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# CopyCapabilityDescriptors

Returns the device’s capability descriptors.

```
virtual const IOUSBBOSDescriptor * CopyCapabilityDescriptors();
```

## Return Value

A pointer to the binary object store (BOS) descriptor, or `NULL` if the descriptor wasn’t found. It’s your responsibility to free the returned descriptor.

## Discussion

This method searches the descriptor cache for the specified descriptors. If they aren’t in the cache, the method retrieves the descriptors from the device using a `GET_DESCRIPTOR` control request (USB 2.0, section 9.4.3) and adds them to the cache. When making a `GET_DESCRIPTOR` control request, this method acquires the service’s workloop lock and may call <doc://com.apple.documentation/documentation/kernel/iocommandgate/1573818-commandsleep>.

---

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