MacOS: Silence pipe error in set_interface_alt_setting()

darwin_set_interface_altsetting() no longer returns the status of the underlying SetAlternateInterface(), but instead the result of a subsequent GetNumEndpoints() call. This reverts to the behaviour prior to commit 065e586.

Since darwin_set_interface_altsetting() resets the interface after SetAlternateInterface(), one of the consequences is that if SetAlternateInterface() returns a kIOUSBPipeStalled error, and the interface is successfully reset, darwin_set_interface_altsetting() now returns LIBUSB_SUCCESS instead of LIBUSB_ERROR_PIPE.

Closes: #838
Signed-off-by: Freek Dijkstra
Signed-off-by: Nathan Hjelm <hjelmn@google.com>

diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index e415589d670f071e6acb03247ba7b448fdb1e096..8055cc05c803b31f3d1207b7149367fb3c124fb4 100644 (file)
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -1567,8 +1567,15 @@ static int darwin_set_interface_altsetting(struct libusb_device_handle *dev_hand
     return LIBUSB_ERROR_NO_DEVICE;
 
   kresult = (*(cInterface->interface))->SetAlternateInterface (cInterface->interface, altsetting);
-  if (kresult != kIOReturnSuccess)
+  /* If a device only supports a default setting for the specified interface, then a STALL
+     (kIOUSBPipeStalled) may be returned. Ref: USB 2.0 specs 9.4.10.
+     Mimick the behaviour in e.g. the Linux kernel: in such case, reset all endpoints,
+     and hide errors.Current implementation resets the entire device, instead of single
+     interface, due to historic reasons. */
+  if (kresult != kIOReturnSuccess) {
+    usbi_warn (HANDLE_CTX (dev_handle), "SetAlternateInterface: %s", darwin_error_str(kresult));
     darwin_reset_device (dev_handle);
+  }
 
   /* update list of endpoints */
   ret = get_endpoints (dev_handle, iface);
@@ -1576,10 +1583,9 @@ static int darwin_set_interface_altsetting(struct libusb_device_handle *dev_hand
     /* this should not happen */
     darwin_release_interface (dev_handle, iface);
     usbi_err (HANDLE_CTX (dev_handle), "could not build endpoint table");
-    return ret;
   }
 
-  return darwin_to_libusb (kresult);
+  return ret;
 }
 
 static int darwin_clear_halt(struct libusb_device_handle *dev_handle, unsigned char endpoint) {

diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index c30b57dc179b89443346ed9322330f71095d10be..ce7c73c200caf7db77a6705459f49ec5d776c088 100644 (file)
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11591
+#define LIBUSB_NANO 11592