Function open_usb_device

LoadFile/teensy_loader_cli.c:203–260

#include <libusb-1.0/libusb.h>

struct libusb_device_handle *open_usb_device( int vid, int pid )
{
	libusb_device **devs;
	struct libusb_device_handle *handle = NULL;
	struct libusb_device_handle *ret = NULL;

	if ( libusb_init( NULL ) != 0 )
		fprintf( stderr, "libusb_init failed.\n" );

	size_t count = libusb_get_device_list( NULL, &devs );
	if ( count < 0 )
		fprintf( stderr, "libusb_get_device_list failed.\n" );

	for ( size_t c = 0; c < count; c++ )
	{
		struct libusb_device_descriptor desc;
		libusb_device *dev = devs[c];

		if ( libusb_get_device_descriptor( dev, &desc ) < 0 )
			fprintf( stderr, "libusb_get_device_descriptor failed.\n" );

		//printf("ID: %04x  Product: %04x\n", desc.idVendor, desc.idProduct );
		// Not correct device
		if ( desc.idVendor != vid || desc.idProduct != pid )
			continue;

		// Attempt to open the device
		if ( libusb_open( dev, &handle ) != 0 )
		{
			fprintf( stderr, "Found device but unable to open\n" );
			continue;
		}

		// Only required on Linux, other platforms will just ignore this call
		libusb_detach_kernel_driver( handle, 0 );

		// Mac OS-X - removing this call to usb_claim_interface() might allow
		// this to work, even though it is a clear misuse of the libusb API.
		// normally Apple's IOKit should be used on Mac OS-X
		// XXX Is this still valid with libusb-1.0?

		// Attempt to claim interface
		int err = libusb_claim_interface( handle, 0 );
		if ( err < 0 )
		{
			libusb_close( handle );
			fprintf( stderr, "Unable to claim interface, check USB permissions: %d\n", err );
			continue;
		}

		ret = handle;
		break;
	}

	libusb_free_device_list( devs, 1 );

	return ret;
}