--- /dev/null
+#!/usr/bin/python2.7
+
+import os
+import KernelCollection
+
+# This verifies that a kext can patch vtables against another kext
+# We put foo.kext in the base KC so that the patch slot in bar.kext has to know to use the correct fixup level in the fixup chain
+
+def check(kernel_cache):
+ kernel_cache.buildKernelCollection("x86_64", "/pageablekc-vtable-patching/main.kc", "/pageablekc-vtable-patching/main.kernel", "/pageablekc-vtable-patching/extensions", ["com.apple.foo"], [])
+ kernel_cache.analyze("/pageablekc-vtable-patching/main.kc", ["-layout", "-arch", "x86_64"])
+
+ assert len(kernel_cache.dictionary()["dylibs"]) == 2
+ assert kernel_cache.dictionary()["dylibs"][0]["name"] == "com.apple.kernel"
+ assert kernel_cache.dictionary()["dylibs"][1]["name"] == "com.apple.foo"
+
+ # Get the addresses for the symbols we are looking at. This will make it easier to work out the fixup slots
+ kernel_cache.analyze("/pageablekc-vtable-patching/main.kc", ["-symbols", "-arch", "x86_64"])
+
+ # From foo, we want to know where the vtable is, and the foo() and fooUsed0() slots in that vtable
+ # Foo::foo()
+ assert kernel_cache.dictionary()["dylibs"][1]["global-symbols"][6]["name"] == "__ZN3Foo3fooEv"
+ assert kernel_cache.dictionary()["dylibs"][1]["global-symbols"][6]["vmAddr"] == "0x16ED0"
+ # Foo::fooUsed0()
+ assert kernel_cache.dictionary()["dylibs"][1]["global-symbols"][7]["name"] == "__ZN3Foo8fooUsed0Ev"
+ assert kernel_cache.dictionary()["dylibs"][1]["global-symbols"][7]["vmAddr"] == "0x16EF0"
+
+
+ # Check the fixups
+ kernel_cache.analyze("/pageablekc-vtable-patching/main.kc", ["-fixups", "-arch", "x86_64"])
+
+ # In vtable for Foo, we match the entry for Foo::foo() by looking for its value on the RHS of the fixup
+ assert kernel_cache.dictionary()["fixups"]["0x1D150"] == "kc(0) + 0x16ED0"
+ # Then the following fixup should be to Foo::fooUsed0()
+ assert kernel_cache.dictionary()["fixups"]["0x1D158"] == "kc(0) + 0x16EF0"
+
+
+ # -----------------------------------------------------------
+ # Now build an pageable cache using the baseline kernel collection
+ kernel_cache.buildPageableKernelCollection("x86_64", "/pageablekc-vtable-patching/pageable.kc", "/pageablekc-vtable-patching/main.kc", "/pageablekc-vtable-patching/extensions", ["com.apple.bar"], [])
+ kernel_cache.analyze("/pageablekc-vtable-patching/pageable.kc", ["-layout", "-arch", "x86_64"])
+
+ assert len(kernel_cache.dictionary()["dylibs"]) == 1
+ assert kernel_cache.dictionary()["dylibs"][0]["name"] == "com.apple.bar"
+
+
+ # Get the addresses for the symbols we are looking at. This will make it easier to work out the fixup slots
+ kernel_cache.analyze("/pageablekc-vtable-patching/pageable.kc", ["-symbols", "-arch", "x86_64"])
+
+ # From bar, find the vtable and its override of foo()
+ # Bar::foo()
+ assert kernel_cache.dictionary()["dylibs"][0]["global-symbols"][3]["name"] == "__ZN3Bar3fooEv"
+ assert kernel_cache.dictionary()["dylibs"][0]["global-symbols"][3]["vmAddr"] == "0x4F10"
+
+
+ # Check the fixups
+ kernel_cache.analyze("/pageablekc-vtable-patching/pageable.kc", ["-fixups", "-arch", "x86_64"])
+
+ # In bar, again match the entry for its Bar::foo() symbol
+ assert kernel_cache.dictionary()["dylibs"][0]["fixups"]["0x8150"] == "kc(1) + 0x4F10"
+ # And if the patching was correct, then following entry should be to Foo::fooUsed0()
+ assert kernel_cache.dictionary()["dylibs"][0]["fixups"]["0x8158"] == "kc(0) + 0x12EF0"
+
+
+# [~]> xcrun -sdk macosx.internal cc -arch x86_64 -Wl,-static -mkernel -nostdlib -Wl,-e,__start -Wl,-pie main.cpp -Wl,-pagezero_size,0x0 -o main.kernel -Wl,-image_base,0x10000 -Wl,-segaddr,__HIB,0x4000 -Wl,-add_split_seg_info -Wl,-install_name,/usr/lib/swift/split.seg.v2.hack -iwithsysroot /System/Library/Frameworks/Kernel.framework/Headers -Wl,-sectcreate,__LINKINFO,__symbolsets,SymbolSets.plist -Wl,-segprot,__LINKINFO,r--,r--
+# [~]> xcrun -sdk macosx.internal cc -arch x86_64 -Wl,-kext -mkernel -nostdlib -Wl,-add_split_seg_info -Wl,-no_data_const foo.cpp -o extensions/foo.kext/foo -iwithsysroot /System/Library/Frameworks/Kernel.framework/Headers -DFOO_USED=1
+# [~]> xcrun -sdk macosx.internal cc -arch x86_64 -Wl,-kext -mkernel -nostdlib -Wl,-add_split_seg_info -Wl,-data_const bar.cpp -o extensions/bar.kext/bar -iwithsysroot /System/Library/Frameworks/Kernel.framework/Headers
+# [~]> rm -r extensions/*.kext/*.ld
+