linsk/cmd/utils.go

package cmd

import (
	"context"
	"os"
	"os/signal"
	"os/user"
	"sync"
	"syscall"

	"log/slog"

	"github.com/AlexSSD7/linsk/vm"
	"github.com/pkg/errors"
)

func checkIfRoot() (bool, error) {
	currentUser, err := user.Current()
	if err != nil {
		return false, errors.Wrap(err, "get current user")
	}
	return currentUser.Username == "root", nil
}

func doRootCheck() {
	ok, err := checkIfRoot()
	if err != nil {
		slog.Error("Failed to check whether the command is ran by root", "error", err)
		os.Exit(1)
	}

	if !ok {
		slog.Error("You must run this program as root")
		os.Exit(1)
	}
}

func runVM(passthroughArg string, fn func(context.Context, *vm.Instance, *vm.FileManager) int) int {
	doRootCheck()

	var passthroughConfig []vm.USBDevicePassthroughConfig

	if passthroughArg != "" {
		passthroughConfig = []vm.USBDevicePassthroughConfig{getDevicePassthroughConfig(passthroughArg)}
	}

	// TODO: Alpine image should be downloaded from somewhere.
	vi, err := vm.NewInstance(slog.Default().With("caller", "vm"), "alpine-img/alpine.qcow2", passthroughConfig, vmDebugFlag)
	if err != nil {
		slog.Error("Failed to create vm instance", "error", err)
		os.Exit(1)
	}

	runErrCh := make(chan error, 1)
	var wg sync.WaitGroup

	ctx, ctxCancel := context.WithCancel(context.Background())
	defer ctxCancel()

	interrupt := make(chan os.Signal, 2)
	signal.Notify(interrupt, syscall.SIGTERM, syscall.SIGINT)

	wg.Add(1)
	go func() {
		defer wg.Done()

		err := vi.Run()
		ctxCancel()
		runErrCh <- err
	}()

	go func() {
		for i := 0; ; i++ {
			select {
			case <-ctx.Done():
				signal.Reset()
				return
			case sig := <-interrupt:
				lg := slog.With("signal", sig)

				if i == 0 {
					lg.Warn("Caught interrupt, safely shutting down")
				} else if i < 10 {
					lg.Warn("Caught subsequent interrupt, please interrupt n more times to panic", "n", 10-i)
				} else {
					panic("force interrupt")
				}

				err := vi.Cancel()
				if err != nil {
					lg.Warn("Failed to cancel VM context", "error", err)
				}
			}
		}
	}()

	fm := vm.NewFileManager(slog.Default().With("caller", "file-manager"), vi)

	for {
		select {
		case err := <-runErrCh:
			slog.Error("Failed to start the VM", "error", err)
			os.Exit(1)
		case <-vi.SSHUpNotifyChan():
			err := fm.Init()
			if err != nil {
				slog.Error("Failed to initialize File Manager", "error", err)
				os.Exit(1)
			}

			exitCode := fn(ctx, vi, fm)

			err = vi.Cancel()
			if err != nil {
				slog.Error("Failed to cancel VM context", "error", err)
				os.Exit(1)
			}

			wg.Wait()

			select {
			case err := <-runErrCh:
				if err != nil {
					slog.Error("Failed to run the VM", "error", err)
					os.Exit(1)
				}
			default:
			}

			return exitCode
		}
	}
}