203 lines
3.8 KiB
C
203 lines
3.8 KiB
C
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/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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smsesnid.c
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Abstract:
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Session Manager Session ID Management
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Author:
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Mark Lucovsky (markl) 04-Oct-1989
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Revision History:
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--*/
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#include "smsrvp.h"
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#include <string.h>
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ULONG
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SmpAllocateSessionId(
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IN PSMPKNOWNSUBSYS OwningSubsystem,
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IN PSMPKNOWNSUBSYS CreatorSubsystem OPTIONAL
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)
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/*++
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Routine Description:
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This function allocates a session ID.
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Arguments:
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OwningSubsystem - Supplies the address of the subsystem that should
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become the owner of this session.
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CreatorSubsystem - An optional parameter that supplies
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the address of the subsystem requesting the creation of this
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session. This subsystem is notified when the session completes.
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Return Value:
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This function returns the session ID for this session.
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--*/
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{
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ULONG SessionId;
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PLIST_ENTRY SessionIdListInsertPoint;
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PSMPSESSION Session;
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RtlEnterCriticalSection(&SmpSessionListLock);
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//
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// SessionIds are allocated by incrementing a 32 bit counter.
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// If the counter wraps, then session IDs are allocated by
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// scanning the sorted list of current session IDs for a hole.
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//
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SessionId = SmpNextSessionId++;
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SessionIdListInsertPoint = SmpSessionListHead.Blink;
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if ( !SmpNextSessionIdScanMode ) {
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if ( SmpNextSessionId == 0 ) {
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//
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// We have used up 32 bits worth of session IDs so
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// enable scan mode session ID allocation.
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//
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SmpNextSessionIdScanMode = TRUE;
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}
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} else {
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//
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// Compute a session ID by scanning the sorted session ID list
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// until a hole is found. When an ID is found, then save it,
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// and recalculate the insert point.
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//
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#if DBG
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DbgPrint("SMSS: SessionId's Wrapped\n");
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DbgBreakPoint();
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#endif
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}
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Session = RtlAllocateHeap(SmpHeap, MAKE_TAG( SM_TAG ), sizeof(SMPSESSION));
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if (Session) {
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Session->SessionId = SessionId;
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Session->OwningSubsystem = OwningSubsystem;
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Session->CreatorSubsystem = CreatorSubsystem;
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InsertTailList(SessionIdListInsertPoint,&Session->SortedSessionIdListLinks);
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} else {
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DbgPrint("SMSS: Unable to keep track of session ID -- no memory available\n");
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}
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RtlLeaveCriticalSection(&SmpSessionListLock);
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return SessionId;
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}
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PSMPSESSION
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SmpSessionIdToSession(
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IN ULONG SessionId
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)
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/*++
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Routine Description:
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This function locates the session structure for the specified
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session ID.
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It is assumed that the caller holds the session list lock.
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Arguments:
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SessionId - Supplies the session ID to locate the structure for.
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Return Value:
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NULL - No session matches the specified session.
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NON-NULL - Returns a pointer to the session structure associated with
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the specified session ID.
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--*/
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{
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PLIST_ENTRY Next;
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PSMPSESSION Session;
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Next = SmpSessionListHead.Flink;
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while ( Next != &SmpSessionListHead ) {
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Session = CONTAINING_RECORD(Next, SMPSESSION, SortedSessionIdListLinks );
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if ( Session->SessionId == SessionId ) {
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return Session;
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}
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Next = Session->SortedSessionIdListLinks.Flink;
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}
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return NULL;
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}
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VOID
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SmpDeleteSession(
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IN ULONG SessionId
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)
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/*++
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Routine Description:
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This function locates and deletes a session ID.
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Arguments:
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SessionId - Supplies the session ID to delete.
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Return Value:
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None.
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--*/
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{
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PSMPSESSION Session;
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RtlEnterCriticalSection(&SmpSessionListLock);
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Session = SmpSessionIdToSession(SessionId);
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if ( Session ) {
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RemoveEntryList(&Session->SortedSessionIdListLinks);
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RtlLeaveCriticalSection(&SmpSessionListLock);
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RtlFreeHeap(SmpHeap,0,Session);
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} else {
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RtlLeaveCriticalSection(&SmpSessionListLock);
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}
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return;
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}
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