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[2020-02] [cominterop] Add coop handle enter/return on native CCW methods #21366

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Merged
lambdageek merged 2 commits into from
Dec 13, 2021
Merged

[2020-02] [cominterop] Add coop handle enter/return on native CCW methods #21366

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5f06e57
[tests] Add CCW GetIUnknownForObject leak test
lambdageek Dec 10, 2021
df6aa4f
[cominterop] Add coop handle enter/return on native CCW methods
lambdageek Dec 10, 2021
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53 changes: 33 additions & 20 deletions mono/metadata/cominterop.c
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Original file line number Diff line number Diff line change
Expand Up @@ -173,6 +173,31 @@ typedef struct {
MonoCCW* ccw;
} MonoCCWInterface;

/*
* COM Callable Wrappers
*
* CCWs may be called on threads that aren't attached to the runtime, they can
* then run managed code or the method implementations may use coop handles.
* Use the macros below to setup the thread state.
*
* For managed methods, the runtime marshaling wrappers handle attaching and
* coop state switching.
*/

#define MONO_CCW_CALL_ENTER do { \
gpointer dummy; \
gpointer orig_domain = mono_threads_attach_coop (mono_domain_get (), &dummy); \
MONO_ENTER_GC_UNSAFE; \
HANDLE_FUNCTION_ENTER (); \
do {} while (0)

#define MONO_CCW_CALL_EXIT \
HANDLE_FUNCTION_RETURN (); \
MONO_EXIT_GC_UNSAFE; \
mono_threads_detach_coop (orig_domain, &dummy); \
} while (0)


/* IUnknown */
static int STDCALL cominterop_ccw_addref (MonoCCWInterface* ccwe);

Expand Down Expand Up @@ -2568,12 +2593,9 @@ static int STDCALL
cominterop_ccw_addref (MonoCCWInterface* ccwe)
{
int result;
gpointer dummy;
gpointer orig_domain = mono_threads_attach_coop (mono_domain_get (), &dummy);
MONO_ENTER_GC_UNSAFE;
MONO_CCW_CALL_ENTER;
result = cominterop_ccw_addref_impl (ccwe);
MONO_EXIT_GC_UNSAFE;
mono_threads_detach_coop (orig_domain, &dummy);
MONO_CCW_CALL_EXIT;
return result;
}

Expand Down Expand Up @@ -2602,12 +2624,9 @@ static int STDCALL
cominterop_ccw_release (MonoCCWInterface* ccwe)
{
int result;
gpointer dummy;
gpointer orig_domain = mono_threads_attach_coop (mono_domain_get (), &dummy);
MONO_ENTER_GC_UNSAFE;
MONO_CCW_CALL_ENTER;
result = cominterop_ccw_release_impl (ccwe);
MONO_EXIT_GC_UNSAFE;
mono_threads_detach_coop (orig_domain, &dummy);
MONO_CCW_CALL_EXIT;
return result;
}

Expand Down Expand Up @@ -2654,12 +2673,9 @@ static int STDCALL
cominterop_ccw_queryinterface (MonoCCWInterface* ccwe, const guint8* riid, gpointer* ppv)
{
int result;
gpointer dummy;
gpointer orig_domain = mono_threads_attach_coop (mono_domain_get (), &dummy);
MONO_ENTER_GC_UNSAFE;
MONO_CCW_CALL_ENTER;
result = cominterop_ccw_queryinterface_impl (ccwe, riid, ppv);
MONO_EXIT_GC_UNSAFE;
mono_threads_detach_coop (orig_domain, &dummy);
MONO_CCW_CALL_EXIT;
return result;
}

Expand Down Expand Up @@ -2777,12 +2793,9 @@ cominterop_ccw_get_ids_of_names (MonoCCWInterface* ccwe, gpointer riid,
guint32 lcid, gint32 *rgDispId)
{
int result;
gpointer dummy;
gpointer orig_domain = mono_threads_attach_coop (mono_domain_get(), &dummy);
MONO_ENTER_GC_UNSAFE;
MONO_CCW_CALL_ENTER;
result = cominterop_ccw_get_ids_of_names_impl (ccwe, riid, rgszNames, cNames, lcid, rgDispId);
MONO_EXIT_GC_UNSAFE;
mono_threads_detach_coop (orig_domain, &dummy);
MONO_CCW_CALL_EXIT;
return result;
}

Expand Down
52 changes: 52 additions & 0 deletions mono/tests/cominterop.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -659,6 +659,9 @@ public static int Main ()
}
}

if (CallableWrapperLeakTest () != 0)
return 209;

#endregion // COM Callable Wrapper Tests

#region SAFEARRAY tests
Expand Down Expand Up @@ -1630,6 +1633,55 @@ public static int mono_test_marshal_struct_with_bstr_callback(StructWithBstr sb)
return 2;
return 0;
}

// Doesn't matter what this is
internal class CallableWrapperLeakTestClass {
}

public static int CallableWrapperLeakTest () {
bool ok = true;
GCHandle h = HideFromGC (() => {
var o = new CallableWrapperLeakTestClass();
var weakHandle = GCHandle.Alloc (o, GCHandleType.Weak);
var pUnk = Marshal.GetIUnknownForObject (o);
int c = Marshal.Release(pUnk);
o = null;
if (c != 0) {
Console.Error.WriteLine ("Expected IUnknown refcount on a CCW to be 0 after Release, was {0}", c);
ok = false;
}
return weakHandle;
});
if (!ok)
return 1;
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
GC.WaitForPendingFinalizers();
HideFromGC(() => {
var o = h.Target;
if (o != null) {
Console.Error.WriteLine ("Expected weak handle to be null after GC, but the object (of type {0}) was retained", o.GetType());
ok = false;
}
return "done"; // doesn't matter
});
if (!ok)
return 2;
return 0;
}

[MethodImpl (MethodImplOptions.NoInlining)]
private static T HideFromGC<T> (Func<T> f) => HideFromGC (20, f);

[MethodImpl (MethodImplOptions.NoInlining)]
private static T HideFromGC<T> (int rec, Func<T> f) {
if (rec <= 0)
return f ();
else
return HideFromGC (rec - 1, f);
}

}

public class TestVisible
Expand Down