thodg/libgit2

diff --git a/src/fetch.c b/src/fetch.c
index 044d4c9..03febe2 100644
--- a/src/fetch.c
+++ b/src/fetch.c
@@ -98,14 +98,8 @@ cleanup:
  */
 int git_fetch_negotiate(git_remote *remote)
 {
-	git_revwalk *walk;
 	int error;
-	unsigned int i;
-	git_reference *ref;
-	git_strarray refs;
 	git_headarray *list = &remote->refs;
-	git_repository *repo = remote->repo;
-	git_oid oid;
 
 	error = filter_wants(remote);
 	if (error < GIT_SUCCESS)
@@ -119,47 +113,11 @@ int git_fetch_negotiate(git_remote *remote)
 	 * what we want and what we have.
 	 */
 	remote->need_pack = 1;
-	git_transport_send_wants(remote->transport, list);
-
-	error = git_reference_listall(&refs, repo, GIT_REF_LISTALL);
-	if (error < GIT_ERROR)
-		return git__rethrow(error, "Failed to list all references");
-
-	error = git_revwalk_new(&walk, repo);
-	if (error < GIT_ERROR) {
-		error = git__rethrow(error, "Failed to list all references");
-		goto cleanup;
-	}
-	git_revwalk_sorting(walk, GIT_SORT_TIME);
-
-	for (i = 0; i < refs.count; ++i) {
-		error = git_reference_lookup(&ref, repo, refs.strings[i]);
-		if (error < GIT_ERROR) {
-			error = git__rethrow(error, "Failed to lookup %s", refs.strings[i]);
-			goto cleanup;
-		}
-
-		error = git_revwalk_push(walk, git_reference_oid(ref));
-		if (error < GIT_ERROR) {
-			error = git__rethrow(error, "Failed to push %s", refs.strings[i]);
-			goto cleanup;
-		}
-	}
-	git_strarray_free(&refs);
-
-	while ((error = git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
-		git_transport_send_have(remote->transport, &oid);
-	}
-	if (error == GIT_EREVWALKOVER)
-		error = GIT_SUCCESS;
-
-	/* TODO: git_pkt_send_flush(fd), or git_transport_flush() */
-	git_transport_send_flush(remote->transport);
-	git_transport_send_done(remote->transport);
+	error = git_transport_send_wants(remote->transport, list);
+	if (error < GIT_SUCCESS)
+		return git__rethrow(error, "Failed to send want list");
 
-cleanup:
-	git_revwalk_free(walk);
-	return error;
+	return git_transport_negotiate_fetch(remote->transport, remote->repo, &remote->refs);
 }
 
 int git_fetch_download_pack(char **out, git_remote *remote)
diff --git a/src/fetch.h b/src/fetch.h
index 2856f12..ad4451f 100644
--- a/src/fetch.h
+++ b/src/fetch.h
@@ -2,5 +2,6 @@
 #define INCLUDE_fetch_h__
 
 int git_fetch_negotiate(git_remote *remote);
+int git_fetch_download_pack(char **out, git_remote *remote);
 
 #endif
diff --git a/src/transport.c b/src/transport.c
index 1bd0c4e..91723df 100644
--- a/src/transport.c
+++ b/src/transport.c
@@ -90,6 +90,11 @@ int git_transport_send_have(struct git_transport *transport, git_oid *oid)
 	return transport->send_have(transport, oid);
 }
 
+int git_transport_negotiate_fetch(struct git_transport *transport, git_repository *repo, git_headarray *list)
+{
+	return transport->negotiate_fetch(transport, repo, list);
+}
+
 int git_transport_send_flush(struct git_transport *transport)
 {
 	return transport->send_flush(transport);
diff --git a/src/transport.h b/src/transport.h
index b14684b..69bec4c 100644
--- a/src/transport.h
+++ b/src/transport.h
@@ -73,6 +73,11 @@ struct git_transport {
 	 */
 	int (*send_done)(struct git_transport *transport);
 	/**
+	 * Negotiate the minimal amount of objects that need to be
+	 * retrieved
+	 */
+	int (*negotiate_fetch)(struct git_transport *transport, git_repository *repo, git_headarray *list);
+	/**
 	 * Send a flush
 	 */
 	int (*send_flush)(struct git_transport *transport);
@@ -99,6 +104,7 @@ int git_transport_git(struct git_transport **transport);
 int git_transport_dummy(struct git_transport **transport);
 
 int git_transport_send_wants(struct git_transport *transport, git_headarray *array);
+int git_transport_negotiate_fetch(struct git_transport *transport, git_repository *repo, git_headarray *array);
 int git_transport_send_have(struct git_transport *transport, git_oid *oid);
 int git_transport_send_done(struct git_transport *transport);
 int git_transport_send_flush(struct git_transport *transport);
diff --git a/src/transport_git.c b/src/transport_git.c
index 60958c9..bb759a1 100644
--- a/src/transport_git.c
+++ b/src/transport_git.c
@@ -27,6 +27,8 @@
 #include "git2/common.h"
 #include "git2/types.h"
 #include "git2/errors.h"
+#include "git2/net.h"
+#include "git2/revwalk.h"
 
 #include "vector.h"
 #include "transport.h"
@@ -325,6 +327,70 @@ static int git_send_have(git_transport *transport, git_oid *oid)
 	return git_pkt_send_have(oid, t->socket);
 }
 
+static int git_negotiate_fetch(git_transport *transport, git_repository *repo, git_headarray *list)
+{
+	transport_git *t = (transport_git *) transport;
+	git_revwalk *walk;
+	git_reference *ref;
+	git_strarray refs;
+	git_oid oid;
+	int error;
+	unsigned int i;
+
+	error = git_reference_listall(&refs, repo, GIT_REF_LISTALL);
+	if (error < GIT_ERROR)
+		return git__rethrow(error, "Failed to list all references");
+
+	error = git_revwalk_new(&walk, repo);
+	if (error < GIT_ERROR) {
+		error = git__rethrow(error, "Failed to list all references");
+		goto cleanup;
+	}
+	git_revwalk_sorting(walk, GIT_SORT_TIME);
+
+	for (i = 0; i < refs.count; ++i) {
+		error = git_reference_lookup(&ref, repo, refs.strings[i]);
+		if (error < GIT_ERROR) {
+			error = git__rethrow(error, "Failed to lookup %s", refs.strings[i]);
+			goto cleanup;
+		}
+
+		error = git_revwalk_push(walk, git_reference_oid(ref));
+		if (error < GIT_ERROR) {
+			error = git__rethrow(error, "Failed to push %s", refs.strings[i]);
+			goto cleanup;
+		}
+	}
+	git_strarray_free(&refs);
+
+	/*
+	 * We don't support any kind of ACK extensions, so the negotiation
+	 * boils down to sending what we have and listening for an ACK
+	 * every once in a while.
+	 */
+	i = 0;
+	while ((error = git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
+		error = git_pkt_send_have(&oid, t->socket);
+		i++;
+		/*
+		 * This is a magic number so we don't flood the server. We
+		 * should check every once in a while to see if the server has
+		 * sent an ACK.
+		 */
+		if (i % 160 == 0)
+			break;
+	}
+	if (error == GIT_EREVWALKOVER)
+		error = GIT_SUCCESS;
+
+	git_pkt_send_flush(t->socket);
+	git_pkt_send_done(t->socket);
+
+cleanup:
+	git_revwalk_free(walk);
+	return error;
+}
+
 static int git_send_flush(git_transport *transport)
 {
 	transport_git *t = (transport_git *) transport;
@@ -476,6 +542,7 @@ int git_transport_git(git_transport **out)
 	t->parent.ls = git_ls;
 	t->parent.send_wants = git_send_wants;
 	t->parent.send_have = git_send_have;
+	t->parent.negotiate_fetch = git_negotiate_fetch;
 	t->parent.send_flush = git_send_flush;
 	t->parent.send_done = git_send_done;
 	t->parent.download_pack = git_download_pack;