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cmd/geth, console: support interrupting the js console (ethereum#23387)
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Previously, Ctrl-C (SIGINT) was ignored during JS execution, so it was not
possible to get out of infinite loops in the console. With this change,
Ctrl-C now interrupts JS.

Fixes ethereum#23344

Co-authored-by: Sina Mahmoodi <[email protected]>
Co-authored-by: Felix Lange <[email protected]>
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@holiman @s1na @fjl
3 people authored Dec 11, 2021
1 parent ae8ff26 commit 72c2c0a
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Showing 5 changed files with 191 additions and 61 deletions.
47 changes: 26 additions & 21 deletions cmd/geth/consolecmd.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -77,43 +77,48 @@ func localConsole(ctx *cli.Context) error {
// Create and start the node based on the CLI flags
prepare(ctx)
stack, backend := makeFullNode(ctx)
startNode(ctx, stack, backend)
startNode(ctx, stack, backend, true)
defer stack.Close()

// Attach to the newly started node and start the JavaScript console
// Attach to the newly started node and create the JavaScript console.
client, err := stack.Attach()
if err != nil {
utils.Fatalf("Failed to attach to the inproc geth: %v", err)
return fmt.Errorf("Failed to attach to the inproc geth: %v", err)
}
config := console.Config{
DataDir: utils.MakeDataDir(ctx),
DocRoot: ctx.GlobalString(utils.JSpathFlag.Name),
Client: client,
Preload: utils.MakeConsolePreloads(ctx),
}

console, err := console.New(config)
if err != nil {
utils.Fatalf("Failed to start the JavaScript console: %v", err)
return fmt.Errorf("Failed to start the JavaScript console: %v", err)
}
defer console.Stop(false)

// If only a short execution was requested, evaluate and return
// If only a short execution was requested, evaluate and return.
if script := ctx.GlobalString(utils.ExecFlag.Name); script != "" {
console.Evaluate(script)
return nil
}
// Otherwise print the welcome screen and enter interactive mode

// Track node shutdown and stop the console when it goes down.
// This happens when SIGTERM is sent to the process.
go func() {
stack.Wait()
console.StopInteractive()
}()

// Print the welcome screen and enter interactive mode.
console.Welcome()
console.Interactive()

return nil
}

// remoteConsole will connect to a remote geth instance, attaching a JavaScript
// console to it.
func remoteConsole(ctx *cli.Context) error {
// Attach to a remotely running geth instance and start the JavaScript console
endpoint := ctx.Args().First()
if endpoint == "" {
path := node.DefaultDataDir()
Expand Down Expand Up @@ -150,7 +155,6 @@ func remoteConsole(ctx *cli.Context) error {
Client: client,
Preload: utils.MakeConsolePreloads(ctx),
}

console, err := console.New(config)
if err != nil {
utils.Fatalf("Failed to start the JavaScript console: %v", err)
Expand All @@ -165,7 +169,6 @@ func remoteConsole(ctx *cli.Context) error {
// Otherwise print the welcome screen and enter interactive mode
console.Welcome()
console.Interactive()

return nil
}

Expand All @@ -189,13 +192,13 @@ func dialRPC(endpoint string) (*rpc.Client, error) {
func ephemeralConsole(ctx *cli.Context) error {
// Create and start the node based on the CLI flags
stack, backend := makeFullNode(ctx)
startNode(ctx, stack, backend)
startNode(ctx, stack, backend, false)
defer stack.Close()

// Attach to the newly started node and start the JavaScript console
client, err := stack.Attach()
if err != nil {
utils.Fatalf("Failed to attach to the inproc geth: %v", err)
return fmt.Errorf("Failed to attach to the inproc geth: %v", err)
}
config := console.Config{
DataDir: utils.MakeDataDir(ctx),
Expand All @@ -206,22 +209,24 @@ func ephemeralConsole(ctx *cli.Context) error {

console, err := console.New(config)
if err != nil {
utils.Fatalf("Failed to start the JavaScript console: %v", err)
return fmt.Errorf("Failed to start the JavaScript console: %v", err)
}
defer console.Stop(false)

// Evaluate each of the specified JavaScript files
// Interrupt the JS interpreter when node is stopped.
go func() {
stack.Wait()
console.Stop(false)
}()

// Evaluate each of the specified JavaScript files.
for _, file := range ctx.Args() {
if err = console.Execute(file); err != nil {
utils.Fatalf("Failed to execute %s: %v", file, err)
return fmt.Errorf("Failed to execute %s: %v", file, err)
}
}

go func() {
stack.Wait()
console.Stop(false)
}()
// The main script is now done, but keep running timers/callbacks.
console.Stop(true)

return nil
}
6 changes: 3 additions & 3 deletions cmd/geth/main.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -320,19 +320,19 @@ func geth(ctx *cli.Context) error {
stack, backend := makeFullNode(ctx)
defer stack.Close()

startNode(ctx, stack, backend)
startNode(ctx, stack, backend, false)
stack.Wait()
return nil
}

// startNode boots up the system node and all registered protocols, after which
// it unlocks any requested accounts, and starts the RPC/IPC interfaces and the
// miner.
func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend) {
func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend, isConsole bool) {
debug.Memsize.Add("node", stack)

// Start up the node itself
utils.StartNode(ctx, stack)
utils.StartNode(ctx, stack, isConsole)

// Unlock any account specifically requested
unlockAccounts(ctx, stack)
Expand Down
36 changes: 26 additions & 10 deletions cmd/utils/cmd.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ func Fatalf(format string, args ...interface{}) {
os.Exit(1)
}

func StartNode(ctx *cli.Context, stack *node.Node) {
func StartNode(ctx *cli.Context, stack *node.Node, isConsole bool) {
if err := stack.Start(); err != nil {
Fatalf("Error starting protocol stack: %v", err)
}
Expand All @@ -87,17 +87,33 @@ func StartNode(ctx *cli.Context, stack *node.Node) {
go monitorFreeDiskSpace(sigc, stack.InstanceDir(), uint64(minFreeDiskSpace)*1024*1024)
}

<-sigc
log.Info("Got interrupt, shutting down...")
go stack.Close()
for i := 10; i > 0; i-- {
<-sigc
if i > 1 {
log.Warn("Already shutting down, interrupt more to panic.", "times", i-1)
shutdown := func() {
log.Info("Got interrupt, shutting down...")
go stack.Close()
for i := 10; i > 0; i-- {
<-sigc
if i > 1 {
log.Warn("Already shutting down, interrupt more to panic.", "times", i-1)
}
}
debug.Exit() // ensure trace and CPU profile data is flushed.
debug.LoudPanic("boom")
}

if isConsole {
// In JS console mode, SIGINT is ignored because it's handled by the console.
// However, SIGTERM still shuts down the node.
for {
sig := <-sigc
if sig == syscall.SIGTERM {
shutdown()
return
}
}
} else {
<-sigc
shutdown()
}
debug.Exit() // ensure trace and CPU profile data is flushed.
debug.LoudPanic("boom")
}()
}

Expand Down
121 changes: 101 additions & 20 deletions console/console.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
package console

import (
"errors"
"fmt"
"io"
"io/ioutil"
Expand All @@ -26,6 +27,7 @@ import (
"regexp"
"sort"
"strings"
"sync"
"syscall"

"github.com/dop251/goja"
Expand Down Expand Up @@ -74,6 +76,13 @@ type Console struct {
histPath string // Absolute path to the console scrollback history
history []string // Scroll history maintained by the console
printer io.Writer // Output writer to serialize any display strings to

interactiveStopped chan struct{}
stopInteractiveCh chan struct{}
signalReceived chan struct{}
stopped chan struct{}
wg sync.WaitGroup
stopOnce sync.Once
}

// New initializes a JavaScript interpreted runtime environment and sets defaults
Expand All @@ -92,19 +101,27 @@ func New(config Config) (*Console, error) {

// Initialize the console and return
console := &Console{
client: config.Client,
jsre: jsre.New(config.DocRoot, config.Printer),
prompt: config.Prompt,
prompter: config.Prompter,
printer: config.Printer,
histPath: filepath.Join(config.DataDir, HistoryFile),
client: config.Client,
jsre: jsre.New(config.DocRoot, config.Printer),
prompt: config.Prompt,
prompter: config.Prompter,
printer: config.Printer,
histPath: filepath.Join(config.DataDir, HistoryFile),
interactiveStopped: make(chan struct{}),
stopInteractiveCh: make(chan struct{}),
signalReceived: make(chan struct{}, 1),
stopped: make(chan struct{}),
}
if err := os.MkdirAll(config.DataDir, 0700); err != nil {
return nil, err
}
if err := console.init(config.Preload); err != nil {
return nil, err
}

console.wg.Add(1)
go console.interruptHandler()

return console, nil
}

Expand Down Expand Up @@ -337,9 +354,63 @@ func (c *Console) Evaluate(statement string) {
}
}()
c.jsre.Evaluate(statement, c.printer)

// Avoid exiting Interactive when jsre was interrupted by SIGINT.
c.clearSignalReceived()
}

// interruptHandler runs in its own goroutine and waits for signals.
// When a signal is received, it interrupts the JS interpreter.
func (c *Console) interruptHandler() {
defer c.wg.Done()

// During Interactive, liner inhibits the signal while it is prompting for
// input. However, the signal will be received while evaluating JS.
//
// On unsupported terminals, SIGINT can also happen while prompting.
// Unfortunately, it is not possible to abort the prompt in this case and
// the c.readLines goroutine leaks.
sig := make(chan os.Signal, 1)
signal.Notify(sig, syscall.SIGINT)
defer signal.Stop(sig)

for {
select {
case <-sig:
c.setSignalReceived()
c.jsre.Interrupt(errors.New("interrupted"))
case <-c.stopInteractiveCh:
close(c.interactiveStopped)
c.jsre.Interrupt(errors.New("interrupted"))
case <-c.stopped:
return
}
}
}

func (c *Console) setSignalReceived() {
select {
case c.signalReceived <- struct{}{}:
default:
}
}

func (c *Console) clearSignalReceived() {
select {
case <-c.signalReceived:
default:
}
}

// Interactive starts an interactive user session, where input is propted from
// StopInteractive causes Interactive to return as soon as possible.
func (c *Console) StopInteractive() {
select {
case c.stopInteractiveCh <- struct{}{}:
case <-c.stopped:
}
}

// Interactive starts an interactive user session, where in.put is propted from
// the configured user prompter.
func (c *Console) Interactive() {
var (
Expand All @@ -349,15 +420,11 @@ func (c *Console) Interactive() {
inputLine = make(chan string, 1) // receives user input
inputErr = make(chan error, 1) // receives liner errors
requestLine = make(chan string) // requests a line of input
interrupt = make(chan os.Signal, 1)
)

// Monitor Ctrl-C. While liner does turn on the relevant terminal mode bits to avoid
// the signal, a signal can still be received for unsupported terminals. Unfortunately
// there is no way to cancel the line reader when this happens. The readLines
// goroutine will be leaked in this case.
signal.Notify(interrupt, syscall.SIGINT, syscall.SIGTERM)
defer signal.Stop(interrupt)
defer func() {
c.writeHistory()
}()

// The line reader runs in a separate goroutine.
go c.readLines(inputLine, inputErr, requestLine)
Expand All @@ -368,7 +435,14 @@ func (c *Console) Interactive() {
requestLine <- prompt

select {
case <-interrupt:
case <-c.interactiveStopped:
fmt.Fprintln(c.printer, "node is down, exiting console")
return

case <-c.signalReceived:
// SIGINT received while prompting for input -> unsupported terminal.
// I'm not sure if the best choice would be to leave the console running here.
// Bash keeps running in this case. node.js does not.
fmt.Fprintln(c.printer, "caught interrupt, exiting")
return

Expand Down Expand Up @@ -476,12 +550,19 @@ func (c *Console) Execute(path string) error {

// Stop cleans up the console and terminates the runtime environment.
func (c *Console) Stop(graceful bool) error {
c.stopOnce.Do(func() {
// Stop the interrupt handler.
close(c.stopped)
c.wg.Wait()
})

c.jsre.Stop(graceful)
return nil
}

func (c *Console) writeHistory() error {
if err := ioutil.WriteFile(c.histPath, []byte(strings.Join(c.history, "\n")), 0600); err != nil {
return err
}
if err := os.Chmod(c.histPath, 0600); err != nil { // Force 0600, even if it was different previously
return err
}
c.jsre.Stop(graceful)
return nil
return os.Chmod(c.histPath, 0600) // Force 0600, even if it was different previously
}
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