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FSCTL_DFS_GET_PKT_ENTRY_STATE control code

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The FSCTL_DFS_GET_PKT_ENTRY_STATE control code can get the same information as the NetDfsGetClientInfo function but can provide better performance in some configurations with high latencies to the DFS servers. It is not recommended to use the FSCTL_DFS_GET_PKT_ENTRY_STATE control code unless there are performance issues.

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL 
   WINAPI 
   DeviceIoControl( (HANDLE)       hDevice,            // handle to device
                    (DWORD)        FSCTL_DFS_GET_PKT_ENTRY_STATE, // dwIoControlCode(LPDWORD)      lpInBuffer,         // input buffer
                    (DWORD)        nInBufferSize,      // size of input buffer
                    (LPDWORD)      lpOutBuffer,        // output buffer
                    (DWORD)        nOutBufferSize,     // size of output buffer
                    (LPDWORD)      lpBytesReturned,    // number of bytes returned
                    (LPOVERLAPPED) lpOverlapped );     // OVERLAPPED structure

Parameters

hDevice [in]

A handle to the device. To obtain a device handle, call the CreateFile function.

dwIoControlCode [in]

The control code for the operation. Use FSCTL_DFS_GET_PKT_ENTRY_STATE for this operation.

lpInBuffer

Address of a DFS_GET_PKT_ENTRY_STATE_ARG structure and the 1-3 Unicode strings that follow.

nInBufferSize [in]

Size, in bytes, of the buffer pointed to by the lpInBuffer parameter.

lpOutBuffer [out]

Address of a DFS_INFO_# structure and any strings and structures pointed to by the DFS_INFO_# structure. The specific structure returned depends on the Level member in the DFS_GET_PKT_ENTRY_STATE_ARG structure passed in the input buffer.

nOutBufferSize [in]

Size, in bytes, of the buffer pointed to by the lpOutBuffer parameter. Due to the strings and structures referenced by the returned DFS_INFO_# structure that are also in the output buffer, this buffer should be larger than the DFS_INFO_# structure specified.

lpBytesReturned [out]

A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

If the output buffer is too small, but at least large enough to hold a DWORD, the call fails, GetLastError returns ERROR_MORE_DATA, and the first DWORD of the output buffer contains the size that would have been required. If the output buffer cannot hold a DWORD then the call fails with ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

lpOverlapped [in]

A pointer to an OVERLAPPED structure.

If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError.

Requirements

Requirement Value
Minimum supported client
 Windows Vista
Minimum supported server
 Windows Server 2008
Header
LmDfs.h (include LmDfs.h)

See also

DeviceIoControl

NetDfsGetClientInfo