/// <summary>
/// This TBS returns a random handle value in the desired handle range (ugh).
/// </summary>
/// <param name="owner"></param>
/// <param name="tpmHandle"></param>
/// <returns></returns>
private uint GetFreeHandle(Tbs.TbsContext owner, TpmHandle tpmHandle)
{
Tbs.SlotType neededType = Tbs.SlotTypeFromHandle(tpmHandle);
if (neededType == Tbs.SlotType.NoSlot)
{
return(tpmHandle.handle);
}
int numTries = 0;
while (true)
{
Ht handleType = tpmHandle.GetType();
var randomPos = (uint)Globs.GetRandomInt((int)TpmHandle.GetRangeLength(tpmHandle.GetType()));
uint candidateHandle = ((uint)handleType << 24) + randomPos;
if (!OwnerHandleInUse(owner, candidateHandle))
{
return(candidateHandle);
}
numTries++;
if (numTries >= 1000)
{
break;
}
}
throw new Exception("Too many TBS contexts");
}
internal int NumFreeSlots(Tbs.SlotType neededSlot)
{
int numUsedSlotsOfType = ObjectContexts.Sum(item => (item.Loaded && (item.TheSlotType == neededSlot)) ? 1 : 0);
switch (neededSlot)
{
case Tbs.SlotType.ObjectSlot:
return(NumObjectSlots - numUsedSlotsOfType);
case Tbs.SlotType.SessionSlot:
return(NumSessionSlots - numUsedSlotsOfType);
default:
throw new Exception("should not be here");
}
}
internal ObjectContext CreateObjectContext(Tbs.TbsContext owner, TpmHandle tpmHandle)
{
Tbs.SlotType newSlotType = Tbs.SlotTypeFromHandle(tpmHandle);
if (newSlotType == Tbs.SlotType.NoSlot)
{
throw new Exception("should not be here");
}
// Make a new slot context of the requisite type
uint tbsHandle = GetFreeHandle(owner, tpmHandle);
var newContext = new ObjectContext {
OwnerHandle = new TpmHandle(tbsHandle),
TheTpmHandle = tpmHandle,
TheSlotType = newSlotType,
LastUseCount = GetUseCount(),
Loaded = true,
Owner = owner
};
ObjectContexts.Add(newContext);
return(newContext);
}
/// <summary>
/// Gets the best eviction candidate for entities of given type. May return NULL.
/// Pinned entities are the ones used by the current command.
/// </summary>
/// <param name="type"></param>
/// <param name="pinnedEntities"></param>
/// <returns></returns>
internal ObjectContext GetEntityToEvict(Tbs.SlotType type,
ObjectContext[] pinnedEntities)
{
ObjectContext candidate = null;
foreach (ObjectContext c in ObjectContexts)
{
// See if this context is a candidate for eviction
if (c.TheSlotType != type || !c.Loaded || pinnedEntities.Contains(c))
{
continue;
}
// ObjectContext c is a candidate for removal. If we don't already
// have a candidate then see if the new candidate is staler.
if (candidate == null || c.LastUseCount < candidate.LastUseCount)
{
candidate = c;
}
}
return(candidate);
}
/// <summary>
/// Gets the best eviction candidate for entities of given type. May return NULL.
/// </summary>
/// <param name="neededSlot"></param>
/// <param name="neededEntities"></param>
/// <returns></returns>
internal ObjectContext GetBestEvictionCandidate(Tbs.SlotType neededSlot, ObjectContext[] neededEntities)
{
ObjectContext candidate = null;
foreach (ObjectContext c in ObjectContexts)
{
// See if this context is a candidate for eviction
if (!c.Loaded)
{
continue;
}
if (c.TheSlotType != neededSlot)
{
continue;
}
// Currently loaded entity of correct type, but is it referenced in this operation?
if (neededEntities.Contains(c))
{
continue;
}
// ObjectContext c is a candidate for removal. If we don't already
// have a candidate then see if the new candidate is staler than the old.
if (candidate == null)
{
candidate = c;
}
else
{
if (c.LastUseCount < candidate.LastUseCount)
{
candidate = c;
}
}
}
return(candidate);
}
void ProcessTpmClear(TbsContext caller, Tbs.SlotType excluded = Tbs.SlotType.NoSlot)
{
ContextManager.ObjectContexts.RemoveAll(ctx => ctx.Owner == caller &&
ctx.TheSlotType != excluded);
Debug.Assert(excluded != Tbs.SlotType.NoSlot || ContextManager.ObjectContexts.Count == 0);
}
