编程与调试 C++ -- Windows 跨模块内存管理

void from_utf8(const std::string &string_str, std::wstring &string_wstr) {
    if (string_str.size() < 1) {
        return;
    }
    string_wstr.clear();
    int len = MultiByteToWideChar(CP_UTF8, 0, string_str.c_str(), -1, NULL, NULL);
    string_wstr.resize(len);
    wchar_t *str_ptr = new wchar_t[len];
    MultiByteToWideChar(CP_UTF8, 0, string_str.c_str(), -1, str_ptr, len);
    string_wstr = str_ptr;
    delete [] str_ptr;
    str_ptr = NULL;
}

void to_utf8(const std::wstring &string_wstr, std::string &string_str) {
    int len = WideCharToMultiByte(CP_UTF8, 0, string_wstr.c_str(), -1, NULL, 0, NULL, NULL);
    if (len == 0) {
        return;
    }
    ++len;
    char* str_ptr = new char[len];
    WideCharToMultiByte(CP_UTF8, 0, string_wstr.c_str(), -1, str_ptr, len, NULL, NULL);
    string_str = str_ptr;
    delete[] str_ptr;
    str_ptr = NULL;
}

int WINAPI GetWindowText(
  _In_   HWND hWnd,
  _Out_  LPTSTR lpString,
  _In_   int nMaxCount
);

int WINAPI GetWindowTextLength(
  _In_  HWND hWnd
);

// 假设你已经根据实际情况定义好了 _DLLEXPORT 用于导出函数。
_DLLEXPORT char* CreateString();
_DLLEXPORT void DeleteString(char* pString);

char* CreateString() {
    char* mystr = new char[100];
    strcpy(mystr, "这是一个测试。");
    return mystr;
}

void DeleteString(char* pString) {
    delete[] pString;
}

char* client = CreateString();
// 对 client 做你想做的事情。
DeleteString(client);

struct writer {
    void* data;
    void (*proc)(void*, const char*, size_t);
};

void write_string(writer w, const char* s, size_t len) {
    w.proc(w.data, s, len);
}

// ABI 这边
mystring s;
get_string(make_writer(s));

// make_writer 函数你自己提供
// 另一边
void get_string(struct writer w) {
    write_string(w, "hello", 6);
}

template<typename T>
interface ISampleBundle {
public:
    virtual T* dataPtr() = 0;
    virtual T* mallocData(int size) = 0;
    virtual void releaseData() = 0;
};

template<typename T>
class KSampleBundle : public ISampleBundle<T> {
public:
    KSampleBundle() {
        data = NULL;
    }
    virtual ~KSampleBundle() {
        if (data) { delete[] data; data = NULL; }
    }

    virtual void releaseData() {
        if (data) { delete[] data; data = NULL; }
    }
    virtual T* dataPtr() { return data; }
    virtual T* mallocData(int size) {
        if (data) { delete[] data; data = NULL; }
        // 当同一个工程使用多个库时，它们的含义可能不同，很容易弄混。
        // 因而很多人会多添加一个字节
        if (size <= 0) { size = 1; }
        data = new T[size + 1];
        memset(data, 0, (size + 1) * sizeof(T));
        return data;
    }

private:
    T* data;
};

[ uuid(311F23B8-165F-4324-8388-29C7E4ADB789) ]
interface ISampleEngine {
    virtual HRESULT __stdcall GetItemInfo(LPCWSTR fpath, ISampleBundle<TCHAR>& info) = 0;
}

void f() {
    std::shared_ptr<Info> tmpInfo;
    getInfo(tmpInfo);
}

// right version
// DLL
std::tr1::shared_ptr<Object> createObject() {
  return std::tr1::shared_ptr<Object>(new Object);
}

// EXE
std::tr1::shared_ptr<Object> p(createObject());
...

typedef struct _OBJECT_NAME_INFORMATION {
    _UNICODE_STRING_T<PWSTR> Name;
    WCHAR NameBuffer[1];
} OBJECT_NAME_INFORMATION, *POBJECT_NAME_INFORMATION;

typedef struct _FILE_STREAM_INFORMATION {
    ULONG NextEntryOffset;
    ULONG StreamNameLength;
    LARGE_INTEGER StreamSize;
    LARGE_INTEGER StreamAllocationSize;
    WCHAR StreamName[1];
} FILE_STREAM_INFORMATION;

typedef struct _FILENAME_ATTRIBUTE { // 文件名属性的值区域
    ULONGLONG DirectoryFileReferenceNumber; // 父目录的 FRN
    ULONGLONG CreationTime;
    ULONGLONG ChangeTime;
    ULONGLONG LastWriteTime; // 最后一次 MFT 更新时间
    ULONGLONG LastAccessTime;
    ULONGLONG AllocatedSize; // 未明
    ULONGLONG DataSize; // 偶尔与文件大小 GetFileSize 不同
    ULONG FileAttributes;
    ULONG AlignmentOrReserved;
    UCHAR NameLength;
    UCHAR NameType; // POSIX 0x0 WIN32 0x01 DOS 0x02 WIN32 & DOS 0x3
    WCHAR Name[1];
} FILENAME_ATTRIBUTE, *PFILENAME_ATTRIBUTE;