[Spice-devel] [PATCH spice-gtk 1/2] display: factor out initialization of stream array

[Victor Toso]

From: Victor Toso <me at victortoso.com>

Including some comment about current implementation of stream-id value
in the Spice.

Signed-off-by: Victor Toso <victortoso at redhat.com>
---
 src/channel-display.c | 42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/channel-display.c b/src/channel-display.c
index 06c503c..9ae2851 100644
--- a/src/channel-display.c
+++ b/src/channel-display.c
@@ -105,6 +105,7 @@ static void channel_set_handlers(SpiceChannelClass *klass);
 
 static void clear_surfaces(SpiceChannel *channel, gboolean keep_primary);
 static void clear_streams(SpiceChannel *channel);
+static void streams_check_init(SpiceChannel *channel, guint stream_id);
 static display_surface *find_surface(SpiceDisplayChannelPrivate *c, guint32 surface_id);
 static void spice_display_channel_reset(SpiceChannel *channel, gboolean migrating);
 static void spice_display_channel_reset_capabilities(SpiceChannel *channel);
@@ -1233,17 +1234,7 @@ static void display_handle_stream_create(SpiceChannel *channel, SpiceMsgIn *in)
 
     CHANNEL_DEBUG(channel, "%s: id %u", __FUNCTION__, op->id);
 
-    if (op->id >= c->nstreams) {
-        int n = c->nstreams;
-        if (!c->nstreams) {
-            c->nstreams = 1;
-        }
-        while (op->id >= c->nstreams) {
-            c->nstreams *= 2;
-        }
-        c->streams = realloc(c->streams, c->nstreams * sizeof(c->streams[0]));
-        memset(c->streams + n, 0, (c->nstreams - n) * sizeof(c->streams[0]));
-    }
+    streams_check_init(channel, op->id);
     g_return_if_fail(c->streams[op->id] == NULL);
 
     c->streams[op->id] = display_stream_create(channel, op->surface_id,
@@ -1593,6 +1584,35 @@ static void clear_streams(SpiceChannel *channel)
     c->nstreams = 0;
 }
 
+/* Always called on SPICE_MSG_DISPLAY_STREAM_CREATE to verify if the c->streams
+ * array is big enough to handle the new stream. This obviously takes in
+ * consideration that the stream_id could grow overtime from 0 to MAX_STREAMS
+ * value but on server side, the id is picked in descending order, starting with
+ * (MAX_STREAMS - 1). As the id itself is not enforced by the protocol, we
+ * should keep the current check to avoid regressions or other unknown issues.
+ */
+static void streams_check_init(SpiceChannel *channel, guint stream_id)
+{
+    SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
+    gint old, new;
+
+    if (stream_id < c->nstreams) {
+        /* No need to increase c->streams */
+        return;
+    }
+
+    old = c->nstreams;
+    new = (c->nstreams == 0) ? 1 : c->nstreams;
+
+    while (stream_id > new) {
+        new *= 2;
+    }
+
+    c->nstreams = new;
+    c->streams = realloc(c->streams, new * sizeof(c->streams[0]));
+    memset(c->streams + old, 0, (new - old) * sizeof(c->streams[0]));
+}
+
 /* coroutine context */
 static void display_handle_stream_destroy(SpiceChannel *channel, SpiceMsgIn *in)
 {
-- 
2.13.0