gpg: Extend the "sig" record in --list-mode.

* g10/getkey.c (get_user_id_string): Add arg R_NOUID.  Change call
callers.
(get_user_id): Add arg R_NOUID.  Change call callers.
* g10/mainproc.c (issuer_fpr_string): Make global.
* g10/keylist.c (list_keyblock_colon): Print a '?' for a missing key
also in --list-mode.  Print the "issuer fpr" field also if there is an
issuer fingerprint subpacket.
--

Scripts used to rely on the "User ID not found" string even in the
--with-colons listing.  However, that is not a good idea because that
string is subject to translations etc.  Now we have an explicit way of
telling that a key is missing.  For example:

  gpg --list-sigs --with-colons | \
    awk -F: '$1=="sig" && $2=="?" {if($13){print $13}else{print $5}}'

Prints all keyids or fingerprint of signing keys for which we do not
have the key in our local keyring.

Signed-off-by: Werner Koch <wk@gnupg.org>

doc/DETAILS

@@ -105,6 +105,19 @@ described here.
     certificate (i.e. for the trust anchor) and an 'f' for all other
     valid certificates.
 
+    In "sig" records, this field may have one of these values as first
+    character:
+
+    - ! :: Signature is good.
+    - - :: Signature is bad.
+    - ? :: No public key to verify signature or public key is not usable.
+    - % :: Other error verifying a signature
+
+    More values may be added later.  The field may also be empty if
+    gpg has been invoked in a non-checking mode (--list-sigs) or in a
+    fast checking mode.  Since 2.2.7 '?' will also be printed by the
+    command --list-sigs if the key is not in the local keyring.
+
 *** Field 3 - Key length
 
     The length of key in bits.
@@ -195,9 +208,11 @@ described here.
     gpg's --edit-key menu does.
 
     For "sig" records, this is the fingerprint of the key that issued
-    the signature.  Note that this is only filled in if the signature
+    the signature.  Note that this may only be filled if the signature
     verified correctly.  Note also that for various technical reasons,
     this fingerprint is only available if --no-sig-cache is used.
+    Since 2.2.7 this field will also be set if the key is missing but
+    the signature carries an issuer fingerprint as meta data.
 
 *** Field 14 - Flag field
 

g10/getkey.c

@@ -4119,15 +4119,20 @@ get_seckey_default_or_card (ctrl_t ctrl, PKT_public_key *pk,
  *********************************************/
 
 /* Return a string with a printable representation of the user_id.
- * this string must be freed by xfree.   */
+ * this string must be freed by xfree.  If R_NOUID is not NULL it is
+ * set to true if a user id was not found; otherwise to false.  */
 static char *
-get_user_id_string (ctrl_t ctrl, u32 * keyid, int mode, size_t *r_len)
+get_user_id_string (ctrl_t ctrl, u32 * keyid, int mode, size_t *r_len,
+                    int *r_nouid)
 {
   user_id_db_t r;
   keyid_list_t a;
   int pass = 0;
   char *p;
 
+  if (r_nouid)
+    *r_nouid = 0;
+
   /* Try it two times; second pass reads from the database.  */
   do
     {
@@ -4174,6 +4179,8 @@ get_user_id_string (ctrl_t ctrl, u32 * keyid, int mode, size_t *r_len)
   else
     p = xasprintf ("%s [?]", keystr (keyid));
 
+  if (r_nouid)
+    *r_nouid = 1;
   if (r_len)
     *r_len = strlen (p);
   return p;
@@ -4183,7 +4190,7 @@ get_user_id_string (ctrl_t ctrl, u32 * keyid, int mode, size_t *r_len)
 char *
 get_user_id_string_native (ctrl_t ctrl, u32 * keyid)
 {
-  char *p = get_user_id_string (ctrl, keyid, 0, NULL);
+  char *p = get_user_id_string (ctrl, keyid, 0, NULL, NULL);
   char *p2 = utf8_to_native (p, strlen (p), 0);
   xfree (p);
   return p2;
@@ -4193,15 +4200,15 @@ get_user_id_string_native (ctrl_t ctrl, u32 * keyid)
 char *
 get_long_user_id_string (ctrl_t ctrl, u32 * keyid)
 {
-  return get_user_id_string (ctrl, keyid, 1, NULL);
+  return get_user_id_string (ctrl, keyid, 1, NULL, NULL);
 }
 
 
 /* Please try to use get_user_byfpr instead of this one.  */
 char *
-get_user_id (ctrl_t ctrl, u32 *keyid, size_t *rn)
+get_user_id (ctrl_t ctrl, u32 *keyid, size_t *rn, int *r_nouid)
 {
-  return get_user_id_string (ctrl, keyid, 2, rn);
+  return get_user_id_string (ctrl, keyid, 2, rn, r_nouid);
 }
 
 
@@ -4210,7 +4217,7 @@ char *
 get_user_id_native (ctrl_t ctrl, u32 *keyid)
 {
   size_t rn;
-  char *p = get_user_id (ctrl, keyid, &rn);
+  char *p = get_user_id (ctrl, keyid, &rn, NULL);
   char *p2 = utf8_to_native (p, rn, 0);
   xfree (p);
   return p2;

g10/keydb.h

@@ -404,10 +404,10 @@ void setup_main_keyids (kbnode_t keyblock);
    data structures.  */
 void merge_keys_and_selfsig (ctrl_t ctrl, kbnode_t keyblock);
 
-char*get_user_id_string_native (ctrl_t ctrl, u32 *keyid);
-char*get_long_user_id_string (ctrl_t ctrl, u32 *keyid);
-char*get_user_id (ctrl_t ctrl, u32 *keyid, size_t *rn);
-char*get_user_id_native (ctrl_t ctrl, u32 *keyid);
+char *get_user_id_string_native (ctrl_t ctrl, u32 *keyid);
+char *get_long_user_id_string (ctrl_t ctrl, u32 *keyid);
+char *get_user_id (ctrl_t ctrl, u32 *keyid, size_t *rn, int *r_nouid);
+char *get_user_id_native (ctrl_t ctrl, u32 *keyid);
 char *get_user_id_byfpr (ctrl_t ctrl, const byte *fpr, size_t *rn);
 char *get_user_id_byfpr_native (ctrl_t ctrl, const byte *fpr);
 

g10/keyedit.c

@@ -264,7 +264,7 @@ keyedit_print_one_sig (ctrl_t ctrl, estream_t fp,
       else
 	{
 	  size_t n;
-	  char *p = get_user_id (ctrl, sig->keyid, &n);
+	  char *p = get_user_id (ctrl, sig->keyid, &n, NULL);
 	  tty_print_utf8_string2 (fp, p, n,
 				  opt.screen_columns - keystrlen () - 26 -
 				  ((opt.

g10/keylist.c

@@ -1145,7 +1145,7 @@ list_keyblock_print (ctrl_t ctrl, kbnode_t keyblock, int secret, int fpr,
 	  else if (!opt.fast_list_mode)
 	    {
 	      size_t n;
-	      char *p = get_user_id (ctrl, sig->keyid, &n);
+	      char *p = get_user_id (ctrl, sig->keyid, &n, NULL);
 	      print_utf8_buffer (es_stdout, p, n);
 	      xfree (p);
 	    }
@@ -1513,6 +1513,7 @@ list_keyblock_colon (ctrl_t ctrl, kbnode_t keyblock,
 	  byte fparray[MAX_FINGERPRINT_LEN];
           char *siguid;
           size_t siguidlen;
+          char *issuer_fpr = NULL;
 
 	  if (sig->sig_class == 0x20 || sig->sig_class == 0x28
 	      || sig->sig_class == 0x30)
@@ -1570,11 +1571,16 @@ list_keyblock_colon (ctrl_t ctrl, kbnode_t keyblock,
 	  else
 	    {
 	      rc = 0;
-	      sigrc = ' ';
+	      sigrc = ' '; /* Note the fix-up below in --list-sigs mode.  */
 	    }
 
 	  if (sigrc != '%' && sigrc != '?' && !opt.fast_list_mode)
-            siguid = get_user_id (ctrl, sig->keyid, &siguidlen);
+            {
+              int nouid;
+              siguid = get_user_id (ctrl, sig->keyid, &siguidlen, &nouid);
+              if (!opt.check_sigs && nouid)
+                sigrc = '?';  /* No key in local keyring.  */
+            }
           else
             {
               siguid = NULL;
@@ -1613,6 +1619,8 @@ list_keyblock_colon (ctrl_t ctrl, kbnode_t keyblock,
 	      for (i = 0; i < fplen; i++)
 		es_fprintf (es_stdout, "%02X", fparray[i]);
 	    }
+          else if ((issuer_fpr = issuer_fpr_string (sig)))
+            es_fputs (issuer_fpr, es_stdout);
 
 	  es_fprintf (es_stdout, ":::%d:\n", sig->digest_algo);
 
@@ -1621,6 +1629,7 @@ list_keyblock_colon (ctrl_t ctrl, kbnode_t keyblock,
 
 	  /* fixme: check or list other sigs here */
           xfree (siguid);
+          xfree (issuer_fpr);
 	}
     }
 

g10/mainproc.c

@@ -1209,7 +1209,7 @@ list_node (CTX c, kbnode_t node)
 	}
       else if (!opt.fast_list_mode)
         {
-          p = get_user_id (c->ctrl, sig->keyid, &n);
+          p = get_user_id (c->ctrl, sig->keyid, &n, NULL);
           es_write_sanitized (es_stdout, p, n,
                               opt.with_colons?":":NULL, NULL );
           xfree (p);
@@ -1630,7 +1630,8 @@ issuer_fpr_raw (PKT_signature *sig, size_t *r_len)
 
 /* Return the ISSUER fingerprint string in human readbale format if
  * available.  Caller must release the string.  */
-static char *
+/* FIXME: Move to another file.  */
+char *
 issuer_fpr_string (PKT_signature *sig)
 {
   const byte *p;

g10/packet.h

@@ -604,6 +604,8 @@ int proc_signature_packets_by_fd (ctrl_t ctrl,
 int proc_encryption_packets (ctrl_t ctrl, void *ctx, iobuf_t a);
 int list_packets( iobuf_t a );
 
+char *issuer_fpr_string (PKT_signature *sig);
+
 /*-- parse-packet.c --*/
 
 /* Sets the packet list mode to MODE (i.e., whether we are dumping a

g10/passphrase.c

@@ -488,7 +488,7 @@ gpg_format_keydesc (ctrl_t ctrl, PKT_public_key *pk, int mode, int escaped)
                && pk->keyid[1] != pk->main_keyid[1]);
   algo_name = openpgp_pk_algo_name (pk->pubkey_algo);
   timestr = strtimestamp (pk->timestamp);
-  uid = get_user_id (ctrl, is_subkey? pk->main_keyid:pk->keyid, &uidlen);
+  uid = get_user_id (ctrl, is_subkey? pk->main_keyid:pk->keyid, &uidlen, NULL);
 
   orig_codeset = i18n_switchto_utf8 ();
 

g10/pkclist.c

@@ -1149,7 +1149,7 @@ build_pk_list (ctrl_t ctrl, strlist_t rcpts, PK_LIST *ret_pk_list)
                   else
                     {
                       size_t n;
-                      char *p = get_user_id (ctrl, keyid, &n );
+                      char *p = get_user_id (ctrl, keyid, &n, NULL);
                       tty_print_utf8_string ( p, n );
                       xfree(p);
                     }

g10/revoke.c

@@ -571,7 +571,7 @@ gen_standard_revoke (ctrl_t ctrl, PKT_public_key *psk, const char *cache_nonce)
 
   kl = opt.keyid_format == KF_NONE? 0 : keystrlen ();
 
-  tmpstr = get_user_id (ctrl, keyid, &len);
+  tmpstr = get_user_id (ctrl, keyid, &len, NULL);
   es_fprintf (memfp, "uid%*s%.*s\n\n",
               kl + 10, "",
               (int)len, tmpstr);