memory_mapped_file.hpp

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#pragma once
 
#include <cstring>  // For memcpy, memset
#include <filesystem>  // For file size
 
#include <cpp-toolbox/cpp-toolbox_export.hpp>
#include <cpp-toolbox/macro.hpp>  // For platform detection CPP_TOOLBOX_PLATFORM_*
 
// Platform-specific includes for memory mapping / 内存映射的平台特定包含文件
#ifdef CPP_TOOLBOX_PLATFORM_WINDOWS
// Define NOMINMAX before including windows.h to prevent min/max macro
// definitions
#  define NOMINMAX
#  define WIN32_LEAN_AND_MEAN
#  include <windows.h>
#else  // Assuming POSIX-like systems (Linux, macOS) / 假设为类 POSIX
       // 系统（Linux, macOS）
#  include <fcntl.h>  // For open() / 用于 open() 函数
#  include <sys/mman.h>  // For mmap(), munmap() / 用于 mmap(), munmap() 函数
#  include <sys/stat.h>  // For fstat() / 用于 fstat() 函数
#  include <unistd.h>  // For close() / 用于 close() 函数
#endif
 
namespace toolbox::file
{
 
class CPP_TOOLBOX_EXPORT memory_mapped_file_t
{
  void* m_mapped_ptr = nullptr;
 
  size_t m_mapped_size = 0;
 
#ifdef CPP_TOOLBOX_PLATFORM_WINDOWS
  HANDLE m_file_handle = INVALID_HANDLE_VALUE;
 
  HANDLE m_mapping_handle = NULL;
#else
  int m_fd = -1;
#endif
 
public:
  memory_mapped_file_t() = default;
 
  ~memory_mapped_file_t();
 
  // Disable copy / 禁用拷贝
  memory_mapped_file_t(const memory_mapped_file_t&) = delete;
 
  memory_mapped_file_t& operator=(const memory_mapped_file_t&) = delete;
 
  // Disable move constructor and assignment / 禁用移动构造和赋值
  memory_mapped_file_t(memory_mapped_file_t&&) = delete;
 
  memory_mapped_file_t& operator=(memory_mapped_file_t&&) = delete;
 
  bool open(const std::filesystem::path& path);
 
  void close();
 
  [[nodiscard]] const unsigned char* data() const
  {
    return static_cast<const unsigned char*>(m_mapped_ptr);
  }
 
  [[nodiscard]] size_t size() const { return m_mapped_size; }
 
  [[nodiscard]] bool is_open() const { return m_mapped_ptr != nullptr; }
};
 
}  // namespace toolbox::file