os.args() and passthru from CLI

cmd/risor/root.go

@@ -66,6 +66,7 @@ func init() {
 
 	rootCmd.Flags().Bool("timing", false, "Show timing information")
 	rootCmd.Flags().StringP("output", "o", "", "Set the output format")
+	rootCmd.Flags().SetInterspersed(false)
 	viper.BindPFlag("timing", rootCmd.Flags().Lookup("timing"))
 	viper.BindPFlag("output", rootCmd.Flags().Lookup("output"))
 
@@ -94,6 +95,45 @@ func fatal(msg string, args ...interface{}) {
 	os.Exit(1)
 }
 
+// this works around issues with cobra not passing args after -- to the script
+// see: https://github.com/spf13/cobra/issues/1877
+// passedargs is everything after the '--'
+// If dropped is true, cobra dropped the double dash in its 'args' slice.
+// argsout returns the cobra args but without the '--' and the items behind it
+// this also supports multiple '--' in the args	list
+func getpassthruargs(args []string) (argsout []string, passedargs []string, dropped bool) {
+	//		lenArgs := len(args)
+	argsout = args
+	ddashcnt := 0
+	for n, arg := range os.Args {
+		if arg == "--" {
+			ddashcnt++
+			if len(passedargs) == 0 {
+				if len(os.Args) > n {
+					passedargs = os.Args[n+1:]
+				}
+			}
+		}
+	}
+	// drop arg0 from count
+	noddash := true
+	for n2, argz := range args {
+		// don't go past the first '--' - this allows one to pass '--' to risor also
+		if argz == "--" {
+			noddash = false
+			argsout = args[:n2]
+			break
+		}
+	}
+	// cobra seems to drop the '--' in its args if everything before it was a flag
+	// if thats the case then args is just empty b/c evrything else is the '--' and the passed args
+	if (noddash || ddashcnt > 1) && len(passedargs) > 0 {
+		dropped = true
+		argsout = []string{}
+	}
+	return
+}
+
 var rootCmd = &cobra.Command{
 	Use:   "risor",
 	Short: "Fast and flexible scripting for Go developers and DevOps",
@@ -102,7 +142,11 @@ var rootCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 
 		ctx := context.Background()
+		var passedargs []string
 
+		args, passedargs, _ = getpassthruargs(args)
+		// pass the 'passthru' args to risor's os package
+		ros.SetScriptArgs(passedargs)
 		// Optionally enable a virtual operating system and add it to
 		// the context so that it's made available to Risor VM.
 		if viper.GetBool("virtual-os") {

modules/os/os.go

@@ -14,6 +14,18 @@ func GetOS(ctx context.Context) os.OS {
 	return os.GetDefaultOS(ctx)
 }
 
+func Args(ctx context.Context, args ...object.Object) object.Object {
+	if err := arg.Require("os.args", 0, args); err != nil {
+		return err
+	}
+	argz := GetOS(ctx).Args()
+	items := make([]object.Object, len(argz))
+	for i, arg := range argz {
+		items[i] = object.NewString(arg)
+	}
+	return object.NewList(items)
+}
+
 func Exit(ctx context.Context, args ...object.Object) object.Object {
 	nArgs := len(args)
 	if nArgs > 1 {
@@ -476,6 +488,7 @@ func Cat(ctx context.Context, args ...object.Object) object.Object {
 
 func Module() *object.Module {
 	return object.NewBuiltinsModule("os", map[string]object.Object{
+		"args":            object.NewBuiltin("chdir", Args),
 		"chdir":           object.NewBuiltin("chdir", Chdir),
 		"create":          object.NewBuiltin("create", Create),
 		"environ":         object.NewBuiltin("environ", Environ),

os/os.go

@@ -47,6 +47,8 @@ type FS interface {
 
 type OS interface {
 	FS
+	Args() []string
+	SetArgs(args []string)
 	Chdir(dir string) error
 	Environ() []string
 	Exit(code int)
@@ -69,6 +71,8 @@ type OS interface {
 
 type contextKey string
 
+var globalScriptargs []string
+
 const osKey = contextKey("risor:os")
 
 // WithOS adds an OS to the context. Subsequently, when this context is present
@@ -93,6 +97,18 @@ func GetDefaultOS(ctx context.Context) OS {
 	return NewSimpleOS(ctx)
 }
 
+// if risor is started from the comand line and args
+// are passed in, this is is how the to tell the os package about them
+func SetScriptArgs(args []string) {
+	globalScriptargs = args
+}
+
+// if risor is started from the comand line and args
+// are passed in, this is is how the to get them
+func GetScriptArgs() []string {
+	return globalScriptargs
+}
+
 // MassagePathError transforms a fs.PathError into a new one with the base path
 // removed from the Path field.
 func MassagePathError(basePath string, err error) error {

os/simple.go

@@ -14,6 +14,7 @@ var (
 type SimpleOS struct {
 	ctx    context.Context
 	limits limits.Limits
+	args   []string
 }
 
 func NewSimpleOS(ctx context.Context) *SimpleOS {
@@ -23,9 +24,20 @@ func NewSimpleOS(ctx context.Context) *SimpleOS {
 	} else {
 		sos.limits = limits.New()
 	}
+	sos.args = globalScriptargs
 	return sos
 }
 
+func (osObj *SimpleOS) Args() []string {
+	return osObj.args
+}
+
+// a way to override or set the args passed to the os package
+// would typically be used when risor is employed in an embedded manner
+func (osObj *SimpleOS) SetArgs(args []string) {
+	osObj.args = args
+}
+
 func (osObj *SimpleOS) Chdir(dir string) error {
 	return os.Chdir(dir)
 }

os/virtual.go

@@ -40,6 +40,7 @@ type VirtualOS struct {
 	exitHandler   ExitHandler
 	stdin         File
 	stdout        File
+	args          []string
 }
 
 // Option is a configuration function for a Virtual Machine.
@@ -158,9 +159,20 @@ func NewVirtualOS(ctx context.Context, opts ...Option) *VirtualOS {
 	for _, opt := range opts {
 		opt(vos)
 	}
+	vos.args = globalScriptargs
 	return vos
 }
 
+func (osObj *VirtualOS) Args() []string {
+	return osObj.args
+}
+
+// a way to override or set the args passed to the os package
+// would typically be used when risor is employed in an embedded manner
+func (osObj *VirtualOS) SetArgs(args []string) {
+	osObj.args = args
+}
+
 func (osObj *VirtualOS) Chdir(dir string) error {
 	osObj.cwd = dir
 	return nil