下面是我终于能够想出的。
请确认这SYSTEM\CurrentControlSet\Control\Print\Printers\{0}\PNPData是受支持的路径，并且不只是在当前实现中恰好存在，可能会在未来发生变化。
结构对齐有一点问题，为此我发布了一个单独的问题。
public static class UsbPrinterResolver
{
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct SP_DEVINFO_DATA
{
public uint cbSize;
public Guid ClassGuid;
public uint DevInst;
public IntPtr Reserved;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct SP_DEVICE_INTERFACE_DATA
{
public uint cbSize;
public Guid InterfaceClassGuid;
public uint Flags;
public IntPtr Reserved;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto, Pack = 1)]
private struct SP_DEVICE_INTERFACE_DETAIL_DATA // Only used for Marshal.SizeOf. NOT!
{
public uint cbSize;
public char DevicePath;
}
[DllImport("cfgmgr32.dll", CharSet = CharSet.Auto, SetLastError = false, ExactSpelling = true)]
private static extern uint CM_Get_Parent(out uint pdnDevInst, uint dnDevInst, uint ulFlags);
[DllImport("cfgmgr32.dll", CharSet = CharSet.Auto, SetLastError = false)]
private static extern uint CM_Get_Device_ID(uint dnDevInst, string Buffer, uint BufferLen, uint ulFlags);
[DllImport("cfgmgr32.dll", CharSet = CharSet.Auto, SetLastError = false, ExactSpelling = true)]
private static extern uint CM_Get_Device_ID_Size(out uint pulLen, uint dnDevInst, uint ulFlags);
[DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetupDiGetClassDevs([In(), MarshalAs(UnmanagedType.LPStruct)] System.Guid ClassGuid, string Enumerator, IntPtr hwndParent, uint Flags);
[DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern int SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet, uint MemberIndex, ref SP_DEVINFO_DATA DeviceInfoData);
[DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern int SetupDiEnumDeviceInterfaces(IntPtr DeviceInfoSet, [In()] ref SP_DEVINFO_DATA DeviceInfoData, [In(), MarshalAs(UnmanagedType.LPStruct)] System.Guid InterfaceClassGuid, uint MemberIndex, ref SP_DEVICE_INTERFACE_DATA DeviceInterfaceData);
[DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern int SetupDiGetDeviceInterfaceDetail(IntPtr DeviceInfoSet, [In()] ref SP_DEVICE_INTERFACE_DATA DeviceInterfaceData, IntPtr DeviceInterfaceDetailData, uint DeviceInterfaceDetailDataSize, out uint RequiredSize, IntPtr DeviceInfoData);
[DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
private static extern int SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, int dwShareMode, IntPtr lpSecurityAttributes, int dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile);
private const uint DIGCF_PRESENT = 0x00000002U;
private const uint DIGCF_DEVICEINTERFACE = 0x00000010U;
private const int ERROR_INSUFFICIENT_BUFFER = 122;
private const uint CR_SUCCESS = 0;
private const int FILE_SHARE_READ = 1;
private const int FILE_SHARE_WRITE = 2;
private const uint GENERIC_READ = 0x80000000;
private const uint GENERIC_WRITE = 0x40000000;
private const int OPEN_EXISTING = 3;
private static readonly Guid GUID_PRINTER_INSTALL_CLASS = new Guid(0x4d36e979, 0xe325, 0x11ce, 0xbf, 0xc1, 0x08, 0x00, 0x2b, 0xe1, 0x03, 0x18);
private static readonly Guid GUID_DEVINTERFACE_USBPRINT = new Guid(0x28d78fad, 0x5a12, 0x11D1, 0xae, 0x5b, 0x00, 0x00, 0xf8, 0x03, 0xa8, 0xc2);
private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
private static string GetPrinterRegistryInstanceID(string PrinterName) {
if (string.IsNullOrEmpty(PrinterName)) throw new ArgumentNullException("PrinterName");
const string key_template = @"SYSTEM\CurrentControlSet\Control\Print\Printers\{0}\PNPData";
using (var hk = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(
string.Format(key_template, PrinterName),
Microsoft.Win32.RegistryKeyPermissionCheck.Default,
System.Security.AccessControl.RegistryRights.QueryValues
)
)
{
if (hk == null) throw new ArgumentOutOfRangeException("PrinterName", "This printer does not have PnP data.");
return (string)hk.GetValue("DeviceInstanceId");
}
}
private static string GetPrinterParentDeviceId(string RegistryInstanceID) {
if (string.IsNullOrEmpty(RegistryInstanceID)) throw new ArgumentNullException("RegistryInstanceID");
IntPtr hdi = SetupDiGetClassDevs(GUID_PRINTER_INSTALL_CLASS, RegistryInstanceID, IntPtr.Zero, DIGCF_PRESENT);
if (hdi.Equals(INVALID_HANDLE_VALUE)) throw new System.ComponentModel.Win32Exception();
try
{
SP_DEVINFO_DATA printer_data = new SP_DEVINFO_DATA();
printer_data.cbSize = (uint)Marshal.SizeOf(typeof(SP_DEVINFO_DATA));
if (SetupDiEnumDeviceInfo(hdi, 0, ref printer_data) == 0) throw new System.ComponentModel.Win32Exception(); // Only one device in the set
uint cmret = 0;
uint parent_devinst = 0;
cmret = CM_Get_Parent(out parent_devinst, printer_data.DevInst, 0);
if (cmret != CR_SUCCESS) throw new Exception(string.Format("Failed to get parent of the device '{0}'. Error code: 0x{1:X8}", RegistryInstanceID, cmret));
uint parent_device_id_size = 0;
cmret = CM_Get_Device_ID_Size(out parent_device_id_size, parent_devinst, 0);
if (cmret != CR_SUCCESS) throw new Exception(string.Format("Failed to get size of the device ID of the parent of the device '{0}'. Error code: 0x{1:X8}", RegistryInstanceID, cmret));
parent_device_id_size++; // To include the null character
string parent_device_id = new string('\0', (int)parent_device_id_size);
cmret = CM_Get_Device_ID(parent_devinst, parent_device_id, parent_device_id_size, 0);
if (cmret != CR_SUCCESS) throw new Exception(string.Format("Failed to get device ID of the parent of the device '{0}'. Error code: 0x{1:X8}", RegistryInstanceID, cmret));
return parent_device_id;
}
finally
{
SetupDiDestroyDeviceInfoList(hdi);
}
}
private static string GetUSBInterfacePath(string SystemDeviceInstanceID) {
if (string.IsNullOrEmpty(SystemDeviceInstanceID)) throw new ArgumentNullException("SystemDeviceInstanceID");
IntPtr hdi = SetupDiGetClassDevs(GUID_DEVINTERFACE_USBPRINT, SystemDeviceInstanceID, IntPtr.Zero, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
if (hdi.Equals(INVALID_HANDLE_VALUE)) throw new System.ComponentModel.Win32Exception();
try
{
SP_DEVINFO_DATA device_data = new SP_DEVINFO_DATA();
device_data.cbSize = (uint)Marshal.SizeOf(typeof(SP_DEVINFO_DATA));
if (SetupDiEnumDeviceInfo(hdi, 0, ref device_data) == 0) throw new System.ComponentModel.Win32Exception(); // Only one device in the set
SP_DEVICE_INTERFACE_DATA interface_data = new SP_DEVICE_INTERFACE_DATA();
interface_data.cbSize = (uint)Marshal.SizeOf(typeof(SP_DEVICE_INTERFACE_DATA));
if (SetupDiEnumDeviceInterfaces(hdi, ref device_data, GUID_DEVINTERFACE_USBPRINT, 0, ref interface_data) == 0) throw new System.ComponentModel.Win32Exception(); // Only one interface in the set
// Get required buffer size
uint required_size = 0;
SetupDiGetDeviceInterfaceDetail(hdi, ref interface_data, IntPtr.Zero, 0, out required_size, IntPtr.Zero);
int last_error_code = Marshal.GetLastWin32Error();
if (last_error_code != ERROR_INSUFFICIENT_BUFFER) throw new System.ComponentModel.Win32Exception(last_error_code);
IntPtr interface_detail_data = Marshal.AllocCoTaskMem((int)required_size);
try
{
// FIXME, don't know how to calculate the size.
// See https://stackoverflow.com/questions/10728644/properly-declare-sp-device-interface-detail-data-for-pinvoke
switch (IntPtr.Size)
{
case 4:
Marshal.WriteInt32(interface_detail_data, 4 + Marshal.SystemDefaultCharSize);
break;
case 8:
Marshal.WriteInt32(interface_detail_data, 8);
break;
default:
throw new NotSupportedException("Architecture not supported.");
}
if (SetupDiGetDeviceInterfaceDetail(hdi, ref interface_data, interface_detail_data, required_size, out required_size, IntPtr.Zero) == 0) throw new System.ComponentModel.Win32Exception();
// TODO: When upgrading to .NET 4, replace that with IntPtr.Add
return Marshal.PtrToStringAuto(new IntPtr(interface_detail_data.ToInt64() + Marshal.OffsetOf(typeof(SP_DEVICE_INTERFACE_DETAIL_DATA), "DevicePath").ToInt64()));
}
finally
{
Marshal.FreeCoTaskMem(interface_detail_data);
}
}
finally
{
SetupDiDestroyDeviceInfoList(hdi);
}
}
public static string GetUSBPath(string PrinterName) {
return GetUSBInterfacePath(GetPrinterParentDeviceId(GetPrinterRegistryInstanceID(PrinterName)));
}
public static Microsoft.Win32.SafeHandles.SafeFileHandle OpenUSBPrinter(string PrinterName) {
return new Microsoft.Win32.SafeHandles.SafeFileHandle(CreateFile(GetUSBPath(PrinterName), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero), true);
}
}
用法：
using (var sh = UsbPrinterResolver.OpenUSBPrinter("Zebra Large"))
{
using (var f = new System.IO.FileStream(sh, System.IO.FileAccess.ReadWrite))
{
// Read from and write to the stream f
}
}