Initial Commit

include/asio/detail/win_fd_set_adapter.hpp

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+//
+// detail/win_fd_set_adapter.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_DETAIL_WIN_FD_SET_ADAPTER_HPP
+#define ASIO_DETAIL_WIN_FD_SET_ADAPTER_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+
+#if defined(ASIO_WINDOWS) || defined(__CYGWIN__)
+
+#include "asio/detail/noncopyable.hpp"
+#include "asio/detail/reactor_op_queue.hpp"
+#include "asio/detail/socket_types.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+// Adapts the FD_SET type to meet the Descriptor_Set concept's requirements.
+class win_fd_set_adapter : noncopyable
+{
+public:
+  enum { default_fd_set_size = 1024 };
+
+  win_fd_set_adapter()
+    : capacity_(default_fd_set_size),
+      max_descriptor_(invalid_socket)
+  {
+    fd_set_ = static_cast<win_fd_set*>(::operator new(
+          sizeof(win_fd_set) - sizeof(SOCKET)
+          + sizeof(SOCKET) * (capacity_)));
+    fd_set_->fd_count = 0;
+  }
+
+  ~win_fd_set_adapter()
+  {
+    ::operator delete(fd_set_);
+  }
+
+  void reset()
+  {
+    fd_set_->fd_count = 0;
+    max_descriptor_ = invalid_socket;
+  }
+
+  bool set(socket_type descriptor)
+  {
+    for (u_int i = 0; i < fd_set_->fd_count; ++i)
+      if (fd_set_->fd_array[i] == descriptor)
+        return true;
+
+    reserve(fd_set_->fd_count + 1);
+    fd_set_->fd_array[fd_set_->fd_count++] = descriptor;
+    return true;
+  }
+
+  void set(reactor_op_queue<socket_type>& operations, op_queue<operation>&)
+  {
+    reactor_op_queue<socket_type>::iterator i = operations.begin();
+    while (i != operations.end())
+    {
+      reactor_op_queue<socket_type>::iterator op_iter = i++;
+      reserve(fd_set_->fd_count + 1);
+      fd_set_->fd_array[fd_set_->fd_count++] = op_iter->first;
+    }
+  }
+
+  bool is_set(socket_type descriptor) const
+  {
+    return !!__WSAFDIsSet(descriptor,
+        const_cast<fd_set*>(reinterpret_cast<const fd_set*>(fd_set_)));
+  }
+
+  operator fd_set*()
+  {
+    return reinterpret_cast<fd_set*>(fd_set_);
+  }
+
+  socket_type max_descriptor() const
+  {
+    return max_descriptor_;
+  }
+
+  void perform(reactor_op_queue<socket_type>& operations,
+      op_queue<operation>& ops) const
+  {
+    for (u_int i = 0; i < fd_set_->fd_count; ++i)
+      operations.perform_operations(fd_set_->fd_array[i], ops);
+  }
+
+private:
+  // This structure is defined to be compatible with the Windows API fd_set
+  // structure, but without being dependent on the value of FD_SETSIZE. We use
+  // the "struct hack" to allow the number of descriptors to be varied at
+  // runtime.
+  struct win_fd_set
+  {
+    u_int fd_count;
+    SOCKET fd_array[1];
+  };
+
+  // Increase the fd_set_ capacity to at least the specified number of elements.
+  void reserve(u_int n)
+  {
+    if (n <= capacity_)
+      return;
+
+    u_int new_capacity = capacity_ + capacity_ / 2;
+    if (new_capacity < n)
+      new_capacity = n;
+
+    win_fd_set* new_fd_set = static_cast<win_fd_set*>(::operator new(
+          sizeof(win_fd_set) - sizeof(SOCKET)
+          + sizeof(SOCKET) * (new_capacity)));
+
+    new_fd_set->fd_count = fd_set_->fd_count;
+    for (u_int i = 0; i < fd_set_->fd_count; ++i)
+      new_fd_set->fd_array[i] = fd_set_->fd_array[i];
+
+    ::operator delete(fd_set_);
+    fd_set_ = new_fd_set;
+    capacity_ = new_capacity;
+  }
+
+  win_fd_set* fd_set_;
+  u_int capacity_;
+  socket_type max_descriptor_;
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // defined(ASIO_WINDOWS) || defined(__CYGWIN__)
+
+#endif // ASIO_DETAIL_WIN_FD_SET_ADAPTER_HPP