BroadcastSystemMessage function

Sends a message to the specified recipients. The recipients can be applications, installable drivers, network drivers, system-level device drivers, or any combination of these system components.

To receive additional information if the request is defined, use the BroadcastSystemMessageEx function.

Syntax


long WINAPI BroadcastSystemMessage(
  _In_         DWORD dwFlags,
  _Inout_opt_  LPDWORD lpdwRecipients,
  _In_         UINT uiMessage,
  _In_         WPARAM wParam,
  _In_         LPARAM lParam
);

Parameters

dwFlags [in]

Type: DWORD

The broadcast option. This parameter can be one or more of the following values.

ValueMeaning
BSF_ALLOWSFW
0x00000080

Enables the recipient to set the foreground window while processing the message.

BSF_FLUSHDISK
0x00000004

Flushes the disk after each recipient processes the message.

BSF_FORCEIFHUNG
0x00000020

Continues to broadcast the message, even if the time-out period elapses or one of the recipients is not responding.

BSF_IGNORECURRENTTASK
0x00000002

Does not send the message to windows that belong to the current task. This prevents an application from receiving its own message.

BSF_NOHANG
0x00000008

Forces a nonresponsive application to time out. If one of the recipients times out, do not continue broadcasting the message.

BSF_NOTIMEOUTIFNOTHUNG
0x00000040

Waits for a response to the message, as long as the recipient is not being unresponsive. Does not time out.

BSF_POSTMESSAGE
0x00000010

Posts the message. Do not use in combination with BSF_QUERY.

BSF_QUERY
0x00000001

Sends the message to one recipient at a time, sending to a subsequent recipient only if the current recipient returns TRUE.

BSF_SENDNOTIFYMESSAGE
0x00000100

Sends the message using SendNotifyMessage function. Do not use in combination with BSF_QUERY.

 

lpdwRecipients [in, out, optional]

Type: LPDWORD

A pointer to a variable that contains and receives information about the recipients of the message.

When the function returns, this variable receives a combination of these values identifying which recipients actually received the message.

If this parameter is NULL, the function broadcasts to all components.

This parameter can be one or more of the following values.

ValueMeaning
BSM_ALLCOMPONENTS
0x00000000

Broadcast to all system components.

BSM_ALLDESKTOPS
0x00000010

Broadcast to all desktops. Requires the SE_TCB_NAME privilege.

BSM_APPLICATIONS
0x00000008

Broadcast to applications.

 

uiMessage [in]

Type: UINT

The message to be sent.

For lists of the system-provided messages, see System-Defined Messages.

wParam [in]

Type: WPARAM

Additional message-specific information.

lParam [in]

Type: LPARAM

Additional message-specific information.

Return value

Type:

Type: long

If the function succeeds, the return value is a positive value.

If the function is unable to broadcast the message, the return value is –1.

If the dwFlags parameter is BSF_QUERY and at least one recipient returned BROADCAST_QUERY_DENY to the corresponding message, the return value is zero. To get extended error information, call GetLastError.

Remarks

If BSF_QUERY is not specified, the function sends the specified message to all requested recipients, ignoring values returned by those recipients.

The system only does marshalling for system messages (those in the range 0 to (WM_USER-1)). To send other messages (those >= WM_USER) to another process, you must do custom marshalling.

Examples

For an example, see Terminating a Process.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Winuser.h (include Windows.h)

Library

User32.lib

DLL

User32.dll

Unicode and ANSI names

BroadcastSystemMessageW (Unicode)

See also

Reference
BroadcastSystemMessageEx
SendNotifyMessage
Conceptual
Messages and Message Queues

 

 

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