pinentry.py: Show errors in GETPIN handling

GnuPG 2.1.15 has exchanges like:

  ...
  C: SETDESC Please enter the passphrase to unlock the OpenPGP secret key...
  S: OK
  C: SETPROMPT Passphrase:
  S: OK
  C: GETPIN
  S: D foo
  S: OK
  C: SETERROR Bad Passphrase (try 2 of 3)
  S: OK
  C: GETPIN
  ...

with this commit we show those errors to the user.

diff --git a/bin/pinentry.py b/bin/pinentry.py
index 50cf3326cdadc1e8f32c97d87c522db1312d111e..8ed3b4dcbb21ed539ff84bf44e0d94dfb1570044 100755 (executable)
--- a/bin/pinentry.py
+++ b/bin/pinentry.py
@@ -218,9 +218,12 @@ class PinEntry (_server.AssuanServer):
         # drop trailing newline
         return self.connection['from_user'].readline()[:-1]
 
-    def _prompt(self, prompt='?', add_colon=True):
+    def _prompt(self, prompt='?', error=None, add_colon=True):
         if add_colon:
             prompt += ':'
+        if error:
+            self.connection['to_user'].write(error)
+            self.connection['to_user'].write('\n')
         self.connection['to_user'].write(prompt)
         self.connection['to_user'].write(' ')
         self.connection['to_user'].flush()
@@ -317,7 +320,10 @@ class PinEntry (_server.AssuanServer):
                 self._write('key: {}'.format(self.strings['key info']))
             if 'qualitybar' in self.strings:
                 self._write(self.strings['qualitybar'])
-            pin = self._prompt(self.strings['prompt'], add_colon=False)
+            pin = self._prompt(
+                prompt=self.strings['prompt'],
+                error=self.strings.get('error'),
+                add_colon=False)
         finally:
             self._disconnect()
         yield _common.Response('D', pin.encode('ascii'))