cmd/camtool: add "camtool whoami" subcommand

Actually add the file, missing from previous commit
38c2a87ad2.

That's what I get for skipping code review. Sigh.

Change-Id: Icfaa7f6922c4ceaae69bd228b8d6498d0a85a7d8

cmd/camtool/whoami.go

@@ -0,0 +1,115 @@
+/*
+Copyright 2018 The Perkeep Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"crypto/rsa"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"sort"
+
+	"perkeep.org/pkg/client"
+	"perkeep.org/pkg/cmdmain"
+	"perkeep.org/pkg/schema"
+)
+
+type whoamiCmd struct{}
+
+func init() {
+	cmdmain.RegisterCommand("whoami", func(flags *flag.FlagSet) cmdmain.CommandRunner {
+		return new(whoamiCmd)
+	})
+}
+
+func (c *whoamiCmd) Describe() string {
+	return "Show Perkeep identity information"
+}
+
+func (c *whoamiCmd) Usage() {
+	fmt.Fprintf(os.Stderr, "camtool whoami [key]\n")
+}
+
+var whoCmds = map[string]func(c *client.Client, s *schema.Signer) error{
+	"identity": whoamiIdentity,
+	"type":     whoamiType,
+	"private":  whoamiPrivate,
+}
+
+func (c *whoamiCmd) RunCommand(args []string) error {
+	if len(args) == 0 {
+		args = []string{"identity"}
+	}
+	if len(args) > 1 {
+		return cmdmain.UsageError("only 0 or 1 arguments allowed")
+	}
+
+	cc, err := client.NewDefault()
+	if err != nil {
+		return fmt.Errorf("creating Client: %v", err)
+	}
+	signer, err := cc.Signer()
+	if err != nil {
+		return fmt.Errorf("no configured Signer: %v", err)
+	}
+
+	cmd, ok := whoCmds[args[0]]
+	if !ok {
+		var cmds []string
+		for k := range whoCmds {
+			cmds = append(cmds, k)
+		}
+		sort.Strings(cmds)
+		return fmt.Errorf("invalid whoami subcommand. Valid options: %q", cmds)
+	}
+	return cmd(cc, signer)
+}
+
+func whoamiIdentity(c *client.Client, s *schema.Signer) error {
+	v := s.KeyIDLong()
+	if v == "" {
+		return errors.New("no configured identity")
+	}
+	fmt.Println("perkeepid:" + v)
+	return nil
+}
+
+func whoamiType(c *client.Client, s *schema.Signer) error {
+	ent := s.Entity()
+	if ent == nil {
+		return errors.New("no identity")
+	}
+	fmt.Println(fmt.Sprintf("%T", ent.PrivateKey.PrivateKey))
+	return nil
+}
+
+func whoamiPrivate(c *client.Client, s *schema.Signer) error {
+	ent := s.Entity()
+	if ent == nil {
+		return errors.New("no identity")
+	}
+	switch v := ent.PrivateKey.PrivateKey.(type) {
+	case *rsa.PrivateKey:
+		fmt.Printf("public.N = %s\n", v.N.String())
+		fmt.Printf("public.E = %v\n", v.E)
+		fmt.Printf("private.D = %s\n", v.D.String())
+		return nil
+	default:
+		return fmt.Errorf("unhandled private key %T", v)
+	}
+}