From 4a8c27eea0eb91c3c030dad8c2d78879784d2d6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ole=20Andr=C3=A9=20Vadla=20Ravn=C3=A5s?= <oleavr@gmail.com>
Date: Wed, 20 Sep 2023 15:01:36 +0200
Subject: [PATCH] [WIP] Handle resilient superclasses
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Co-authored-by: Håvard Sørbø <havard@hsorbo.no>
---
 gum/gumswiftapiresolver.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/gum/gumswiftapiresolver.c b/gum/gumswiftapiresolver.c
index a4c2f4e84..d3ef04243 100644
--- a/gum/gumswiftapiresolver.c
+++ b/gum/gumswiftapiresolver.c
@@ -41,6 +41,8 @@
     ((flags & GUM_CLASS_HAS_VTABLE) != 0)
 #define GUM_TYPE_FLAGS_CLASS_HAS_OVERRIDE_TABLE(flags) \
     ((flags & GUM_CLASS_HAS_OVERRIDE_TABLE) != 0)
+#define GUM_TYPE_FLAGS_CLASS_HAS_RESILIENT_SUPERCLASS(flags) \
+    ((flags & GUM_CLASS_HAS_RESILIENT_SUPERCLASS) != 0)
 
 #define GUM_GENERIC_DESCRIPTOR_FLAGS_HAS_TYPE_PACKS(flags) \
     ((flags & GUM_GENERIC_DESCRIPTOR_HAS_TYPE_PACKS) != 0)
@@ -70,6 +72,7 @@ typedef struct _GumGenericParamDescriptor GumGenericParamDescriptor;
 typedef struct _GumGenericRequirementDescriptor GumGenericRequirementDescriptor;
 typedef struct _GumTypeGenericContextDescriptorHeader
     GumTypeGenericContextDescriptorHeader;
+typedef struct _GumResilientSuperclass GumResilientSuperclass;
 typedef struct _GumSingletonMetadataInitialization GumSingletonMetadataInitialization;
 typedef struct _GumForeignMetadataInitialization GumForeignMetadataInitialization;
 typedef struct _GumVTableDescriptorHeader GumVTableDescriptorHeader;
@@ -151,8 +154,9 @@ enum _GumAnonymousContextDescriptorFlags
 
 enum _GumTypeContextDescriptorFlags
 {
-  GUM_CLASS_HAS_VTABLE             = (1 << 15),
-  GUM_CLASS_HAS_OVERRIDE_TABLE     = (1 << 14),
+  GUM_CLASS_HAS_VTABLE               = (1 << 15),
+  GUM_CLASS_HAS_OVERRIDE_TABLE       = (1 << 14),
+  GUM_CLASS_HAS_RESILIENT_SUPERCLASS = (1 << 13),
 };
 
 enum _GumTypeMetadataInitializationKind
@@ -231,6 +235,11 @@ struct _GumTypeGenericContextDescriptorHeader
   GumGenericContextDescriptorHeader base;
 };
 
+struct _GumResilientSuperclass
+{
+  GumRelativeDirectPtr superclass;
+};
+
 struct _GumSingletonMetadataInitialization
 {
   GumRelativeDirectPtr initialization_cache;
@@ -312,6 +321,8 @@ static void gum_skip_generic_type_trailers (gconstpointer * trailer_ptr,
     const GumTypeContextDescriptor * t);
 static void gum_skip_generic_parts (gconstpointer * trailer_ptr,
     const GumGenericContextDescriptorHeader * h);
+static void gum_skip_resilient_superclass_trailer (gconstpointer * trailer_ptr,
+    const GumTypeContextDescriptor * t);
 static void gum_skip_metadata_initialization_trailers (
     gconstpointer * trailer_ptr, const GumTypeContextDescriptor * t);
 
@@ -980,6 +991,8 @@ gum_class_parse (GumClass * klass,
 
   gum_skip_generic_type_trailers (&trailer, type);
 
+  gum_skip_resilient_superclass_trailer (&trailer, type);
+
   gum_skip_metadata_initialization_trailers (&trailer, type);
 
   type_flags = GUM_DESCRIPTOR_FLAGS_KIND_FLAGS (type->context.flags);
@@ -1221,6 +1234,23 @@ gum_skip_generic_parts (gconstpointer * trailer_ptr,
   *trailer_ptr = trailer;
 }
 
+static void
+gum_skip_resilient_superclass_trailer (gconstpointer * trailer_ptr,
+                                       const GumTypeContextDescriptor * t)
+{
+  gconstpointer trailer = *trailer_ptr;
+
+  if (GUM_TYPE_FLAGS_CLASS_HAS_RESILIENT_SUPERCLASS (
+        GUM_DESCRIPTOR_FLAGS_KIND_FLAGS (t->context.flags)))
+  {
+    const GumResilientSuperclass * rs =
+        GUM_ALIGN (trailer, GumResilientSuperclass);
+    trailer = rs + 1;
+  }
+
+  *trailer_ptr = trailer;
+}
+
 static void
 gum_skip_metadata_initialization_trailers (gconstpointer * trailer_ptr,
                                            const GumTypeContextDescriptor * t)