_When_(return == 0, _Post_satisfies_(String->Buffer != NULL))
NTSTATUS
RWBAllocateUnicodeString(
_Inout_ PUNICODE_STRING String
)
/*++

Routine Description:

This routine allocates a unicode string

Arguments:

Size - the size in bytes needed for the string buffer

String - supplies the size of the string to be allocated in the MaximumLength field
return the unicode string

Return Value:

STATUS_SUCCESS                  - success
STATUS_INSUFFICIENT_RESOURCES   - failure

--*/
{

    PAGED_CODE();

    String->Buffer = ExAllocatePoolWithTag(NonPagedPool,
        String->MaximumLength,
        RWB_STRING_TAG);

    if (String->Buffer == NULL) {

        PT_DBG_PRINT(PTDBG_TRACE_ROUTINES,
            ("[SimRep]: Failed to allocate unicode string of size 0x%x\n",
            String->MaximumLength));

        return STATUS_INSUFFICIENT_RESOURCES;
    }

    String->Length = 0;

    return STATUS_SUCCESS;
}

VOID
RWBFreeUnicodeString(
_Inout_ PUNICODE_STRING String
)
/*++

Routine Description:

This routine frees a unicode string

Arguments:

String - supplies the string to be freed

Return Value:

None

--*/
{
    PAGED_CODE();

    if (String->Buffer) {

        ExFreePoolWithTag(String->Buffer,
            RWB_STRING_TAG);
        String->Buffer = NULL;
    }

    String->Length = String->MaximumLength = 0;
    String->Buffer = NULL;
}

NTSTATUS
RWBRollPath(
    _In_ UNICODE_STRING Path,
    _In_ PFLT_FILTER Filter,
    _In_ PFLT_INSTANCE Instance
)
/*
Routine Description:

This routine creates the directory specified as input

Arguments:

Path - The path to create

Return Value:

STATUS_SUCCESS                  - success

*/
{
    NTSTATUS status = STATUS_SUCCESS;
    HANDLE directoryHandle = NULL;
    OBJECT_ATTRIBUTES objectAttributes;
    IO_STATUS_BLOCK ioStatusBlock;
    UNICODE_STRING previousFolder;

    // Initialize object attributes to set the path
    InitializeObjectAttributes(
        &objectAttributes,
        &Path,
        OBJ_CASE_INSENSITIVE,
        NULL,
        NULL
        );

    // Tries to create the directory.
    status = FltCreateFile(
        Filter,
        Instance,
        &directoryHandle,
        FILE_LIST_DIRECTORY | FILE_TRAVERSE,
        &objectAttributes,
        &ioStatusBlock,
        NULL,
        FILE_ATTRIBUTE_NORMAL,
        FILE_SHARE_READ | FILE_SHARE_WRITE,
        FILE_OPEN_IF,
        FILE_DIRECTORY_FILE,
        NULL,
        (ULONG) 0,
        IO_IGNORE_SHARE_ACCESS_CHECK
        );

    // If the directory already exists or it have been created, returns STATUS_SUCCESS
    if (ioStatusBlock.Information == FILE_OPENED || ioStatusBlock.Information == FILE_CREATED){
        status = STATUS_SUCCESS;
        goto RWBRollPathCleanup;
    }

    // If the create failed, it means that we have to create the previous directories and then try again to create this directory
    if (!NT_SUCCESS(status)){
        UNICODE_STRING finalComponent;
        // Get the final component of the name and creates a new string without
        // it in order to create the previous folder
        FltParseFileName(&Path,
            NULL,
            NULL,
            &finalComponent
            );

        previousFolder.MaximumLength = Path.Length - finalComponent.Length - sizeof(WCHAR);
        RWBAllocateUnicodeString(&previousFolder);
        RtlCopyMemory(
            previousFolder.Buffer,
            Path.Buffer,
            previousFolder.MaximumLength
            );
        previousFolder.Length = previousFolder.MaximumLength;

        // Creates the previous folders
        RWBRollPath(
            previousFolder,
            Filter,
            Instance
            );

        // TODO: check status

        // Tries to create the directory again. This time should not fail since the previous folder have been created
        status = FltCreateFile(
            Filter,
            Instance,
            &directoryHandle,
            FILE_LIST_DIRECTORY | FILE_TRAVERSE,
            &objectAttributes,
            &ioStatusBlock,
            NULL,
            FILE_ATTRIBUTE_NORMAL,
            FILE_SHARE_READ | FILE_SHARE_WRITE,
            FILE_OPEN_IF,
            FILE_DIRECTORY_FILE,
            NULL,
            (ULONG)0,
            IO_IGNORE_SHARE_ACCESS_CHECK
            );
        RWBFreeUnicodeString(&previousFolder);
    }

RWBRollPathCleanup:

    if (directoryHandle != NULL)
        FltClose(directoryHandle);

    return status;
}