Darwin: Reduce race likelihood between cancellation and device disconnect

References #88. The race condition still remains, but this change
makes it less likely to trigger.

diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index 9ebb150..1f356ee 100644 (file)
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -1449,6 +1449,9 @@ static int cancel_control_transfer(struct usbi_transfer *itransfer) {
 
   usbi_info (ITRANSFER_CTX (itransfer), "WARNING: aborting all transactions control pipe");
 
+  if (!dpriv->device)
+    return LIBUSB_ERROR_NO_DEVICE;
+
   kresult = (*(dpriv->device))->USBDeviceAbortPipeZero (dpriv->device);
 
   return darwin_to_libusb (kresult);
@@ -1456,6 +1459,7 @@ static int cancel_control_transfer(struct usbi_transfer *itransfer) {
 
 static int darwin_abort_transfers (struct usbi_transfer *itransfer) {
   struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+  struct darwin_device_priv *dpriv = (struct darwin_device_priv *)transfer->dev_handle->dev->os_priv;
   struct darwin_device_handle_priv *priv = (struct darwin_device_handle_priv *)transfer->dev_handle->os_priv;
   struct darwin_interface *cInterface;
   uint8_t pipeRef, iface;
@@ -1469,6 +1473,9 @@ static int darwin_abort_transfers (struct usbi_transfer *itransfer) {
 
   cInterface = &priv->interfaces[iface];
 
+  if (!dpriv->device)
+    return LIBUSB_ERROR_NO_DEVICE;
+
   usbi_info (ITRANSFER_CTX (itransfer), "WARNING: aborting all transactions on interface %d pipe %d", iface, pipeRef);
 
   /* abort transactions */