new: new -script allows to run JS code to instrument session

js/fs.go

@@ -0,0 +1,70 @@
+package js
+
+import (
+	"github.com/robertkrimen/otto"
+	"io/ioutil"
+)
+
+func readDir(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+	if argc != 1 {
+		return ReportError("readDir: expected 1 argument, %d given instead.", argc)
+	}
+
+	path := argv[0].String()
+	dir, err := ioutil.ReadDir(path)
+	if err != nil {
+		return ReportError("Could not read directory %s: %s", path, err)
+	}
+
+	entry_list := []string{}
+	for _, file := range dir {
+		entry_list = append(entry_list, file.Name())
+	}
+
+	v, err := otto.Otto.ToValue(*call.Otto, entry_list)
+	if err != nil {
+		return ReportError("Could not convert to array: %s", err)
+	}
+
+	return v
+}
+
+func readFile(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+	if argc != 1 {
+		return ReportError("readFile: expected 1 argument, %d given instead.", argc)
+	}
+
+	filename := argv[0].String()
+	raw, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return ReportError("Could not read file %s: %s", filename, err)
+	}
+
+	v, err := otto.ToValue(string(raw))
+	if err != nil {
+		return ReportError("Could not convert to string: %s", err)
+	}
+	return v
+}
+
+func writeFile(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+	if argc != 2 {
+		return ReportError("writeFile: expected 2 arguments, %d given instead.", argc)
+	}
+
+	filename := argv[0].String()
+	data := argv[1].String()
+
+	err := ioutil.WriteFile(filename, []byte(data), 0644)
+	if err != nil {
+		return ReportError("Could not write %d bytes to %s: %s", len(data), filename, err)
+	}
+
+	return otto.NullValue()
+}