Question

我在初始化结构指针时遇到了一些问题。

struct Hook{
    DWORD64 Address;
    vector<BYTE> OriginalBytes;
    vector<BYTE> HookBytes;
    SIZE_T length;
    bool Initialized;
};
Hook *hFuncHook;
void InitializeHookInfo(Hook* hook, DWORD64 address, SIZE_T size){
    hook = new Hook;
    hook->Address = address;
    hook->OriginalBytes = GetAOB(address, size);
    hook->HookBytes.reserve(size);
    hook->length = size;
    hook->Initialized = false;
}
void EndHookInfoInit(Hook* hook, DWORD64 address, SIZE_T size){
    printf("Hook size: %i\n", sizeof(hook)); //returns 8
    hook->HookBytes = GetAOB(address, size);//Crash right there
    hook->Initialized = true;
}

void InitMyHooks(){
     InitializeHookInfo(hFuncHook, mBase + 0xA100FC, 6);
     HookFunction(...);
     EndHookInfoInit(hFuncHook, mBase + 0xA100FC, 6);
}

我无法弄清楚为什么会崩溃。 InitializeHookInfo部分不会导致任何问题，但EndHookInfoInit只会崩溃。

删除hook->HookBytes = GetAOB(...);也会导致崩溃

Answer 1

指针（T*）并不比一个变量更复杂，该变量的值将被视为T实例的内存中的地址，除非它包含nullptr的值。

将变量传递给C ++函数的默认行为是按值传递。

int f(int i) {  // i is local copy of source parameter
    i = 2;  // only modifies local copy
}

传递指针

时没有什么不同

int f(T* p) {
    p = new T;
}

您的代码按值获取指针：

void InitializeHookInfo(Hook* hook, DWORD64 address, SIZE_T size);

所以这行代码：

InitializeHookInfo(hFuncHook, mBase + 0xA100FC, 6);

将hFuncHook的值复制到函数的第一个参数槽中，InitializeHookInfo

void InitializeHookInfo(Hook* hook, DWORD64 address, SIZE_T size) {
    hook = new Hook;

这会分配一个新的Hook并将地址分配给一个本地变量。

你应该考虑：

一个。从函数中返回指针

Hook* InitializeHookInfo(DWORD64 address, SIZE_T size) {
    Hook* hook = new Hook;
    // ...
    return hook;
}

湾按地址指针

void InitializeHookInfo(Hook** hook, DWORD64 address, SIZE_T size) {
    *hook = new Hook;

℃。通过引用获取指针（稍微讨厌，因为它不透明）

void InitializeHookInfo(Hook*& hook, DWORD64 address, SIZE_T size) {
    hook = new Hook;  // affects source parameter

或者您可能更愿意考虑使用成员函数

struct Hook{
    DWORD64 Address { 0 };
    vector<BYTE> OriginalBytes;
    vector<BYTE> HookBytes;
    SIZE_T length { 0 };
    bool Initialized { false };

    Hook() {}

    Hook(DWORD64 address, SIZE_T size)
        : Address { address }
        , OriginalBytes { GetAOB(address, size) }
        , length(size)
    {
        HookBytes.reserve(size);
    }

    void EndInit(DWORD64 address, SIZE_T size)
    {
        std::cout << "Hook size: " << sizeof(*this) << "\n";
        HookBytes = GetAOB(address, size);  // didn't we already do this?
        Initialized = true;
    }
};

std::unique_ptr<Hook> hFuncHook;

void InitMyHooks()
{
    hFuncHook = std::make_unique<Hook>(mBase + 0xA100FC, 6);
    HookFunction(hFuncHook.get());
    hFuncHook->EndInit(mBase + 0xA100FC, 6);
}

最后，

printf("Hook size: %i\n", sizeof(hook)); //returns 8

这是因为hook是指针，您正在打印

printf("Hook size: %i\n", sizeof(Hook*)); //returns 8

你可能想要

printf("Hook size: %i\n", sizeof(*hook)); //returns 8

初始化结构指针

1 个答案: