qga: handle G_IO_STATUS_AGAIN in ga_channel_write_all()

glib may return G_IO_STATUS_AGAIN which is actually not an error.
Also fixed a bug when on incomplete write buf pointer was not adjusted.
Signed-off-by: NYuri Pudgorodskiy <yur@virtuozzo.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

qga/channel-posix.c

@@ -217,25 +217,24 @@ GIOStatus ga_channel_write_all(GAChannel *c, const gchar *buf, gsize size)
     GIOStatus status = G_IO_STATUS_NORMAL;
 
     while (size) {
+        g_debug("sending data, count: %d", (int)size);
         status = g_io_channel_write_chars(c->client_channel, buf, size,
                                           &written, &err);
-        g_debug("sending data, count: %d", (int)size);
-        if (err != NULL) {
+        if (status == G_IO_STATUS_NORMAL) {
+            size -= written;
+            buf += written;
+        } else if (status != G_IO_STATUS_AGAIN) {
             g_warning("error writing to channel: %s", err->message);
-            return G_IO_STATUS_ERROR;
-        }
-        if (status != G_IO_STATUS_NORMAL) {
-            break;
+            return status;
         }
-        size -= written;
     }
 
-    if (status == G_IO_STATUS_NORMAL) {
+    do {
         status = g_io_channel_flush(c->client_channel, &err);
-        if (err != NULL) {
-            g_warning("error flushing channel: %s", err->message);
-            return G_IO_STATUS_ERROR;
-        }
+    } while (status == G_IO_STATUS_AGAIN);
+
+    if (status != G_IO_STATUS_NORMAL) {
+        g_warning("error flushing channel: %s", err->message);
     }
 
     return status;