Initial Commit

include/asio/detail/buffer_resize_guard.hpp

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+//
+// detail/buffer_resize_guard.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_BUFFER_RESIZE_GUARD_HPP
+#define ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include "asio/detail/limits.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+// Helper class to manage buffer resizing in an exception safe way.
+template <typename Buffer>
+class buffer_resize_guard
+{
+public:
+  // Constructor.
+  buffer_resize_guard(Buffer& buffer)
+    : buffer_(buffer),
+      old_size_(buffer.size())
+  {
+  }
+
+  // Destructor rolls back the buffer resize unless commit was called.
+  ~buffer_resize_guard()
+  {
+    if (old_size_ != (std::numeric_limits<size_t>::max)())
+    {
+      buffer_.resize(old_size_);
+    }
+  }
+
+  // Commit the resize transaction.
+  void commit()
+  {
+    old_size_ = (std::numeric_limits<size_t>::max)();
+  }
+
+private:
+  // The buffer being managed.
+  Buffer& buffer_;
+
+  // The size of the buffer at the time the guard was constructed.
+  size_t old_size_;
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP