c++怎么创建一个跨平台的共享内存区域_C++中跨进程共享内存的实现方式

#include <string>
#include <cstdint>
#ifdef _WIN32
    #include <windows.h>
#else
    #include <sys/mman.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <errno.h>
#endif

class SharedMemory {
public:
    SharedMemory(const std::string& name, size_t size) : m_name(name), m_size(size), m_handle(nullptr), m_ptr(nullptr) {
        open();
    }

    ~SharedMemory() {
        close();
    }

    void* data() const { return m_ptr; }
    bool is_valid() const { return m_ptr != nullptr; }

private:
    void open() {
#ifdef _WIN32
        // Windows: 使用 CreateFileMapping 和 MapViewOfFile
        HANDLE hMapFile = CreateFileMappingA(
            INVALID_HANDLE_VALUE,    // 使用分页文件，而非磁盘文件
            nullptr,
            PAGE_READWRITE,
            0,
            static_cast<DWORD>(m_size),
            m_name.c_str()
        );

        if (hMapFile == nullptr) return;

        m_handle = hMapFile;
        m_ptr = MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, m_size);
#else
        // POSIX: 使用 shm_open + mmap
        int fd = shm_open(m_name.c_str(), O_CREAT | O_RDWR, 0666);
        if (fd == -1) return;

        // 设置共享内存大小
        if (ftruncate(fd, m_size) == -1) {
            close(fd);
            return;
        }

        void* ptr = mmap(nullptr, m_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (ptr == MAP_FAILED) {
            close(fd);
            return;
        }

        m_handle = reinterpret_cast<void*>(static_cast<intptr_t>(fd));
        m_ptr = ptr;
#endif
    }

    void close() {
        if (m_ptr) {
#ifdef _WIN32
            UnmapViewOfFile(m_ptr);
            CloseHandle(static_cast<HANDLE>(m_handle));
#else
            munmap(m_ptr, m_size);
            int fd = static_cast<int>(reinterpret_cast<intptr_t>(m_handle));
            close(fd);
            shm_unlink(m_name.c_str()); // 可选：删除共享内存对象
#endif
            m_ptr = nullptr;
            m_handle = nullptr;
        }
    }

private:
    std::string m_name;
    size_t m_size;
    void* m_handle;
    void* m_ptr;
};

int main() {
    SharedMemory shm("my_shared_memory", 4096);

    if (!shm.is_valid()) {
        // 处理错误
        return 1;
    }

    // 写入数据
    char* data = static_cast<char*>(shm.data());
    std::strcpy(data, "Hello from process!");

    // 其他进程可读取该数据
    return 0;
}