// +build !linux,!windows

/*
   Copyright The containerd Authors.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package oci

import (
	"context"
	"io/ioutil"
	"os"
	"path/filepath"

	"github.com/containerd/containerd/containers"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/pkg/errors"
	"golang.org/x/sys/unix"
)

// WithHostDevices adds all the hosts device nodes to the container's spec
func WithHostDevices(_ context.Context, _ Client, _ *containers.Container, s *Spec) error {
	setLinux(s)

	devs, err := getDevices("/dev")
	if err != nil {
		return err
	}
	s.Linux.Devices = append(s.Linux.Devices, devs...)
	return nil
}

var errNotADevice = errors.New("not a device node")

func getDevices(path string) ([]specs.LinuxDevice, error) {
	files, err := ioutil.ReadDir(path)
	if err != nil {
		return nil, err
	}
	var out []specs.LinuxDevice
	for _, f := range files {
		switch {
		case f.IsDir():
			switch f.Name() {
			// ".lxc" & ".lxd-mounts" added to address https://github.com/lxc/lxd/issues/2825
			// ".udev" added to address https://github.com/opencontainers/runc/issues/2093
			case "pts", "shm", "fd", "mqueue", ".lxc", ".lxd-mounts", ".udev":
				continue
			default:
				sub, err := getDevices(filepath.Join(path, f.Name()))
				if err != nil {
					return nil, err
				}

				out = append(out, sub...)
				continue
			}
		case f.Name() == "console":
			continue
		}
		device, err := deviceFromPath(filepath.Join(path, f.Name()), "rwm")
		if err != nil {
			if err == errNotADevice {
				continue
			}
			if os.IsNotExist(err) {
				continue
			}
			return nil, err
		}
		out = append(out, *device)
	}
	return out, nil
}

func deviceFromPath(path, permissions string) (*specs.LinuxDevice, error) {
	var stat unix.Stat_t
	if err := unix.Lstat(path, &stat); err != nil {
		return nil, err
	}

	var (
		devNumber = uint64(stat.Rdev)
		major     = unix.Major(devNumber)
		minor     = unix.Minor(devNumber)
	)
	if major == 0 {
		return nil, errNotADevice
	}

	var (
		devType string
		mode    = stat.Mode
	)
	switch {
	case mode&unix.S_IFBLK == unix.S_IFBLK:
		devType = "b"
	case mode&unix.S_IFCHR == unix.S_IFCHR:
		devType = "c"
	}
	fm := os.FileMode(mode &^ unix.S_IFMT)
	return &specs.LinuxDevice{
		Type:     devType,
		Path:     path,
		Major:    int64(major),
		Minor:    int64(minor),
		FileMode: &fm,
		UID:      &stat.Uid,
		GID:      &stat.Gid,
	}, nil
}

// WithCPUCFS sets the container's Completely fair scheduling (CFS) quota and period
func WithCPUCFS(quota int64, period uint64) SpecOpts {
	return func(ctx context.Context, _ Client, c *containers.Container, s *Spec) error {
		return nil
	}
}
