winfsp/src/dll/fsctl.c

/**
 * @file dll/fsctl.c
 *
 * @copyright 2015 Bill Zissimopoulos
 */

#include <dll/library.h>

#define GLOBALROOT                      L"\\\\?\\GLOBALROOT"
#define PREFIXW                         L"" FSP_FSCTL_VOLUME_PARAMS_PREFIX
#define PREFIXW_SIZE                    (sizeof PREFIXW - sizeof(WCHAR))

FSP_API NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath,
    const FSP_FSCTL_VOLUME_PARAMS *VolumeParams,
    PWCHAR VolumePathBuf, SIZE_T VolumePathSize,
    PHANDLE PVolumeHandle)
{
    NTSTATUS Result;
    PWSTR DeviceRoot;
    SIZE_T DeviceRootSize, DevicePathSize;
    WCHAR DevicePathBuf[MAX_PATH], *DevicePathPtr, *DevicePathEnd;
    HANDLE VolumeHandle = INVALID_HANDLE_VALUE;
    DWORD Bytes;

    if (sizeof(WCHAR) <= VolumePathSize)
        VolumePathBuf[0] = L'\0';
    *PVolumeHandle = INVALID_HANDLE_VALUE;

    /* check lengths; everything (including encoded volume params) must fit within MAX_PATH */
    DeviceRoot = L'\\' == DevicePath[0] ? GLOBALROOT : GLOBALROOT "\\Device\\";
    DeviceRootSize = lstrlenW(DeviceRoot) * sizeof(WCHAR);
    DevicePathSize = lstrlenW(DevicePath) * sizeof(WCHAR);
    if (DeviceRootSize + DevicePathSize + PREFIXW_SIZE +
        sizeof *VolumeParams * sizeof(WCHAR) + sizeof(WCHAR) > sizeof DevicePathBuf)
        return STATUS_INVALID_PARAMETER;

    /* prepare the device path to be opened; encode the volume params in the Unicode private area */
    DevicePathPtr = DevicePathBuf;
    memcpy(DevicePathPtr, DeviceRoot, DeviceRootSize);
    DevicePathPtr = (PVOID)((PUINT8)DevicePathPtr + DeviceRootSize);
    memcpy(DevicePathPtr, DevicePath, DevicePathSize);
    DevicePathPtr = (PVOID)((PUINT8)DevicePathPtr + DevicePathSize);
    memcpy(DevicePathPtr, PREFIXW, PREFIXW_SIZE);
    DevicePathPtr = (PVOID)((PUINT8)DevicePathPtr + PREFIXW_SIZE);
    DevicePathEnd = (PVOID)((PUINT8)DevicePathPtr + sizeof *VolumeParams * sizeof(WCHAR));
    for (PUINT8 VolumeParamsPtr = (PVOID)VolumeParams;
        DevicePathEnd > DevicePathPtr; DevicePathPtr++, VolumeParamsPtr++)
    {
        WCHAR Value = 0xF000 | *VolumeParamsPtr;
        *DevicePathPtr = Value;
    }
    *DevicePathPtr = L'\0';

    VolumeHandle = CreateFileW(DevicePathBuf,
        0, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, 0, 0);
    if (INVALID_HANDLE_VALUE == VolumeHandle)
    {
        Result = FspNtStatusFromWin32(GetLastError());
        if (STATUS_OBJECT_PATH_NOT_FOUND == Result ||
            STATUS_OBJECT_NAME_NOT_FOUND == Result)
            Result = STATUS_NO_SUCH_DEVICE;
        goto exit;
    }

    if (!DeviceIoControl(VolumeHandle, FSP_FSCTL_VOLUME_NAME,
        0, 0,
        VolumePathBuf, (DWORD)VolumePathSize,
        &Bytes, 0))
    {
        Result = FspNtStatusFromWin32(GetLastError());
        goto exit;
    }

    Result = STATUS_SUCCESS;

exit:
    if (NT_SUCCESS(Result))
        *PVolumeHandle = VolumeHandle;
    else
        CloseHandle(VolumeHandle);

    return Result;
}

FSP_API NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
    PVOID ResponseBuf, SIZE_T ResponseBufSize,
    PVOID RequestBuf, SIZE_T *PRequestBufSize)
{
    NTSTATUS Result = STATUS_SUCCESS;
    DWORD Bytes = 0;

    if (0 != PRequestBufSize)
    {
        Bytes = (DWORD)*PRequestBufSize;
        *PRequestBufSize = 0;
    }

    if (!DeviceIoControl(VolumeHandle, FSP_FSCTL_TRANSACT,
        ResponseBuf, (DWORD)ResponseBufSize, RequestBuf, Bytes,
        &Bytes, 0))
    {
        Result = FspNtStatusFromWin32(GetLastError());
        goto exit;
    }

    if (0 != PRequestBufSize)
        *PRequestBufSize = Bytes;

exit:
    return Result;
}