From b3fb0618da777d1ce58418ab36bc4321f5cf77ef Mon Sep 17 00:00:00 2001
From: Jonathan McDowell <noodles@earth.li>
Date: Sun, 24 Apr 2011 18:47:24 -0700
Subject: [PATCH] Make compare_packet follow memcmp semantics and export to
 other modules

  compare_packet is potentially useful elsewhere, but rather than a
  true/false comparison provide -1/0/1 for less than/equal/greater
  than, as memcmp does.
---
 merge.c | 31 ++++++++++++++++++++++---------
 merge.h | 10 ++++++++++
 2 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/merge.c b/merge.c
index be97eb4..118e757 100644
--- a/merge.c
+++ b/merge.c
@@ -24,13 +24,26 @@
  *	@a: The first packet to compare.
  *	@b: The second packet to compare.
  *
- *	Takes 2 packets and returns true if they are the same and false
- *	otherwise.
+ *	Takes 2 packets and returns 0 if they are the same, -1 if a is
+ *      less than b, or 1 if a is greater than b.
  */
-bool compare_packets(struct openpgp_packet *a, struct openpgp_packet *b)
+int compare_packets(struct openpgp_packet *a, struct openpgp_packet *b)
 {
-	return (a->tag == b->tag && a->length == b->length &&
-		!memcmp(a->data, b->data, b->length));
+	int ret, len;
+
+	if (a->tag > b->tag) {
+		ret = 1;
+	} else if (b->tag > a->tag) {
+		ret = -1;
+	} else {
+		len = (a->length < b->length) ? a->length : b->length;
+		ret = memcmp(a->data, b->data, len);
+		if (ret == 0 && a->length != b->length) {
+			ret = (a->length < b->length) ? -1 : 1;
+		}
+	}
+
+	return ret;
 }
 
 /**
@@ -73,7 +86,7 @@ bool find_packet(struct openpgp_packet_list *packet_list,
 	bool found = false;
 
 	while (!found && packet_list != NULL) {
-		if (compare_packets(packet_list->packet, packet)) {
+		if (compare_packets(packet_list->packet, packet) == 0) {
 			found = true;
 		}
 		packet_list = packet_list -> next;
@@ -122,7 +135,7 @@ struct openpgp_signedpacket_list *find_signed_packet(
 	struct openpgp_signedpacket_list *found = NULL;
 
 	while (found == NULL && packet_list != NULL) {
-		if (compare_packets(packet_list->packet, packet)) {
+		if (compare_packets(packet_list->packet, packet) == 0) {
 			found = packet_list;
 		}
 		packet_list = packet_list -> next;
@@ -149,7 +162,7 @@ bool remove_signed_packet(struct openpgp_signedpacket_list **packet_list,
 	bool found = false;
 
 	for (cur = *packet_list; !found && (cur != NULL); cur = cur->next) {
-		if (compare_packets(cur->packet, packet)) {
+		if (compare_packets(cur->packet, packet) == 0) {
 			found = true;
 			if (prev == NULL) {
 				*packet_list = cur->next;
@@ -186,7 +199,7 @@ int merge_packet_sigs(struct openpgp_signedpacket_list *old,
 	struct openpgp_packet_list	*curpacket = NULL;
 	struct openpgp_packet_list	*nextpacket = NULL;
 
-	log_assert(compare_packets(old->packet, new->packet));
+	log_assert(compare_packets(old->packet, new->packet) == 0);
 
 	curpacket = new->sigs;
 	while (curpacket != NULL) {
diff --git a/merge.h b/merge.h
index cabbc18..770da9e 100644
--- a/merge.h
+++ b/merge.h
@@ -10,6 +10,16 @@
 
 #include "keystructs.h"
 
+/**
+ *	compare_packets - Check to see if 2 OpenPGP packets are the same.
+ *	@a: The first packet to compare.
+ *	@b: The second packet to compare.
+ *
+ *	Takes 2 packets and returns 0 if they are the same, -1 if a is
+ *      less than b, or 1 if a is greater than b.
+ */
+int compare_packets(struct openpgp_packet *a, struct openpgp_packet *b);
+
 /**
  *	merge_keys - Takes 2 public keys and merges them.
  *	@a: The old key. The merged key is returned in this structure.
-- 
2.39.5