private ExtractedPointer ExtractRandomPointer(Snapshot snapshot)
{
SnapshotRegion extractedRegion = snapshot.SnapshotRegions[Random.Next(0, snapshot.SnapshotRegions.Length)];
SnapshotElementIndexer extractedElement = extractedRegion[Random.Next(0, extractedRegion.GetElementCount(PointerSize.ToSize()))];
return(this.ExtractPointerFromElement(extractedElement));
}
protected override void OnUpdate()
{
ConcurrentDictionary <dynamic, Int64> histogram = new ConcurrentDictionary <dynamic, Int64>();
Int32 processedPages = 0;
lock (this.SnapshotLock)
{
if (this.Snapshot == null)
{
this.Cancel();
return;
}
Parallel.ForEach(
this.Snapshot.Cast <Object>(),
SettingsViewModel.GetInstance().ParallelSettings,
(regionObject) =>
{
SnapshotRegion region = regionObject as SnapshotRegion;
if (((dynamic)region).GetElementLabels() == null || region.GetElementCount() <= 0)
{
return;
}
foreach (SnapshotElementRef element in region)
{
lock (this.ItemLock)
{
if (histogram.ContainsKey(((dynamic)element).GetElementLabel()))
{
histogram[((dynamic)element).GetElementLabel()]++;
}
else
{
histogram.TryAdd(((dynamic)element).GetElementLabel(), 1);
}
}
}
lock (this.ProgressLock)
{
processedPages++;
this.UpdateProgress(processedPages, this.Snapshot.GetRegionCount());
}
//// End foreach element
});
//// End foreach region
}
this.Histogram = new SortedList <dynamic, Int64>(histogram);
this.UpdateHistogram();
this.Cancel();
base.OnUpdate();
}
/// <summary>
/// Gets a random pointer from the pointer collection.
/// </summary>
/// <returns>A random discovered pointer, or null if unable to find one.</returns>
public Pointer GetRandomPointer(Int32 levelIndex)
{
if (levelIndex >= this.Levels.Count || this.Levels[levelIndex].StaticPointers == null)
{
return(null);
}
Snapshot currentSnapshot = this.Levels[levelIndex].StaticPointers;
ExtractedPointer pointer = this.ExtractRandomPointer(currentSnapshot);
UInt64 pointerBase = pointer.BaseAddress;
List <Int32> offsets = new List <Int32>();
foreach (Level level in this.Levels.Take(levelIndex + 1).Reverse())
{
IEnumerable <Int32> shuffledOffsets = Enumerable.Range(-(Int32)this.MaxOffset, (Int32)(this.MaxOffset * 2) + 1).Shuffle();
Boolean found = false;
// Brute force all possible offsets in a random order to find the next path (this guarantees uniform path probabilities)
foreach (Int32 nextRandomOffset in shuffledOffsets)
{
UInt64 newDestination = nextRandomOffset < 0 ? pointer.Destination.Subtract(-nextRandomOffset, wrapAround: false) : pointer.Destination.Add(nextRandomOffset, wrapAround: false);
SnapshotRegion snapshotRegion = level.HeapPointers.SnapshotRegions.Select(x => x).Where(y => newDestination >= y.BaseAddress && newDestination <= y.EndAddress).FirstOrDefault();
if (snapshotRegion != null)
{
// We may have sampled an offset that results in a mis-aligned index, so just randomly take an element from this snapshot rather than using the random offset
SnapshotElementIndexer randomElement = snapshotRegion[Random.Next(0, snapshotRegion.GetElementCount(PointerSize.ToSize()))];
UInt64 baseAddress = randomElement.GetBaseAddress(PointerSize.ToSize());
Int32 alignedOffset = pointer.Destination >= baseAddress ? -((Int32)(pointer.Destination - baseAddress)) : ((Int32)(baseAddress - pointer.Destination));
pointer = this.ExtractPointerFromElement(randomElement);
offsets.Add(alignedOffset);
found = true;
break;
}
}
if (!found)
{
Logger.Log(LogLevel.Error, "Unable to collect a pointer, encountered dead end path");
return(null);
}
}
return(new Pointer(pointerBase, this.PointerSize, offsets.ToArray()));
}