tools/fuzz/launcher.go - fuchsia - Git at Google

 // Copyright 2020 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 package fuzz

 import (
 	"bufio"
 	"crypto/rand"
 	"encoding/hex"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net"
 	"os"
 	"os/exec"
 	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"syscall"
 	"time"

 	"github.com/golang/glog"
 	"go.fuchsia.dev/fuchsia/tools/qemu"
 )

 // A Launcher manages the lifecycle of an instance; e.g. starting and stopping
 type Launcher interface {
 	// Do any preparation necessary before starting. This is idempotent, and
 	// does not need to be explicitly called by the client, as it will be
 	// automatically called by Start as necessary.
 	Prepare() error

 	// Starts the instance, returning a Connector that can be used to communicate with it
 	Start() (Connector, error)

 	// Returns true iff the instance is running.
 	IsRunning() (bool, error)

 	// Stops the instance. This is allowed to take up to 3 seconds to return.
 	Kill() error

 	// Dump any available system or debug logs to `out`
 	GetLogs(out io.Writer) error
 }

 const successfulBootMarker = "{{{reset}}}"
 const qemuBootTimeout = 10 * time.Second

 // A QemuLauncher starts Fuchsia on QEMU
 type QemuLauncher struct {
 	Pid    int
 	TmpDir string

 	build Build

 	// Paths to files that are created by Prepare():
 	initrd       string
 	extendedBlk  string
 	sshKey       string
 	sshPublicKey string

 	// Overridable for testing
 	timeout time.Duration
 }

 // qemuConfig contains all the configuration parameters that need to be passed
 // from the Launcher to the qemu invocation
 type qemuConfig struct {
 	binary  string
 	kernel  string
 	initrd  string
 	blk     string
 	logFile string
 	port    int
 }

 // NewQemuLauncher constructs a new QemuLauncher
 func NewQemuLauncher(build Build) *QemuLauncher {
 	return &QemuLauncher{build: build, timeout: qemuBootTimeout}
 }

 // Find an unused TCP port on the host
 func getFreePort() (int, error) {
 	listener, err := net.Listen("tcp", "localhost:0")
 	if err != nil {
 		return 0, err
 	}

 	port := listener.Addr().(*net.TCPAddr).Port

 	// Technically this might get used before QEMU starts...
 	listener.Close()
 	return port, nil
 }

 // Configure QEMU appropriately
 func getQemuInvocation(config qemuConfig) ([]string, error) {
 	qemuCmd := &qemu.QEMUCommandBuilder{}

 	qemuCmd.SetBinary(config.binary)
 	qemuCmd.SetTarget(qemu.TargetEnum.X86_64, true /* KVM */)
 	qemuCmd.SetKernel(config.kernel)
 	qemuCmd.SetInitrd(config.initrd)

 	qemuCmd.SetCPUCount(4)
 	qemuCmd.SetMemory(3072 /* MiB */)

 	qemuCmd.AddVirtioBlkPciDrive(qemu.Drive{
 		ID:   "d0",
 		File: config.blk,
 	})

 	network := qemu.Netdev{
 		ID:     "net0",
 		Device: qemu.Device{Model: qemu.DeviceModelVirtioNetPCI},
 		User: &qemu.NetdevUser{
 			Network:   "192.168.3.0/24",
 			DHCPStart: "192.168.3.9",
 			Host:      "192.168.3.2",
 			Forwards:  []qemu.Forward{{HostPort: config.port, GuestPort: 22}},
 		},
 	}
 	network.Device.AddOption("mac", "52:54:00:63:5e:7b")
 	qemuCmd.AddNetwork(network)

 	// The system will halt on a kernel panic instead of rebooting.
 	qemuCmd.AddKernelArg("kernel.halt-on-panic=true")
 	// Do not print colors.
 	qemuCmd.AddKernelArg("TERM=dumb")
 	// Necessary to redirect serial to stdout for x86.
 	qemuCmd.AddKernelArg("kernel.serial=legacy")

 	qemuCmd.SetFlag("-nographic")
 	qemuCmd.SetFlag("-monitor", "none")

 	// Send serial to a log file, while also echoing to stdout (used during
 	// early boot). This is done by enabling the `logfile` option on the qemu
 	// chardev (which the qemu library constructs as a `stdio` device).
 	qemuCmd.AddSerial(
 		qemu.Chardev{
 			ID:      "char0",
 			Logfile: config.logFile,
 			Signal:  false,
 		},
 	)

 	entropy := make([]byte, 32)
 	if _, err := rand.Read(entropy); err == nil {
 		qemuCmd.AddKernelArg("kernel.entropy-mixin=" + hex.EncodeToString(entropy))
 	}

 	return qemuCmd.Build()
 }

 func fileExists(path string) bool {
 	_, err := os.Stat(path)
 	return !os.IsNotExist(err)
 }

 // Prepare files that are needed by QEMU, if they haven't already been prepared.
 //
 // If Prepare succeeds, it is up to the caller to clean up by calling Kill later.
 // However, if it fails, any resources will have been automatically released.
 func (q *QemuLauncher) Prepare() (returnErr error) {
 	paths, err := q.build.Path("zbi", "fvm", "blk", "zbitool")
 	if err != nil {
 		return fmt.Errorf("Error resolving qemu dependencies: %s", err)
 	}
 	zbi, fvm, blk, zbitool := paths[0], paths[1], paths[2], paths[3]

 	// Create a tmpdir to store files we need
 	if q.TmpDir == "" {
 		tmpDir, err := ioutil.TempDir("", "clusterfuchsia-qemu-")
 		if err != nil {
 			return fmt.Errorf("Error creating tempdir: %s", err)
 		}
 		q.TmpDir = tmpDir
 	}

 	// If we fail after this point, we need to make sure to clean up
 	defer func() {
 		if returnErr != nil {
 			q.cleanup()
 		}
 	}()

 	sshKey := filepath.Join(q.TmpDir, "sshid")
 	sshPublicKey := filepath.Join(q.TmpDir, "sshid.pub")
 	initrd := filepath.Join(q.TmpDir, "ssh-"+path.Base(zbi))
 	if !fileExists(sshKey) || !fileExists(sshPublicKey) {
 		// Generate SSH key pair
 		key, err := createSSHKey()
 		if err != nil {
 			return fmt.Errorf("error generating ssh key: %s", err)
 		}
 		if err := writeSSHPrivateKeyFile(key, sshKey); err != nil {
 			return fmt.Errorf("error writing ssh key: %s", err)
 		}
 		if err := writeSSHPublicKeyFile(key, sshPublicKey); err != nil {
 			return fmt.Errorf("error writing ssh public key: %s", err)
 		}
 		// Force rebuild of any existing ZBI in the next step, to reflect the new key
 		if err := os.RemoveAll(initrd); err != nil {
 			return fmt.Errorf("error removing zbi: %s", err)
 		}
 	}
 	q.sshKey = sshKey
 	q.sshPublicKey = sshPublicKey

 	// Stick our SSH key into the authorized_keys files
 	if !fileExists(initrd) {
 		entry := "data/ssh/authorized_keys=" + q.sshPublicKey
 		if err := CreateProcessForeground(zbitool, "-o", initrd, zbi, "-e", entry); err != nil {
 			return fmt.Errorf("adding ssh key failed: %s", err)
 		}
 	}
 	q.initrd = initrd

 	// Make an expanded copy of the disk image
 	extendedBlk := path.Join(q.TmpDir, "extended-"+path.Base(blk))
 	if !fileExists(extendedBlk) {
 		if err := CreateProcessForeground("cp", blk, extendedBlk); err != nil {
 			return fmt.Errorf("cp failed: %s", err)
 		}
 		if err := CreateProcessForeground(fvm, extendedBlk, "extend",
 			"--length", "3G"); err != nil {
 			return fmt.Errorf("fvm failed: %s", err)
 		}
 	}
 	q.extendedBlk = extendedBlk

 	return nil
 }

 // Start launches QEMU and waits for it to get through the basic boot sequence.
 // Note that networking will not necessarily be fully up by the time Start() returns
 //
 // If Start succeeds, it is up to the caller to clean up by calling Kill later.
 // However, if it fails, any resources will have been automatically released.
 func (q *QemuLauncher) Start() (conn Connector, returnErr error) {
 	running, err := q.IsRunning()
 	if err != nil {
 		return nil, fmt.Errorf("Error checking run state: %s", err)
 	}

 	if running {
 		return nil, fmt.Errorf("Start called but already running")
 	}

 	paths, err := q.build.Path("qemu", "kernel")
 	if err != nil {
 		return nil, fmt.Errorf("Error resolving qemu dependencies: %s", err)
 	}
 	binary, kernel := paths[0], paths[1]

 	port, err := getFreePort()
 	if err != nil {
 		return nil, fmt.Errorf("couldn't get free port: %s", err)
 	}

 	if err := q.Prepare(); err != nil {
 		return nil, fmt.Errorf("error while preparing to start: %s", err)
 	}

 	// If we fail after this point, we need to make sure to clean up
 	defer func() {
 		if returnErr != nil {
 			q.cleanup()
 		}
 	}()

 	invocation, err := getQemuInvocation(qemuConfig{
 		binary:  binary,
 		kernel:  kernel,
 		initrd:  q.initrd,
 		blk:     q.extendedBlk,
 		logFile: q.logPath(),
 		port:    port})
 	if err != nil {
 		return nil, fmt.Errorf("qemu configuration error: %s", err)
 	}

 	cmd := NewCommand(invocation[0], invocation[1:]...)

 	outPipe, err := cmd.StdoutPipe()
 	if err != nil {
 		return nil, fmt.Errorf("error attaching stdout: %s", err)
 	}
 	cmd.Stderr = cmd.Stdout // capture stderr too

 	// Save early log in case of error
 	var log []string

 	errCh := make(chan error)
 	go func() {
 		scanner := bufio.NewScanner(outPipe)
 		for scanner.Scan() {
 			line := scanner.Text()
 			log = append(log, line)
 			if strings.Contains(line, successfulBootMarker) {
 				// Early boot has finished
 				errCh <- nil
 				return
 			}
 		}

 		if err := scanner.Err(); err != nil {
 			errCh <- fmt.Errorf("failed during scan: %s", err)
 			return
 		}

 		errCh <- fmt.Errorf("qemu exited early")
 	}()

 	if err := cmd.Start(); err != nil {
 		return nil, fmt.Errorf("failed to start qemu: %s", err)
 	}

 	q.Pid = cmd.Process.Pid

 	glog.Info("Waiting for boot to complete...")

 	select {
 	case err := <-errCh:
 		if err != nil {
 			// Kill the process, just in case this was an error other than EOF
 			cmd.Process.Kill()

 			// Dump the boot log
 			glog.Errorf(strings.Join(log, "\n"))

 			return nil, fmt.Errorf("error during boot: %s", err)
 		}
 	case <-time.After(q.timeout):
 		// Kill the process, and wait for the goroutine above to terminate
 		cmd.Process.Kill()
 		<-errCh

 		// Dump the boot log
 		glog.Errorf(strings.Join(log, "\n"))

 		return nil, fmt.Errorf("timeout waiting for boot")
 	}

 	glog.Info("Instance started.")

 	// Detach from the child, since we will never wait on it
 	cmd.Process.Release()

 	return &SSHConnector{Host: "localhost", Port: port, Key: q.sshKey}, nil
 }

 // IsRunning checks if the qemu process is alive
 func (q *QemuLauncher) IsRunning() (bool, error) {
 	if q.Pid == 0 {
 		return false, nil
 	}

 	if err := CreateProcess("ps", "-p", strconv.Itoa(q.Pid)); err != nil {
 		if cmderr, ok := err.(*exec.ExitError); ok && cmderr.ExitCode() == 1 {
 			return false, nil
 		}
 		return false, fmt.Errorf("error running ps: %s", err)
 	}

 	return true, nil
 }

 // Cleans up any temporary files used by the launcher
 func (q *QemuLauncher) cleanup() {
 	if q.TmpDir != "" {
 		if err := os.RemoveAll(q.TmpDir); err != nil {
 			glog.Warningf("failed to remove temp dir: %s", err)
 		}
 		q.TmpDir = ""
 	}
 }

 // Kill tells the QEMU process to terminate, and cleans up the TmpDir
 func (q *QemuLauncher) Kill() error {
 	if q.Pid != 0 {
 		glog.Infof("Killing PID %d", q.Pid)

 		// TODO(fxbug.dev/45431): More gracefully, with timeout
 		if err := syscall.Kill(q.Pid, syscall.SIGKILL); err != nil {
 			glog.Warningf("failed to kill instance: %s", err)
 		}

 		q.Pid = 0
 	}

 	q.cleanup()

 	return nil
 }

 func (q *QemuLauncher) logPath() string {
 	return filepath.Join(q.TmpDir, "qemu.log")
 }

 // GetLogs writes any system logs from QEMU to `out`
 func (q *QemuLauncher) GetLogs(out io.Writer) error {
 	f, err := os.Open(q.logPath())
 	if err != nil {
 		return fmt.Errorf("error opening file: %s", err)
 	}
 	defer f.Close()

 	if _, err := io.Copy(out, f); err != nil {
 		return fmt.Errorf("error while dumping log file %q: %s", q.logPath(), err)
 	}

 	return nil
 }

 func loadLauncherFromHandle(build Build, handle Handle) (Launcher, error) {
 	handleData, err := handle.GetData()
 	if err != nil {
 		return nil, err
 	}

 	// Check that the Launcher is in a valid state
 	switch launcher := handleData.launcher.(type) {
 	case *QemuLauncher:
 		if launcher.Pid == 0 {
 			return nil, fmt.Errorf("pid not found in handle")
 		}

 		if launcher.TmpDir == "" {
 			return nil, fmt.Errorf("tmpdir not found in handle")
 		}

 		launcher.build = build
 		return launcher, nil
 	default:
 		return nil, fmt.Errorf("unknown launcher type: %T", handleData.launcher)
 	}
 }
	// Copyright 2020 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	package fuzz

	import (
	"bufio"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"

	"github.com/golang/glog"
	"go.fuchsia.dev/fuchsia/tools/qemu"
	)

	// A Launcher manages the lifecycle of an instance; e.g. starting and stopping
	type Launcher interface {
	// Do any preparation necessary before starting. This is idempotent, and
	// does not need to be explicitly called by the client, as it will be
	// automatically called by Start as necessary.
	Prepare() error

	// Starts the instance, returning a Connector that can be used to communicate with it
	Start() (Connector, error)

	// Returns true iff the instance is running.
	IsRunning() (bool, error)

	// Stops the instance. This is allowed to take up to 3 seconds to return.
	Kill() error

	// Dump any available system or debug logs to `out`
	GetLogs(out io.Writer) error
	}

	const successfulBootMarker = "{{{reset}}}"
	const qemuBootTimeout = 10 * time.Second

	// A QemuLauncher starts Fuchsia on QEMU
	type QemuLauncher struct {
	Pid int
	TmpDir string

	build Build

	// Paths to files that are created by Prepare():
	initrd string
	extendedBlk string
	sshKey string
	sshPublicKey string

	// Overridable for testing
	timeout time.Duration
	}

	// qemuConfig contains all the configuration parameters that need to be passed
	// from the Launcher to the qemu invocation
	type qemuConfig struct {
	binary string
	kernel string
	initrd string
	blk string
	logFile string
	port int
	}

	// NewQemuLauncher constructs a new QemuLauncher
	func NewQemuLauncher(build Build) *QemuLauncher {
	return &QemuLauncher{build: build, timeout: qemuBootTimeout}
	}

	// Find an unused TCP port on the host
	func getFreePort() (int, error) {
	listener, err := net.Listen("tcp", "localhost:0")
	if err != nil {
	return 0, err
	}

	port := listener.Addr().(*net.TCPAddr).Port

	// Technically this might get used before QEMU starts...
	listener.Close()
	return port, nil
	}

	// Configure QEMU appropriately
	func getQemuInvocation(config qemuConfig) ([]string, error) {
	qemuCmd := &qemu.QEMUCommandBuilder{}

	qemuCmd.SetBinary(config.binary)
	qemuCmd.SetTarget(qemu.TargetEnum.X86_64, true /* KVM */)
	qemuCmd.SetKernel(config.kernel)
	qemuCmd.SetInitrd(config.initrd)

	qemuCmd.SetCPUCount(4)
	qemuCmd.SetMemory(3072 /* MiB */)

	qemuCmd.AddVirtioBlkPciDrive(qemu.Drive{
	ID: "d0",
	File: config.blk,
	})

	network := qemu.Netdev{
	ID: "net0",
	Device: qemu.Device{Model: qemu.DeviceModelVirtioNetPCI},
	User: &qemu.NetdevUser{
	Network: "192.168.3.0/24",
	DHCPStart: "192.168.3.9",
	Host: "192.168.3.2",
	Forwards: []qemu.Forward{{HostPort: config.port, GuestPort: 22}},
	},
	}
	network.Device.AddOption("mac", "52:54:00:63:5e:7b")
	qemuCmd.AddNetwork(network)

	// The system will halt on a kernel panic instead of rebooting.
	qemuCmd.AddKernelArg("kernel.halt-on-panic=true")
	// Do not print colors.
	qemuCmd.AddKernelArg("TERM=dumb")
	// Necessary to redirect serial to stdout for x86.
	qemuCmd.AddKernelArg("kernel.serial=legacy")

	qemuCmd.SetFlag("-nographic")
	qemuCmd.SetFlag("-monitor", "none")

	// Send serial to a log file, while also echoing to stdout (used during
	// early boot). This is done by enabling the `logfile` option on the qemu
	// chardev (which the qemu library constructs as a `stdio` device).
	qemuCmd.AddSerial(
	qemu.Chardev{
	ID: "char0",
	Logfile: config.logFile,
	Signal: false,
	},
	)

	entropy := make([]byte, 32)
	if _, err := rand.Read(entropy); err == nil {
	qemuCmd.AddKernelArg("kernel.entropy-mixin=" + hex.EncodeToString(entropy))
	}

	return qemuCmd.Build()
	}

	func fileExists(path string) bool {
	_, err := os.Stat(path)
	return !os.IsNotExist(err)
	}

	// Prepare files that are needed by QEMU, if they haven't already been prepared.
	//
	// If Prepare succeeds, it is up to the caller to clean up by calling Kill later.
	// However, if it fails, any resources will have been automatically released.
	func (q *QemuLauncher) Prepare() (returnErr error) {
	paths, err := q.build.Path("zbi", "fvm", "blk", "zbitool")
	if err != nil {
	return fmt.Errorf("Error resolving qemu dependencies: %s", err)
	}
	zbi, fvm, blk, zbitool := paths[0], paths[1], paths[2], paths[3]

	// Create a tmpdir to store files we need
	if q.TmpDir == "" {
	tmpDir, err := ioutil.TempDir("", "clusterfuchsia-qemu-")
	if err != nil {
	return fmt.Errorf("Error creating tempdir: %s", err)
	}
	q.TmpDir = tmpDir
	}

	// If we fail after this point, we need to make sure to clean up
	defer func() {
	if returnErr != nil {
	q.cleanup()
	}
	}()

	sshKey := filepath.Join(q.TmpDir, "sshid")
	sshPublicKey := filepath.Join(q.TmpDir, "sshid.pub")
	initrd := filepath.Join(q.TmpDir, "ssh-"+path.Base(zbi))
	if !fileExists(sshKey) \|\| !fileExists(sshPublicKey) {
	// Generate SSH key pair
	key, err := createSSHKey()
	if err != nil {
	return fmt.Errorf("error generating ssh key: %s", err)
	}
	if err := writeSSHPrivateKeyFile(key, sshKey); err != nil {
	return fmt.Errorf("error writing ssh key: %s", err)
	}
	if err := writeSSHPublicKeyFile(key, sshPublicKey); err != nil {
	return fmt.Errorf("error writing ssh public key: %s", err)
	}
	// Force rebuild of any existing ZBI in the next step, to reflect the new key
	if err := os.RemoveAll(initrd); err != nil {
	return fmt.Errorf("error removing zbi: %s", err)
	}
	}
	q.sshKey = sshKey
	q.sshPublicKey = sshPublicKey

	// Stick our SSH key into the authorized_keys files
	if !fileExists(initrd) {
	entry := "data/ssh/authorized_keys=" + q.sshPublicKey
	if err := CreateProcessForeground(zbitool, "-o", initrd, zbi, "-e", entry); err != nil {
	return fmt.Errorf("adding ssh key failed: %s", err)
	}
	}
	q.initrd = initrd

	// Make an expanded copy of the disk image
	extendedBlk := path.Join(q.TmpDir, "extended-"+path.Base(blk))
	if !fileExists(extendedBlk) {
	if err := CreateProcessForeground("cp", blk, extendedBlk); err != nil {
	return fmt.Errorf("cp failed: %s", err)
	}
	if err := CreateProcessForeground(fvm, extendedBlk, "extend",
	"--length", "3G"); err != nil {
	return fmt.Errorf("fvm failed: %s", err)
	}
	}
	q.extendedBlk = extendedBlk

	return nil
	}

	// Start launches QEMU and waits for it to get through the basic boot sequence.
	// Note that networking will not necessarily be fully up by the time Start() returns
	//
	// If Start succeeds, it is up to the caller to clean up by calling Kill later.
	// However, if it fails, any resources will have been automatically released.
	func (q *QemuLauncher) Start() (conn Connector, returnErr error) {
	running, err := q.IsRunning()
	if err != nil {
	return nil, fmt.Errorf("Error checking run state: %s", err)
	}

	if running {
	return nil, fmt.Errorf("Start called but already running")
	}

	paths, err := q.build.Path("qemu", "kernel")
	if err != nil {
	return nil, fmt.Errorf("Error resolving qemu dependencies: %s", err)
	}
	binary, kernel := paths[0], paths[1]

	port, err := getFreePort()
	if err != nil {
	return nil, fmt.Errorf("couldn't get free port: %s", err)
	}

	if err := q.Prepare(); err != nil {
	return nil, fmt.Errorf("error while preparing to start: %s", err)
	}

	// If we fail after this point, we need to make sure to clean up
	defer func() {
	if returnErr != nil {
	q.cleanup()
	}
	}()

	invocation, err := getQemuInvocation(qemuConfig{
	binary: binary,
	kernel: kernel,
	initrd: q.initrd,
	blk: q.extendedBlk,
	logFile: q.logPath(),
	port: port})
	if err != nil {
	return nil, fmt.Errorf("qemu configuration error: %s", err)
	}

	cmd := NewCommand(invocation[0], invocation[1:]...)

	outPipe, err := cmd.StdoutPipe()
	if err != nil {
	return nil, fmt.Errorf("error attaching stdout: %s", err)
	}
	cmd.Stderr = cmd.Stdout // capture stderr too

	// Save early log in case of error
	var log []string

	errCh := make(chan error)
	go func() {
	scanner := bufio.NewScanner(outPipe)
	for scanner.Scan() {
	line := scanner.Text()
	log = append(log, line)
	if strings.Contains(line, successfulBootMarker) {
	// Early boot has finished
	errCh <- nil
	return
	}
	}

	if err := scanner.Err(); err != nil {
	errCh <- fmt.Errorf("failed during scan: %s", err)
	return
	}

	errCh <- fmt.Errorf("qemu exited early")
	}()

	if err := cmd.Start(); err != nil {
	return nil, fmt.Errorf("failed to start qemu: %s", err)
	}

	q.Pid = cmd.Process.Pid

	glog.Info("Waiting for boot to complete...")

	select {
	case err := <-errCh:
	if err != nil {
	// Kill the process, just in case this was an error other than EOF
	cmd.Process.Kill()

	// Dump the boot log
	glog.Errorf(strings.Join(log, "\n"))

	return nil, fmt.Errorf("error during boot: %s", err)
	}
	case <-time.After(q.timeout):
	// Kill the process, and wait for the goroutine above to terminate
	cmd.Process.Kill()
	<-errCh

	// Dump the boot log
	glog.Errorf(strings.Join(log, "\n"))

	return nil, fmt.Errorf("timeout waiting for boot")
	}

	glog.Info("Instance started.")

	// Detach from the child, since we will never wait on it
	cmd.Process.Release()

	return &SSHConnector{Host: "localhost", Port: port, Key: q.sshKey}, nil
	}

	// IsRunning checks if the qemu process is alive
	func (q *QemuLauncher) IsRunning() (bool, error) {
	if q.Pid == 0 {
	return false, nil
	}

	if err := CreateProcess("ps", "-p", strconv.Itoa(q.Pid)); err != nil {
	if cmderr, ok := err.(*exec.ExitError); ok && cmderr.ExitCode() == 1 {
	return false, nil
	}
	return false, fmt.Errorf("error running ps: %s", err)
	}

	return true, nil
	}

	// Cleans up any temporary files used by the launcher
	func (q *QemuLauncher) cleanup() {
	if q.TmpDir != "" {
	if err := os.RemoveAll(q.TmpDir); err != nil {
	glog.Warningf("failed to remove temp dir: %s", err)
	}
	q.TmpDir = ""
	}
	}

	// Kill tells the QEMU process to terminate, and cleans up the TmpDir
	func (q *QemuLauncher) Kill() error {
	if q.Pid != 0 {
	glog.Infof("Killing PID %d", q.Pid)

	// TODO(fxbug.dev/45431): More gracefully, with timeout
	if err := syscall.Kill(q.Pid, syscall.SIGKILL); err != nil {
	glog.Warningf("failed to kill instance: %s", err)
	}

	q.Pid = 0
	}

	q.cleanup()

	return nil
	}

	func (q *QemuLauncher) logPath() string {
	return filepath.Join(q.TmpDir, "qemu.log")
	}

	// GetLogs writes any system logs from QEMU to `out`
	func (q *QemuLauncher) GetLogs(out io.Writer) error {
	f, err := os.Open(q.logPath())
	if err != nil {
	return fmt.Errorf("error opening file: %s", err)
	}
	defer f.Close()

	if _, err := io.Copy(out, f); err != nil {
	return fmt.Errorf("error while dumping log file %q: %s", q.logPath(), err)
	}

	return nil
	}

	func loadLauncherFromHandle(build Build, handle Handle) (Launcher, error) {
	handleData, err := handle.GetData()
	if err != nil {
	return nil, err
	}

	// Check that the Launcher is in a valid state
	switch launcher := handleData.launcher.(type) {
	case *QemuLauncher:
	if launcher.Pid == 0 {
	return nil, fmt.Errorf("pid not found in handle")
	}

	if launcher.TmpDir == "" {
	return nil, fmt.Errorf("tmpdir not found in handle")
	}

	launcher.build = build
	return launcher, nil
	default:
	return nil, fmt.Errorf("unknown launcher type: %T", handleData.launcher)
	}
	}