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Retrieves session information for the specified session on the specified Remote Desktop Session Host (RD Session Host) server. It can be used to query session information on local and remote RD Session Host servers.

Syntax

BOOL WTSQuerySessionInformationA(
  [in]  HANDLE         hServer,
  [in]  DWORD          SessionId,
  [in]  WTS_INFO_CLASS WTSInfoClass,
  [out] LPSTR          *ppBuffer,
  [out] DWORD          *pBytesReturned
Parameters
[in] hServer
A handle to an RD Session Host server. Specify a handle opened by the
WTSOpenServer function, or specify
WTS_CURRENT_SERVER_HANDLE to indicate the RD Session Host server on which your application
is running.
[in] SessionId
A Remote Desktop Services session identifier. To indicate the session in which the calling application is running
(or the current session) specify WTS_CURRENT_SESSION. Only specify
WTS_CURRENT_SESSION when obtaining session information on the local server. If
WTS_CURRENT_SESSION is specified when querying session information on a remote server,
the returned session information will be inconsistent. Do not use the returned data.
You can use the WTSEnumerateSessions
function to retrieve the identifiers of all sessions on a specified RD Session Host server.
To query information for another user's session, you must have Query Information permission. For more
information, see Remote Desktop Services
Permissions. To modify permissions on a session, use the Remote Desktop Services Configuration administrative
tool.
[in] WTSInfoClass
A value of the WTS_INFO_CLASS enumeration that indicates the type of
session information to retrieve in a call to the
WTSQuerySessionInformation function.
[out] ppBuffer
A pointer to a variable that receives a pointer to the requested information. The format and contents of the
data depend on the information class specified in the WTSInfoClass parameter. To free
the returned buffer, call the WTSFreeMemory
function.
[out] pBytesReturned
A pointer to a variable that receives the size, in bytes, of the data returned in
ppBuffer.
Return value
If the function succeeds, the return value is a nonzero value.
If the function fails, the return value is zero. To get extended error information, call
GetLastError.
Remarks
To retrieve the session ID for the current session when Remote Desktop Services is running, call
WTSQuerySessionInformation and specify
WTS_CURRENT_SESSION for the SessionId parameter and
WTSSessionId for the WTSInfoClass parameter. The session ID
will be returned in the ppBuffer parameter. If Remote Desktop Services is not running, calls
to WTSQuerySessionInformation fail. In
this situation, you can retrieve the current session ID by calling the
ProcessIdToSessionId function.
To determine whether your application is running on the physical console, you must specify
WTS_CURRENT_SESSION for the SessionId parameter, and
WTSClientProtocolType as the WTSInfoClass parameter.
If ppBuffer is "0", the session is attached to the physical console.
The wtsapi32.h header defines WTSQuerySessionInformation as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
Requirements