pgp-provider: set default value to auto

Change the default provider to gpg unless the internal keyring is
initialized and contains one key.

This should be more user friendly.

Link: https://lists.sr.ht/~rjarry/aerc-discuss/%3CCO783CI3IU9F.184DBQTPMIPBS%40paul%3E
Signed-off-by: Robin Jarry <robin@jarry.cc>
Acked-by: Moritz Poldrack <moritz@poldrack.dev>

6 files changed, 43 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5e29ea5c..555f8c0f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - LIST-STATUS support for imap
 - built-in `wrap` filter that does not mess up nested quotes and lists.
 
+### Changed
+
+- `pgp-provider` now defaults to `auto`. It will use the system `gpg` unless
+  the internal keyring exists and contains at least one key.
+
 ### Fixed
 
 - `:pipe -m git am -3` on patch series when `Message-Id` headers have not been
diff --git a/config/aerc.conf b/config/aerc.conf
index 862b3be8..8f3fd097 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -8,12 +8,13 @@
 #
 #default-save-path=
 
-#
 # If set to "gpg", aerc will use system gpg binary and keystore for all crypto
-# operations. Otherwise, the internal openpgp implementation will be used.
+# operations. If set to "internal", the internal openpgp keyring will be used.
+# If set to "auto", the system gpg will be preferred unless the internal
+# keyring already exists, in which case the latter will be used.
 #
-# Default: internal
-#pgp-provider=internal
+# Default: auto
+#pgp-provider=auto
 
 # By default, the file permissions of accounts.conf must be restrictive and
 # only allow reading by the file owner (0600). Set this option to true to
diff --git a/config/general.go b/config/general.go
index 8ca22471..b06eddde 100644
--- a/config/general.go
+++ b/config/general.go
@@ -20,7 +20,7 @@ type GeneralConfig struct {
 
 func defaultGeneralConfig() GeneralConfig {
 	return GeneralConfig{
-		PgpProvider:        "internal",
+		PgpProvider:        "auto",
 		UnsafeAccountsConf: false,
 		LogLevel:           log.INFO,
 	}
@@ -71,9 +71,9 @@ end:
 
 func (gen *GeneralConfig) validatePgpProvider() error {
 	switch gen.PgpProvider {
-	case "gpg", "internal":
+	case "gpg", "internal", "auto":
 		return nil
 	default:
-		return fmt.Errorf("pgp-provider must be either gpg or internal")
+		return fmt.Errorf("pgp-provider must be either auto, gpg or internal")
 	}
 }
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index c95e5aab..e7000b4c 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -31,12 +31,14 @@ These options are configured in the *[general]* section of _aerc.conf_.
 *default-save-path* = _<path>_
 	Used as a default path for save operations if no other path is specified.
 
-*pgp-provider* = _gpg_|_internal_
+*pgp-provider* = _auto_|_gpg_|_internal_
 	If set to _gpg_, aerc will use system gpg binary and keystore for all
 	crypto operations. If set to _internal_, the internal openpgp keyring
-	will be used.
+	will be used. If set to _auto_, the system gpg will be preferred unless
+	the internal keyring already exists, in which case the latter will be
+	used.
 
-	Default: _internal_
+	Default: _auto_
 
 *unsafe-accounts-conf* = _true_|_false_
 	By default, the file permissions of _accounts.conf_ must be restrictive
diff --git a/lib/crypto/crypto.go b/lib/crypto/crypto.go
index b7afe638..cb026696 100644
--- a/lib/crypto/crypto.go
+++ b/lib/crypto/crypto.go
@@ -6,6 +6,7 @@ import (
 
 	"git.sr.ht/~rjarry/aerc/lib/crypto/gpg"
 	"git.sr.ht/~rjarry/aerc/lib/crypto/pgp"
+	"git.sr.ht/~rjarry/aerc/log"
 	"git.sr.ht/~rjarry/aerc/models"
 	"github.com/ProtonMail/go-crypto/openpgp"
 	"github.com/emersion/go-message/mail"
@@ -25,10 +26,20 @@ type Provider interface {
 
 func New(s string) Provider {
 	switch s {
+	case "auto":
+		internal := &pgp.Mail{}
+		if internal.KeyringExists() {
+			log.Debugf("internal pgp keyring exists")
+			return internal
+		}
+		log.Debugf("no internal pgp keyring, using system gpg")
+		fallthrough
 	case "gpg":
 		return &gpg.Mail{}
-	default:
+	case "internal":
 		return &pgp.Mail{}
+	default:
+		return nil
 	}
 }
 
diff --git a/lib/crypto/pgp/pgp.go b/lib/crypto/pgp/pgp.go
index b2f5fa24..8d7c135a 100644
--- a/lib/crypto/pgp/pgp.go
+++ b/lib/crypto/pgp/pgp.go
@@ -28,6 +28,17 @@ var (
 	locked bool
 )
 
+func (m *Mail) KeyringExists() bool {
+	keypath := path.Join(xdg.DataHome(), "aerc", "keyring.asc")
+	keyfile, err := os.Open(keypath)
+	if err != nil {
+		return false
+	}
+	defer keyfile.Close()
+	_, err = openpgp.ReadKeyRing(keyfile)
+	return err == nil
+}
+
 func (m *Mail) Init() error {
 	log.Debugf("Initializing PGP keyring")
 	err := os.MkdirAll(path.Join(xdg.DataHome(), "aerc"), 0o700)
@@ -50,13 +61,13 @@ func (m *Mail) Init() error {
 	if os.IsNotExist(err) {
 		return nil
 	} else if err != nil {
-		panic(err)
+		return err
 	}
 	defer keyfile.Close()
 
 	Keyring, err = openpgp.ReadKeyRing(keyfile)
 	if err != nil {
-		panic(err)
+		return err
 	}
 	return nil
 }