Allow progress callback to cancel fetch

This works by having the indexer watch the return
code of the callback, so will only take effect
on object boundaries.

3 files changed, 12 insertions, 9 deletions

diff --git a/src/clone.c b/src/clone.c
index 333bf2148..c7a24f40a 100644
--- a/src/clone.c
+++ b/src/clone.c
@@ -355,8 +355,8 @@ static int setup_remotes_and_fetch(
 
 		/* Connect and download everything */
 		if (!git_remote_connect(origin, GIT_DIRECTION_FETCH)) {
-			if (!git_remote_download(origin, options->fetch_progress_cb,
-						options->fetch_progress_payload)) {
+			if (!(retcode = git_remote_download(origin, options->fetch_progress_cb,
+						options->fetch_progress_payload))) {
 				/* Create "origin/foo" branches for all remote branches */
 				if (!git_remote_update_tips(origin)) {
 					/* Point HEAD to the requested branch */
diff --git a/src/indexer.c b/src/indexer.c
index 3f6b1076e..08c88ba18 100644
--- a/src/indexer.c
+++ b/src/indexer.c
@@ -394,15 +394,15 @@ on_error:
 	return -1;
 }
 
-static void do_progress_callback(git_indexer_stream *idx, git_transfer_progress *stats)
+static int do_progress_callback(git_indexer_stream *idx, git_transfer_progress *stats)
 {
-	if (!idx->progress_cb) return;
-	idx->progress_cb(stats, idx->progress_payload);
+	if (!idx->progress_cb) return 0;
+	return idx->progress_cb(stats, idx->progress_payload);
 }
 
 int git_indexer_stream_add(git_indexer_stream *idx, const void *data, size_t size, git_transfer_progress *stats)
 {
-	int error;
+	int error = -1;
 	struct git_pack_header hdr;
 	size_t processed; 
 	git_mwindow_file *mwf = &idx->pack->mwf;
@@ -536,14 +536,17 @@ int git_indexer_stream_add(git_indexer_stream *idx, const void *data, size_t siz
 		}
 		stats->received_objects++;
 
-		do_progress_callback(idx, stats);
+		if (do_progress_callback(idx, stats) < 0) {
+			error = GIT_EUSER;
+			goto on_error;
+		}
 	}
 
 	return 0;
 
 on_error:
 	git_mwindow_free_all(mwf);
-	return -1;
+	return error;
 }
 
 static int index_path_stream(git_buf *path, git_indexer_stream *idx, const char *suffix)
diff --git a/src/transports/smart_protocol.c b/src/transports/smart_protocol.c
index 184b21a0b..a68d242bc 100644
--- a/src/transports/smart_protocol.c
+++ b/src/transports/smart_protocol.c
@@ -493,7 +493,7 @@ int git_smart__download_pack(
 			git__free(pkt);
 		} else if (pkt->type == GIT_PKT_DATA) {
 			git_pkt_data *p = (git_pkt_data *) pkt;
-			if (writepack->add(writepack, p->data, p->len, stats) < 0)
+			if ((error = writepack->add(writepack, p->data, p->len, stats)) < 0)
 				goto on_error;
 
 			git__free(pkt);