Merge pull request #172 from orange-cpp/feaute/methods_calling_improvement

Feaute/methods calling improvement

include/omath/rev_eng/internal_rev_object.hpp

@@ -3,11 +3,43 @@
 //
 
 #pragma once
+#include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <string_view>
+
+#ifdef _WIN32
+#include "omath/utility/pe_pattern_scan.hpp"
+#include <windows.h>
+#elif defined(__APPLE__)
+#include "omath/utility/macho_pattern_scan.hpp"
+#include <mach-o/dyld.h>
+#else
+#include "omath/utility/elf_pattern_scan.hpp"
+#include <link.h>
+#endif
 
 namespace omath::rev_eng
 {
+    template<std::size_t N>
+    struct FixedString final
+    {
+        char data[N]{};
+        // ReSharper disable once CppNonExplicitConvertingConstructor
+        constexpr FixedString(const char (&str)[N]) noexcept // NOLINT(*-explicit-constructor)
+        {
+            for (std::size_t i = 0; i < N; ++i)
+                data[i] = str[i];
+        }
+        // ReSharper disable once CppNonExplicitConversionOperator
+        constexpr operator std::string_view() const noexcept // NOLINT(*-explicit-constructor)
+        {
+            return {data, N - 1};
+        }
+    };
+    template<std::size_t N>
+    FixedString(const char (&)[N]) -> FixedString<N>;
+
     class InternalReverseEngineeredObject
     {
     protected:
@@ -23,26 +55,123 @@ namespace omath::rev_eng
             return *reinterpret_cast<Type*>(reinterpret_cast<std::uintptr_t>(this) + offset);
         }
 
-        template<std::size_t id, class ReturnType>
+        template<class ReturnType>
+        ReturnType call_method(const void* ptr, auto... arg_list)
+        {
+#ifdef _MSC_VER
+            using MethodType = ReturnType(__thiscall*)(void*, decltype(arg_list)...);
+#else
+            using MethodType = ReturnType (*)(void*, decltype(arg_list)...);
+#endif
+            return reinterpret_cast<MethodType>(const_cast<void*>(ptr))(this, arg_list...);
+        }
+        template<class ReturnType>
+        ReturnType call_method(const void* ptr, auto... arg_list) const
+        {
+#ifdef _MSC_VER
+            using MethodType = ReturnType(__thiscall*)(const void*, decltype(arg_list)...);
+#else
+            using MethodType = ReturnType (*)(const void*, decltype(arg_list)...);
+#endif
+            return reinterpret_cast<MethodType>(const_cast<void*>(ptr))(this, arg_list...);
+        }
+
+        template<FixedString ModuleName, FixedString Pattern, class ReturnType>
+        ReturnType call_method(auto... arg_list)
+        {
+            static const auto* address = resolve_pattern(ModuleName, Pattern);
+            return call_method<ReturnType>(address, arg_list...);
+        }
+
+        template<FixedString ModuleName, FixedString Pattern, class ReturnType>
+        ReturnType call_method(auto... arg_list) const
+        {
+            static const auto* address = resolve_pattern(ModuleName, Pattern);
+            return call_method<ReturnType>(address, arg_list...);
+        }
+
+        template<class ReturnType>
+        ReturnType call_method(const std::string_view& module_name,const std::string_view& pattern, auto... arg_list)
+        {
+            static const auto* address = resolve_pattern(module_name, pattern);
+            return call_method<ReturnType>(address, arg_list...);
+        }
+
+        template<class ReturnType>
+        ReturnType call_method(const std::string_view& module_name,const std::string_view& pattern, auto... arg_list) const
+        {
+            static const auto* address = resolve_pattern(module_name, pattern);
+            return call_method<ReturnType>(address, arg_list...);
+        }
+        template<std::size_t Id, class ReturnType>
         ReturnType call_virtual_method(auto... arg_list)
         {
-#ifdef _MSC_VER
+            const auto vtable = *reinterpret_cast<void***>(this);
-            using VirtualMethodType = ReturnType(__thiscall*)(void*, decltype(arg_list)...);
+            return call_method<ReturnType>(vtable[Id], arg_list...);
-#else
-            using VirtualMethodType = ReturnType (*)(void*, decltype(arg_list)...);
-#endif
-            return (*reinterpret_cast<VirtualMethodType**>(this))[id](this, arg_list...);
         }
-        template<std::size_t id, class ReturnType>
+        template<std::size_t Id, class ReturnType>
         ReturnType call_virtual_method(auto... arg_list) const
         {
-#ifdef _MSC_VER
+            const auto vtable = *reinterpret_cast<void* const* const*>(this);
-            using VirtualMethodType = ReturnType(__thiscall*)(void*, decltype(arg_list)...);
+            return call_method<ReturnType>(vtable[Id], arg_list...);
+        }
+
+    private:
+        [[nodiscard]]
+        static const void* resolve_pattern(const std::string_view module_name, const std::string_view pattern)
+        {
+            const auto* base = get_module_base(module_name);
+            assert(base && "Failed to find module");
+
+#ifdef _WIN32
+            const auto result = PePatternScanner::scan_for_pattern_in_loaded_module(base, pattern);
+#elif defined(__APPLE__)
+            const auto result = MachOPatternScanner::scan_for_pattern_in_loaded_module(base, pattern);
 #else
-            using VirtualMethodType = ReturnType (*)(void*, decltype(arg_list)...);
+            const auto result = ElfPatternScanner::scan_for_pattern_in_loaded_module(base, pattern);
+#endif
+            assert(result.has_value() && "Pattern scan failed");
+            return reinterpret_cast<const void*>(*result);
+        }
+
+        [[nodiscard]]
+        static const void* get_module_base(const std::string_view module_name)
+        {
+#ifdef _WIN32
+            return GetModuleHandleA(module_name.data());
+#elif defined(__APPLE__)
+            // On macOS, iterate loaded images to find the module by name
+            const auto count = _dyld_image_count();
+            for (std::uint32_t i = 0; i < count; ++i)
+            {
+                const auto* name = _dyld_get_image_name(i);
+                if (name && std::string_view{name}.find(module_name) != std::string_view::npos)
+                    return static_cast<const void*>(_dyld_get_image_header(i));
+            }
+            return nullptr;
+#else
+            // On Linux, use dl_iterate_phdr to find loaded module by name
+            struct CallbackData
+            {
+                std::string_view name;
+                const void* base;
+            } cb_data{module_name, nullptr};
+
+            dl_iterate_phdr(
+                    [](dl_phdr_info* info, std::size_t, void* data) -> int
+                    {
+                        auto* cb = static_cast<CallbackData*>(data);
+                        if (info->dlpi_name
+                            && std::string_view{info->dlpi_name}.find(cb->name) != std::string_view::npos)
+                        {
+                            cb->base = reinterpret_cast<const void*>(info->dlpi_addr);
+                            return 1;
+                        }
+                        return 0;
+                    },
+                    &cb_data);
+            return cb_data.base;
 #endif
-            return (*static_cast<VirtualMethodType**>((void*)(this)))[id](
-                    const_cast<void*>(static_cast<const void*>(this)), arg_list...);
         }
     };
 } // namespace omath::rev_eng

tests/general/unit_test_reverse_enineering.cpp

@@ -20,6 +20,13 @@ public:
     int m_health{123};
 };
 
+// Extract a raw function pointer from an object's vtable
+inline const void* get_vtable_entry(const void* obj, const std::size_t index)
+{
+    const auto vtable = *static_cast<void* const* const*>(obj);
+    return vtable[index];
+}
+
 class RevPlayer final : omath::rev_eng::InternalReverseEngineeredObject
 {
 public:
@@ -51,6 +58,17 @@ public:
     {
         return call_virtual_method<1, int>();
     }
+
+    // Wrappers exposing call_method for testing — use vtable entries as known-good function pointers
+    int call_foo_via_ptr(const void* fn_ptr) const
+    {
+        return call_method<int>(fn_ptr);
+    }
+
+    int call_bar_via_ptr(const void* fn_ptr) const
+    {
+        return call_method<int>(fn_ptr);
+    }
 };
 
 TEST(unit_test_reverse_enineering, read_test)
@@ -64,4 +82,39 @@ TEST(unit_test_reverse_enineering, read_test)
     EXPECT_EQ(player_original.bar(), player_reversed->rev_bar());
     EXPECT_EQ(player_original.foo(), player_reversed->rev_foo());
     EXPECT_EQ(player_original.bar(), player_reversed->rev_bar_const());
+}
+
+TEST(unit_test_reverse_enineering, call_method_with_vtable_ptr)
+{
+    // Extract raw function pointers from Player's vtable, then call them via call_method
+    Player player;
+    const auto* rev = reinterpret_cast<const RevPlayer*>(&player);
+
+    const auto* foo_ptr = get_vtable_entry(&player, 0);
+    const auto* bar_ptr = get_vtable_entry(&player, 1);
+
+    EXPECT_EQ(player.foo(), rev->call_foo_via_ptr(foo_ptr));
+    EXPECT_EQ(player.bar(), rev->call_bar_via_ptr(bar_ptr));
+    EXPECT_EQ(1, rev->call_foo_via_ptr(foo_ptr));
+    EXPECT_EQ(2, rev->call_bar_via_ptr(bar_ptr));
+}
+
+TEST(unit_test_reverse_enineering, call_method_same_result_as_virtual)
+{
+    // call_virtual_method delegates to call_method — both paths must agree
+    Player player;
+    const auto* rev = reinterpret_cast<const RevPlayer*>(&player);
+
+    EXPECT_EQ(rev->rev_foo(), rev->call_foo_via_ptr(get_vtable_entry(&player, 0)));
+    EXPECT_EQ(rev->rev_bar(), rev->call_bar_via_ptr(get_vtable_entry(&player, 1)));
+}
+
+TEST(unit_test_reverse_enineering, call_virtual_method_delegates_to_call_method)
+{
+    Player player;
+    auto* rev = reinterpret_cast<RevPlayer*>(&player);
+
+    EXPECT_EQ(1, rev->rev_foo());
+    EXPECT_EQ(2, rev->rev_bar());
+    EXPECT_EQ(2, rev->rev_bar_const());
 }