gpg: Add --list-filter properties key_expires and key_expires_d.

* g10/import.c (impex_filter_getval): Support new filter properties.
--

Here is how to list all subkeys expiring in the year 2061:

 gpg --list-keys --list-filter
      'select= sub/key_expires_d -gt 2061-01-01 \
               && sub/key_expires_d -lt 2061-12-31'

To list all primary key expirations, use the "pub/" prefix and to list
all expiration dates use no prefix.

GnuPG-bug-id: 6509

2 files changed, 20 insertions, 0 deletions

diff --git a/doc/gpg.texi b/doc/gpg.texi
index 6b584a913..61f047cc7 100644
--- a/doc/gpg.texi
+++ b/doc/gpg.texi
@@ -2671,6 +2671,12 @@ The available properties are:
   created.  The second is the same but given as an ISO string,
   e.g. "2016-08-17". (drop-subkey)
 
+  @item key_expires
+  @itemx key_expires_d
+  The expiration time of a public key or subkey or 0 if it does not
+  expire.  The second is the same but given as an ISO date string or
+  an empty string e.g. "2038-01-19".
+
   @item fpr
   The hexified fingerprint of the current subkey or primary key.
   (drop-subkey)
diff --git a/g10/import.c b/g10/import.c
index 987fef3cd..d84a083cc 100644
--- a/g10/import.c
+++ b/g10/import.c
@@ -1564,6 +1564,20 @@ impex_filter_getval (void *cookie, const char *propname)
         {
           result = dateonlystr_from_pk (pk);
         }
+      else if (!strcmp (propname, "key_expires"))
+        {
+          snprintf (numbuf, sizeof numbuf, "%lu", (ulong)pk->expiredate);
+          result = numbuf;
+        }
+      else if (!strcmp (propname, "key_expires_d"))
+        {
+          static char exdatestr[MK_DATESTR_SIZE];
+
+          if (pk->expiredate)
+            result = mk_datestr (exdatestr, sizeof exdatestr, pk->expiredate);
+          else
+            result = "";
+        }
       else if (!strcmp (propname, "expired"))
         {
           result = pk->has_expired? "1":"0";