[Spice-devel] [usbredir PATCH v3] usbredirhost: new callback for iso streams

[Victor Toso]

For streaming devices it might be necessary from application to drop
data for different reasons. This patch provides a new callback that it
is called before queueing the most recent iso packages.

Related: https://bugzilla.redhat.com/show_bug.cgi?id=1264156
---
 usbredirhost/usbredirhost.c | 19 +++++++++++++++++--
 usbredirhost/usbredirhost.h | 12 ++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/usbredirhost/usbredirhost.c b/usbredirhost/usbredirhost.c
index ad30722..ecc57e3 100644
--- a/usbredirhost/usbredirhost.c
+++ b/usbredirhost/usbredirhost.c
@@ -109,6 +109,7 @@ struct usbredirhost {
     usbredirparser_read read_func;
     usbredirparser_write write_func;
     usbredirhost_flush_writes flush_writes_func;
+    usbredirhost_can_write_iso can_write_iso_func;
     void *func_priv;
     int verbose;
     libusb_context *ctx;
@@ -1028,8 +1029,11 @@ static void usbredirhost_send_stream_data(struct usbredirhost *host,
             .status   = status,
             .length   = len,
         };
-        usbredirparser_send_iso_packet(host->parser, id, &iso_packet,
-                                       data, len);
+
+        if (!host->can_write_iso_func ||
+                host->can_write_iso_func(host->func_priv) != 0)
+            usbredirparser_send_iso_packet(host->parser, id, &iso_packet,
+                                           data, len);
         break;
     }
     case usb_redir_type_bulk: {
@@ -1358,6 +1362,17 @@ static void usbredirhost_log_data(struct usbredirhost *host, const char *desc,
 
 /**************************************************************************/
 
+void usbredirhost_set_cb_can_write_iso(struct usbredirhost *host,
+    usbredirhost_can_write_iso can_write_iso_func)
+{
+    if (!host) {
+        ERROR("invalid usbredirhost");
+        return;
+    }
+
+    host->can_write_iso_func = can_write_iso_func;
+}
+
 /* Return value:
     0 All ok
     1 Packet borked, continue with next packet / urb
diff --git a/usbredirhost/usbredirhost.h b/usbredirhost/usbredirhost.h
index c0042c9..98c81c8 100644
--- a/usbredirhost/usbredirhost.h
+++ b/usbredirhost/usbredirhost.h
@@ -33,6 +33,8 @@ struct usbredirhost;
 
 typedef void (*usbredirhost_flush_writes)(void *priv);
 
+typedef int (*usbredirhost_can_write_iso)(void *priv);
+
 /* This function creates an usbredirhost instance, including its embedded
    libusbredirparser instance and sends the initial usb_redir_hello packet to
    the usb-guest.
@@ -114,6 +116,16 @@ void usbredirhost_close(struct usbredirhost *host);
 int usbredirhost_set_device(struct usbredirhost *host,
                             libusb_device_handle *usb_dev_handle);
 
+/* Call this function to set a callback in usbredirhost to be called prior any
+   iso packets are queued. If the callback returns 0 the iso packets will be
+   dropped; In case the callback returns any other value, the iso packets will
+   be queued to be written to the client;
+
+   Call this function with NULL to erase previous callback;
+*/
+void usbredirhost_set_cb_can_write_iso(struct usbredirhost *host,
+    usbredirhost_can_write_iso can_write_iso_func);
+
 /* Call this whenever there is data ready for the usbredirhost to read from
    the usb-guest
    returns 0 on success, or an error code from the below enum on error.
-- 
2.5.0