openbyintf.~cpp

一个通用的usb驱动程序列程

#pragma option push -b -a1 -pc -A-
#include <windows.h>
#include <winioctl.h>
#include <initguid.h>
#include <setupapi.h>

HANDLE OpenByInterface(GUID* pClassGuid,DWORD instance)
{
	HDEVINFO info = SetupDiGetClassDevs(pClassGuid, NULL, NULL, DIGCF_PRESENT | DIGCF_INTERFACEDEVICE);
	if(info==INVALID_HANDLE_VALUE)
	{
	       //	printf("No HDEVINFO available for this GUID\n");
		return NULL;
	}

	// Get interface data for the requested instance
	SP_INTERFACE_DEVICE_DATA ifdata;
	ifdata.cbSize = sizeof(ifdata);
	if(!SetupDiEnumDeviceInterfaces(info, NULL, pClassGuid, instance, &ifdata))
	{
	      //	printf("No SP_INTERFACE_DEVICE_DATA available for this GUID instance\n");
		SetupDiDestroyDeviceInfoList(info);
		return NULL ;
	}

	// Get size of symbolic link name
	DWORD ReqLen;
	SetupDiGetDeviceInterfaceDetail(info, &ifdata, NULL, 0, &ReqLen, NULL);
	PSP_INTERFACE_DEVICE_DETAIL_DATA ifDetail = (PSP_INTERFACE_DEVICE_DETAIL_DATA)(new char[ReqLen]);
	if( ifDetail==NULL)
	{
		SetupDiDestroyDeviceInfoList(info);
		return NULL;
	}

	// Get symbolic link name
	ifDetail->cbSize = sizeof(SP_INTERFACE_DEVICE_DETAIL_DATA);
	if( !SetupDiGetDeviceInterfaceDetail(info, &ifdata, ifDetail, ReqLen, NULL, NULL))
	{
		SetupDiDestroyDeviceInfoList(info);
		delete ifDetail;
		return NULL;
	}

       //	printf("Symbolic link is %s\n",ifDetail->DevicePath);
	// Open file
	HANDLE rv = CreateFile( ifDetail->DevicePath,
		GENERIC_READ | GENERIC_WRITE,
		FILE_SHARE_READ | FILE_SHARE_WRITE,
		NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
	if( rv==INVALID_HANDLE_VALUE) rv = NULL;

	delete ifDetail;
	SetupDiDestroyDeviceInfoList(info);
	return rv;
}
#pragma option pop