boost/asio/read.hpp
// // read.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_READ_HPP #define BOOST_ASIO_READ_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/config.hpp> #include <cstddef> #include <boost/asio/async_result.hpp> #include <boost/asio/buffer.hpp> #include <boost/asio/completion_condition.hpp> #include <boost/asio/error.hpp> #if !defined(BOOST_ASIO_NO_EXTENSIONS) # include <boost/asio/basic_streambuf_fwd.hpp> #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { namespace detail { template <typename> class initiate_async_read; #if !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) template <typename> class initiate_async_read_dynbuf_v1; #endif // !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) template <typename> class initiate_async_read_dynbuf_v2; } // namespace detail /** * @defgroup read boost::asio::read * * @brief The @c read function is a composed operation that reads a certain * amount of data from a stream before returning. */ /*@{*/ /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. * * @par Example * To read into a single data buffer use the @ref buffer function as follows: * @code boost::asio::read(s, boost::asio::buffer(data, size)); @endcode * See the @ref buffer documentation for information on reading into multiple * buffers in one go, and how to use it with arrays, boost::array or * std::vector. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all()); @endcode */ template <typename SyncReadStream, typename MutableBufferSequence> std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes transferred. * * @par Example * To read into a single data buffer use the @ref buffer function as follows: * @code boost::asio::read(s, boost::asio::buffer(data, size), ec); @endcode * See the @ref buffer documentation for information on reading into multiple * buffers in one go, and how to use it with arrays, boost::array or * std::vector. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all(), ec); @endcode */ template <typename SyncReadStream, typename MutableBufferSequence> std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, boost::system::error_code& ec, constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. * * @par Example * To read into a single data buffer use the @ref buffer function as follows: * @code boost::asio::read(s, boost::asio::buffer(data, size), * boost::asio::transfer_at_least(32)); @endcode * See the @ref buffer documentation for information on reading into multiple * buffers in one go, and how to use it with arrays, boost::array or * std::vector. */ template <typename SyncReadStream, typename MutableBufferSequence, typename CompletionCondition> std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, CompletionCondition completion_condition, constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes read. If an error occurs, returns the total * number of bytes successfully transferred prior to the error. */ template <typename SyncReadStream, typename MutableBufferSequence, typename CompletionCondition> std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, CompletionCondition completion_condition, boost::system::error_code& ec, constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0); #if !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all()); @endcode */ template <typename SyncReadStream, typename DynamicBuffer_v1> std::size_t read(SyncReadStream& s, DynamicBuffer_v1&& buffers, constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes transferred. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all(), ec); @endcode */ template <typename SyncReadStream, typename DynamicBuffer_v1> std::size_t read(SyncReadStream& s, DynamicBuffer_v1&& buffers, boost::system::error_code& ec, constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. */ template <typename SyncReadStream, typename DynamicBuffer_v1, typename CompletionCondition> std::size_t read(SyncReadStream& s, DynamicBuffer_v1&& buffers, CompletionCondition completion_condition, constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes read. If an error occurs, returns the total * number of bytes successfully transferred prior to the error. */ template <typename SyncReadStream, typename DynamicBuffer_v1, typename CompletionCondition> std::size_t read(SyncReadStream& s, DynamicBuffer_v1&& buffers, CompletionCondition completion_condition, boost::system::error_code& ec, constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0); #if !defined(BOOST_ASIO_NO_EXTENSIONS) #if !defined(BOOST_ASIO_NO_IOSTREAM) /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param b The basic_streambuf object into which the data will be read. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, b, * boost::asio::transfer_all()); @endcode */ template <typename SyncReadStream, typename Allocator> std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param b The basic_streambuf object into which the data will be read. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes transferred. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, b, * boost::asio::transfer_all(), ec); @endcode */ template <typename SyncReadStream, typename Allocator> std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, boost::system::error_code& ec); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param b The basic_streambuf object into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. */ template <typename SyncReadStream, typename Allocator, typename CompletionCondition> std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, CompletionCondition completion_condition); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param b The basic_streambuf object into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes read. If an error occurs, returns the total * number of bytes successfully transferred prior to the error. */ template <typename SyncReadStream, typename Allocator, typename CompletionCondition> std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, CompletionCondition completion_condition, boost::system::error_code& ec); #endif // !defined(BOOST_ASIO_NO_IOSTREAM) #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) #endif // !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all()); @endcode */ template <typename SyncReadStream, typename DynamicBuffer_v2> std::size_t read(SyncReadStream& s, DynamicBuffer_v2 buffers, constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes transferred. * * @note This overload is equivalent to calling: * @code boost::asio::read( * s, buffers, * boost::asio::transfer_all(), ec); @endcode */ template <typename SyncReadStream, typename DynamicBuffer_v2> std::size_t read(SyncReadStream& s, DynamicBuffer_v2 buffers, boost::system::error_code& ec, constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @returns The number of bytes transferred. * * @throws boost::system::system_error Thrown on failure. */ template <typename SyncReadStream, typename DynamicBuffer_v2, typename CompletionCondition> std::size_t read(SyncReadStream& s, DynamicBuffer_v2 buffers, CompletionCondition completion_condition, constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0); /// Attempt to read a certain amount of data from a stream before returning. /** * This function is used to read a certain number of bytes of data from a * stream. The call will block until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * read_some function. * * @param s The stream from which the data is to be read. The type must support * the SyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's read_some function. * * @param ec Set to indicate what error occurred, if any. * * @returns The number of bytes read. If an error occurs, returns the total * number of bytes successfully transferred prior to the error. */ template <typename SyncReadStream, typename DynamicBuffer_v2, typename CompletionCondition> std::size_t read(SyncReadStream& s, DynamicBuffer_v2 buffers, CompletionCondition completion_condition, boost::system::error_code& ec, constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0); /*@}*/ /** * @defgroup async_read boost::asio::async_read * * @brief The @c async_read function is a composed asynchronous operation that * reads a certain amount of data from a stream before completion. */ /*@{*/ /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. Although the buffers object may be copied as necessary, ownership of * the underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @par Example * To read into a single data buffer use the @ref buffer function as follows: * @code * boost::asio::async_read(s, boost::asio::buffer(data, size), handler); * @endcode * See the @ref buffer documentation for information on reading into multiple * buffers in one go, and how to use it with arrays, boost::array or * std::vector. * * @note This overload is equivalent to calling: * @code boost::asio::async_read( * s, buffers, * boost::asio::transfer_all(), * handler); @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename MutableBufferSequence, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, const MutableBufferSequence& buffers, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read<AsyncReadStream>>(), token, buffers, transfer_all())); /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The supplied buffers are full. That is, the bytes transferred is equal to * the sum of the buffer sizes. * * @li The completion_condition function object returns 0. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers One or more buffers into which the data will be read. The sum * of the buffer sizes indicates the maximum number of bytes to read from the * stream. Although the buffers object may be copied as necessary, ownership of * the underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest async_read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's async_read_some function. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @par Example * To read into a single data buffer use the @ref buffer function as follows: * @code boost::asio::async_read(s, * boost::asio::buffer(data, size), * boost::asio::transfer_at_least(32), * handler); @endcode * See the @ref buffer documentation for information on reading into multiple * buffers in one go, and how to use it with arrays, boost::array or * std::vector. * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename MutableBufferSequence, typename CompletionCondition, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, const MutableBufferSequence& buffers, CompletionCondition completion_condition, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_mutable_buffer_sequence<MutableBufferSequence>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read<AsyncReadStream>>(), token, buffers, static_cast<CompletionCondition&&>(completion_condition))); #if !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * Although the buffers object may be copied as necessary, ownership of the * underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @note This overload is equivalent to calling: * @code boost::asio::async_read( * s, buffers, * boost::asio::transfer_all(), * handler); @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename DynamicBuffer_v1, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, DynamicBuffer_v1&& buffers, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v1<AsyncReadStream>>(), token, static_cast<DynamicBuffer_v1&&>(buffers), transfer_all())); /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * Although the buffers object may be copied as necessary, ownership of the * underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest async_read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's async_read_some function. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename DynamicBuffer_v1, typename CompletionCondition, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, DynamicBuffer_v1&& buffers, CompletionCondition completion_condition, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_dynamic_buffer_v1<decay_t<DynamicBuffer_v1>>::value > = 0, constraint_t< !is_dynamic_buffer_v2<decay_t<DynamicBuffer_v1>>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v1<AsyncReadStream>>(), token, static_cast<DynamicBuffer_v1&&>(buffers), static_cast<CompletionCondition&&>(completion_condition))); #if !defined(BOOST_ASIO_NO_EXTENSIONS) #if !defined(BOOST_ASIO_NO_IOSTREAM) /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param b A basic_streambuf object into which the data will be read. Ownership * of the streambuf is retained by the caller, which must guarantee that it * remains valid until the completion handler is called. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @note This overload is equivalent to calling: * @code boost::asio::async_read( * s, b, * boost::asio::transfer_all(), * handler); @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename Allocator, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>()) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v1<AsyncReadStream>>(), token, basic_streambuf_ref<Allocator>(b), transfer_all())); /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The supplied buffer is full (that is, it has reached maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param b A basic_streambuf object into which the data will be read. Ownership * of the streambuf is retained by the caller, which must guarantee that it * remains valid until the completion handler is called. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest async_read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's async_read_some function. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename Allocator, typename CompletionCondition, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b, CompletionCondition completion_condition, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>()) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v1<AsyncReadStream>>(), token, basic_streambuf_ref<Allocator>(b), static_cast<CompletionCondition&&>(completion_condition))); #endif // !defined(BOOST_ASIO_NO_IOSTREAM) #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) #endif // !defined(BOOST_ASIO_NO_DYNAMIC_BUFFER_V1) /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li An error occurred. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * Although the buffers object may be copied as necessary, ownership of the * underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @note This overload is equivalent to calling: * @code boost::asio::async_read( * s, buffers, * boost::asio::transfer_all(), * handler); @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename DynamicBuffer_v2, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, DynamicBuffer_v2 buffers, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v2<AsyncReadStream>>(), token, static_cast<DynamicBuffer_v2&&>(buffers), transfer_all())); /// Start an asynchronous operation to read a certain amount of data from a /// stream. /** * This function is used to asynchronously read a certain number of bytes of * data from a stream. It is an initiating function for an @ref * asynchronous_operation, and always returns immediately. The asynchronous * operation will continue until one of the following conditions is true: * * @li The specified dynamic buffer sequence is full (that is, it has reached * maximum size). * * @li The completion_condition function object returns 0. * * This operation is implemented in terms of zero or more calls to the stream's * async_read_some function, and is known as a <em>composed operation</em>. The * program must ensure that the stream performs no other read operations (such * as async_read, the stream's async_read_some function, or any other composed * operations that perform reads) until this operation completes. * * @param s The stream from which the data is to be read. The type must support * the AsyncReadStream concept. * * @param buffers The dynamic buffer sequence into which the data will be read. * Although the buffers object may be copied as necessary, ownership of the * underlying memory blocks is retained by the caller, which must guarantee * that they remain valid until the completion handler is called. * * @param completion_condition The function object to be called to determine * whether the read operation is complete. The signature of the function object * must be: * @code std::size_t completion_condition( * // Result of latest async_read_some operation. * const boost::system::error_code& error, * * // Number of bytes transferred so far. * std::size_t bytes_transferred * ); @endcode * A return value of 0 indicates that the read operation is complete. A non-zero * return value indicates the maximum number of bytes to be read on the next * call to the stream's async_read_some function. * * @param token The @ref completion_token that will be used to produce a * completion handler, which will be called when the read completes. * Potential completion tokens include @ref use_future, @ref use_awaitable, * @ref yield_context, or a function object with the correct completion * signature. The function signature of the completion handler must be: * @code void handler( * // Result of operation. * const boost::system::error_code& error, * * // Number of bytes copied into the buffers. If an error * // occurred, this will be the number of bytes successfully * // transferred prior to the error. * std::size_t bytes_transferred * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the completion handler will not be invoked from within this function. * On immediate completion, invocation of the handler will be performed in a * manner equivalent to using boost::asio::post(). * * @par Completion Signature * @code void(boost::system::error_code, std::size_t) @endcode * * @par Per-Operation Cancellation * This asynchronous operation supports cancellation for the following * boost::asio::cancellation_type values: * * @li @c cancellation_type::terminal * * @li @c cancellation_type::partial * * if they are also supported by the @c AsyncReadStream type's * @c async_read_some operation. */ template <typename AsyncReadStream, typename DynamicBuffer_v2, typename CompletionCondition, BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, std::size_t)) ReadToken = default_completion_token_t< typename AsyncReadStream::executor_type>> auto async_read(AsyncReadStream& s, DynamicBuffer_v2 buffers, CompletionCondition completion_condition, ReadToken&& token = default_completion_token_t< typename AsyncReadStream::executor_type>(), constraint_t< is_dynamic_buffer_v2<DynamicBuffer_v2>::value > = 0) -> decltype( async_initiate<ReadToken, void (boost::system::error_code, std::size_t)>( declval<detail::initiate_async_read_dynbuf_v2<AsyncReadStream>>(), token, static_cast<DynamicBuffer_v2&&>(buffers), static_cast<CompletionCondition&&>(completion_condition))); /*@}*/ } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #include <boost/asio/impl/read.hpp> #endif // BOOST_ASIO_READ_HPP