feat: allow key export in online mode

Export does not require repo lock and it is safe to do even when ipfs
daemon is running. This enables apps like Brave browser to do
import/export without stopping/starting daemon.

Ref. brave/brave-browser#15422

Author: lidel

core/commands/keystore.go

@@ -12,6 +12,7 @@ import (
 
 	cmds "github.com/ipfs/go-ipfs-cmds"
 	config "github.com/ipfs/go-ipfs-config"
+	keystore "github.com/ipfs/go-ipfs-keystore"
 	oldcmds "github.com/ipfs/go-ipfs/commands"
 	cmdenv "github.com/ipfs/go-ipfs/core/commands/cmdenv"
 	"github.com/ipfs/go-ipfs/core/commands/e"
@@ -150,7 +151,6 @@ path can be specified with '--output=<path>' or '-o=<path>'.
 		cmds.StringOption(outputOptionName, "o", "The path where the output should be stored."),
 	},
 	NoRemote: true,
-	PreRun:   DaemonNotRunning,
 	Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
 		name := req.Arguments[0]
 
@@ -163,13 +163,15 @@ path can be specified with '--output=<path>' or '-o=<path>'.
 			return err
 		}
 
-		r, err := fsrepo.Open(cfgRoot)
+		// Export is read-only: safe to read it without acquiring repo lock
+		// (this makes export work when ipfs daemon is already running)
+		ksp := filepath.Join(cfgRoot, "keystore")
+		ks, err := keystore.NewFSKeystore(ksp)
 		if err != nil {
 			return err
 		}
-		defer r.Close()
 
-		sk, err := r.Keystore().Get(name)
+		sk, err := ks.Get(name)
 		if err != nil {
 			return fmt.Errorf("key with name '%s' doesn't exist", name)
 		}

test/sharness/t0165-keystore.sh

@@ -175,8 +175,13 @@ ipfs key rm key_ed25519
     test_cmp rsa_key_id roundtrip_rsa_key_id
   '
 
-  test_expect_success "online export rsa key" '
-    test_must_fail ipfs key export generated_rsa_key
+  test_expect_success "export and import ed25519 key while daemon is running" '
+    edhash=$(ipfs key gen exported_ed25519_key --type=ed25519)
+    echo $edhash > ed25519_key_id
+    ipfs key export exported_ed25519_key &&
+    ipfs key rm exported_ed25519_key &&
+    ipfs key import exported_ed25519_key exported_ed25519_key.key > roundtrip_ed25519_key_id &&
+    test_cmp ed25519_key_id roundtrip_ed25519_key_id
   '
 
   test_expect_success "online rotate rsa key" '