core: Kill backend get_device_descriptor() function

Simplify the library by moving device descriptor initialization to the
backend, while the device is being set up. This removes the duplication
of essentially the same code in every backend.

Add some missing calls to libusb_le16_to_cpu() when reading multi-byte
fields from the "raw" device descriptor. It has worked thus far because
the platforms not using the calls happen to be the same endianness as
the USB bus.

While here, throw in some static assertions to ensure there is no
mismatch between the libusb device descriptor structure and any
device descriptor structure provided by the platform headers.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

1 files changed, 12 insertions, 16 deletions

diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index 61722c0..de5ce9c 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -661,15 +661,6 @@ static void darwin_exit (struct libusb_context *ctx) {
   pthread_mutex_unlock (&libusb_darwin_init_mutex);
 }
 
-static int darwin_get_device_descriptor(struct libusb_device *dev, void *buffer, int *host_endian) {
-  struct darwin_cached_device *priv = DARWIN_CACHED_DEVICE(dev);
-
-  /* return cached copy */
-  memmove (buffer, &(priv->dev_descriptor), LIBUSB_DT_DEVICE_SIZE);
-
-  return LIBUSB_SUCCESS;
-}
-
 static int get_configuration_index (struct libusb_device *dev, int config_value) {
   struct darwin_cached_device *priv = DARWIN_CACHED_DEVICE(dev);
   UInt8 i, numConfig;
@@ -749,7 +740,8 @@ static enum libusb_error darwin_check_configuration (struct libusb_context *ctx,
 
   /* checking the configuration of a root hub simulation takes ~1 s in 10.11. the device is
      not usable anyway */
-  if (0x05ac == dev->dev_descriptor.idVendor && 0x8005 == dev->dev_descriptor.idProduct) {
+  if (0x05ac == libusb_le16_to_cpu (dev->dev_descriptor.idVendor) &&
+      0x8005 == libusb_le16_to_cpu (dev->dev_descriptor.idProduct)) {
     usbi_dbg ("ignoring configuration on root hub simulation");
     dev->active_config = 0;
     return LIBUSB_SUCCESS;
@@ -930,14 +922,14 @@ static enum libusb_error darwin_cache_device_descriptor (struct darwin_cached_de
 
   usbi_dbg ("cached device descriptor:");
   usbi_dbg ("  bDescriptorType:    0x%02x", dev->dev_descriptor.bDescriptorType);
-  usbi_dbg ("  bcdUSB:             0x%04x", dev->dev_descriptor.bcdUSB);
+  usbi_dbg ("  bcdUSB:             0x%04x", libusb_le16_to_cpu (dev->dev_descriptor.bcdUSB));
   usbi_dbg ("  bDeviceClass:       0x%02x", dev->dev_descriptor.bDeviceClass);
   usbi_dbg ("  bDeviceSubClass:    0x%02x", dev->dev_descriptor.bDeviceSubClass);
   usbi_dbg ("  bDeviceProtocol:    0x%02x", dev->dev_descriptor.bDeviceProtocol);
   usbi_dbg ("  bMaxPacketSize0:    0x%02x", dev->dev_descriptor.bMaxPacketSize0);
-  usbi_dbg ("  idVendor:           0x%04x", dev->dev_descriptor.idVendor);
-  usbi_dbg ("  idProduct:          0x%04x", dev->dev_descriptor.idProduct);
-  usbi_dbg ("  bcdDevice:          0x%04x", dev->dev_descriptor.bcdDevice);
+  usbi_dbg ("  idVendor:           0x%04x", libusb_le16_to_cpu (dev->dev_descriptor.idVendor));
+  usbi_dbg ("  idProduct:          0x%04x", libusb_le16_to_cpu (dev->dev_descriptor.idProduct));
+  usbi_dbg ("  bcdDevice:          0x%04x", libusb_le16_to_cpu (dev->dev_descriptor.bcdDevice));
   usbi_dbg ("  iManufacturer:      0x%02x", dev->dev_descriptor.iManufacturer);
   usbi_dbg ("  iProduct:           0x%02x", dev->dev_descriptor.iProduct);
   usbi_dbg ("  iSerialNumber:      0x%02x", dev->dev_descriptor.iSerialNumber);
@@ -1074,7 +1066,8 @@ static enum libusb_error darwin_get_cached_device(io_service_t service, struct d
 
     if (new_device->can_enumerate) {
       snprintf(new_device->sys_path, 20, "%03i-%04x-%04x-%02x-%02x", new_device->address,
-               new_device->dev_descriptor.idVendor, new_device->dev_descriptor.idProduct,
+               libusb_le16_to_cpu (new_device->dev_descriptor.idVendor),
+               libusb_le16_to_cpu (new_device->dev_descriptor.idProduct),
                new_device->dev_descriptor.bDeviceClass, new_device->dev_descriptor.bDeviceSubClass);
     }
   } while (0);
@@ -1122,6 +1115,10 @@ static enum libusb_error process_new_device (struct libusb_context *ctx, struct
       dev->bus_number     = cached_device->location >> 24;
       assert(cached_device->address <= UINT8_MAX);
       dev->device_address = (uint8_t)cached_device->address;
+      static_assert(sizeof(dev->device_descriptor) == sizeof(cached_device->dev_descriptor),
+                    "mismatch between libusb and IOKit device descriptor sizes");
+      memcpy(&dev->device_descriptor, &cached_device->dev_descriptor, LIBUSB_DT_DEVICE_SIZE);
+      usbi_localize_device_descriptor(&dev->device_descriptor);
     } else {
       priv = usbi_get_device_priv(dev);
     }
@@ -2260,7 +2257,6 @@ const struct usbi_os_backend usbi_backend = {
         .caps = 0,
         .init = darwin_init,
         .exit = darwin_exit,
-        .get_device_descriptor = darwin_get_device_descriptor,
         .get_active_config_descriptor = darwin_get_active_config_descriptor,
         .get_config_descriptor = darwin_get_config_descriptor,
         .hotplug_poll = darwin_hotplug_poll,