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[release/10.0] Add cast to ComAwareWeakReference rehydrate path #119141

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Merged
merged 1 commit into from
Aug 27, 2025
Merged

[release/10.0] Add cast to ComAwareWeakReference rehydrate path #119141

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27 changes: 12 additions & 15 deletions src/libraries/System.Private.CoreLib/src/System/ComAwareWeakReference.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,21 +100,24 @@ private void SetTarget(object? target, ComInfo? comInfo)
}
}

internal object? Target => GCHandle.InternalGet(_weakHandle) ?? RehydrateTarget();
internal object? Target => GCHandle.InternalGet(_weakHandle);

private object? RehydrateTarget()
internal nint WeakHandle => _weakHandle;

internal T? RehydrateTarget<T>() where T: class?
{
object? target = null;
T? target = null;
lock (this)
{
if (_comInfo != null)
{
// check if the target is still null
target = GCHandle.InternalGet(_weakHandle);
// Check if the target is still null
target = Unsafe.As<T?>(GCHandle.InternalGet(_weakHandle));
if (target == null)
{
// resolve and reset
target = _comInfo.ResolveTarget();
// Resolve and reset. Perform runtime cast to catch bugs
// in COM interop where it rehydrates wrong type.
target = (T?)_comInfo.ResolveTarget();
if (target != null)
GCHandle.InternalSet(_weakHandle, target);
}
Expand Down Expand Up @@ -147,16 +150,10 @@ private static ComAwareWeakReference EnsureComAwareReference(ref nint taggedHand
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static object? GetTarget(nint taggedHandle)
{
Debug.Assert((taggedHandle & ComAwareBit) != 0);
return Unsafe.As<ComAwareWeakReference>(GCHandle.InternalGet(taggedHandle & ~HandleTagBits)).Target;
}

internal static nint GetWeakHandle(nint taggedHandle)
internal static ComAwareWeakReference GetFromTaggedReference(nint taggedHandle)
{
Debug.Assert((taggedHandle & ComAwareBit) != 0);
return Unsafe.As<ComAwareWeakReference>(GCHandle.InternalGet(taggedHandle & ~HandleTagBits))._weakHandle;
return Unsafe.As<ComAwareWeakReference>(GCHandle.InternalGet(taggedHandle & ~HandleTagBits));
}

[MethodImpl(MethodImplOptions.NoInlining)]
Expand Down
4 changes: 3 additions & 1 deletion src/libraries/System.Private.CoreLib/src/System/WeakReference.T.cs
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Expand Up @@ -141,7 +141,9 @@ private T? Target
#if FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
if ((th & ComAwareBit) != 0)
{
target = Unsafe.As<T?>(ComAwareWeakReference.GetTarget(th));
ComAwareWeakReference cwr = ComAwareWeakReference.GetFromTaggedReference(th);

target = Unsafe.As<T?>(cwr.Target) ?? cwr.RehydrateTarget<T>();

// must keep the instance alive as long as we use the handle.
GC.KeepAlive(this);
Expand Down
6 changes: 4 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/WeakReference.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ internal nint WeakHandle

#if FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
if ((th & ComAwareBit) != 0)
return ComAwareWeakReference.GetWeakHandle(th);
return ComAwareWeakReference.GetFromTaggedReference(th).WeakHandle;
#endif
return th & ~HandleTagBits;
}
Expand Down Expand Up @@ -166,7 +166,9 @@ public virtual object? Target
#if FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
if ((th & ComAwareBit) != 0)
{
target = ComAwareWeakReference.GetTarget(th);
ComAwareWeakReference cwr = ComAwareWeakReference.GetFromTaggedReference(th);

target = cwr.Target ?? cwr.RehydrateTarget<object>();

// must keep the instance alive as long as we use the handle.
GC.KeepAlive(this);
Expand Down
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