IOCTL_BATTERY_QUERY_STATUS

Using the IOCTL_BATTERY_QUERY_STATUS operation returns the current status of the battery.

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

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

Parameters

hDevice

[in] Handle to the battery from which information is to be returned. To obtain a device handle, call the CreateFile function.

dwIoControlCode

[in] Control code for the operation. This value identifies the specific operation to be performed and the type of device on which to perform it. Use IOCTL_BATTERY_QUERY_STATUS for this operation.

lpInBuffer

[in] Pointer to a BATTERY_WAIT_STATUS structure.

nInBufferSize

[in] Size, in bytes, of the input buffer.

lpOutBuffer

[out] Pointer to a BATTERY_STATUS structure.

nOutBufferSize

[in] Size, in bytes, of the output buffer.

lpBytesReturned

[out] Pointer to a variable that receives the size, in bytes, of the data stored in the buffer pointed to by lpOutBuffer.

If the output buffer is too small to return any data then the call fails, GetLastError returns the error code ERROR_INSUFFICIENT_BUFFER, and the returned byte count is zero.

If the output buffer is too small to hold all of the data but can hold some entries, then the operating system returns as much as fits, the call fails, GetLastError returns the error code ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data returned. Your application should call DeviceIoControl again with the same operation, specifying a new starting point.

If lpOverlapped is NULL (nonoverlapped I/O), lpBytesReturned cannot be NULL.

If lpOverlapped is not NULL (overlapped I/O), lpBytesReturned can be NULL. If this is an overlapped operation, you can retrieve the number of bytes returned by calling the GetOverlappedResult function. If hDevice is associated with an I/O completion port, you can get the number of bytes returned by calling the GetQueuedCompletionStatus function.

lpOverlapped

[in] Pointer to an OVERLAPPED structure.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, lpOverlapped must point to a valid OVERLAPPED structure. In this case, DeviceIoControl is performed as an overlapped (asynchronous) operation. If the device was opened with the FILE_FLAG_OVERLAPPED flag and lpOverlapped is NULL, the function fails in unpredictable ways.

If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, lpOverlapped is ignored and the DeviceIoControl function does not return until the operation has been completed, or until an error occurs.

Return Values

If the operation succeeds, DeviceIoControl returns a nonzero value.

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

Remarks

This battery IOCTL returns the status of the battery at the time the operation returns. The input parameter structure, BATTERY_WAIT_STATUS, indicates when the battery status is to be processed and returned.

Requests for battery status can be for immediate return or can be set to wait for a particular condition before completing. For example, a request for battery information can be made that waits until the battery capacity reaches a specified point or the battery state changes.

All requests for battery information will complete with the status of ERROR_FILE_NOT_FOUND whenever the BatteryTag element of the request does not match that of the current battery tag. (See Battery Tags for more information.) This is used to ensure that the returned battery information matches that of the requested battery.

For the implications of overlapped I/O on this operation, see the Remarks section of the DeviceIoControl topic.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Unsupported.
  Header: Declared in Batclass.h.

See Also

Device Input and Output Overview, Device Input and Output Control Codes, DeviceIoControl, BATTERY_STATUS, BATTERY_WAIT_STATUS, IOCTL_BATTERY_QUERY_INFORMATION, IOCTL_BATTERY_QUERY_TAG, IOCTL_BATTERY_SET_INFORMATION