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moby--moby/rcli/types.go

97 lines
2.6 KiB
Go

package rcli
// rcli (Remote Command-Line Interface) is a simple protocol for...
// serving command-line interfaces remotely.
//
// rcli can be used over any transport capable of a) sending binary streams in
// both directions, and b) capable of half-closing a connection. TCP and Unix sockets
// are the usual suspects.
import (
"errors"
"flag"
"fmt"
"io"
"log"
"reflect"
"strings"
)
type Service interface {
Name() string
Help() string
}
type Cmd func(io.ReadCloser, io.Writer, ...string) error
type CmdMethod func(Service, io.ReadCloser, io.Writer, ...string) error
// FIXME: For reverse compatibility
func call(service Service, stdin io.ReadCloser, stdout io.Writer, args ...string) error {
return LocalCall(service, stdin, stdout, args...)
}
func LocalCall(service Service, stdin io.ReadCloser, stdout io.Writer, args ...string) error {
if len(args) == 0 {
args = []string{"help"}
}
flags := flag.NewFlagSet("main", flag.ContinueOnError)
flags.SetOutput(stdout)
flags.Usage = func() { stdout.Write([]byte(service.Help())) }
if err := flags.Parse(args); err != nil {
return err
}
cmd := flags.Arg(0)
log.Printf("%s\n", strings.Join(append(append([]string{service.Name()}, cmd), flags.Args()[1:]...), " "))
if cmd == "" {
cmd = "help"
}
method := getMethod(service, cmd)
if method != nil {
return method(stdin, stdout, flags.Args()[1:]...)
}
return errors.New("No such command: " + cmd)
}
func getMethod(service Service, name string) Cmd {
if name == "help" {
return func(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
if len(args) == 0 {
stdout.Write([]byte(service.Help()))
} else {
if method := getMethod(service, args[0]); method == nil {
return errors.New("No such command: " + args[0])
} else {
method(stdin, stdout, "--help")
}
}
return nil
}
}
methodName := "Cmd" + strings.ToUpper(name[:1]) + strings.ToLower(name[1:])
method, exists := reflect.TypeOf(service).MethodByName(methodName)
if !exists {
return nil
}
return func(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
ret := method.Func.CallSlice([]reflect.Value{
reflect.ValueOf(service),
reflect.ValueOf(stdin),
reflect.ValueOf(stdout),
reflect.ValueOf(args),
})[0].Interface()
if ret == nil {
return nil
}
return ret.(error)
}
}
func Subcmd(output io.Writer, name, signature, description string) *flag.FlagSet {
flags := flag.NewFlagSet(name, flag.ContinueOnError)
flags.SetOutput(output)
flags.Usage = func() {
fmt.Fprintf(output, "\nUsage: docker %s %s\n\n%s\n\n", name, signature, description)
flags.PrintDefaults()
}
return flags
}