bug#23619: Some epg tests fail

[npostavs]

Daiki Ueno <ueno@gnu.org> writes:

> npostavs@users.sourceforge.net writes:
>
>>
>> These tests popup a dialog box to enter a passphrase before failing.
>> The following patch which sets pinentry mode to 'loopback' fixes it for
>> me (I have not tested with other gpg versions though):
>
> Thank you.  That sounds like a good idea, but the version actually
> matters: gpg 1.x and 2.0.x refuse the --pinentry-mode option and exit
> abnormally...
>
> Maybe you could add a version check around the call (or in epg--start)?
> epg-config.el provides a few functions to do that.

Does this look right?

>From 9cd6f55d3d01fe0781ce81b2e394ed3e8febd6fa Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sun, 19 Feb 2017 10:34:50 -0500
Subject: [PATCH v2] Fix passphrase callback with gpg 2.1+ (Bug#23619)

* lisp/epg.el (epg-context-set-passphrase-callback): Set CONTEXT's
pinentry mode to `loopback'.
(epg--start): Only pass `--pinentry-mode' for gpg 2.1+.
---
 lisp/epg.el | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/lisp/epg.el b/lisp/epg.el
index 587271b000..ba7125f232 100644
--- a/lisp/epg.el
+++ b/lisp/epg.el
@@ -246,16 +246,15 @@ epg-context-set-passphrase-callback
 The function gets three arguments: the context, the key-id in
 question, and the callback data (if any).
 
-The callback may not be called if you use GnuPG 2.x, which relies
-on the external program called `gpg-agent' for passphrase query.
-If you really want to intercept passphrase query, consider
-installing GnuPG 1.x _along with_ GnuPG 2.x, which does passphrase
-query by itself and Emacs can intercept them."
+Also set CONTEXT's pinentry mode to `loopback' (when using GnuPG
+2.x, the callback would not be called otherwise)."
   ;; (declare (obsolete setf "25.1"))
   (setf (epg-context-passphrase-callback context)
         (if (functionp passphrase-callback)
            (list passphrase-callback)
-         passphrase-callback)))
+         passphrase-callback))
+  (when passphrase-callback
+    (setf (epg-context-pinentry-mode context) 'loopback)))
 
 (defun epg-context-set-progress-callback (context
                                          progress-callback)
@@ -578,7 +577,13 @@ epg--start
                       (if (epg-context-textmode context) '("--textmode"))
                       (if (epg-context-output-file context)
                           (list "--output" (epg-context-output-file context)))
-                      (if (epg-context-pinentry-mode context)
+                      (if (and (epg-context-pinentry-mode context)
+                                ;; GPG 1.x and 2.0.x reject `--pinentry-mode'.
+                                (version<= "2.1"
+                                           (alist-get
+                                            'version (epg-find-configuration
+                                                      (epg-context-protocol 
context))
+                                            "1.0")))
                           (list "--pinentry-mode"
                                 (symbol-name (epg-context-pinentry-mode
                                               context))))
-- 
2.11.1