def _resize_xfs(mount_point, devpth):
    return ("xfs_growfs", mount_point)


def _resize_ufs(mount_point, devpth):
    return ("growfs", "-y", mount_point)


def _resize_zfs(mount_point, devpth):
    return ("zpool", "online", "-e", mount_point, devpth)


def _resize_hammer2(mount_point, devpth):
    return ("hammer2", "growfs", mount_point)


def _can_skip_resize_ufs(mount_point, devpth):
    # possible errors cases on the code-path to growfs -N following:
    # https://github.com/freebsd/freebsd/blob/HEAD/sbin/growfs/growfs.c
    # This is the "good" error:
    skip_start = "growfs: requested size"
    skip_contain = "is not larger than the current filesystem size"
    # growfs exits with 1 for almost all cases up to this one.
    # This means we can't just use rcs=[0, 1] as subp parameter:
    try:
        subp.subp(["growfs", "-N", devpth])
    except subp.ProcessExecutionError as e:
        if e.stderr.startswith(skip_start) and skip_contain in e.stderr:
            # This FS is already at the desired size
            return True
        else:
            raise e
    return False


# Do not use a dictionary as these commands should be able to be used
# for multiple filesystem types if possible, e.g. one command for
# ext2, ext3 and ext4.
RESIZE_FS_PREFIXES_CMDS = [
    ("btrfs", _resize_btrfs),
    ("ext", _resize_ext),
    ("xfs", _resize_xfs),
    ("ufs", _resize_ufs),
    ("zfs", _resize_zfs),
    ("hammer2", _resize_hammer2),
]

RESIZE_FS_PRECHECK_CMDS = {"ufs": _can_skip_resize_ufs}


def can_skip_resize(fs_type, resize_what, devpth):
    fstype_lc = fs_type.lower()
    for i, func in RESIZE_FS_PRECHECK_CMDS.items():
        if fstype_lc.startswith(i):
            return func(resize_what, devpth)
    return False


def maybe_get_writable_device_path(devpath, info, log):
    """Return updated devpath if the devpath is a writable block device.

    @param devpath: Requested path to the root device we want to resize.
    @param info: String representing information about the requested device.
    @param log: Logger to which logs will be added upon error.

    @returns devpath or updated devpath per kernel commandline if the device
        path is a writable block device, returns None otherwise.
    """
    container = util.is_container()

    # Ensure the path is a block device.
    if (
        devpath == "/dev/root"
        and not os.path.exists(devpath)
        and not container
    ):
        devpath = util.rootdev_from_cmdline(util.get_cmdline())
        if devpath is None:
            log.warning("Unable to find device '/dev/root'")
            return None
        log.debug("Converted /dev/root to '%s' per kernel cmdline", devpath)

    if devpath == "overlayroot":
        log.debug("Not attempting to resize devpath '%s': %s", devpath, info)
        return None

    # FreeBSD zpool can also just use gpt/<label>
    # with that in mind we can not do an os.stat on "gpt/whatever"
    # therefore return the devpath already here.
    if devpath.startswith("gpt/"):
        log.debug("We have a gpt label - just go ahead")
        return devpath
    # Alternatively, our device could simply be a name as returned by gpart,
    # such as da0p3
    if not devpath.startswith("/dev/") and not os.path.exists(devpath):
        fulldevpath = "/dev/" + devpath.lstrip("/")
        log.debug(
            "'%s' doesn't appear to be a valid device path. Trying '%s'",
            devpath,
            fulldevpath,
        )
        devpath = fulldevpath

    try:
        statret = os.stat(devpath)
    except OSError as exc:
        if container and exc.errno == errno.ENOENT:
            log.debug(
                "Device '%s' did not exist in container. cannot resize: %s",
                devpath,
                info,
            )
        elif exc.errno == errno.ENOENT:
            log.warning(
                "Device '%s' did not exist. cannot resize: %s", devpath, info
            )
        else:
            raise exc
        return None

    if not stat.S_ISBLK(statret.st_mode) and not stat.S_ISCHR(statret.st_mode):
        if container:
            log.debug(
                "device '%s' not a block device in container."
                " cannot resize: %s" % (devpath, info)
            )
        else:
            log.warning(
                "device '%s' not a block device. cannot resize: %s"
                % (devpath, info)
            )
        return None
    return devpath  # The writable block devpath


def handle(name, cfg, _cloud, log, args):
    if len(args) != 0:
        resize_root = args[0]
    else:
        resize_root = util.get_cfg_option_str(cfg, "resize_rootfs", True)
    validate_cloudconfig_schema(cfg, schema)
    if not util.translate_bool(resize_root, addons=[NOBLOCK]):
        log.debug("Skipping module named %s, resizing disabled", name)
        return

    # TODO(harlowja): allow what is to be resized to be configurable??
    resize_what = "/"
    result = util.get_mount_info(resize_what, log)
    if not result:
        log.warning("Could not determine filesystem type of %s", resize_what)
        return

    (devpth, fs_type, mount_point) = result

    # if we have a zfs then our device path at this point
    # is the zfs label. For example: vmzroot/ROOT/freebsd
    # we will have to get the zpool name out of this
    # and set the resize_what variable to the zpool
    # so the _resize_zfs function gets the right attribute.
    if fs_type == "zfs":
        zpool = devpth.split("/")[0]
        devpth = util.get_device_info_from_zpool(zpool)
        if not devpth:
            return  # could not find device from zpool
        resize_what = zpool

    info = "dev=%s mnt_point=%s path=%s" % (devpth, mount_point, resize_what)
    log.debug("resize_info: %s" % info)

    devpth = maybe_get_writable_device_path(devpth, info, log)
    if not devpth:
        return  # devpath was not a writable block device

    resizer = None
    if can_skip_resize(fs_type, resize_what, devpth):
        log.debug(
            "Skip resize filesystem type %s for %s", fs_type, resize_what
        )
        return

    fstype_lc = fs_type.lower()
    for (pfix, root_cmd) in RESIZE_FS_PREFIXES_CMDS:
        if fstype_lc.startswith(pfix):
            resizer = root_cmd
            break

    if not resizer:
        log.warning(
            "Not resizing unknown filesystem type %s for %s",
            fs_type,
            resize_what,
        )
        return

    resize_cmd = resizer(resize_what, devpth)
    log.debug(
        "Resizing %s (%s) using %s", resize_what, fs_type, " ".join(resize_cmd)
    )

    if resize_root == NOBLOCK:
        # Fork to a child that will run
        # the resize command
        util.fork_cb(
            util.log_time,
            logfunc=log.debug,
            msg="backgrounded Resizing",
            func=do_resize,
            args=(resize_cmd, log),
        )
    else:
        util.log_time(
            logfunc=log.debug,
            msg="Resizing",
            func=do_resize,
            args=(resize_cmd, log),
        )

    action = "Resized"
    if resize_root == NOBLOCK:
        action = "Resizing (via forking)"
    log.debug(
        "%s root filesystem (type=%s, val=%s)", action, fs_type, resize_root
    )


def do_resize(resize_cmd, log):
    try:
        subp.subp(resize_cmd)
    except subp.ProcessExecutionError:
        util.logexc(log, "Failed to resize filesystem (cmd=%s)", resize_cmd)
        raise
    # TODO(harlowja): Should we add a fsck check after this to make
    # sure we didn't corrupt anything?


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