Add ad API for retrieving algorithm values from digest parameter containers

- Mildly annoying but necessary in order to make pgpDigParams properly
  opaque some day (and also allow sane access to this data)

rpmio/rpmpgp.c

@@ -920,6 +920,22 @@ exit:
     return rc;
 }
 
+unsigned int pgpDigParamsAlgo(pgpDigParams digp, unsigned int algotype)
+{
+    unsigned int algo = 0; /* assume failure */
+    if (digp) {
+	switch (algotype) {
+	case PGPVAL_PUBKEYALGO:
+	    algo = digp->pubkey_algo;
+	    break;
+	case PGPVAL_HASHALGO:
+	    algo = digp->hash_algo;
+	    break;
+	}
+    }
+    return algo;
+}
+
 int pgpPrtPkts(const uint8_t * pkts, size_t pktlen, pgpDig dig, int printing)
 {
     const uint8_t *p = pkts;

rpmio/rpmpgp.h

@@ -1060,6 +1060,14 @@ pgpDigParams pgpDigGetParams(pgpDig dig, unsigned int pkttype);
  */
 int pgpDigParamsCmp(pgpDigParams p1, pgpDigParams p2);
 
+/** \ingroup rpmpgp
+ * Retrieve OpenPGP algorithm parameters
+ * param digp		parameter container
+ * param algotype	PGPVAL_HASHALGO / PGPVAL_PUBKEYALGO
+ * return		algorithm value, 0 on error
+ */
+unsigned int pgpDigParamsAlgo(pgpDigParams digp, unsigned int algotype);
+
 /** \ingroup rpmpgp
  * Verify a PGP signature.
  * @param key		public key