[PATCH spice-server] StreamDevice: Handle incomplete reads of StreamMsgFormat

[Jonathon Jongsma <jjongsma@xxxxxxxxxx>]

This is currently unlikely to happen since we communicate over a pipe
and the pipe buffer is sufficiently large to avoid splitting the
message. But for completeness, we should handle this scenario.

Signed-off-by: Jonathon Jongsma <jjongsma@xxxxxxxxxx>
---
 server/stream-device.c | 33 +++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/server/stream-device.c b/server/stream-device.c
index fc5b50659..259527246 100644
--- a/server/stream-device.c
+++ b/server/stream-device.c
@@ -42,6 +42,12 @@ struct StreamDevice {
 
     StreamDevHeader hdr;
     uint8_t hdr_pos;
+    union {
+        StreamMsgFormat format;
+        StreamMsgCapabilities capabilities;
+        uint8_t buf[1024];
+    } msg;
+    uint8_t msg_pos;
     bool has_error;
     bool opened;
     bool flow_stopped;
@@ -155,20 +161,27 @@ handle_msg_invalid(StreamDevice *dev, SpiceCharDeviceInstance *sin, const char *
 static bool
 handle_msg_format(StreamDevice *dev, SpiceCharDeviceInstance *sin)
 {
-    StreamMsgFormat fmt;
     SpiceCharDeviceInterface *sif = spice_char_device_get_interface(sin);
-    int n = sif->read(sin, (uint8_t *) &fmt, sizeof(fmt));
-    if (n == 0) {
-        return false;
-    }
-    if (n != sizeof(fmt)) {
+
+    spice_assert(dev->hdr_pos >= sizeof(StreamDevHeader));
+    spice_assert(dev->hdr.type == STREAM_TYPE_FORMAT);
+
+    int n = sif->read(sin, dev->msg.buf + dev->msg_pos, sizeof(StreamMsgFormat) - dev->msg_pos);
+    if (n < 0) {
         return handle_msg_invalid(dev, sin, NULL);
     }
-    fmt.width = GUINT32_FROM_LE(fmt.width);
-    fmt.height = GUINT32_FROM_LE(fmt.height);
-    stream_channel_change_format(dev->stream_channel, &fmt);
 
-    return true;
+    dev->msg_pos += n;
+
+    if (dev->msg_pos >= sizeof(StreamMsgFormat)) {
+        dev->msg.format.width = GUINT32_FROM_LE(dev->msg.format.width);
+        dev->msg.format.height = GUINT32_FROM_LE(dev->msg.format.height);
+        stream_channel_change_format(dev->stream_channel, &dev->msg.format);
+        dev->msg_pos = 0;
+        return true;
+    }
+
+    return false;
 }
 
 static bool
-- 
2.13.6

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