1 files changed, 327 insertions, 0 deletions
diff --git a/internal/jsre/jsre.go b/internal/jsre/jsre.go
new file mode 100644
index 000000000..8d8f4fc2a
--- /dev/null
+++ b/internal/jsre/jsre.go
@@ -0,0 +1,327 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package jsre provides execution environment for JavaScript.
+package jsre
+
+import (
+	crand "crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/robertkrimen/otto"
+)
+
+/*
+JSRE is a generic JS runtime environment embedding the otto JS interpreter.
+It provides some helper functions to
+- load code from files
+- run code snippets
+- require libraries
+- bind native go objects
+*/
+type JSRE struct {
+	assetPath     string
+	output        io.Writer
+	evalQueue     chan *evalReq
+	stopEventLoop chan bool
+	loopWg        sync.WaitGroup
+}
+
+// jsTimer is a single timer instance with a callback function
+type jsTimer struct {
+	timer    *time.Timer
+	duration time.Duration
+	interval bool
+	call     otto.FunctionCall
+}
+
+// evalReq is a serialized vm execution request processed by runEventLoop.
+type evalReq struct {
+	fn   func(vm *otto.Otto)
+	done chan bool
+}
+
+// runtime must be stopped with Stop() after use and cannot be used after stopping
+func New(assetPath string, output io.Writer) *JSRE {
+	re := &JSRE{
+		assetPath:     assetPath,
+		output:        output,
+		evalQueue:     make(chan *evalReq),
+		stopEventLoop: make(chan bool),
+	}
+	re.loopWg.Add(1)
+	go re.runEventLoop()
+	re.Set("loadScript", re.loadScript)
+	re.Set("inspect", prettyPrintJS)
+	return re
+}
+
+// randomSource returns a pseudo random value generator.
+func randomSource() *rand.Rand {
+	bytes := make([]byte, 8)
+	seed := time.Now().UnixNano()
+	if _, err := crand.Read(bytes); err == nil {
+		seed = int64(binary.LittleEndian.Uint64(bytes))
+	}
+
+	src := rand.NewSource(seed)
+	return rand.New(src)
+}
+
+// This function runs the main event loop from a goroutine that is started
+// when JSRE is created. Use Stop() before exiting to properly stop it.
+// The event loop processes vm access requests from the evalQueue in a
+// serialized way and calls timer callback functions at the appropriate time.
+
+// Exported functions always access the vm through the event queue. You can
+// call the functions of the otto vm directly to circumvent the queue. These
+// functions should be used if and only if running a routine that was already
+// called from JS through an RPC call.
+func (self *JSRE) runEventLoop() {
+	vm := otto.New()
+	r := randomSource()
+	vm.SetRandomSource(r.Float64)
+
+	registry := map[*jsTimer]*jsTimer{}
+	ready := make(chan *jsTimer)
+
+	newTimer := func(call otto.FunctionCall, interval bool) (*jsTimer, otto.Value) {
+		delay, _ := call.Argument(1).ToInteger()
+		if 0 >= delay {
+			delay = 1
+		}
+		timer := &jsTimer{
+			duration: time.Duration(delay) * time.Millisecond,
+			call:     call,
+			interval: interval,
+		}
+		registry[timer] = timer
+
+		timer.timer = time.AfterFunc(timer.duration, func() {
+			ready <- timer
+		})
+
+		value, err := call.Otto.ToValue(timer)
+		if err != nil {
+			panic(err)
+		}
+		return timer, value
+	}
+
+	setTimeout := func(call otto.FunctionCall) otto.Value {
+		_, value := newTimer(call, false)
+		return value
+	}
+
+	setInterval := func(call otto.FunctionCall) otto.Value {
+		_, value := newTimer(call, true)
+		return value
+	}
+
+	clearTimeout := func(call otto.FunctionCall) otto.Value {
+		timer, _ := call.Argument(0).Export()
+		if timer, ok := timer.(*jsTimer); ok {
+			timer.timer.Stop()
+			delete(registry, timer)
+		}
+		return otto.UndefinedValue()
+	}
+	vm.Set("_setTimeout", setTimeout)
+	vm.Set("_setInterval", setInterval)
+	vm.Run(`var setTimeout = function(args) {
+		if (arguments.length < 1) {
+			throw TypeError("Failed to execute 'setTimeout': 1 argument required, but only 0 present.");
+		}
+		return _setTimeout.apply(this, arguments);
+	}`)
+	vm.Run(`var setInterval = function(args) {
+		if (arguments.length < 1) {
+			throw TypeError("Failed to execute 'setInterval': 1 argument required, but only 0 present.");
+		}
+		return _setInterval.apply(this, arguments);
+	}`)
+	vm.Set("clearTimeout", clearTimeout)
+	vm.Set("clearInterval", clearTimeout)
+
+	var waitForCallbacks bool
+
+loop:
+	for {
+		select {
+		case timer := <-ready:
+			// execute callback, remove/reschedule the timer
+			var arguments []interface{}
+			if len(timer.call.ArgumentList) > 2 {
+				tmp := timer.call.ArgumentList[2:]
+				arguments = make([]interface{}, 2+len(tmp))
+				for i, value := range tmp {
+					arguments[i+2] = value
+				}
+			} else {
+				arguments = make([]interface{}, 1)
+			}
+			arguments[0] = timer.call.ArgumentList[0]
+			_, err := vm.Call(`Function.call.call`, nil, arguments...)
+			if err != nil {
+				fmt.Println("js error:", err, arguments)
+			}
+
+			_, inreg := registry[timer] // when clearInterval is called from within the callback don't reset it
+			if timer.interval && inreg {
+				timer.timer.Reset(timer.duration)
+			} else {
+				delete(registry, timer)
+				if waitForCallbacks && (len(registry) == 0) {
+					break loop
+				}
+			}
+		case req := <-self.evalQueue:
+			// run the code, send the result back
+			req.fn(vm)
+			close(req.done)
+			if waitForCallbacks && (len(registry) == 0) {
+				break loop
+			}
+		case waitForCallbacks = <-self.stopEventLoop:
+			if !waitForCallbacks || (len(registry) == 0) {
+				break loop
+			}
+		}
+	}
+
+	for _, timer := range registry {
+		timer.timer.Stop()
+		delete(registry, timer)
+	}
+
+	self.loopWg.Done()
+}
+
+// Do executes the given function on the JS event loop.
+func (self *JSRE) Do(fn func(*otto.Otto)) {
+	done := make(chan bool)
+	req := &evalReq{fn, done}
+	self.evalQueue <- req
+	<-done
+}
+
+// stops the event loop before exit, optionally waits for all timers to expire
+func (self *JSRE) Stop(waitForCallbacks bool) {
+	self.stopEventLoop <- waitForCallbacks
+	self.loopWg.Wait()
+}
+
+// Exec(file) loads and runs the contents of a file
+// if a relative path is given, the jsre's assetPath is used
+func (self *JSRE) Exec(file string) error {
+	code, err := ioutil.ReadFile(common.AbsolutePath(self.assetPath, file))
+	if err != nil {
+		return err
+	}
+	var script *otto.Script
+	self.Do(func(vm *otto.Otto) {
+		script, err = vm.Compile(file, code)
+		if err != nil {
+			return
+		}
+		_, err = vm.Run(script)
+	})
+	return err
+}
+
+// Bind assigns value v to a variable in the JS environment
+// This method is deprecated, use Set.
+func (self *JSRE) Bind(name string, v interface{}) error {
+	return self.Set(name, v)
+}
+
+// Run runs a piece of JS code.
+func (self *JSRE) Run(code string) (v otto.Value, err error) {
+	self.Do(func(vm *otto.Otto) { v, err = vm.Run(code) })
+	return v, err
+}
+
+// Get returns the value of a variable in the JS environment.
+func (self *JSRE) Get(ns string) (v otto.Value, err error) {
+	self.Do(func(vm *otto.Otto) { v, err = vm.Get(ns) })
+	return v, err
+}
+
+// Set assigns value v to a variable in the JS environment.
+func (self *JSRE) Set(ns string, v interface{}) (err error) {
+	self.Do(func(vm *otto.Otto) { err = vm.Set(ns, v) })
+	return err
+}
+
+// loadScript executes a JS script from inside the currently executing JS code.
+func (self *JSRE) loadScript(call otto.FunctionCall) otto.Value {
+	file, err := call.Argument(0).ToString()
+	if err != nil {
+		// TODO: throw exception
+		return otto.FalseValue()
+	}
+	file = common.AbsolutePath(self.assetPath, file)
+	source, err := ioutil.ReadFile(file)
+	if err != nil {
+		// TODO: throw exception
+		return otto.FalseValue()
+	}
+	if _, err := compileAndRun(call.Otto, file, source); err != nil {
+		// TODO: throw exception
+		fmt.Println("err:", err)
+		return otto.FalseValue()
+	}
+	// TODO: return evaluation result
+	return otto.TrueValue()
+}
+
+// Evaluate executes code and pretty prints the result to the specified output
+// stream.
+func (self *JSRE) Evaluate(code string, w io.Writer) error {
+	var fail error
+
+	self.Do(func(vm *otto.Otto) {
+		val, err := vm.Run(code)
+		if err != nil {
+			fail = err
+		} else {
+			prettyPrint(vm, val, w)
+			fmt.Fprintln(w)
+		}
+	})
+	return fail
+}
+
+// Compile compiles and then runs a piece of JS code.
+func (self *JSRE) Compile(filename string, src interface{}) (err error) {
+	self.Do(func(vm *otto.Otto) { _, err = compileAndRun(vm, filename, src) })
+	return err
+}
+
+func compileAndRun(vm *otto.Otto, filename string, src interface{}) (otto.Value, error) {
+	script, err := vm.Compile(filename, src)
+	if err != nil {
+		return otto.Value{}, err
+	}
+	return vm.Run(script)
+}