gpg: don't send messages that failed encryption

Add error handling for messages that were unable to be encrypted.
Previously, messages that failed encryption would be sent with no
content. This patch adds error handling - when encryption fails, the
user is returned to the Review screen and instructed to check the public
keys for their recipients.

Reported-by: Moritz Poldrack <moritz@poldrack.dev>
Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Moritz Poldrack <moritz@poldrack.dev>

lib/crypto/gpg/gpgbin/encrypt.go

@@ -2,6 +2,7 @@ package gpgbin
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 
 	"git.sr.ht/~rjarry/aerc/models"
@@ -27,7 +28,10 @@ func Encrypt(r io.Reader, to []string, from string) ([]byte, error) {
 	g.cmd.Run()
 	outRdr := bytes.NewReader(g.stdout.Bytes())
 	var md models.MessageDetails
-	parse(outRdr, &md)
+	err := parse(outRdr, &md)
+	if err != nil {
+		return nil, fmt.Errorf("gpg: failure to encrypt: %v. check public key(s)", err)
+	}
 	var buf bytes.Buffer
 	io.Copy(&buf, md.Body)
 

lib/crypto/gpg/gpgbin/gpgbin.go

@@ -228,6 +228,8 @@ func parse(r io.Reader, md *models.MessageDetails) error {
 			md.Micalg = micalgs[micalg]
 		case "NODATA":
 			md.SignatureError = "gpg: no signature packet found"
+		case "FAILURE":
+			return fmt.Errorf(strings.TrimPrefix(line, "[GNUPG:] "))
 		}
 	}
 	md.Body = bytes.NewReader(msgContent)

widgets/compose.go

@@ -598,7 +598,10 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 		if err != nil {
 			return err
 		}
-		cleartext.Close()
+		err = cleartext.Close()
+		if err != nil {
+			return err
+		}
 		io.Copy(writer, &buf)
 		return nil