# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

# Don't use the unicode-wrapped os and shutil modules here since
# the whole _selinux module itself will be wrapped.
import os
import shutil
import warnings

try:
    import selinux
except ImportError:
    selinux = None

import portage
from portage import _encodings
from portage import _native_string, _unicode_encode
from portage.localization import _


def copyfile(src, dest):
    src = _native_string(src, encoding=_encodings["fs"], errors="strict")
    dest = _native_string(dest, encoding=_encodings["fs"], errors="strict")
    (rc, ctx) = selinux.lgetfilecon(src)
    if rc < 0:
        raise OSError(_('copyfile: Failed getting context of "%s".') % src)

    setfscreate(ctx)
    try:
        shutil.copyfile(src, dest)
    finally:
        setfscreate()


def getcontext():
    (rc, ctx) = selinux.getcon()
    if rc < 0:
        raise OSError(_("getcontext: Failed getting current process context."))

    return ctx


def is_selinux_enabled():
    return selinux.is_selinux_enabled()


def mkdir(target, refdir):
    refdir = _native_string(refdir, encoding=_encodings["fs"], errors="strict")
    (rc, ctx) = selinux.getfilecon(refdir)
    if rc < 0:
        raise OSError(
            _('mkdir: Failed getting context of reference directory "%s".') % refdir
        )

    setfscreate(ctx)
    try:
        os.mkdir(_unicode_encode(target, encoding=_encodings["fs"], errors="strict"))
    finally:
        setfscreate()


def rename(src, dest):
    src = _native_string(src, encoding=_encodings["fs"], errors="strict")
    (rc, ctx) = selinux.lgetfilecon(src)
    if rc < 0:
        raise OSError(_('rename: Failed getting context of "%s".') % src)

    setfscreate(ctx)
    try:
        os.rename(
            _unicode_encode(src, encoding=_encodings["fs"], errors="strict"),
            _unicode_encode(dest, encoding=_encodings["fs"], errors="strict"),
        )
    finally:
        setfscreate()


def settype(newtype):
    try:
        ret = getcontext().split(":")
        ret[2] = newtype
        return ":".join(ret)
    except IndexError:
        warnings.warn("Invalid SELinux context: %s" % getcontext())
        return None


def setexec(ctx="\n"):
    ctx = _native_string(ctx, encoding=_encodings["content"], errors="strict")
    rc = 0
    try:
        rc = selinux.setexeccon(ctx)
    except OSError:
        msg = _(
            "Failed to set new SELinux execution context. "
            + "Is your current SELinux context allowed to run Portage?"
        )
        if selinux.security_getenforce() == 1:
            raise OSError(msg)
        else:
            portage.writemsg("!!! %s\n" % msg, noiselevel=-1)

    if rc < 0:
        if selinux.security_getenforce() == 1:
            raise OSError(_('Failed setting exec() context "%s".') % ctx)
        else:
            portage.writemsg(
                "!!! " + _('Failed setting exec() context "%s".') % ctx, noiselevel=-1
            )


def setfscreate(ctx="\n"):
    ctx = _native_string(ctx, encoding=_encodings["content"], errors="strict")
    if selinux.setfscreatecon(ctx) < 0:
        raise OSError(_('setfscreate: Failed setting fs create context "%s".') % ctx)


class spawn_wrapper:
    """
    Create a wrapper function for the given spawn function. When the wrapper
    is called, it will adjust the arguments such that setexec() to be called
    *after* the fork (thereby avoiding any interference with concurrent
    threads in the calling process).
    """

    __slots__ = ("_con", "_spawn_func")

    def __init__(self, spawn_func, selinux_type):
        self._spawn_func = spawn_func
        selinux_type = _native_string(
            selinux_type, encoding=_encodings["content"], errors="strict"
        )
        self._con = settype(selinux_type)

    def __call__(self, *args, **kwargs):
        if self._con is not None:
            pre_exec = kwargs.get("pre_exec")

            def _pre_exec():
                if pre_exec is not None:
                    pre_exec()
                setexec(self._con)

            kwargs["pre_exec"] = _pre_exec

        return self._spawn_func(*args, **kwargs)


def symlink(target, link, reflnk):
    reflnk = _native_string(reflnk, encoding=_encodings["fs"], errors="strict")
    (rc, ctx) = selinux.lgetfilecon(reflnk)
    if rc < 0:
        raise OSError(
            _('symlink: Failed getting context of reference symlink "%s".') % reflnk
        )

    setfscreate(ctx)
    try:
        os.symlink(
            _unicode_encode(target, encoding=_encodings["fs"], errors="strict"),
            _unicode_encode(link, encoding=_encodings["fs"], errors="strict"),
        )
    finally:
        setfscreate()