// Copyright 2018 Google Inc.
//
// 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.

// Binary runsc is an implementation of the Open Container Initiative Runtime
// that runs applications inside a sandbox.
package main

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"context"
	"flag"

	"github.com/google/subcommands"
	"gvisor.googlesource.com/gvisor/pkg/log"
	"gvisor.googlesource.com/gvisor/runsc/boot"
	"gvisor.googlesource.com/gvisor/runsc/cmd"
)

var (
	// Although these flags are not part of the OCI spec, they are used by
	// Docker, and thus should not be changed.
	rootDir     = flag.String("root", "", "root directory for storage of container state")
	logFilename = flag.String("log", "", "file path where internal debug information is written, default is stdout")
	logFormat   = flag.String("log-format", "text", "log format: text (default) or json")
	debug       = flag.Bool("debug", false, "enable debug logging")

	// These flags are unique to runsc, and are used to configure parts of the
	// system that are not covered by the runtime spec.

	// Debugging flags.
	debugLogDir = flag.String("debug-log-dir", "", "additional location for logs. It creates individual log files per command")
	logPackets  = flag.Bool("log-packets", false, "enable network packet logging")

	// Debugging flags: strace related
	strace         = flag.Bool("strace", false, "enable strace")
	straceSyscalls = flag.String("strace-syscalls", "", "comma-separated list of syscalls to trace. If --strace is true and this list is empty, then all syscalls will be traced.")
	straceLogSize  = flag.Uint("strace-log-size", 1024, "default size (in bytes) to log data argument blobs")

	// Flags that control sandbox runtime behavior.
	platform       = flag.String("platform", "ptrace", "specifies which platform to use: ptrace (default), kvm")
	network        = flag.String("network", "sandbox", "specifies which network to use: sandbox (default), host, none. Using network inside the sandbox is more secure because it's isolated from the host network.")
	fileAccess     = flag.String("file-access", "proxy", "specifies which filesystem to use: proxy (default), direct. Using a proxy is more secure because it disallows the sandbox from opennig files directly in the host.")
	overlay        = flag.Bool("overlay", false, "wrap filesystem mounts with writable overlay. All modifications are stored in memory inside the sandbox.")
	multiContainer = flag.Bool("multi-container", false, "enable *experimental* multi-container support.")
	watchdogAction = flag.String("watchdog-action", "log", "sets what action the watchdog takes when triggered: log (default), panic.")
)

var gitRevision = ""

func main() {
	// Help and flags commands are generated automatically.
	subcommands.Register(subcommands.HelpCommand(), "")
	subcommands.Register(subcommands.FlagsCommand(), "")

	// Register user-facing runsc commands.
	subcommands.Register(new(cmd.Create), "")
	subcommands.Register(new(cmd.Delete), "")
	subcommands.Register(new(cmd.Events), "")
	subcommands.Register(new(cmd.Exec), "")
	subcommands.Register(new(cmd.Gofer), "")
	subcommands.Register(new(cmd.Kill), "")
	subcommands.Register(new(cmd.List), "")
	subcommands.Register(new(cmd.Pause), "")
	subcommands.Register(new(cmd.PS), "")
	subcommands.Register(new(cmd.Resume), "")
	subcommands.Register(new(cmd.Run), "")
	subcommands.Register(new(cmd.Start), "")
	subcommands.Register(new(cmd.State), "")

	// Register internal commands with the internal group name. This causes
	// them to be sorted below the user-facing commands with empty group.
	// The string below will be printed above the commands.
	const internalGroup = "internal use only"
	subcommands.Register(new(cmd.Boot), internalGroup)
	subcommands.Register(new(cmd.Debug), internalGroup)
	subcommands.Register(new(cmd.Gofer), internalGroup)

	// All subcommands must be registered before flag parsing.
	flag.Parse()

	platformType, err := boot.MakePlatformType(*platform)
	if err != nil {
		cmd.Fatalf("%v", err)
	}

	fsAccess, err := boot.MakeFileAccessType(*fileAccess)
	if err != nil {
		cmd.Fatalf("%v", err)
	}

	netType, err := boot.MakeNetworkType(*network)
	if err != nil {
		cmd.Fatalf("%v", err)
	}

	wa, err := boot.MakeWatchdogAction(*watchdogAction)
	if err != nil {
		cmd.Fatalf("%v", err)
	}

	// Create a new Config from the flags.
	conf := &boot.Config{
		RootDir:        *rootDir,
		Debug:          *debug,
		LogFilename:    *logFilename,
		LogFormat:      *logFormat,
		DebugLogDir:    *debugLogDir,
		FileAccess:     fsAccess,
		Overlay:        *overlay,
		Network:        netType,
		LogPackets:     *logPackets,
		Platform:       platformType,
		Strace:         *strace,
		StraceLogSize:  *straceLogSize,
		MultiContainer: *multiContainer,
		WatchdogAction: wa,
	}
	if len(*straceSyscalls) != 0 {
		conf.StraceSyscalls = strings.Split(*straceSyscalls, ",")
	}

	// Set up logging.
	if *debug {
		log.SetLevel(log.Debug)
	}

	var logFile io.Writer = os.Stderr
	if *logFilename != "" {
		// We must set O_APPEND and not O_TRUNC because Docker passes
		// the same log file for all commands (and also parses these
		// log files), so we can't destroy them on each command.
		f, err := os.OpenFile(*logFilename, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
		if err != nil {
			cmd.Fatalf("error opening log file %q: %v", *logFilename, err)
		}
		logFile = f
	}

	var e log.Emitter
	switch *logFormat {
	case "text":
		e = log.GoogleEmitter{&log.Writer{Next: logFile}}
	case "json":
		e = log.JSONEmitter{log.Writer{Next: logFile}}
	default:
		cmd.Fatalf("invalid log format %q, must be 'json' or 'text'", *logFormat)
	}

	if *debugLogDir != "" {
		if err := os.MkdirAll(*debugLogDir, 0775); err != nil {
			cmd.Fatalf("error creating dir %q: %v", *debugLogDir, err)
		}

		// Format: <debug-log-dir>/runsc.log.<yyymmdd-hhmmss.uuuuuu>.<command>
		scmd := flag.CommandLine.Arg(0)
		filename := fmt.Sprintf("runsc.log.%s.%s", time.Now().Format("20060102-150405.000000"), scmd)
		path := filepath.Join(*debugLogDir, filename)
		f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0664)
		if err != nil {
			cmd.Fatalf("error opening log file %q: %v", filename, err)
		}
		e = log.MultiEmitter{e, log.GoogleEmitter{&log.Writer{Next: f}}}
	}

	log.SetTarget(e)

	log.Infof("***************************")
	log.Infof("Args: %s", os.Args)
	log.Infof("Git Revision: %s", gitRevision)
	log.Infof("PID: %d", os.Getpid())
	log.Infof("UID: %d, GID: %d", os.Getuid(), os.Getgid())
	log.Infof("Configuration:")
	log.Infof("\t\tRootDir: %s", conf.RootDir)
	log.Infof("\t\tPlatform: %v", conf.Platform)
	log.Infof("\t\tFileAccess: %v, overlay: %t", conf.FileAccess, conf.Overlay)
	log.Infof("\t\tNetwork: %v, logging: %t", conf.Network, conf.LogPackets)
	log.Infof("\t\tStrace: %t, max size: %d, syscalls: %s", conf.Strace, conf.StraceLogSize, conf.StraceSyscalls)
	log.Infof("***************************")

	// Call the subcommand and pass in the configuration.
	var ws syscall.WaitStatus
	subcmdCode := subcommands.Execute(context.Background(), conf, &ws)
	if subcmdCode == subcommands.ExitSuccess {
		log.Infof("Exiting with status: %v", ws)
		if ws.Signaled() {
			// No good way to return it, emulate what the shell does. Maybe raise
			// signall to self?
			os.Exit(128 + int(ws.Signal()))
		}
		os.Exit(ws.ExitStatus())
	}
	// Return an error that is unlikely to be used by the application.
	log.Warningf("Failure to execute command, err: %v", subcmdCode)
	os.Exit(128)
}

func init() {
	// Set default root dir to something (hopefully) user-writeable.
	*rootDir = "/var/run/runsc"
	if runtimeDir := os.Getenv("XDG_RUNTIME_DIR"); runtimeDir != "" {
		*rootDir = filepath.Join(runtimeDir, "runsc")
	}
}