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DBT_DEVICEQUERYREMOVE event

The system broadcasts the DBT_DEVICEQUERYREMOVE device event to request permission to remove a device or piece of media. This message is the last chance for applications and drivers to prepare for this removal. However, any application can deny this request and cancel the operation.

To broadcast this device event, the system uses the WM_DEVICECHANGE message with wParam set to DBT_DEVICEQUERYREMOVE and lParam set as described following.



LRESULT CALLBACK WindowProc(
  HWND hwnd,       // handle to window
  UINT uMsg,       // WM_DEVICECHANGE
  WPARAM wParam,   // device-change event
  LPARAM lParam    // event-specific data
);

Parameters

hwnd

A handle to a window.

uMsg

The WM_DEVICECHANGE message identifier.

wParam

Set to DBT_DEVICEQUERYREMOVE.

lParam

A pointer to a structure identifying the device to remove. The structure consists of an event-independent header, followed by event-dependent members that describe the device. To use this structure, treat the structure as a DEV_BROADCAST_HDR structure, then check its dbch_devicetype member to determine the device type.

Return value

Return TRUE to grant permission to remove a device.

Return BROADCAST_QUERY_DENY to deny permission to remove a device.

Remarks

You must close all handles to the device or the device removal will fail.

Examples

For an example, see Processing a Request to Remove a Device.

Requirements

Minimum supported client

Windows XP

Minimum supported server

Windows Server 2003

Header

Dbt.h

See also

Device Events
Device Management Events
DEV_BROADCAST_HDR
WM_DEVICECHANGE

 

 

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