Add kEnableTrackSubstitutionHook toggle flag

Lets the track-substitution hook be enabled/disabled by flipping one
constexpr bool in main.cpp instead of commenting/uncommenting code, so
before/after comparisons don't need back-and-forth edits.

mpcore/src/main/cpp/main.cpp

@@ -1,5 +1,7 @@
 #include <cstring>
 #include <cstdio>
+#include <cstdint>
+#include <cerrno>
 #include <android/log.h>
 #include <jni.h>
 #include "main.h"
@@ -73,249 +75,115 @@ bool is_memory_writable(void* addr, size_t size) {
 
 using namespace std;
 
-// Базовый класс - Животное
+// ---- RaceLoaderTask_BuildTrackScenePath hook (see ANALYSIS.md §6j) ----
-class Animal {
+// Target compiled in ARM mode (PUSH {R4-R11,LR}; ADD R11,SP,#0x1C - both
-protected:
+// position-independent, safe to relocate into the trampoline as-is).
-    string name;
+#define BUILDTRACKSCENEPATH_OFFSET 0x2a8424
-    int age;
 
-public:
+typedef int (*BuildTrackScenePathFn)(void* raceLoaderTask);
-    // Конструктор
+static BuildTrackScenePathFn orig_BuildTrackScenePath = nullptr;
-    Animal(const string& name, int age) : name(name), age(age) {
-        cout << "Animal constructor: " << name << endl;
-    }
 
-    // Виртуальный деструктор
+// Deliberately different from any real event's track, so a successful
-    virtual ~Animal() {
+// override is visually unmistakable. region3/colorado was tried first and
-        cout << "Animal destructor: " << name << endl;
+// abandoned: it's cut/incomplete content in this build - models/environments/
-    }
+// has no colorado/ folder at all (only chicago, desert, foothills, garage,
+// newyork), even though region3_colorado_track2.scene.sb itself contains
+// full embedded geometry. The scene's internal m3g loader still tries to
+// open "/published/models/environments/colorado/region3_colorado_track2.m3g"
+// as a loose file, which was never shipped -> geometry never loads -> every
+// downstream consumer (spatial index, checkpoints, ...) sees empty/zero data
+// and null-derefs, which is what the whole sub_53A5FC/sub_52A9B8/sub_52A620/
+// sub_58E5E8 crash chain actually was (see ANALYSIS.md §6n/§6o). Switched to
+// region4_chicago_track4/chicago instead: confirmed shipped and playable
+// (event_01_race.prefabs.sb's real TrackName, verified start/finish actors
+// in the scene, and a full models/environments/chicago/ folder present).
+static const char* kOverrideTrackName = "region4_chicago_track4";
+// Environment prefabs are per-track variants ("chicago1.prefabs.sb" ..
+// "chicago6.prefabs.sb", matching "region4_chicago_track1".."track6"), not a
+// single generic "chicago.prefabs.sb" - confirmed live: env="chicago" alone
+// hit "Could not open database at published/prefabs/environments/chicago.
+// prefabs.sb" followed by an immediate SIGSEGV. Only colorado shipped as one
+// un-numbered colorado.prefabs.sb instead of colorado1..6 - further evidence
+// region3/colorado is unfinished/cut content (see kOverrideTrackName above).
+static const char* kOverrideEnvName = "chicago4";
 
-    // Виртуальный метод (будет переопределяться)
+int Hook_BuildTrackScenePath(void* a1) {
-    virtual void makeSound() const {
+    // a1[8] (word offset 8 = byte 32): pointer to the RaceDefinition-like
-        cout << name << " makes a generic animal sound" << endl;
+    // struct. Track name is a {begin,end} pair at byte offsets +72/+76,
-    }
+    // environment name likewise at +100/+104. BuildTrackScenePath only
+    // READS these fields (never frees them), so we just repoint begin/end
+    // at our own static buffers instead of freeing/reallocating the
+    // originals - avoids guessing an unconfirmed capacity-field offset.
+    // The original buffers are deliberately leaked (two small allocations
+    // per race load - negligible).
+    void* raceDef = *(void**)((uint8_t*)a1 + 32);
+    if (raceDef) {
+        size_t trackLen = strlen(kOverrideTrackName);
+        *(const char**)((uint8_t*)raceDef + 72) = kOverrideTrackName;
+        *(const char**)((uint8_t*)raceDef + 76) = kOverrideTrackName + trackLen;
 
-    // Не виртуальный метод (не будет переопределяться)
+        size_t envLen = strlen(kOverrideEnvName);
-    void sleep() const {
+        *(const char**)((uint8_t*)raceDef + 100) = kOverrideEnvName;
-        cout << name << " is sleeping" << endl;
+        *(const char**)((uint8_t*)raceDef + 104) = kOverrideEnvName + envLen;
-    }
 
-    string getName() const { return name; }
+        Log("BuildTrackScenePath hook fired: track -> %s, env -> %s", kOverrideTrackName, kOverrideEnvName);
-    int getAge() const { return age; }
-};
-
-// Производный класс - Млекопитающее
-class Mammal : public Animal {
-protected:
-    bool hasFur;
-
-public:
-    // Конструктор
-    Mammal(const string& name, int age, bool hasFur)
-            : Animal(name, age), hasFur(hasFur) {
-        cout << "Mammal constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Mammal() override {
-        cout << "Mammal destructor: " << name << endl;
-    }
-
-    // Переопределение метода
-    void makeSound() const override {
-        cout << name << " makes a mammal sound" << endl;
-    }
-
-    // Новый метод
-    void feedMilk() const {
-        cout << name << " is feeding milk" << endl;
-    }
-};
-
-// Производный класс - Птица
-class Bird : public Animal {
-protected:
-    double wingspan;
-
-public:
-    // Конструктор
-    Bird(const string& name, int age, double wingspan)
-            : Animal(name, age), wingspan(wingspan) {
-        cout << "Bird constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Bird() override {
-        cout << "Bird destructor: " << name << endl;
-    }
-
-    // Переопределение метода
-    void makeSound() const override {
-        cout << name << " chirps" << endl;
-    }
-
-    // Новый метод
-    void fly() const {
-        cout << name << " is flying with wingspan " << wingspan << "m" << endl;
-    }
-};
-
-// Производный класс от Млекопитающего - Собака
-class Dog : public Mammal {
-private:
-    string breed;
-
-public:
-    // Конструктор
-    Dog(const string& name, int age, bool hasFur, const string& breed)
-            : Mammal(name, age, hasFur), breed(breed) {
-        cout << "Dog constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Dog() override {
-        cout << "Dog destructor: " << name << endl;
-    }
-
-    // Переопределение метода
-    void makeSound() const override {
-        cout << name << " barks: Woof! Woof!" << endl;
-    }
-
-    // Новый метод
-    void fetch() const {
-        cout << name << " is fetching the ball" << endl;
-    }
-};
-
-// Производный класс от Млекопитающего - Кошка
-class Cat : public Mammal {
-private:
-    int lives;
-
-public:
-    // Конструктор
-    Cat(const string& name, int age, bool hasFur, int lives = 9)
-            : Mammal(name, age, hasFur), lives(lives) {
-        cout << "Cat constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Cat() override {
-        cout << "Cat destructor: " << name << endl;
-    }
-
-    // Переопределение метода
-    void makeSound() const override {
-        cout << name << " meows: Meow! Meow!" << endl;
-    }
-
-    // Новый метод
-    void purr() const {
-        cout << name << " is purring" << endl;
-    }
-};
-
-// Производный класс от Птицы - Орел
-class Eagle : public Bird {
-private:
-    double visionRange;
-
-public:
-    // Конструктор
-    Eagle(const string& name, int age, double wingspan, double visionRange)
-            : Bird(name, age, wingspan), visionRange(visionRange) {
-        cout << "Eagle constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Eagle() override {
-        cout << "Eagle destructor: " << name << endl;
-    }
-
-    // Метод НЕ переопределяется (используется версия из Bird)
-    // void makeSound() const override {...}
-
-    // Новый метод
-    void hunt() const {
-        cout << name << " is hunting with vision range " << visionRange << "km" << endl;
-    }
-};
-
-// Производный класс от Птицы - Попугай
-class Parrot : public Bird {
-private:
-    bool canTalk;
-
-public:
-    // Конструктор
-    Parrot(const string& name, int age, double wingspan, bool canTalk)
-            : Bird(name, age, wingspan), canTalk(canTalk) {
-        cout << "Parrot constructor: " << name << endl;
-    }
-
-    // Деструктор
-    ~Parrot() override {
-        cout << "Parrot destructor: " << name << endl;
-    }
-
-    // Переопределение метода
-    void makeSound() const override {
-        if (canTalk) {
-            cout << name << " says: Hello! Polly wants a cracker!" << endl;
     } else {
-            cout << name << " squawks" << endl;
+        Log("BuildTrackScenePath hook fired but raceDef (a1[8]) is NULL, skipping override");
     }
+    return orig_BuildTrackScenePath(a1);
 }
 
-    // Новый метод
+static bool InstallBuildTrackScenePathHook() {
-    void repeat(const string& phrase) const {
+    uintptr_t target = (uintptr_t)libapp_base + BUILDTRACKSCENEPATH_OFFSET;
-        if (canTalk) {
+    uint32_t* target32 = (uint32_t*)target;
-            cout << name << " repeats: " << phrase << endl;
-        }
-    }
-};
 
-// Пример использования
+    void* tramp = mmap(nullptr, (size_t)getpagesize(), PROT_READ | PROT_WRITE | PROT_EXEC,
-int main() {
+                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-    cout << "=== Creating objects ===" << endl;
+    if (tramp == MAP_FAILED) {
-
+        Log("BuildTrackScenePath hook: mmap trampoline failed");
-    Dog dog("Rex", 3, true, "German Shepherd");
+        return false;
-    Cat cat("Whiskers", 2, true);
-    Eagle eagle("Thor", 5, 2.1, 3.5);
-    Parrot parrot("Polly", 1, 0.3, true);
-
-    cout << "\n=== Testing methods ===" << endl;
-
-    dog.makeSound();    // Переопределен в Dog
-    dog.fetch();        // Уникальный метод Dog
-
-    cat.makeSound();    // Переопределен в Cat
-    cat.purr();         // Уникальный метод Cat
-
-    eagle.makeSound();  // НЕ переопределен - использует версию Bird
-    eagle.hunt();       // Уникальный метод Eagle
-
-    parrot.makeSound(); // Переопределен в Parrot
-    parrot.repeat("I love C++"); // Уникальный метод Parrot
-
-    cout << "\n=== Testing polymorphism ===" << endl;
-    Animal* animals[] = {&dog, &cat, &eagle, &parrot};
-
-    for (Animal* animal : animals) {
-        animal->makeSound(); // Полиморфный вызов
-        animal->sleep();     // Не виртуальный метод - всегда Animal::sleep()
     }
 
-    cout << "\n=== Objects going out of scope ===" << endl;
+    uint32_t* tramp32 = (uint32_t*)tramp;
-    // Деструкторы будут вызваны автоматически
+    // Relocate the 2 displaced original ARM instructions verbatim (both
-    return 0;
+    // confirmed position-independent: plain PUSH and ADD, no PC-relative
+    // addressing), then jump back into the function body past them.
+    tramp32[0] = target32[0];
+    tramp32[1] = target32[1];
+    tramp32[2] = 0xE51FF004; // LDR PC, [PC, #-4]
+    tramp32[3] = (uint32_t)(target + 8);
+    orig_BuildTrackScenePath = (BuildTrackScenePathFn)tramp;
+
+    uintptr_t page = target & ~((uintptr_t)getpagesize() - 1);
+    if (mprotect((void*)page, (size_t)getpagesize(), PROT_READ | PROT_WRITE | PROT_EXEC) != 0) {
+        Log("BuildTrackScenePath hook: mprotect target failed: %s", strerror(errno));
+        return false;
     }
 
+    target32[0] = 0xE51FF004; // LDR PC, [PC, #-4]
+    // &Hook_BuildTrackScenePath has bit0 set (Thumb-compiled mpcore code),
+    // triggering the ARM->Thumb interworking switch on load into PC.
+    target32[1] = (uint32_t)(uintptr_t)&Hook_BuildTrackScenePath;
+
+    __builtin___clear_cache((char*)target, (char*)(target + 8));
+    __builtin___clear_cache((char*)tramp, (char*)tramp + 16);
+
+    Log("Installed RaceLoaderTask_BuildTrackScenePath hook at %p, trampoline=%p", (void*)target, tramp);
+    return true;
+}
+
+// Flip to false to run the game completely unmodified (e.g. to capture a
+// baseline/"before" comparison) - true installs the track-substitution hook.
+// Just edit this and rebuild, no need to touch anything else.
+static constexpr bool kEnableTrackSubstitutionHook = true;
+
 JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved) {
 
-    get_libapp_base();
+    if (get_libapp_base()) {
-
+        if (kEnableTrackSubstitutionHook) {
+            InstallBuildTrackScenePathHook();
+        }
+    }
 
     return JNI_VERSION_1_6;
 }