[gnome-keysign: 4/16] gpgmeh: add signature import with seahorse DBus

[Tobias Mueller <tobiasmue src gnome org>]

commit 51d283c2ddc32fa3e733fda718158b93f64e17ee
Author: RyuzakiKK <aasonykk gmail com>
Date:   Wed Jan 2 15:06:07 2019 +0100

    gpgmeh: add signature import with seahorse DBus
    
    This alternative import method comes handy when we are inside Flatpak,
    because we will be able to import signatures even without requiring
    write permission in the gpg folder of the user.

 keysign/gpgmeh.py | 35 +++++++++++++++++++++++++++++------
 1 file changed, 29 insertions(+), 6 deletions(-)
---
diff --git a/keysign/gpgmeh.py b/keysign/gpgmeh.py
index dbdd9ca..5aa2af8 100755
--- a/keysign/gpgmeh.py
+++ b/keysign/gpgmeh.py
@@ -17,6 +17,7 @@
 #    along with GNOME Keysign.  If not, see <http://www.gnu.org/licenses/>.
 from __future__ import unicode_literals
 
+import base64
 import logging
 import os  # The SigningKeyring uses os.symlink for the agent
 from subprocess import check_output
@@ -24,8 +25,10 @@ import sys
 from tempfile import mkdtemp
 import platform
 
+import dbus
 import gpg
 from gpg.constants import PROTOCOL_OpenPGP
+from gpg.errors import GPGMEError
 
 
 from .gpgkey import Key, UID
@@ -473,11 +476,31 @@ def sign_keydata_and_encrypt(keydata, error_cb=None, homedir=None):
                 yield (UID.from_gpgme(uid), ciphertext)
 
 
-def import_signature(signature, homedir=None):
+def import_signature(encrypted_sig, homedir=None):
     # ctx = gpg.Context()
     ctx = DirectoryContext(homedir)
-    decrypted = ctx.decrypt(signature)
-    ctx.op_import(decrypted[0])
-    result = ctx.op_import_result()
-    if len(result.imports) < 0:
-        raise gpg.errors.GPGMEError
+    signature = ctx.decrypt(encrypted_sig)
+
+    # Try Seahorse DBus
+    name = "org.gnome.seahorse"
+    path = "/org/gnome/seahorse/keys"
+    bus = dbus.SessionBus()
+    result = []
+
+    try:
+        proxy = bus.get_object(name, path)
+        iface = "org.gnome.seahorse.KeyService"
+        gpg_iface = dbus.Interface(proxy, iface)
+        payload = base64.b64encode(signature[0]).decode('latin-1')
+        payload = '\n'.join(payload[i:(i + 64)] for i in range(0, len(payload), 64))
+        payload = "-----BEGIN PGP PUBLIC KEY BLOCK-----\n\n" + payload + "\n-----END PGP PUBLIC KEY 
BLOCK-----"
+        result = gpg_iface.ImportKeys("openpgp", payload)
+    except dbus.exceptions.DBusException:
+        log.debug("Seahorse DBus is not available")
+
+    # If Seahorse failed we try op_import
+    if len(result) < 1:
+        ctx.op_import(signature[0])
+        result = ctx.op_import_result()
+        if len(result.imports) < 1:
+            raise GPGMEError