boost/asio/impl/read_at.hpp
// // impl/read_at.hpp // ~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2024 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 BOOST_ASIO_IMPL_READ_AT_HPP #define BOOST_ASIO_IMPL_READ_AT_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <algorithm> #include <boost/asio/associator.hpp> #include <boost/asio/buffer.hpp> #include <boost/asio/detail/array_fwd.hpp> #include <boost/asio/detail/base_from_cancellation_state.hpp> #include <boost/asio/detail/base_from_completion_cond.hpp> #include <boost/asio/detail/bind_handler.hpp> #include <boost/asio/detail/consuming_buffers.hpp> #include <boost/asio/detail/dependent_type.hpp> #include <boost/asio/detail/handler_cont_helpers.hpp> #include <boost/asio/detail/handler_tracking.hpp> #include <boost/asio/detail/handler_type_requirements.hpp> #include <boost/asio/detail/non_const_lvalue.hpp> #include <boost/asio/detail/throw_error.hpp> #include <boost/asio/error.hpp> #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { namespace detail { template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence, typename MutableBufferIterator, typename CompletionCondition> std::size_t read_at_buffer_sequence(SyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers, const MutableBufferIterator&, CompletionCondition completion_condition, boost::system::error_code& ec) { ec = boost::system::error_code(); boost::asio::detail::consuming_buffers<mutable_buffer, MutableBufferSequence, MutableBufferIterator> tmp(buffers); while (!tmp.empty()) { if (std::size_t max_size = detail::adapt_completion_condition_result( completion_condition(ec, tmp.total_consumed()))) { tmp.consume(d.read_some_at(offset + tmp.total_consumed(), tmp.prepare(max_size), ec)); } else break; } return tmp.total_consumed(); } } // namespace detail template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence, typename CompletionCondition> std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers, CompletionCondition completion_condition, boost::system::error_code& ec, constraint_t< is_completion_condition<CompletionCondition>::value >) { return detail::read_at_buffer_sequence(d, offset, buffers, boost::asio::buffer_sequence_begin(buffers), static_cast<CompletionCondition&&>(completion_condition), ec); } template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers) { boost::system::error_code ec; std::size_t bytes_transferred = read_at( d, offset, buffers, transfer_all(), ec); boost::asio::detail::throw_error(ec, "read_at"); return bytes_transferred; } template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers, boost::system::error_code& ec) { return read_at(d, offset, buffers, transfer_all(), ec); } template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence, typename CompletionCondition> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers, CompletionCondition completion_condition, constraint_t< is_completion_condition<CompletionCondition>::value >) { boost::system::error_code ec; std::size_t bytes_transferred = read_at(d, offset, buffers, static_cast<CompletionCondition&&>(completion_condition), ec); boost::asio::detail::throw_error(ec, "read_at"); return bytes_transferred; } #if !defined(BOOST_ASIO_NO_EXTENSIONS) #if !defined(BOOST_ASIO_NO_IOSTREAM) template <typename SyncRandomAccessReadDevice, typename Allocator, typename CompletionCondition> std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, boost::asio::basic_streambuf<Allocator>& b, CompletionCondition completion_condition, boost::system::error_code& ec, constraint_t< is_completion_condition<CompletionCondition>::value >) { ec = boost::system::error_code(); std::size_t total_transferred = 0; std::size_t max_size = detail::adapt_completion_condition_result( completion_condition(ec, total_transferred)); std::size_t bytes_available = read_size_helper(b, max_size); while (bytes_available > 0) { std::size_t bytes_transferred = d.read_some_at( offset + total_transferred, b.prepare(bytes_available), ec); b.commit(bytes_transferred); total_transferred += bytes_transferred; max_size = detail::adapt_completion_condition_result( completion_condition(ec, total_transferred)); bytes_available = read_size_helper(b, max_size); } return total_transferred; } template <typename SyncRandomAccessReadDevice, typename Allocator> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, boost::asio::basic_streambuf<Allocator>& b) { boost::system::error_code ec; std::size_t bytes_transferred = read_at( d, offset, b, transfer_all(), ec); boost::asio::detail::throw_error(ec, "read_at"); return bytes_transferred; } template <typename SyncRandomAccessReadDevice, typename Allocator> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, boost::asio::basic_streambuf<Allocator>& b, boost::system::error_code& ec) { return read_at(d, offset, b, transfer_all(), ec); } template <typename SyncRandomAccessReadDevice, typename Allocator, typename CompletionCondition> inline std::size_t read_at(SyncRandomAccessReadDevice& d, uint64_t offset, boost::asio::basic_streambuf<Allocator>& b, CompletionCondition completion_condition, constraint_t< is_completion_condition<CompletionCondition>::value >) { boost::system::error_code ec; std::size_t bytes_transferred = read_at(d, offset, b, static_cast<CompletionCondition&&>(completion_condition), ec); boost::asio::detail::throw_error(ec, "read_at"); return bytes_transferred; } #endif // !defined(BOOST_ASIO_NO_IOSTREAM) #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) namespace detail { template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence, typename MutableBufferIterator, typename CompletionCondition, typename ReadHandler> class read_at_op : public base_from_cancellation_state<ReadHandler>, base_from_completion_cond<CompletionCondition> { public: read_at_op(AsyncRandomAccessReadDevice& device, uint64_t offset, const MutableBufferSequence& buffers, CompletionCondition& completion_condition, ReadHandler& handler) : base_from_cancellation_state<ReadHandler>( handler, enable_partial_cancellation()), base_from_completion_cond<CompletionCondition>(completion_condition), device_(device), offset_(offset), buffers_(buffers), start_(0), handler_(static_cast<ReadHandler&&>(handler)) { } read_at_op(const read_at_op& other) : base_from_cancellation_state<ReadHandler>(other), base_from_completion_cond<CompletionCondition>(other), device_(other.device_), offset_(other.offset_), buffers_(other.buffers_), start_(other.start_), handler_(other.handler_) { } read_at_op(read_at_op&& other) : base_from_cancellation_state<ReadHandler>( static_cast<base_from_cancellation_state<ReadHandler>&&>(other)), base_from_completion_cond<CompletionCondition>( static_cast<base_from_completion_cond<CompletionCondition>&&>(other)), device_(other.device_), offset_(other.offset_), buffers_(static_cast<buffers_type&&>(other.buffers_)), start_(other.start_), handler_(static_cast<ReadHandler&&>(other.handler_)) { } void operator()(boost::system::error_code ec, std::size_t bytes_transferred, int start = 0) { std::size_t max_size; switch (start_ = start) { case 1: max_size = this->check_for_completion(ec, buffers_.total_consumed()); for (;;) { { BOOST_ASIO_HANDLER_LOCATION((__FILE__, __LINE__, "async_read_at")); device_.async_read_some_at( offset_ + buffers_.total_consumed(), buffers_.prepare(max_size), static_cast<read_at_op&&>(*this)); } return; default: buffers_.consume(bytes_transferred); if ((!ec && bytes_transferred == 0) || buffers_.empty()) break; max_size = this->check_for_completion(ec, buffers_.total_consumed()); if (max_size == 0) break; if (this->cancelled() != cancellation_type::none) { ec = boost::asio::error::operation_aborted; break; } } static_cast<ReadHandler&&>(handler_)( static_cast<const boost::system::error_code&>(ec), static_cast<const std::size_t&>(buffers_.total_consumed())); } } //private: typedef boost::asio::detail::consuming_buffers<mutable_buffer, MutableBufferSequence, MutableBufferIterator> buffers_type; AsyncRandomAccessReadDevice& device_; uint64_t offset_; buffers_type buffers_; int start_; ReadHandler handler_; }; template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence, typename MutableBufferIterator, typename CompletionCondition, typename ReadHandler> inline bool asio_handler_is_continuation( read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence, MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler) { return this_handler->start_ == 0 ? true : boost_asio_handler_cont_helpers::is_continuation( this_handler->handler_); } template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence, typename MutableBufferIterator, typename CompletionCondition, typename ReadHandler> inline void start_read_at_op(AsyncRandomAccessReadDevice& d, uint64_t offset, const MutableBufferSequence& buffers, const MutableBufferIterator&, CompletionCondition& completion_condition, ReadHandler& handler) { detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence, MutableBufferIterator, CompletionCondition, ReadHandler>( d, offset, buffers, completion_condition, handler)( boost::system::error_code(), 0, 1); } template <typename AsyncRandomAccessReadDevice> class initiate_async_read_at { public: typedef typename AsyncRandomAccessReadDevice::executor_type executor_type; explicit initiate_async_read_at(AsyncRandomAccessReadDevice& device) : device_(device) { } executor_type get_executor() const noexcept { return device_.get_executor(); } template <typename ReadHandler, typename MutableBufferSequence, typename CompletionCondition> void operator()(ReadHandler&& handler, uint64_t offset, const MutableBufferSequence& buffers, CompletionCondition&& completion_cond) const { // If you get an error on the following line it means that your handler // does not meet the documented type requirements for a ReadHandler. BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check; non_const_lvalue<ReadHandler> handler2(handler); non_const_lvalue<CompletionCondition> completion_cond2(completion_cond); start_read_at_op(device_, offset, buffers, boost::asio::buffer_sequence_begin(buffers), completion_cond2.value, handler2.value); } private: AsyncRandomAccessReadDevice& device_; }; } // namespace detail #if !defined(GENERATING_DOCUMENTATION) template <template <typename, typename> class Associator, typename AsyncRandomAccessReadDevice, typename MutableBufferSequence, typename MutableBufferIterator, typename CompletionCondition, typename ReadHandler, typename DefaultCandidate> struct associator<Associator, detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence, MutableBufferIterator, CompletionCondition, ReadHandler>, DefaultCandidate> : Associator<ReadHandler, DefaultCandidate> { static typename Associator<ReadHandler, DefaultCandidate>::type get( const detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence, MutableBufferIterator, CompletionCondition, ReadHandler>& h) noexcept { return Associator<ReadHandler, DefaultCandidate>::get(h.handler_); } static auto get( const detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence, MutableBufferIterator, CompletionCondition, ReadHandler>& h, const DefaultCandidate& c) noexcept -> decltype(Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c)) { return Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c); } }; #endif // !defined(GENERATING_DOCUMENTATION) #if !defined(BOOST_ASIO_NO_EXTENSIONS) #if !defined(BOOST_ASIO_NO_IOSTREAM) namespace detail { template <typename AsyncRandomAccessReadDevice, typename Allocator, typename CompletionCondition, typename ReadHandler> class read_at_streambuf_op : public base_from_cancellation_state<ReadHandler>, base_from_completion_cond<CompletionCondition> { public: read_at_streambuf_op(AsyncRandomAccessReadDevice& device, uint64_t offset, basic_streambuf<Allocator>& streambuf, CompletionCondition& completion_condition, ReadHandler& handler) : base_from_cancellation_state<ReadHandler>( handler, enable_partial_cancellation()), base_from_completion_cond<CompletionCondition>(completion_condition), device_(device), offset_(offset), streambuf_(streambuf), start_(0), total_transferred_(0), handler_(static_cast<ReadHandler&&>(handler)) { } read_at_streambuf_op(const read_at_streambuf_op& other) : base_from_cancellation_state<ReadHandler>(other), base_from_completion_cond<CompletionCondition>(other), device_(other.device_), offset_(other.offset_), streambuf_(other.streambuf_), start_(other.start_), total_transferred_(other.total_transferred_), handler_(other.handler_) { } read_at_streambuf_op(read_at_streambuf_op&& other) : base_from_cancellation_state<ReadHandler>( static_cast<base_from_cancellation_state<ReadHandler>&&>(other)), base_from_completion_cond<CompletionCondition>( static_cast<base_from_completion_cond<CompletionCondition>&&>(other)), device_(other.device_), offset_(other.offset_), streambuf_(other.streambuf_), start_(other.start_), total_transferred_(other.total_transferred_), handler_(static_cast<ReadHandler&&>(other.handler_)) { } void operator()(boost::system::error_code ec, std::size_t bytes_transferred, int start = 0) { std::size_t max_size, bytes_available; switch (start_ = start) { case 1: max_size = this->check_for_completion(ec, total_transferred_); bytes_available = read_size_helper(streambuf_, max_size); for (;;) { { BOOST_ASIO_HANDLER_LOCATION((__FILE__, __LINE__, "async_read_at")); device_.async_read_some_at(offset_ + total_transferred_, streambuf_.prepare(bytes_available), static_cast<read_at_streambuf_op&&>(*this)); } return; default: total_transferred_ += bytes_transferred; streambuf_.commit(bytes_transferred); max_size = this->check_for_completion(ec, total_transferred_); bytes_available = read_size_helper(streambuf_, max_size); if ((!ec && bytes_transferred == 0) || bytes_available == 0) break; if (this->cancelled() != cancellation_type::none) { ec = boost::asio::error::operation_aborted; break; } } static_cast<ReadHandler&&>(handler_)( static_cast<const boost::system::error_code&>(ec), static_cast<const std::size_t&>(total_transferred_)); } } //private: AsyncRandomAccessReadDevice& device_; uint64_t offset_; boost::asio::basic_streambuf<Allocator>& streambuf_; int start_; std::size_t total_transferred_; ReadHandler handler_; }; template <typename AsyncRandomAccessReadDevice, typename Allocator, typename CompletionCondition, typename ReadHandler> inline bool asio_handler_is_continuation( read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator, CompletionCondition, ReadHandler>* this_handler) { return this_handler->start_ == 0 ? true : boost_asio_handler_cont_helpers::is_continuation( this_handler->handler_); } template <typename AsyncRandomAccessReadDevice> class initiate_async_read_at_streambuf { public: typedef typename AsyncRandomAccessReadDevice::executor_type executor_type; explicit initiate_async_read_at_streambuf( AsyncRandomAccessReadDevice& device) : device_(device) { } executor_type get_executor() const noexcept { return device_.get_executor(); } template <typename ReadHandler, typename Allocator, typename CompletionCondition> void operator()(ReadHandler&& handler, uint64_t offset, basic_streambuf<Allocator>* b, CompletionCondition&& completion_cond) const { // If you get an error on the following line it means that your handler // does not meet the documented type requirements for a ReadHandler. BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check; non_const_lvalue<ReadHandler> handler2(handler); non_const_lvalue<CompletionCondition> completion_cond2(completion_cond); read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator, CompletionCondition, decay_t<ReadHandler>>( device_, offset, *b, completion_cond2.value, handler2.value)( boost::system::error_code(), 0, 1); } private: AsyncRandomAccessReadDevice& device_; }; } // namespace detail #if !defined(GENERATING_DOCUMENTATION) template <template <typename, typename> class Associator, typename AsyncRandomAccessReadDevice, typename Executor, typename CompletionCondition, typename ReadHandler, typename DefaultCandidate> struct associator<Associator, detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Executor, CompletionCondition, ReadHandler>, DefaultCandidate> : Associator<ReadHandler, DefaultCandidate> { static typename Associator<ReadHandler, DefaultCandidate>::type get( const detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Executor, CompletionCondition, ReadHandler>& h) noexcept { return Associator<ReadHandler, DefaultCandidate>::get(h.handler_); } static auto get( const detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Executor, CompletionCondition, ReadHandler>& h, const DefaultCandidate& c) noexcept -> decltype(Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c)) { return Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c); } }; #endif // !defined(GENERATING_DOCUMENTATION) #endif // !defined(BOOST_ASIO_NO_IOSTREAM) #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_IMPL_READ_AT_HPP