Backport of the signature comparison on package resigning fixes:
http://rpm.org/gitweb?p=rpm.git;a=commitdiff;h=e29313061313a9e29d38a005f1b5f5bdc47ccd84
http://rpm.org/gitweb?p=rpm.git;a=commitdiff;h=c0aad81e9b17afcbea4008485d354673495eb148
http://rpm.org/gitweb?p=rpm.git;a=commitdiff;h=17b433ce8c8613199e40b3b27e9ca5398a2027e3
diff --git a/lib/rpmchecksig.c b/lib/rpmchecksig.c
index babbe76..1545269 100644
--- a/lib/rpmchecksig.c
+++ b/lib/rpmchecksig.c
@@ -105,28 +105,96 @@ exit:
 }
 
 /**
- * Retrieve signer fingerprint from an OpenPGP signature tag.
- * @param sig		signature header
+ * Retrieve signature from header tag
+ * @param sigh		signature header
  * @param sigtag	signature tag
- * @retval signid	signer fingerprint
- * @return		0 on success
+ * @return		parsed pgp dig or NULL
  */
-static int getSignid(Header sig, rpmSigTag sigtag, pgpKeyID_t signid)
+static pgpDig getSig(Header sigh, rpmSigTag sigtag)
 {
     struct rpmtd_s pkt;
-    int rc = 1;
+    pgpDig dig = NULL;
 
-    if (headerGet(sig, sigtag, &pkt, HEADERGET_DEFAULT) && pkt.data != NULL) {
-	pgpDig dig = pgpNewDig();
+    if (headerGet(sigh, sigtag, &pkt, HEADERGET_DEFAULT) && pkt.data != NULL) {
+	dig = pgpNewDig();
 
-	if (!pgpPrtPkts(pkt.data, pkt.count, dig, 0)) {
-	    memcpy(signid, dig->signature.signid, sizeof(dig->signature.signid));
-	    rc = 0;
+	if (pgpPrtPkts(pkt.data, pkt.count, dig, 0) != 0) {
+	    dig = pgpFreeDig(dig);
 	}
-     
-	dig = pgpFreeDig(dig);
 	rpmtdFreeData(&pkt);
     }
+    return dig;
+}
+
+static void deleteSigs(Header sigh)
+{
+    headerDel(sigh, RPMSIGTAG_GPG);
+    headerDel(sigh, RPMSIGTAG_PGP);
+    headerDel(sigh, RPMSIGTAG_DSA);
+    headerDel(sigh, RPMSIGTAG_RSA);
+    headerDel(sigh, RPMSIGTAG_PGP5);
+}
+
+static int sameSignature(rpmSigTag sigtag, Header h1, Header h2)
+{
+    pgpDig dig1 = getSig(h1, sigtag);
+    pgpDig dig2 = getSig(h2, sigtag);
+    int rc = 0; /* assume different, eg if either signature doesn't exist */
+
+    /* XXX This part really belongs to rpmpgp.[ch] */
+    if (dig1 && dig2) {
+	pgpDigParams sig1 = &dig1->signature;
+	pgpDigParams sig2 = &dig2->signature;
+
+	/* XXX Should we compare something else too? */
+	if (sig1->hash_algo != sig2->hash_algo)
+	    goto exit;
+	if (sig1->pubkey_algo != sig2->pubkey_algo)
+	    goto exit;
+	if (sig1->version != sig2->version)
+	    goto exit;
+	if (sig1->sigtype != sig2->sigtype)
+	    goto exit;
+	if (memcmp(sig1->signid, sig2->signid, sizeof(sig1->signid)) != 0)
+	    goto exit;
+
+	/* Parameters match, assume same signature */
+	rc = 1;
+    }
+
+exit:
+    pgpFreeDig(dig1);
+    pgpFreeDig(dig2);
+    return rc;
+}
+
+static int replaceSignature(Header sigh, const char *sigtarget,
+			    const char *passPhrase)
+{
+    /* Grab a copy of the header so we can compare the result */
+    Header oldsigh = headerCopy(sigh);
+    int rc = -1;
+    
+    /* Nuke all signature tags */
+    deleteSigs(sigh);
+
+    /*
+     * rpmAddSignature() internals parse the actual signing result and 
+     * use appropriate DSA/RSA tags regardless of what we pass from here.
+     * RPMSIGTAG_GPG is only used to signal its an actual signature
+     * and not just a digest we're adding, and says nothing
+     * about the actual tags that gets created. 
+     */
+    if (rpmAddSignature(sigh, sigtarget, RPMSIGTAG_GPG, passPhrase) == 0) {
+	/* Lets see what we got and whether its the same signature as before */
+	rpmSigTag sigtag = headerIsEntry(sigh, RPMSIGTAG_DSA) ?
+					RPMSIGTAG_DSA : RPMSIGTAG_RSA;
+
+	rc = sameSignature(sigtag, sigh, oldsigh);
+
+    }
+
+    headerFree(oldsigh);
     return rc;
 }
 
@@ -253,62 +321,18 @@ static int rpmReSign(rpmts ts, QVA_t qva, ARGV_const_t argv)
 	}
 
 	if (deleting) {	/* Nuke all the signature tags. */
-	    xx = headerDel(sigh, RPMSIGTAG_GPG);
-	    xx = headerDel(sigh, RPMSIGTAG_DSA);
-	    xx = headerDel(sigh, RPMSIGTAG_PGP5);
-	    xx = headerDel(sigh, RPMSIGTAG_PGP);
-	    xx = headerDel(sigh, RPMSIGTAG_RSA);
-	} else		/* If gpg/pgp is configured, replace the signature. */
-	if ((sigtag = rpmLookupSignatureType(RPMLOOKUPSIG_QUERY)) > 0) {
-	    pgpKeyID_t oldsignid, newsignid;
-
-	    /* Grab the old signature fingerprint (if any) */
-	    memset(oldsignid, 0, sizeof(oldsignid));
-	    xx = getSignid(sigh, sigtag, oldsignid);
-
-	    switch (sigtag) {
-	    case RPMSIGTAG_DSA:
-		xx = headerDel(sigh, RPMSIGTAG_GPG);
-		break;
-	    case RPMSIGTAG_RSA:
-		xx = headerDel(sigh, RPMSIGTAG_PGP);
-		break;
-	    case RPMSIGTAG_GPG:
-		xx = headerDel(sigh, RPMSIGTAG_DSA);
-	    case RPMSIGTAG_PGP5:
-	    case RPMSIGTAG_PGP:
-		xx = headerDel(sigh, RPMSIGTAG_RSA);
-		break;
-	    default:
-		break;
-	    }
-
-	    xx = headerDel(sigh, sigtag);
-	    if (rpmAddSignature(sigh, sigtarget, sigtag, qva->passPhrase)) {
-		goto exit;
-	    }
-
-	    /* If package was previously signed, check for same signer. */
-	    memset(newsignid, 0, sizeof(newsignid));
-	    if (memcmp(oldsignid, newsignid, sizeof(oldsignid))) {
-
-		/* Grab the new signature fingerprint */
-		xx = getSignid(sigh, sigtag, newsignid);
-
-		/* If same signer, skip resigning the package. */
-		if (!memcmp(oldsignid, newsignid, sizeof(oldsignid))) {
-
-		    char *signid = pgpHexStr(newsignid+4, sizeof(newsignid)-4);
+	    deleteSigs(sigh);
+	} else if ((sigtag = rpmLookupSignatureType(RPMLOOKUPSIG_QUERY)) > 0) {
+	    res = replaceSignature(sigh, sigtarget, qva->passPhrase);
+	    if (res != 0) {
+		if (res == 1) {
 		    rpmlog(RPMLOG_WARNING,
-			_("%s: was already signed by key ID %s, skipping\n"),
-			rpm, signid);
-		    free(signid);
-
-		    /* Clean up intermediate target */
-		    xx = unlink(sigtarget);
-		    sigtarget = _free(sigtarget);
-		    continue;
+		       _("%s already contains identical signature, skipping\n"),
+		       rpm);
+		    /* Identical signature is not an error */
+		    res = 0;
 		}
+		goto exit;
 	    }
 	}
 
diff --git a/lib/signature.c b/lib/signature.c
index 7d50db7..d5aad52 100644
--- a/lib/signature.c
+++ b/lib/signature.c
@@ -584,12 +584,12 @@ int rpmAddSignature(Header sigh, const char * file, rpmSigTag sigTag,
     case RPMSIGTAG_PGP5:	/* XXX legacy */
     case RPMSIGTAG_PGP:
     case RPMSIGTAG_GPG: {
-	rpmSigTag hdrtag = (sigTag == RPMSIGTAG_GPG) ?
-			    RPMSIGTAG_DSA : RPMSIGTAG_RSA;
+	rpmSigTag hdrtag;
 	if (makeGPGSignature(file, &sigTag, &pkt, &pktlen, passPhrase)
 	 || !sighdrPut(sigh, sigTag, RPM_BIN_TYPE, pkt, pktlen))
 	    break;
 	/* XXX Piggyback a header-only DSA/RSA signature as well. */
+	hdrtag = (sigTag == RPMSIGTAG_GPG) ?  RPMSIGTAG_DSA : RPMSIGTAG_RSA;
 	ret = makeHDRSignature(sigh, file, hdrtag, passPhrase);
 	} break;
     case RPMSIGTAG_RSA: