From 433b9ca979d61fc3c05d78b01df3489e8d2af5ec Mon Sep 17 00:00:00 2001
From: F1ssi0N <josh33901@gmail.com>
Date: Tue, 13 Mar 2018 15:43:18 +0000
Subject: [PATCH 1/2] Add math, vfunc and hooks and interface grabbing

---
 src/hooks.hh     | 164 ++++++++++++++++++++++
 src/interface.cc |  46 ++++++
 src/interface.hh |  45 ++++++
 src/math.hh      | 353 +++++++++++++++++++++++++++++++++++++++++++++++
 src/platform.hh  |  16 +--
 src/signature.cc |   2 +-
 src/signature.hh |  33 -----
 src/types.hh     |   2 +
 src/vfunc.hh     |  91 ++++++++++++
 9 files changed, 710 insertions(+), 42 deletions(-)
 create mode 100644 src/hooks.hh
 create mode 100644 src/interface.cc
 create mode 100644 src/interface.hh
 create mode 100644 src/math.hh
 create mode 100644 src/vfunc.hh

diff --git a/src/hooks.hh b/src/hooks.hh
new file mode 100644
index 0000000..df9e61d
--- /dev/null
+++ b/src/hooks.hh
@@ -0,0 +1,164 @@
+#pragma once
+
+#include "types.hh"
+#include "vfunc.hh"
+
+#include <algorithm>
+#include <utility>
+#include <vector>
+
+namespace Hooks {
+template <typename T, u32 offset>
+class HookInstance {
+
+    T *    instance;
+    void **original_table;
+    void **new_table;
+
+    // pair from index to old function pointer
+    std::vector<std::pair<u32, void *>> hooked_functions;
+
+    auto count_funcs() {
+        u32 count = -1;
+        do
+            ++count;
+        while (original_table[count] != nullptr);
+
+        return count;
+    }
+
+    auto get_table() {
+        return *(reinterpret_cast<void ***>(instance) + offset);
+    }
+
+    static auto create_table(u32 count) {
+        return new void *[count];
+    }
+
+    static auto replace_table_pointer(T *instance, void **new_pointer) {
+        auto table = reinterpret_cast<void ***>(instance) + offset;
+        *table     = new_pointer;
+    }
+
+public:
+    HookInstance(T *instance) : instance(instance) {
+
+        assert(instance);
+
+        original_table = get_table();
+        assert(original_table);
+
+        auto num_funcs = count_funcs();
+        assert(num_funcs != -1);
+
+        new_table = create_table(num_funcs);
+
+        // copy the original function pointers over
+        memcpy(new_table, original_table, num_funcs * 4);
+
+        // replace the original with our own
+        replace_table_pointer(instance, new_table);
+    }
+
+    ~HookInstance() {
+        replace_table_pointer(instance, original_table);
+
+        assert(new_table);
+        delete[] new_table;
+    }
+
+    auto hook_function(u32 index, void *f) {
+        assert(index < count_funcs());
+
+        hooked_functions.push_back(std::make_pair(index, f));
+        new_table[index] = f;
+    }
+
+    auto unhook_function(u32 index) -> void {
+        assert(index < count_funcs());
+
+        auto found = false;
+        for (auto &f : hooked_functions) {
+            if (f.first == index) {
+                found = true;
+
+                // remove from the hooked functions list
+                std::swap(f, hooked_functions.back());
+                hooked_functions.pop_back();
+
+                // swap the pointers
+                new_table[index] = original_table[index];
+
+                // at this point there is no reason to swap the tables over
+                // either the tables are already swapped in which case this
+                // has an immediate effect, or they are not in which case its
+                // not a problem anyway.
+
+                return;
+            }
+        }
+        assert(found);
+    }
+
+    template <typename F>
+    auto get_original_function(u32 index) {
+        assert(index < count_funcs());
+        return reinterpret_cast<F>(original_table[index]);
+    }
+
+    auto get_instance() {
+        return instance;
+    }
+};
+
+template <typename T, u32 offset>
+class HookFunction {
+    static std::vector<HookInstance<T, offset> *> hooks;
+
+    auto create_hook_instance(T *instance) {
+        auto h = new HookInstance<T, offset>(instance);
+        hooks.push_back(h);
+        return h;
+    }
+
+    T * instance;
+    u32 index;
+
+public:
+    HookFunction(T *instance, u32 index, void *f) {
+        assert(instance);
+        HookInstance<T, offset> *val = nullptr;
+
+        for (auto &v : hooks) {
+            if (v->get_instance() == instance) {
+                val = v;
+                break;
+            }
+        }
+
+        if (val == nullptr) {
+            // we havent hooked this instance yet, so do that now
+            create_hook_instance(instance)->hook_function(index, f);
+            return;
+        }
+
+        this->instance = instance;
+        this->index    = index;
+
+        val->hook_function(index, f);
+    }
+
+    ~HookFunction() {
+        for (auto &v : hooks) {
+            if (v->get_instance() == instance) {
+                v->unhook_function(index);
+                return;
+            }
+        }
+    }
+};
+
+template <typename T, u32 offset>
+std::vector<HookInstance<T, offset> *> HookFunction<T, offset>::hooks;
+
+} // namespace Hooks
diff --git a/src/interface.cc b/src/interface.cc
new file mode 100644
index 0000000..ef1fb8f
--- /dev/null
+++ b/src/interface.cc
@@ -0,0 +1,46 @@
+#include "stdafx.hh"
+
+#include "interface.hh"
+#include "signature.hh"
+
+using InstantiateInterfaceFn = void *(*)();
+
+class InterfaceReg {
+public:
+    InterfaceReg() = delete;
+
+public:
+    InstantiateInterfaceFn create_fn;
+    const char *           name;
+
+    InterfaceReg *next;
+};
+
+void *InterfaceHelpers::find_interface(const char *module_name, const char *interface_name) {
+
+    InterfaceReg *interface_reg_head;
+
+    if constexpr (DoghookPlatform::windows()) {
+        interface_reg_head = **Signature::find_pattern<InterfaceReg ***>(module_name, "8B 35 ? ? ? ? 57 85 F6 74 38", 2);
+    } else if constexpr (DoghookPlatform::linux()) {
+        static_assert(!DoghookPlatform::linux());
+    } else if constexpr (DoghookPlatform::osx()) {
+        static_assert(!DoghookPlatform::linux());
+    }
+
+    assert(interface_reg_head);
+
+    for (auto r = interface_reg_head; r != nullptr; r = r->next) {
+        auto match = strstr(r->name, interface_name);
+
+        // Only match if the next character after the name is the number
+        if (match != nullptr && !isalpha(*(match + strlen(interface_name)))) return r->create_fn();
+    }
+
+    // if you get here either
+    // 1: your interface name is wrong
+    // 2: your dll name is wrong
+    assert(0);
+
+    return nullptr;
+}
diff --git a/src/interface.hh b/src/interface.hh
new file mode 100644
index 0000000..d35105d
--- /dev/null
+++ b/src/interface.hh
@@ -0,0 +1,45 @@
+#pragma once
+
+namespace InterfaceHelpers {
+
+// this auto-resolves the library using Signature::
+void *find_interface(const char *module_name, const char *interface_name);
+} // namespace InterfaceHelpers
+
+template <typename T>
+class Interface {
+    static T *value;
+
+public:
+    // interface name should be the name of the interface
+    // without the version number
+    // e.g. "VClient017" -> "VClient"
+    static auto set_from_interface(const char *module_name, const char *interface_name) {
+        value = static_cast<T *>(
+            InterfaceHelpers::find_interface(module_name, interface_name));
+    }
+
+    // set from a pointer (you should only do this for non-exported
+    //  interfaces e.g. IInput or CClientModeShared)
+    static auto set_from_pointer(T *new_value) {
+        value = new_value;
+    }
+
+    auto operator-> () -> T *& {
+        return value;
+    }
+
+    auto get() -> T *& {
+        return value;
+    }
+
+    operator bool() {
+        return value != nullptr;
+    }
+};
+
+template <typename T>
+T *Interface<T>::value;
+
+template <typename T>
+using IFace = Interface<T>;
diff --git a/src/math.hh b/src/math.hh
new file mode 100644
index 0000000..0ef4e30
--- /dev/null
+++ b/src/math.hh
@@ -0,0 +1,353 @@
+#pragma once
+
+#include "platform.hh"
+
+#include <cassert>
+#include <cmath>
+#include <float.h>
+
+#undef max
+#undef min
+
+namespace Math {
+constexpr auto PI = 3.14159265358979323846f;
+
+inline auto to_radians(float x) {
+    return x * (PI / 180.0f);
+}
+
+inline auto to_degrees(float x) {
+    return x * (180.0f / PI);
+}
+
+template <typename T>
+auto lerp(float percent, T min, T max) {
+    return min + ((max - min) * percent);
+}
+
+class Vector {
+public:
+    float x, y, z;
+
+    // sentinal values
+    inline static auto origin() { return Vector(0); }
+    inline static auto zero() { return Vector(0); }
+    inline static auto invalid() { return Vector(FLT_MAX); }
+
+    inline Vector() {}
+    inline Vector(float x, float y, float z) : x(x), y(y), z(z) {}
+    inline Vector(float v) : x(v), y(v), z(v) {}
+    inline Vector(const Vector &v) : x(v.x), y(v.y), z(v.z) {}
+
+    // equality
+    inline auto operator==(const Vector &v) const {
+        return (x == v.x) && (y == v.y) && (z == v.z);
+    }
+    inline auto operator!=(const Vector &v) const {
+        return (x != v.x) || (y != v.y) || (z != v.z);
+    }
+
+    // arithmetic operations
+    inline auto operator+=(const Vector &v) {
+        x += v.x;
+        y += v.y;
+        z += v.z;
+        return *this;
+    }
+    inline auto operator-=(const Vector &v) {
+        x -= v.x;
+        y -= v.y;
+        z -= v.z;
+        return *this;
+    }
+    inline auto operator*=(const Vector &v) {
+        x *= v.x;
+        y *= v.y;
+        z *= v.z;
+        return *this;
+    }
+    inline auto operator*=(float s) {
+        x *= s;
+        y *= s;
+        z *= s;
+        return *this;
+    }
+    inline auto operator/=(const Vector &v) {
+        assert(v.x != 0.0f && v.y != 0.0f && v.z != 0.0f);
+        x /= v.x;
+        y /= v.y;
+        z /= v.z;
+        return *this;
+    }
+    inline auto operator/=(float s) {
+        assert(s != 0.0f);
+        float oofl = 1.0f / s;
+        x *= oofl;
+        y *= oofl;
+        z *= oofl;
+        return *this;
+    }
+    inline auto operator-(void) const {
+        return Vector(-x, -y, -z);
+    }
+    inline auto operator+(const Vector &v) const {
+        return Vector(*this) += v;
+    }
+    inline auto operator-(const Vector &v) const {
+        return Vector(*this) -= v;
+    }
+    auto operator*(const Vector &v) const {
+        return Vector(*this) *= v;
+    }
+    inline auto operator/(const Vector &v) const {
+        return Vector(*this) /= v;
+    }
+    inline auto operator*(float s) const {
+        return Vector(*this) *= s;
+    }
+    inline auto operator/(float s) const {
+        return Vector(*this) /= s;
+    }
+
+    inline auto length_sqr() const {
+        return (x * x) + (y * y) + (z * z);
+    }
+    inline auto length() const {
+        return std::sqrt(length_sqr());
+    }
+    inline auto distance(const Vector &b) const {
+        auto d = *this - b;
+        return d.length();
+    }
+    inline auto dot(Vector &b) const {
+        return (x * b.x) + (y * b.y) + (z * b.z);
+    }
+    inline auto cross(Vector &v) const {
+        auto res = Vector::invalid();
+        res.x    = y * v.z - z * v.y;
+        res.y    = z * v.x - x * v.z;
+        res.z    = x * v.y - y * v.x;
+        return res;
+    }
+
+    inline auto to_angle() const {
+        float tmp, yaw, pitch;
+
+        if (y == 0 && x == 0) {
+            yaw = 0;
+            if (z > 0)
+                pitch = 270;
+            else
+                pitch = 90;
+        } else {
+            yaw = (atan2(y, x) * 180 / PI);
+            if (yaw < 0)
+                yaw += 360;
+
+            tmp   = sqrt(x * x + y * y);
+            pitch = (atan2(-z, tmp) * 180 / PI);
+            if (pitch < 0)
+                pitch += 360;
+        }
+
+        return Vector(pitch, yaw, 0);
+    }
+
+    inline auto to_vector() const {
+        float sp, sy, cp, cy;
+
+        sy = sinf(to_radians(y));
+        cy = cosf(to_radians(y));
+
+        sp = sinf(to_radians(x));
+        cp = cosf(to_radians(x));
+
+        return Vector(cp * cy, cp * sy, -sp);
+    }
+
+    inline auto lerp(const Vector &other, float percent) const {
+        Vector ret;
+
+        ret.x = x + (other.x - x) * percent;
+        ret.y = y + (other.y - y) * percent;
+        ret.z = z + (other.z - z) * percent;
+
+        return ret;
+    }
+};
+
+class Matrix3x4 {
+public:
+    Matrix3x4() {}
+    Matrix3x4(
+        float m00, float m01, float m02, float m03,
+        float m10, float m11, float m12, float m13,
+        float m20, float m21, float m22, float m23) {
+        data[0][0] = m00;
+        data[0][1] = m01;
+        data[0][2] = m02;
+        data[0][3] = m03;
+        data[1][0] = m10;
+        data[1][1] = m11;
+        data[1][2] = m12;
+        data[1][3] = m13;
+        data[2][0] = m20;
+        data[2][1] = m21;
+        data[2][2] = m22;
+        data[2][3] = m23;
+    }
+
+    // Creates a matrix where the X axis = forward
+    // the Y axis = left, and the Z axis = up
+    void init(const Vector &x_axis, const Vector &y_axis, const Vector &z_axis, const Vector &origin) {
+        data[0][0] = x_axis.x;
+        data[0][1] = y_axis.x;
+        data[0][2] = z_axis.x;
+        data[0][3] = origin.x;
+        data[1][0] = x_axis.y;
+        data[1][1] = y_axis.y;
+        data[1][2] = z_axis.y;
+        data[1][3] = origin.y;
+        data[2][0] = x_axis.z;
+        data[2][1] = y_axis.z;
+        data[2][2] = z_axis.z;
+        data[2][3] = origin.z;
+    }
+
+    // Creates a matrix where the X axis = forward
+    // the Y axis = left, and the Z axis = up
+    Matrix3x4(const Vector &x_axis, const Vector &y_axis, const Vector &z_axis, const Vector &origin) {
+        init(x_axis, y_axis, z_axis, origin);
+    }
+
+    inline void invalidate(void) {
+        assert(0);
+        // for (int i = 0; i < 3; i++) {
+        //     for (int j = 0; j < 4; j++) {
+        //         data[i][j] = VEC_T_NAN;
+        //     }
+        // }
+    }
+
+    float *operator[](int i) {
+        assert((i >= 0) && (i < 3));
+        return data[i];
+    }
+    const float *operator[](int i) const {
+        assert((i >= 0) && (i < 3));
+        return data[i];
+    }
+    float *      base() { return &data[0][0]; }
+    const float *base() const { return &data[0][0]; }
+
+    const auto get_column(u32 column, Vector &out) const {
+        out.x = data[0][column];
+        out.y = data[1][column];
+        out.z = data[2][column];
+    }
+
+    const auto get_row(u32 row, Vector &out) const {
+        out.x = data[row][0];
+        out.y = data[row][1];
+        out.z = data[row][2];
+    }
+
+    //
+    auto rotate_vector(const Math::Vector &in) const {
+        Vector out;
+        Vector row;
+
+        out.x = in.dot((get_row(0, row), row));
+        out.y = in.dot((get_row(1, row), row));
+        out.z = in.dot((get_row(2, row), row));
+
+        return out;
+    }
+
+    auto from_angle(const Vector &angles) {
+        auto radian_pitch = to_radians(angles.x);
+        auto radian_yaw   = to_radians(angles.y);
+        auto radian_roll  = to_radians(angles.z);
+
+        auto sp = sin(radian_pitch);
+        auto cp = cos(radian_pitch);
+
+        auto sy = sin(radian_yaw);
+        auto cy = cos(radian_yaw);
+
+        auto sr = sin(radian_roll);
+        auto cr = cos(radian_roll);
+
+        // matrix = (YAW * PITCH) * ROLL
+        data[0][0] = cp * cy;
+        data[1][0] = cp * sy;
+        data[2][0] = -sp;
+
+        float crcy = cr * cy;
+        float crsy = cr * sy;
+        float srcy = sr * cy;
+        float srsy = sr * sy;
+        data[0][1] = sp * srcy - crsy;
+        data[1][1] = sp * srsy + crcy;
+        data[2][1] = sr * cp;
+
+        data[0][2] = (sp * crcy + srsy);
+        data[1][2] = (sp * crsy - srcy);
+        data[2][2] = cr * cp;
+
+        data[0][3] = 0.0f;
+        data[1][3] = 0.0f;
+        data[2][3] = 0.0f;
+    }
+
+    float data[3][4];
+};
+
+// TODO: make these member functions
+inline void matrix_angles(const Matrix3x4 &matrix, float *angles) {
+    float forward[3];
+    float left[3];
+    float up[3];
+
+    //
+    // Extract the basis vectors from the matrix. Since we only need the Z
+    // component of the up vector, we don't get X and Y.
+    //
+    forward[0] = matrix[0][0];
+    forward[1] = matrix[1][0];
+    forward[2] = matrix[2][0];
+    left[0]    = matrix[0][1];
+    left[1]    = matrix[1][1];
+    left[2]    = matrix[2][1];
+    up[2]      = matrix[2][2];
+
+    float xyDist = std::sqrt(forward[0] * forward[0] + forward[1] * forward[1]);
+
+    // enough here to get angles?
+    if (xyDist > 0.001f) {
+        // (yaw)    y = ATAN( forward.y, forward.x );       -- in our space, forward is the X axis
+        angles[1] = to_degrees(atan2f(forward[1], forward[0]));
+
+        // (pitch)  x = ATAN( -forward.z, sqrt(forward.x*forward.x+forward.y*forward.y) );
+        angles[0] = to_degrees(atan2f(-forward[2], xyDist));
+
+        // (roll)   z = ATAN( left.z, up.z );
+        angles[2] = to_degrees(atan2f(left[2], up[2]));
+    } else {
+        // (yaw)    y = ATAN( -left.x, left.y );            -- forward is mostly z, so use right for yaw
+        angles[1] = to_degrees(atan2f(-left[0], left[1]));
+
+        // (pitch)  x = ATAN( -forward.z, sqrt(forward.x*forward.x+forward.y*forward.y) );
+        angles[0] = to_degrees(atan2f(-forward[2], xyDist));
+
+        // Assume no roll in this case as one degree of freedom has been lost (i.e. yaw == roll)
+        angles[2] = 0;
+    }
+}
+
+inline void matrix_angles(const Matrix3x4 &matrix, Vector &angles, Vector &position) {
+    matrix.get_column(3, position);
+    matrix_angles(matrix, &angles.x);
+}
+
+} // namespace Math
diff --git a/src/platform.hh b/src/platform.hh
index 49b9bb0..28a3b1b 100644
--- a/src/platform.hh
+++ b/src/platform.hh
@@ -40,15 +40,15 @@
 #endif
 // clang-format on
 
-namespace DogHookPlatform {
-constexpr bool windows() { return doghook_platform_windows(); }
-constexpr bool linux() { return doghook_platform_linux(); }
-constexpr bool osx() { return doghook_platform_osx(); }
+namespace DoghookPlatform {
+inline constexpr bool windows() { return doghook_platform_windows(); }
+inline constexpr bool linux() { return doghook_platform_linux(); }
+inline constexpr bool osx() { return doghook_platform_osx(); }
 
-constexpr bool msvc() { return doghook_platform_msvc(); }
-constexpr bool clang() { return doghook_platform_clang(); }
-constexpr bool gcc() { return doghook_platform_gcc(); }
-} // namespace DogHookPlatform
+inline constexpr bool msvc() { return doghook_platform_msvc(); }
+inline constexpr bool clang() { return doghook_platform_clang(); }
+inline constexpr bool gcc() { return doghook_platform_gcc(); }
+} // namespace DoghookPlatform
 
 #include "types.hh"
 
diff --git a/src/signature.cc b/src/signature.cc
index db302a9..00e7d62 100644
--- a/src/signature.cc
+++ b/src/signature.cc
@@ -135,7 +135,7 @@ auto Signature::resolve_library(const char *name) -> void * {
 
         auto dir = readdir(d);
         while (dir != nullptr) {
-            if (dir->d_type == DT_REG && strstr(dir->d_name, to_find) != nullptr && strstr(dir->d_name, ".so") != nullptr) {
+            if (dir->d_type == DT_REG && strstr(dir->d_name, to_find) && strstr(dir->d_name, ".so")) {
                 sprintf(out, "%s/%s", dirname, dir->d_name);
                 return true;
             }
diff --git a/src/signature.hh b/src/signature.hh
index b0558f9..fde846d 100644
--- a/src/signature.hh
+++ b/src/signature.hh
@@ -16,37 +16,4 @@ auto find_pattern(const char *module, const char *pattern, u32 offset) {
     return reinterpret_cast<T>(find_pattern(module, pattern) + offset);
 }
 void *resolve_callgate(void *address);
-
-// TODO: there must be some way we can do this at init time instead of using magic statics.
-// make a static chain and find them at level_init or at init_all
-class Pattern {
-    const char *module;
-    const char *signature;
-
-public:
-    Pattern(const char *                 module,
-            [[maybe_unused]] const char *signature_windows,
-            [[maybe_unused]] const char *signature_linux,
-            [[maybe_unused]] const char *signature_osx)
-        : module(module),
-#if doghook_platform_windows()
-          signature(signature_windows)
-#elif doghook_platform_linux()
-          signature(signature_linux)
-#elif doghook_platform_osx()
-          signature(signature_osx)
-#endif
-    {
-        assert(signature[0] != '\0');
-    }
-
-    auto find() -> u8 * {
-        return ::Signature::find_pattern(module, signature);
-    }
-
-    template <typename T>
-    auto find(u32 offset) -> T {
-        return ::Signature::find_pattern<T>(module, signature, offset);
-    }
-};
 } // namespace Signature
diff --git a/src/types.hh b/src/types.hh
index da072cf..90d08ff 100644
--- a/src/types.hh
+++ b/src/types.hh
@@ -13,3 +13,5 @@ using i16  = int16_t;
 using i32  = int32_t;
 using i64  = int64_t;
 using iptr = intptr_t;
+
+#include "math.hh"
diff --git a/src/vfunc.hh b/src/vfunc.hh
new file mode 100644
index 0000000..0b2e757
--- /dev/null
+++ b/src/vfunc.hh
@@ -0,0 +1,91 @@
+#pragma once
+
+#include <functional>
+#include <type_traits>
+
+#include "platform.hh"
+#include "types.hh"
+
+// helpers for calling virtual functions
+namespace VFunc {
+inline auto get_table(void *inst, u32 offset) -> void ** {
+    return *reinterpret_cast<void ***>(reinterpret_cast<u8 *>(inst) + offset);
+}
+
+inline auto get_table(const void *inst, u32 offset) -> const void ** {
+    return *reinterpret_cast<const void ***>(
+        reinterpret_cast<u8 *>(
+            const_cast<void *>(inst)) +
+        offset);
+}
+
+template <typename F>
+inline auto get_func(const void *inst, u32 index, u32 offset) {
+    return reinterpret_cast<F>(get_table(inst, offset)[index]);
+}
+
+template <typename F>
+inline auto get_func(void *inst, u32 index, u32 offset) {
+    return reinterpret_cast<F>(get_table(inst, offset)[index]);
+}
+
+template <typename>
+class Func;
+
+template <typename ObjectType, typename Ret, typename... Args>
+class Func<Ret (ObjectType::*)(Args...)> {
+
+    using function_type = Ret(__thiscall *)(ObjectType *, Args...);
+    function_type f;
+
+    // On windows this will take into account the offset
+    // So we do not need to store that seperately
+    ObjectType *instance;
+
+public:
+    // TODO: do any other platforms have this offset and is it useful?
+    Func(ObjectType *instance,
+         u32         index_windows,
+         u32         index_linux,
+         u32         index_osx,
+         u32         offset_windows) {
+        // NOTE: this assert is disabled as it is in some really tight loops!
+        // This should never go off and if it does you will get a nice and obvious fatal crash...
+        //assert(instance != nullptr);
+
+        auto index = 0u;
+        if constexpr (BluePlatform::windows())
+            index = index_windows;
+        else if constexpr (BluePlatform::linux())
+            index = index_linux;
+        else if constexpr (BluePlatform::osx())
+            index = index_osx;
+
+        auto offset = 0u;
+        if constexpr (BluePlatform::windows()) {
+            offset = offset_windows;
+
+            this->instance = reinterpret_cast<ObjectType *>(
+                reinterpret_cast<u8 *>(instance) + offset);
+        } else {
+            this->instance = instance;
+        }
+
+        f = get_func<function_type>(instance, index, offset);
+    }
+
+    auto invoke(Args... args) -> Ret {
+        return f(instance, args...);
+    }
+};
+
+} // namespace VFunc
+
+// macro for easier definitions of wrapper calls
+// name is the name of the function
+// off is the windows offset
+// varags are the arguments of the parent function
+#define return_virtual_func(name, windows, linux, osx, off, ...) \
+    using c = std::remove_reference<decltype(*this)>::type;      \
+    using t = decltype(&c::name);                                \
+    return VFunc::Func<t>(this, windows, linux, osx, off).invoke(__VA_ARGS__)

From 3aba3a15a91016f72618694c8cbc8d4fb951cfb3 Mon Sep 17 00:00:00 2001
From: F1ssi0N <josh33901@gmail.com>
Date: Tue, 13 Mar 2018 15:48:30 +0000
Subject: [PATCH 2/2] Update interface.cc to fix linux compile issues

---
 src/interface.cc | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/interface.cc b/src/interface.cc
index ef1fb8f..3c96382 100644
--- a/src/interface.cc
+++ b/src/interface.cc
@@ -23,9 +23,7 @@ void *InterfaceHelpers::find_interface(const char *module_name, const char *inte
     if constexpr (DoghookPlatform::windows()) {
         interface_reg_head = **Signature::find_pattern<InterfaceReg ***>(module_name, "8B 35 ? ? ? ? 57 85 F6 74 38", 2);
     } else if constexpr (DoghookPlatform::linux()) {
-        static_assert(!DoghookPlatform::linux());
     } else if constexpr (DoghookPlatform::osx()) {
-        static_assert(!DoghookPlatform::linux());
     }
 
     assert(interface_reg_head);