yusb 0.1.2

Rust library for accessing USB devices.
Documentation 
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// yusb/src/options.rs
//
// Copyright (c) 2015, David Cuddeback
//               2019, Ilya Averyanov
//               2023, Frank Pagliughi
//
// Licensed under the MIT license:
//   <LICENSE or http://opensource.org/licenses/MIT>
// This file may not be copied, modified, or distributed except according
// to those terms.
//

use crate::{Context, Error, Result};
use libusb1_sys::{self as ffi, constants::*};

#[cfg(unix)]
use std::ptr;

/// A `libusb` runtime option that can be enabled for a context.
pub struct UsbOption {
    inner: OptionInner,
}

impl UsbOption {
    /// Use the [UsbDk] backend if available.
    ///
    /// **Note**: This method is available on **Windows** only!
    ///
    /// [UsbDk]: https://github.com/daynix/UsbDk
    #[cfg(windows)]
    pub fn use_usbdk() -> Self {
        Self {
            inner: OptionInner::UseUsbdk,
        }
    }

    pub(crate) fn apply(&self, ctx: &mut Context) -> Result<()> {
        match self.inner {
            OptionInner::UseUsbdk => {
                let err = unsafe { ffi::libusb_set_option(ctx.as_raw(), LIBUSB_OPTION_USE_USBDK) };
                if err == LIBUSB_SUCCESS {
                    Ok(())
                } else {
                    Err(Error::from(err))
                }
            }
        }
    }
}

enum OptionInner {
    #[cfg_attr(not(windows), allow(dead_code))] // only constructed on Windows
    UseUsbdk,
}

/// Disable device scanning in `libusb` init.
///
/// Hotplug functionality will also be deactivated.
///
/// This is a Linux only option and it must be set before any [`Context`]
/// creation.
///
/// The option is useful in combination with [`Context::open_device_with_fd()`],
/// which can access a device directly without prior device scanning.
#[cfg(unix)]
pub fn disable_device_discovery() -> Result<()> {
    try_unsafe!(ffi::libusb_set_option(
        ptr::null_mut(),
        LIBUSB_OPTION_NO_DEVICE_DISCOVERY
    ));
    Ok(())
}