usbdump: fail early if dump file is not available

This allows for less less checking by the consumer and avoids
unnecessary work if the capture cannot be written anyway.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>

1 files changed, 5 insertions, 0 deletions

diff --git a/hw/usb/dump.h b/hw/usb/dump.h
index 1478fdc44c..08134e82e3 100644
--- a/hw/usb/dump.h
+++ b/hw/usb/dump.h
@@ -59,12 +59,17 @@ typedef struct UsbDumpState UsbDumpState;
  * direction, but setup_buf[0]. data is empty for PID == SETUP; for PID == IN,
  * data is of length setup_len. PID == OUT is not possible because handle_ctrl
  * is never called from that point.
+ *
+ * If s is NULL or if no dump file is available, no action is performed.
  */
 void usb_dump_submit(UsbDumpState *s, USBPacket *p);
+
 /*
  * complete (ctrl): setup_is irrelevant. If PID == SETUP, then the data was just
  * inserted by the "device" in handle_ctrl. Length is actual_length. If PID ==
  * IN, then data is empty. PID == OUT is again not possible (see submit).
+ *
+ * If s is NULL or if no dump file is available, no action is performed.
  */
 void usb_dump_complete(UsbDumpState *s, USBPacket *p);