X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/243f15e69ed3a5514be89115d3ec231551d31cb8..13f6d45704efc68ca8419e8917376aa44fdee1be:/lib/cmd/cmd.go

diff --git a/lib/cmd/cmd.go b/lib/cmd/cmd.go
index a3d5ae8767..a03cb90f68 100644
--- a/lib/cmd/cmd.go
+++ b/lib/cmd/cmd.go
@@ -2,77 +2,162 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 
-// package cmd defines a RunFunc type, representing a process that can
-// be invoked from a command line.
+// Package cmd helps define reusable functions that can be exposed as
+// [subcommands of] command line programs.
 package cmd
 
 import (
 	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"sort"
+	"strings"
+
+	"github.com/sirupsen/logrus"
 )
 
-// A RunFunc runs a command with the given args, and returns an exit
-// code.
-type RunFunc func(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int
+type Handler interface {
+	RunCommand(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int
+}
+
+type HandlerFunc func(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int
+
+func (f HandlerFunc) RunCommand(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
+	return f(prog, args, stdin, stdout, stderr)
+}
+
+// Version is a Handler that prints the package version (set at build
+// time using -ldflags) and Go runtime version to stdout, and returns
+// 0.
+var Version versionCommand
+
+var version = "dev"
+
+type versionCommand struct{}
 
-// Multi returns a command that looks up its first argument in m, and
-// runs the resulting RunFunc with the remaining args.
+func (versionCommand) String() string {
+	return fmt.Sprintf("%s (%s)", version, runtime.Version())
+}
+
+func (versionCommand) RunCommand(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
+	prog = regexp.MustCompile(` -*version$`).ReplaceAllLiteralString(prog, "")
+	fmt.Fprintf(stdout, "%s %s (%s)\n", prog, version, runtime.Version())
+	return 0
+}
+
+// Multi is a Handler that looks up its first argument in a map (after
+// stripping any "arvados-" or "crunch-" prefix), and invokes the
+// resulting Handler with the remaining args.
 //
 // Example:
 //
-//     os.Exit(Multi(map[string]RunFunc{
-//             "foobar": func(prog string, args []string) int {
+//     os.Exit(Multi(map[string]Handler{
+//             "foobar": HandlerFunc(func(prog string, args []string) int {
 //                     fmt.Println(args[0])
 //                     return 2
-//             },
-//     })("/usr/bin/multi", []string{"foobar", "baz"}))
+//             }),
+//     })("/usr/bin/multi", []string{"foobar", "baz"}, os.Stdin, os.Stdout, os.Stderr))
 //
 // ...prints "baz" and exits 2.
-func Multi(m map[string]RunFunc) RunFunc {
-	return func(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
-		if len(args) < 1 {
-			fmt.Fprintf(stderr, "usage: %s command [args]", prog)
-			return 2
+type Multi map[string]Handler
+
+func (m Multi) RunCommand(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
+	_, basename := filepath.Split(prog)
+	if i := strings.Index(basename, "~"); i >= 0 {
+		// drop "~anything" suffix (arvados-dispatch-cloud's
+		// DeployRunnerBinary feature relies on this)
+		basename = basename[:i]
+	}
+	cmd, ok := m[basename]
+	if !ok {
+		// "controller" command exists, and binary is named "arvados-controller"
+		cmd, ok = m[strings.TrimPrefix(basename, "arvados-")]
+	}
+	if !ok {
+		// "dispatch-slurm" command exists, and binary is named "crunch-dispatch-slurm"
+		cmd, ok = m[strings.TrimPrefix(basename, "crunch-")]
+	}
+	if ok {
+		return cmd.RunCommand(prog, args, stdin, stdout, stderr)
+	} else if len(args) < 1 {
+		fmt.Fprintf(stderr, "usage: %s command [args]\n", prog)
+		m.Usage(stderr)
+		return 2
+	} else if cmd, ok = m[args[0]]; ok {
+		return cmd.RunCommand(prog+" "+args[0], args[1:], stdin, stdout, stderr)
+	} else {
+		fmt.Fprintf(stderr, "%s: unrecognized command %q\n", prog, args[0])
+		m.Usage(stderr)
+		return 2
+	}
+}
+
+func (m Multi) Usage(stderr io.Writer) {
+	fmt.Fprintf(stderr, "\nAvailable commands:\n")
+	m.listSubcommands(stderr, "")
+}
+
+func (m Multi) listSubcommands(out io.Writer, prefix string) {
+	var subcommands []string
+	for sc := range m {
+		if strings.HasPrefix(sc, "-") {
+			// Some subcommands have alternate versions
+			// like "--version" for compatibility. Don't
+			// clutter the subcommand summary with those.
+			continue
 		}
-		if cmd, ok := m[args[0]]; !ok {
-			fmt.Fprintf(stderr, "unrecognized command %q", args[0])
-			return 2
-		} else {
-			return cmd(prog+" "+args[0], args[1:], stdin, stdout, stderr)
+		subcommands = append(subcommands, sc)
+	}
+	sort.Strings(subcommands)
+	for _, sc := range subcommands {
+		switch cmd := m[sc].(type) {
+		case Multi:
+			cmd.listSubcommands(out, prefix+sc+" ")
+		default:
+			fmt.Fprintf(out, "    %s%s\n", prefix, sc)
 		}
 	}
 }
 
-// WithLateSubcommand wraps a RunFunc by skipping over some known
-// flags to find a subcommand, and moving that subcommand to the front
-// of the args before calling the wrapped RunFunc. For example:
+type FlagSet interface {
+	Init(string, flag.ErrorHandling)
+	Args() []string
+	NArg() int
+	Parse([]string) error
+	SetOutput(io.Writer)
+	PrintDefaults()
+}
+
+// SubcommandToFront silently parses args using flagset, and returns a
+// copy of args with the first non-flag argument moved to the
+// front. If parsing fails or consumes all of args, args is returned
+// unchanged.
 //
-//	// Translate [           --format foo subcommand bar]
-//	//        to [subcommand --format foo            bar]
-//	WithLateSubcommand(fn, []string{"format"}, nil)
-func WithLateSubcommand(run RunFunc, argFlags, boolFlags []string) RunFunc {
-	return func(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
-		flags := flag.NewFlagSet("prog", flag.ContinueOnError)
-		for _, arg := range argFlags {
-			flags.String(arg, "", "")
-		}
-		for _, arg := range boolFlags {
-			flags.Bool(arg, false, "")
-		}
-		// Ignore errors. We can't report a useful error
-		// message anyway.
-		flags.Parse(args)
-		if flags.NArg() > 0 {
-			// Move the first arg after the recognized
-			// flags up to the front.
-			flagargs := len(args) - flags.NArg()
-			newargs := make([]string, len(args))
-			newargs[0] = args[flagargs]
-			copy(newargs[1:flagargs+1], args[:flagargs])
-			copy(newargs[flagargs+1:], args[flagargs+1:])
-			args = newargs
-		}
-		return run(prog, args, stdin, stdout, stderr)
+// SubcommandToFront invokes methods on flagset that have side
+// effects, including Parse. In typical usage, flagset will not used
+// for anything else after being passed to SubcommandToFront.
+func SubcommandToFront(args []string, flagset FlagSet) []string {
+	flagset.Init("", flag.ContinueOnError)
+	flagset.SetOutput(ioutil.Discard)
+	if err := flagset.Parse(args); err != nil || flagset.NArg() == 0 {
+		// No subcommand found.
+		return args
 	}
+	// Move subcommand to the front.
+	flagargs := len(args) - flagset.NArg()
+	newargs := make([]string, len(args))
+	newargs[0] = args[flagargs]
+	copy(newargs[1:flagargs+1], args[:flagargs])
+	copy(newargs[flagargs+1:], args[flagargs+1:])
+	return newargs
+}
+
+type NoPrefixFormatter struct{}
+
+func (NoPrefixFormatter) Format(entry *logrus.Entry) ([]byte, error) {
+	return []byte(entry.Message + "\n"), nil
 }