epg: Automatically start pinentry server

* epg-config.el (epg-gpgconf-program): New variable.
* epg.el (epg--start): Call `pinentry-start' if
allow-emacs-pinentry is set in ~/.gnupg/gpg-agent.conf.

2 files changed, 15 insertions, 0 deletions

diff --git a/lisp/epg-config.el b/lisp/epg-config.el
index 10f0dd3f4bf..db2951306d0 100644
--- a/lisp/epg-config.el
+++ b/lisp/epg-config.el
@@ -51,6 +51,11 @@
   :group 'epg
   :type 'string)
 
+(defcustom epg-gpgconf-program "gpgconf"
+  "The `gpgconf' executable."
+  :group 'epg
+  :type 'string)
+
 (defcustom epg-gpg-home-directory nil
   "The directory which contains the configuration files of `epg-gpg-program'."
   :group 'epg
diff --git a/lisp/epg.el b/lisp/epg.el
index b3d39bb8505..4ba96272aae 100644
--- a/lisp/epg.el
+++ b/lisp/epg.el
@@ -602,6 +602,16 @@ callback data (if any)."
       (setq process-environment
             (cons (concat "GPG_TTY=" terminal-name)
                   (cons "TERM=xterm" process-environment))))
+    ;; Start the Emacs Pinentry server if allow-emacs-pinentry is set
+    ;; in ~/.gnupg/gpg-agent.conf.
+    (when (and (fboundp 'pinentry-start)
+               (with-temp-buffer
+                 (when (= (call-process epg-gpgconf-program nil t nil
+                                        "--list-options" "gpg-agent")
+                          0)
+                   (goto-char (point-min))
+                   (re-search-forward "^allow-emacs-pinentry:.*:1$" nil t))))
+      (pinentry-start))
     (setq process-environment
           (cons (format "INSIDE_EMACS=%s,epg" emacs-version)
                 process-environment))