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 // Copyright 2014 Renato Tegon Forti, Antony Polukhin.
 // Copyright Antony Polukhin, 2015-2023.
 //
 // 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 BOOST_DLL_SHARED_LIBRARY_HPP
 #define BOOST_DLL_SHARED_LIBRARY_HPP
 
 /// \file boost/dll/shared_library.hpp
 /// \brief Contains the boost::dll::shared_library class, core class for all the
 /// DLL/DSO operations.
 
 #include <boost/dll/config.hpp>
 #include <boost/predef/os.h>
 #include <boost/core/enable_if.hpp>
 #include <boost/core/explicit_operator_bool.hpp>
 #include <boost/type_traits/is_member_pointer.hpp>
 #include <boost/dll/detail/system_error.hpp>
 #include <boost/dll/detail/aggressive_ptr_cast.hpp>
 
 #if BOOST_OS_WINDOWS
 #   include <boost/dll/detail/windows/shared_library_impl.hpp>
 #else
 #   include <boost/dll/detail/posix/shared_library_impl.hpp>
 #endif
 
 #ifdef BOOST_HAS_PRAGMA_ONCE
 # pragma once
 #endif
 
 namespace boost { namespace dll {
 
 /*!
 * \brief This class can be used to load a
 *        Dynamic link libraries (DLL's) or Shared Libraries, also know
 *        as dynamic shared objects (DSO's) and get their exported
 *        symbols (functions and variables).
 *
 * shared_library instances share reference count to an actual loaded DLL/DSO, so it
 * is safe and memory efficient to have multiple instances of shared_library referencing the same DLL/DSO
 * even if those instances were loaded using different paths (relative + absolute) referencing the same object.
 *
 * On Linux/POSIX link with library "dl". "-fvisibility=hidden" flag is also recommended for use on Linux/POSIX.
 */
 class shared_library
 /// @cond
     : private boost::dll::detail::shared_library_impl
 /// @endcond
 {
     typedef boost::dll::detail::shared_library_impl base_t;
     BOOST_COPYABLE_AND_MOVABLE(shared_library)
 
 public:
 #ifdef BOOST_DLL_DOXYGEN
     typedef platform_specific native_handle_t;
 #else
     typedef shared_library_impl::native_handle_t native_handle_t;
 #endif
 
     /*!
     * Creates in anstance that does not reference any DLL/DSO.
     *
     * \post this->is_loaded() returns false.
     * \throw Nothing.
     */
     shared_library() BOOST_NOEXCEPT {}
 
     /*!
     * Copy constructor that increments the reference count of an underlying shared library.
     * Same as calling constructor with `lib.location()` parameter.
     *
     * \param lib A library to copy.
     * \post lib == *this
     * \throw \forcedlinkfs{system_error}, std::bad_alloc in case of insufficient memory.
     */
     shared_library(const shared_library& lib)
         : base_t()
     {
         assign(lib);
     }
 
     /*!
     * Copy constructor that increments the reference count of an underlying shared library.
     * Same as calling constructor with `lib.location(), ec` parameters.
     *
     * \param lib A shared library to copy.
     * \param ec Variable that will be set to the result of the operation.
     * \post lib == *this
     * \throw std::bad_alloc in case of insufficient memory.
     */
     shared_library(const shared_library& lib, boost::dll::fs::error_code& ec)
         : base_t()
     {
         assign(lib, ec);
     }
 
     /*!
     * Move constructor. Does not invalidate existing symbols and functions loaded from lib.
     *
     * \param lib A shared library to move from.
     * \post lib.is_loaded() returns false, this->is_loaded() return true.
     * \throw Nothing.
     */
     shared_library(BOOST_RV_REF(shared_library) lib) BOOST_NOEXCEPT
         : base_t(boost::move(static_cast<base_t&>(lib)))
     {}
 
     /*!
     * Loads a library by specified path with a specified mode.
     *
     * \param lib_path Library file name. Can handle std::string, const char*, std::wstring,
     *           const wchar_t* or \forcedlinkfs{path}.
     * \param mode A mode that will be used on library load.
     * \throw \forcedlinkfs{system_error}, std::bad_alloc in case of insufficient memory.
     */
     explicit shared_library(const boost::dll::fs::path& lib_path, load_mode::type mode = load_mode::default_mode) {
         shared_library::load(lib_path, mode);
     }
 
     /*!
     * Loads a library by specified path with a specified mode.
     *
     * \param lib_path Library file name. Can handle std::string, const char*, std::wstring,
     *           const wchar_t* or \forcedlinkfs{path}.
     * \param mode A mode that will be used on library load.
     * \param ec Variable that will be set to the result of the operation.
     * \throw std::bad_alloc in case of insufficient memory.
     */
     shared_library(const boost::dll::fs::path& lib_path, boost::dll::fs::error_code& ec, load_mode::type mode = load_mode::default_mode) {
         shared_library::load(lib_path, mode, ec);
     }
 
     //! \overload shared_library(const boost::dll::fs::path& lib_path, boost::dll::fs::error_code& ec, load_mode::type mode = load_mode::default_mode)
     shared_library(const boost::dll::fs::path& lib_path, load_mode::type mode, boost::dll::fs::error_code& ec) {
         shared_library::load(lib_path, mode, ec);
     }
 
     /*!
     * Assignment operator. If this->is_loaded() then calls this->unload(). Does not invalidate existing symbols and functions loaded from lib.
     *
     * \param lib A shared library to assign from.
     * \post lib == *this
     * \throw \forcedlinkfs{system_error}, std::bad_alloc in case of insufficient memory.
     */
     shared_library& operator=(BOOST_COPY_ASSIGN_REF(shared_library) lib) {
         boost::dll::fs::error_code ec;
         assign(lib, ec);
         if (ec) {
             boost::dll::detail::report_error(ec, "boost::dll::shared_library::operator= failed");
         }
 
         return *this;
     }
 
     /*!
     * Move assignment operator. If this->is_loaded() then calls this->unload(). Does not invalidate existing symbols and functions loaded from lib.
     *
     * \param lib A library to move from.
     * \post lib.is_loaded() returns false.
     * \throw Nothing.
     */
     shared_library& operator=(BOOST_RV_REF(shared_library) lib) BOOST_NOEXCEPT {
         if (lib.native() != native()) {
             swap(lib);
         }
 
         return *this;
     }
 
     /*!
     * Destroys the object by calling `unload()`. If library was loaded multiple times
     * by different instances, the actual DLL/DSO won't be unloaded until
     * there is at least one instance that references the DLL/DSO.
     *
     * \throw Nothing.
     */
     ~shared_library() BOOST_NOEXCEPT {}
 
     /*!
     * Makes *this share the same shared object as lib. If *this is loaded, then unloads it.
     *
     * \post lib.location() == this->location(), lib == *this
     * \param lib A library to copy.
     * \param ec Variable that will be set to the result of the operation.
     * \throw std::bad_alloc in case of insufficient memory.
     */
     shared_library& assign(const shared_library& lib, boost::dll::fs::error_code& ec) {
         ec.clear();
 
         if (native() == lib.native()) {
             return *this;
         }
 
         if (!lib) {
             unload();
             return *this;
         }
 
         boost::dll::fs::path loc = lib.location(ec);
         if (ec) {
             return *this;
         }
 
         shared_library copy(loc, ec);
         if (ec) {
             return *this;
         }
 
         swap(copy);
         return *this;
     }
 
     /*!
     * Makes *this share the same shared object as lib. If *this is loaded, then unloads it.
     *
     * \param lib A library instance to assign from.
     * \post lib.location() == this->location()
     * \throw \forcedlinkfs{system_error}, std::bad_alloc in case of insufficient memory.
     */
     shared_library& assign(const shared_library& lib) {
         boost::dll::fs::error_code ec;
         assign(lib, ec);
         if (ec) {
             boost::dll::detail::report_error(ec, "boost::dll::shared_library::assign() failed");
         }
 
         return *this;
     }
 
     /*!
     * Loads a library by specified path with a specified mode.
     *
     * Note that if some library is already loaded in this instance, load will
     * call unload() and then load the new provided library.
     *
     * \param lib_path Library file name. Can handle std::string, const char*, std::wstring,
     *           const wchar_t* or \forcedlinkfs{path}.
     * \param mode A mode that will be used on library load.
     * \throw \forcedlinkfs{system_error}, std::bad_alloc in case of insufficient memory.
     *
     */
     void load(const boost::dll::fs::path& lib_path, load_mode::type mode = load_mode::default_mode) {
         boost::dll::fs::error_code ec;
 
         base_t::load(lib_path, mode, ec);
 
         if (ec) {
             boost::dll::detail::report_error(ec, "boost::dll::shared_library::load() failed");
         }
     }
 
     /*!
     * Loads a library by specified path with a specified mode.
     *
     * Note that if some library is already loaded in this instance, load will
     * call unload() and then load the new provided library.
     *
     * \param lib_path Library file name. Can handle std::string, const char*, std::wstring,
     *           const wchar_t* or \forcedlinkfs{path}.
     * \param ec Variable that will be set to the result of the operation.
     * \param mode A mode that will be used on library load.
     * \throw std::bad_alloc in case of insufficient memory.
     */
     void load(const boost::dll::fs::path& lib_path, boost::dll::fs::error_code& ec, load_mode::type mode = load_mode::default_mode) {
         ec.clear();
         base_t::load(lib_path, mode, ec);
     }
 
     //! \overload void load(const boost::dll::fs::path& lib_path, boost::dll::fs::error_code& ec, load_mode::type mode = load_mode::default_mode)
     void load(const boost::dll::fs::path& lib_path, load_mode::type mode, boost::dll::fs::error_code& ec) {
         ec.clear();
         base_t::load(lib_path, mode, ec);
     }
 
     /*!
     * Unloads a shared library.  If library was loaded multiple times
     * by different instances, the actual DLL/DSO won't be unloaded until
     * there is at least one instance that references the DLL/DSO.
     *
     * \post this->is_loaded() returns false.
     * \throw Nothing.
     */
     void unload() BOOST_NOEXCEPT {
         base_t::unload();
     }
 
     /*!
     * Check if an library is loaded.
     *
     * \return true if a library has been loaded.
     * \throw Nothing.
     */
     bool is_loaded() const BOOST_NOEXCEPT {
         return base_t::is_loaded();
     }
 
     /*!
     * Check if an library is not loaded.
     *
     * \return true if a library has not been loaded.
     * \throw Nothing.
     */
     bool operator!() const BOOST_NOEXCEPT {
         return !is_loaded();
     }
 
     /*!
     * Check if an library is loaded.
     *
     * \return true if a library has been loaded.
     * \throw Nothing.
     */
     BOOST_EXPLICIT_OPERATOR_BOOL()
 
     /*!
     * Search for a given symbol on loaded library. Works for all symbols, including alias names.
     *
     * \param symbol_name Null-terminated symbol name. Can handle std::string, char*, const char*.
     * \return `true` if the loaded library contains a symbol with a given name.
     * \throw Nothing.
     */
     bool has(const char* symbol_name) const BOOST_NOEXCEPT {
         boost::dll::fs::error_code ec;
         return is_loaded() && !!base_t::symbol_addr(symbol_name, ec) && !ec;
     }
 
     //! \overload bool has(const char* symbol_name) const
     bool has(const std::string& symbol_name) const BOOST_NOEXCEPT {
         return has(symbol_name.c_str());
     }
 
     /*!
     * Returns reference to the symbol (function or variable) with the given name from the loaded library.
     * This call will always succeed and throw nothing if call to `has(const char* )`
     * member function with the same symbol name returned `true`.
     *
     * \b Example:
     * \code
     * int& i0 = lib.get<int>("integer_name");
     * int& i1 = *lib.get<int*>("integer_alias_name");
     * \endcode
     *
     * \tparam T Type of the symbol that we are going to import. Must be explicitly specified.
     * \param symbol_name Null-terminated symbol name. Can handle std::string, char*, const char*.
     * \return Reference to the symbol.
     * \throw \forcedlinkfs{system_error} if symbol does not exist or if the DLL/DSO was not loaded.
     */
     template <typename T>
     inline typename boost::enable_if_c<boost::is_member_pointer<T>::value || boost::is_reference<T>::value, T>::type  get(const std::string& symbol_name) const {
         return get<T>(symbol_name.c_str());
     }
 
     //! \overload T& get(const std::string& symbol_name) const
     template <typename T>
     inline typename boost::disable_if_c<boost::is_member_pointer<T>::value || boost::is_reference<T>::value, T&>::type get(const std::string& symbol_name) const {
         return get<T>(symbol_name.c_str());
     }
 
     //! \overload T& get(const std::string& symbol_name) const
     template <typename T>
     inline typename boost::enable_if_c<boost::is_member_pointer<T>::value || boost::is_reference<T>::value, T>::type get(const char* symbol_name) const {
         return boost::dll::detail::aggressive_ptr_cast<T>(
             get_void(symbol_name)
         );
     }
 
     //! \overload T& get(const std::string& symbol_name) const
     template <typename T>
     inline typename boost::disable_if_c<boost::is_member_pointer<T>::value || boost::is_reference<T>::value, T&>::type get(const char* symbol_name) const {
         return *boost::dll::detail::aggressive_ptr_cast<T*>(
             get_void(symbol_name)
         );
     }
 
     /*!
     * Returns a symbol (function or variable) from a shared library by alias name of the symbol.
     *
     * \b Example:
     * \code
     * int& i = lib.get_alias<int>("integer_alias_name");
     * \endcode
     *
     * \tparam T Type of the symbol that we are going to import. Must be explicitly specified..
     * \param alias_name Null-terminated alias symbol name. Can handle std::string, char*, const char*.
     * \throw \forcedlinkfs{system_error} if symbol does not exist or if the DLL/DSO was not loaded.
     */
     template <typename T>
     inline T& get_alias(const char* alias_name) const {
         return *get<T*>(alias_name);
     }
 
     //! \overload T& get_alias(const char* alias_name) const
     template <typename T>
     inline T& get_alias(const std::string& alias_name) const {
         return *get<T*>(alias_name.c_str());
     }
 
 private:
     /// @cond
     // get_void is required to reduce binary size: it does not depend on a template
     // parameter and will be instantiated only once.
     void* get_void(const char* sb) const {
         boost::dll::fs::error_code ec;
 
         if (!is_loaded()) {
             ec = boost::dll::fs::make_error_code(
                 boost::dll::fs::errc::bad_file_descriptor
             );
 
             // report_error() calls dlsym, do not use it here!
             boost::throw_exception(
                 boost::dll::fs::system_error(
                     ec, "boost::dll::shared_library::get() failed: no library was loaded"
                 )
             );
         }
 
         void* const ret = base_t::symbol_addr(sb, ec);
         if (ec || !ret) {
             boost::dll::detail::report_error(ec, "boost::dll::shared_library::get() failed");
         }
 
         return ret;
     }
     /// @endcond
 
 public:
 
     /*!
     * Returns the native handler of the loaded library.
     *
     * \return Platform-specific handle.
     */
     native_handle_t native() const BOOST_NOEXCEPT {
         return base_t::native();
     }
 
    /*!
     * Returns full path and name of this shared object.
     *
     * \b Example:
     * \code
     * shared_library lib("test_lib.dll");
     * filesystem::path full_path = lib.location(); // C:\Windows\System32\test_lib.dll
     * \endcode
     *
     * \return Full path to the shared library.
     * \throw \forcedlinkfs{system_error}, std::bad_alloc.
     */
     boost::dll::fs::path location() const {
         boost::dll::fs::error_code ec;
         if (!is_loaded()) {
             ec = boost::dll::fs::make_error_code(
                 boost::dll::fs::errc::bad_file_descriptor
             );
 
             boost::throw_exception(
                 boost::dll::fs::system_error(
                     ec, "boost::dll::shared_library::location() failed (no library was loaded)"
                 )
             );
         }
 
         boost::dll::fs::path full_path = base_t::full_module_path(ec);
 
         if (ec) {
             boost::dll::detail::report_error(ec, "boost::dll::shared_library::location() failed");
         }
 
         return full_path;
     }
 
    /*!
     * Returns full path and name of shared module.
     *
     * \b Example:
     * \code
     * shared_library lib("test_lib.dll");
     * filesystem::path full_path = lib.location(); // C:\Windows\System32\test_lib.dll
     * \endcode
     *
     * \param ec Variable that will be set to the result of the operation.
     * \return Full path to the shared library.
     * \throw std::bad_alloc.
     */
     boost::dll::fs::path location(boost::dll::fs::error_code& ec) const {
         if (!is_loaded()) {
             ec = boost::dll::fs::make_error_code(
                 boost::dll::fs::errc::bad_file_descriptor
             );
 
             return boost::dll::fs::path();
         }
 
         ec.clear();
         return base_t::full_module_path(ec);
     }
 
     /*!
     * Returns suffix of shared module:
     * in a call to load() or the constructor/load.
     *
     * \return The suffix od shared module: ".dll" (Windows), ".so" (Unix/Linux/BSD), ".dylib" (MacOS/IOS)
     */
     static boost::dll::fs::path suffix() {
         return base_t::suffix();
     }
 
     /*!
     * Returns the decorated path to a shared module name, i.e. with needed prefix/suffix added.
     *
     * \b Recommendations: Use `load` with `load_mode::append_decorations` instead of constructing the decorated path via `decorate()` and loading by it.
     *
     * For instance, for a path like "path/to/boost" it returns :
     * - path/to/libboost.so on posix platforms
     * - path/to/libboost.dylib on OSX
     * - path/to/boost.dll on Windows
     *
     * Method handles both relative and absolute paths.
     *
     * - Windows note: `decorate()` does not prepend "lib" to the decorated path. Use `load` with `load_mode::append_decorations` for MinGW compatibility purpose.
     * - Posix note: if the initial module name is already prepended with lib, only the suffix() is appended to the path
     *
     * \param sl the module name and path to decorate - for instance : /usr/lib/boost
     *
     * \return The decorated unportable path that may not exists in the filesystem or could be wrong due to platform specifics.
     */
     static boost::dll::fs::path decorate(const boost::dll::fs::path& sl) {
         return base_t::decorate(sl);
     }
 
     /*!
     * Swaps two libraries. Does not invalidate existing symbols and functions loaded from libraries.
     *
     * \param rhs Library to swap with.
     * \throw Nothing.
     */
     void swap(shared_library& rhs) BOOST_NOEXCEPT {
         base_t::swap(rhs);
     }
 };
 
 
 
 /// Very fast equality check that compares the actual DLL/DSO objects. Throws nothing.
 inline bool operator==(const shared_library& lhs, const shared_library& rhs) BOOST_NOEXCEPT {
     return lhs.native() == rhs.native();
 }
 
 /// Very fast inequality check that compares the actual DLL/DSO objects. Throws nothing.
 inline bool operator!=(const shared_library& lhs, const shared_library& rhs) BOOST_NOEXCEPT {
     return lhs.native() != rhs.native();
 }
 
 /// Compare the actual DLL/DSO objects without any guarantee to be stable between runs. Throws nothing.
 inline bool operator<(const shared_library& lhs, const shared_library& rhs) BOOST_NOEXCEPT {
     return lhs.native() < rhs.native();
 }
 
 /// Swaps two shared libraries. Does not invalidate symbols and functions loaded from libraries. Throws nothing.
 inline void swap(shared_library& lhs, shared_library& rhs) BOOST_NOEXCEPT {
     lhs.swap(rhs);
 }
 
 }} // boost::dll
 
 #endif // BOOST_DLL_SHARED_LIBRARY_HPP

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