Initial Commit

include/asio/ssl/detail/openssl_init.hpp

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+//
+// ssl/detail/openssl_init.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_SSL_DETAIL_OPENSSL_INIT_HPP
+#define ASIO_SSL_DETAIL_OPENSSL_INIT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <cstring>
+#include "asio/detail/memory.hpp"
+#include "asio/detail/noncopyable.hpp"
+#include "asio/ssl/detail/openssl_types.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace ssl {
+namespace detail {
+
+class openssl_init_base
+  : private noncopyable
+{
+protected:
+  // Class that performs the actual initialisation.
+  class do_init;
+
+  // Helper function to manage a do_init singleton. The static instance of the
+  // openssl_init object ensures that this function is always called before
+  // main, and therefore before any other threads can get started. The do_init
+  // instance must be static in this function to ensure that it gets
+  // initialised before any other global objects try to use it.
+  ASIO_DECL static asio::detail::shared_ptr<do_init> instance();
+
+#if !defined(SSL_OP_NO_COMPRESSION) \
+  && (OPENSSL_VERSION_NUMBER >= 0x00908000L)
+  // Get an empty stack of compression methods, to be used when disabling
+  // compression.
+  ASIO_DECL static STACK_OF(SSL_COMP)* get_null_compression_methods();
+#endif // !defined(SSL_OP_NO_COMPRESSION)
+       // && (OPENSSL_VERSION_NUMBER >= 0x00908000L)
+};
+
+template <bool Do_Init = true>
+class openssl_init : private openssl_init_base
+{
+public:
+  // Constructor.
+  openssl_init()
+    : ref_(instance())
+  {
+    using namespace std; // For memmove.
+
+    // Ensure openssl_init::instance_ is linked in.
+    openssl_init* tmp = &instance_;
+    memmove(&tmp, &tmp, sizeof(openssl_init*));
+  }
+
+  // Destructor.
+  ~openssl_init()
+  {
+  }
+
+#if !defined(SSL_OP_NO_COMPRESSION) \
+  && (OPENSSL_VERSION_NUMBER >= 0x00908000L)
+  using openssl_init_base::get_null_compression_methods;
+#endif // !defined(SSL_OP_NO_COMPRESSION)
+       // && (OPENSSL_VERSION_NUMBER >= 0x00908000L)
+
+private:
+  // Instance to force initialisation of openssl at global scope.
+  static openssl_init instance_;
+
+  // Reference to singleton do_init object to ensure that openssl does not get
+  // cleaned up until the last user has finished with it.
+  asio::detail::shared_ptr<do_init> ref_;
+};
+
+template <bool Do_Init>
+openssl_init<Do_Init> openssl_init<Do_Init>::instance_;
+
+} // namespace detail
+} // namespace ssl
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#if defined(ASIO_HEADER_ONLY)
+# include "asio/ssl/detail/impl/openssl_init.ipp"
+#endif // defined(ASIO_HEADER_ONLY)
+
+#endif // ASIO_SSL_DETAIL_OPENSSL_INIT_HPP