Refuse an existing vault before asking for the mnemonic (closes #151)

`secret init` and `secret vault create` asked for the mnemonic and the
unlocker passphrase, and `secret init` printed "Initialized secrets
manager at", before refusing a vault that already exists. The check
`vault.CreateVault` made before writing is now `vault.CheckNewVaultName`,
which both commands call while holding the state directory lock, before
the first prompt; `CreateVault` still calls it. `secret init` prints the
"Initialized" line only once the vault is created, so
`TestMnemonicNotReadNamesOnlyMnemonic` no longer expects it.

Judgement call: the same check validates the name, so `secret vault
create` with an invalid name also fails before the prompts.

Model: opus-5-5

README.md

@@ -90,7 +90,8 @@ remove things pass `--force`.
 #### `secret init`
 
 Initializes the secret manager with a default vault. Prompts for a BIP39
-mnemonic phrase and creates the initial directory structure.
+mnemonic phrase and creates the initial directory structure. When the vault
+`default` already exists, it fails before asking for the mnemonic or passphrase.
 
 **Environment Variables:**
 
@@ -105,7 +106,8 @@ Lists all available vaults. The current vault is marked.
 
 #### `secret vault create <name>`
 
-Creates a new vault with the specified name.
+Creates a new vault with the specified name. When a vault of that name already
+exists, it fails before asking for the mnemonic or passphrase.
 
 **Vault Name Format:** only lowercase ASCII letters, digits, `.`, `-` and `_`
 are allowed, and a name must not be empty, `.` or `..`.

internal/cli/create_vault_test.go

@@ -222,12 +222,51 @@ func TestMnemonicNotReadNamesOnlyMnemonic(t *testing.T) {
 	output, err := cmd.CombinedOutput()
 	require.Error(t, err)
 
-	require.Equal(t, "Initialized secrets manager at: "+stateDir+"\n"+
-		"Error: failed to read mnemonic: there is no terminal to ask on. "+
-		"Please set the SB_SECRET_MNEMONIC environment variable or run "+
+	require.Equal(t, "Error: failed to read mnemonic: there is no terminal to "+
+		"ask on. Please set the SB_SECRET_MNEMONIC environment variable or run "+
 		"interactively\n", string(output))
 }
 
+// TestCreateExistingVaultAsksForNothing is a regression test for
+// https://git.eeqj.de/sneak/secret/issues/151: `secret init` and `secret
+// vault create` asked for the mnemonic and the unlocker passphrase before
+// refusing a vault that already exists, and `secret init` printed
+// "Initialized secrets manager at" first. Each runs here as the built binary,
+// in a new session, which has no terminal, and with neither
+// SB_SECRET_MNEMONIC nor SB_UNLOCK_PASSPHRASE set, so asking for either
+// fails. Each must fail saying only that the vault exists.
+func TestCreateExistingVaultAsksForNothing(t *testing.T) {
+	t.Parallel()
+
+	stateDir := t.TempDir()
+	_, err := vault.CreateVault(afero.NewOsFs(), stateDir, "default", nil, nil)
+	require.NoError(t, err)
+
+	// run runs the built binary with args, which must fail, and returns what
+	// it printed
+	run := func(args ...string) string {
+		//nolint:gosec // G204: test executes the freshly built secret binary
+		cmd := exec.CommandContext(t.Context(), secretBinaryPath(t), args...)
+		cmd.Env = []string{
+			secret.EnvStateDir + "=" + stateDir,
+			"PATH=" + os.Getenv("PATH"),
+			"HOME=" + os.Getenv("HOME"),
+		}
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
+
+		output, err := cmd.CombinedOutput()
+		require.Error(t, err, "secret %v", args)
+
+		return string(output)
+	}
+
+	require.Equal(t,
+		"Error: failed to create default vault: vault default already exists\n",
+		run("init"))
+	require.Equal(t, "Error: vault default already exists\n",
+		run("vault", "create", "default"))
+}
+
 // TestStopDuringCreateLeavesWholeVaultOrNone is a regression test for
 // https://git.eeqj.de/sneak/secret/issues/105: `secret init` or `secret vault
 // create` killed after the passphrase prompt but before the unlocker was

internal/cli/init.go

@@ -17,6 +17,9 @@ import (
 // errPassphraseMismatch is returned when passphrase confirmation fails
 var errPassphraseMismatch = errors.New("passphrases do not match")
 
+// defaultVaultName is the name of the vault `secret init` creates
+const defaultVaultName = "default"
+
 // NewInitCmd creates the init command
 func NewInitCmd() *cobra.Command {
 	return &cobra.Command{
@@ -92,8 +95,10 @@ func (cli *Instance) initialize(cmd *cobra.Command) error {
 		return fmt.Errorf("failed to create state directory: %w", err)
 	}
 
-	if cmd != nil {
-		cmd.Printf("Initialized secrets manager at: %s\n", stateDir)
+	// Refuse an existing default vault before asking for anything
+	err = vault.CheckNewVaultName(cli.fs, cli.stateDir, defaultVaultName)
+	if err != nil {
+		return fmt.Errorf("failed to create default vault: %w", err)
 	}
 
 	// Prompt for mnemonic
@@ -133,7 +138,7 @@ func (cli *Instance) initialize(cmd *cobra.Command) error {
 	// Create the default vault with its passphrase unlocker
 	secret.Debug("Creating default vault")
 
-	vlt, err := vault.CreateVault(cli.fs, cli.stateDir, "default",
+	vlt, err := vault.CreateVault(cli.fs, cli.stateDir, defaultVaultName,
 		mnemonic, passphraseBuffer)
 	if err != nil {
 		secret.Debug("Failed to create default vault", "error", err)
@@ -152,6 +157,7 @@ func (cli *Instance) initialize(cmd *cobra.Command) error {
 	}
 
 	if cmd != nil {
+		cmd.Printf("Initialized secrets manager at: %s\n", stateDir)
 		cmd.Printf("\nDefault vault created and configured\n")
 		cmd.Printf("Long-term public key: %s\n", ltIdentity.Recipient().String())
 		cmd.Printf("Unlocker ID: %s\n", unlocker.GetID())

internal/cli/vault.go

@@ -267,6 +267,12 @@ func (cli *Instance) CreateVault(cmd *cobra.Command, name string) error {
 	}
 	defer release()
 
+	// Refuse an invalid name or an existing vault before asking for anything
+	err = vault.CheckNewVaultName(cli.fs, cli.stateDir, name)
+	if err != nil {
+		return err
+	}
+
 	mnemonic, cleanupMnemonic, err := cli.promptMnemonic()
 	if err != nil {
 		return err

internal/vault/management.go

@@ -212,16 +212,40 @@ func processMnemonicForVault(
 	return ltIdentity, derivationIndex, publicKeyHash, familyHash, nil
 }
 
+// CheckNewVaultName returns an error when name cannot be the name of a new
+// vault: one wrapping ErrInvalidVaultName when it is not a valid vault name,
+// and one wrapping ErrVaultExists when that vault already exists. Creating an
+// existing vault again would replace its keys, and its secrets could no
+// longer be decrypted. CreateVault checks this before writing anything; the
+// commands that create a vault also check it before they ask for the
+// mnemonic or passphrase, holding the state directory lock.
+func CheckNewVaultName(fs afero.Fs, stateDir string, name string) error {
+	err := ValidateVaultName(name)
+	if err != nil {
+		return err
+	}
+
+	exists, err := afero.DirExists(fs, filepath.Join(stateDir, "vaults.d", name))
+	if err != nil {
+		return fmt.Errorf("failed to check if vault exists: %w", err)
+	}
+
+	if exists {
+		return fmt.Errorf("vault %s %w", name, ErrVaultExists)
+	}
+
+	return nil
+}
+
 // CreateVault creates a new vault and selects it as the current vault. When
 // mnemonic is not nil, the vault's long-term key is derived from it, and the
 // returned vault has it as its Mnemonic; when it is nil, the vault has no
 // long-term key until one is imported. When passphrase is not nil, the vault
 // gets a passphrase unlocker protected by it, as its current unlocker; that
-// needs a mnemonic. It refuses a vault that already exists before writing
-// anything: creating it again would replace its keys, and its secrets could
-// no longer be decrypted. The commands that call it hold the state directory
-// lock, so no other command can create the vault between the check and the
-// writes.
+// needs a mnemonic. It refuses an invalid name or a vault that already exists,
+// as CheckNewVaultName does, before writing anything. The commands that call
+// it hold the state directory lock, so no other command can create the vault
+// between the check and the writes.
 //
 // The vault is written whole into a temporary directory, which is renamed
 // into vaults.d only once complete, and only then selected: a crash at any
@@ -233,30 +257,17 @@ func CreateVault(
 ) (*Vault, error) {
 	secret.Debug("Creating new vault", "name", name, "state_dir", stateDir)
 
-	err := ValidateVaultName(name)
+	err := CheckNewVaultName(fs, stateDir, name)
 	if err != nil {
-		secret.Debug("Invalid vault name provided", "vault_name", name)
-
 		return nil, err
 	}
 
-	secret.Debug("Vault name validation passed", "vault_name", name)
-
-	vaultDir := filepath.Join(stateDir, "vaults.d", name)
-
-	exists, err := afero.DirExists(fs, vaultDir)
-	if err != nil {
-		return nil, fmt.Errorf("failed to check if vault exists: %w", err)
-	}
-
-	if exists {
-		return nil, fmt.Errorf("vault %s %w", name, ErrVaultExists)
-	}
-
 	if passphrase != nil && mnemonic == nil {
 		return nil, fmt.Errorf("vault %s %w", name, ErrUnlockerWithoutMnemonic)
 	}
 
+	vaultDir := filepath.Join(stateDir, "vaults.d", name)
+
 	secret.Debug("Creating vault directory structure", "vault_dir", vaultDir)
 
 	err = secret.WriteDir(fs, vaultDir, func(dir string) error {