From c66d60fbdbe26f51cc89e6ebec82ca5d6cf5716a Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Mon, 9 Mar 2020 16:53:03 +0100
Subject: [PATCH] buffers: handle param enum errors

When filtering parameters, return an error when something went
wrong as opposed to 0. This way we can see if there was an error
or just no parameters.  Fail when there was an error negotiating
the buffer size because that means incompatible values.
---
 src/pipewire/buffers.c | 53 ++++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/src/pipewire/buffers.c b/src/pipewire/buffers.c
index 4f685f7b9..6724a8f20 100644
--- a/src/pipewire/buffers.c
+++ b/src/pipewire/buffers.c
@@ -159,20 +159,24 @@ param_filter(struct pw_buffers *this,
         struct spa_pod_builder ib = { 0 };
 	struct spa_pod *oparam, *iparam;
 	uint32_t iidx, oidx, num = 0;
-	int res;
+	int in_res = -EIO, out_res = -EIO;
 
 	for (iidx = 0;;) {
 	        spa_pod_builder_init(&ib, ibuf, sizeof(ibuf));
 		pw_log_debug(NAME" %p: input param %d id:%d", this, iidx, id);
-		if ((res = spa_node_port_enum_params_sync(in_port->node,
+		in_res = spa_node_port_enum_params_sync(in_port->node,
 						in_port->direction, in_port->port_id,
-						id, &iidx, NULL, &iparam, &ib)) < 0)
-			break;
+						id, &iidx, NULL, &iparam, &ib);
 
-		if (res != 1) {
-			if (num > 0)
+		if (in_res < 1) {
+			/* in_res == -ENOENT  : unknown parameter, assume NULL and we will
+			 *                      exit the loop below.
+			 * in_res < 1         : some error or no data, exit now
+			 */
+			if (in_res == -ENOENT)
+				iparam = NULL;
+			else
 				break;
-			iparam = NULL;
 		}
 
 		if (pw_log_level_enabled(SPA_LOG_LEVEL_DEBUG) && iparam != NULL)
@@ -180,24 +184,33 @@ param_filter(struct pw_buffers *this,
 
 		for (oidx = 0;;) {
 			pw_log_debug(NAME" %p: output param %d id:%d", this, oidx, id);
-			res = spa_node_port_enum_params_sync(out_port->node,
+			out_res = spa_node_port_enum_params_sync(out_port->node,
 						out_port->direction, out_port->port_id,
 						id, &oidx, iparam, &oparam, result);
-			if (res != 1) {
-				if (res == -ENOENT && iparam) {
-					spa_pod_builder_raw_padded(result, iparam, SPA_POD_SIZE(iparam));
-					num++;
-				}
+
+			/* out_res < 1 : no value or error, exit now */
+			if (out_res < 1)
 				break;
-			}
+
 			if (pw_log_level_enabled(SPA_LOG_LEVEL_DEBUG))
 				spa_debug_pod(2, NULL, oparam);
-
 			num++;
 		}
-		if (iparam == NULL && num == 0)
+		if (out_res == -ENOENT && iparam) {
+			/* no output param known but we have an input param,
+			 * use that one */
+			spa_pod_builder_raw_padded(result, iparam, SPA_POD_SIZE(iparam));
+			num++;
+		}
+		/* no more input values, exit */
+		if (in_res < 1)
 			break;
 	}
+	if (num == 0) {
+		if (out_res == -ENOENT && in_res == -ENOENT)
+			return 0;
+		return in_res < 0 ? in_res : out_res < 0 ? out_res : -EINVAL;
+	}
 	return num;
 }
 
@@ -232,8 +245,12 @@ int pw_buffers_negotiate(struct pw_context *context, uint32_t flags,
 	const char *str;
 	int res;
 
-	n_params = param_filter(result, &input, &output, SPA_PARAM_Buffers, &b);
-	n_params += param_filter(result, &input, &output, SPA_PARAM_Meta, &b);
+	res = param_filter(result, &input, &output, SPA_PARAM_Buffers, &b);
+	if (res < 0)
+		return res;
+	n_params = res;
+	if ((res = param_filter(result, &input, &output, SPA_PARAM_Meta, &b)) > 0)
+		n_params += res;
 
 	params = alloca(n_params * sizeof(struct spa_pod *));
 	for (i = 0, offset = 0; i < n_params; i++) {