123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696 |
- //
- // read_at.hpp
- // ~~~~~~~~~~~
- //
- // Copyright (c) 2003-2021 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_AT_HPP
- #define BOOST_ASIO_READ_AT_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/detail/cstdint.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 {
- /**
- * @defgroup read_at boost::asio::read_at
- *
- * @brief The @c read_at function is a composed operation that reads a certain
- * amount of data at the specified offset before returning.
- */
- /*@{*/
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. 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 device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device.
- *
- * @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_at(d, 42, 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_at(
- * d, 42, buffers,
- * boost::asio::transfer_all()); @endcode
- */
- template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, const MutableBufferSequence& buffers);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. 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 device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device.
- *
- * @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_at(d, 42,
- * 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_at(
- * d, 42, buffers,
- * boost::asio::transfer_all(), ec); @endcode
- */
- template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, const MutableBufferSequence& buffers,
- boost::system::error_code& ec);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. 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 device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device.
- *
- * @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_at 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 device's read_some_at 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_at(d, 42, 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 SyncRandomAccessReadDevice, typename MutableBufferSequence,
- typename CompletionCondition>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, const MutableBufferSequence& buffers,
- CompletionCondition completion_condition);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. 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 device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device.
- *
- * @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_at 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 device's read_some_at 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 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);
- #if !defined(BOOST_ASIO_NO_EXTENSIONS)
- #if !defined(BOOST_ASIO_NO_IOSTREAM)
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. The call will block until one
- * of the following conditions is true:
- *
- * @li An error occurred.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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_at(
- * d, 42, b,
- * boost::asio::transfer_all()); @endcode
- */
- template <typename SyncRandomAccessReadDevice, typename Allocator>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. The call will block until one
- * of the following conditions is true:
- *
- * @li An error occurred.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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_at(
- * d, 42, b,
- * boost::asio::transfer_all(), ec); @endcode
- */
- template <typename SyncRandomAccessReadDevice, typename Allocator>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b,
- boost::system::error_code& ec);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. The call will block until one
- * of the following conditions is true:
- *
- * @li The completion_condition function object returns 0.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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_at 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 device's read_some_at function.
- *
- * @returns The number of bytes transferred.
- *
- * @throws boost::system::system_error Thrown on failure.
- */
- template <typename SyncRandomAccessReadDevice, typename Allocator,
- typename CompletionCondition>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b,
- CompletionCondition completion_condition);
- /// Attempt to read a certain amount of data at the specified offset before
- /// returning.
- /**
- * This function is used to read a certain number of bytes of data from a
- * random access device at the specified offset. The call will block until one
- * of the following conditions is true:
- *
- * @li The completion_condition function object returns 0.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the SyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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_at 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 device's read_some_at 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 SyncRandomAccessReadDevice, typename Allocator,
- typename CompletionCondition>
- std::size_t read_at(SyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b,
- CompletionCondition completion_condition, boost::system::error_code& ec);
- #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
- #endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
- /*@}*/
- /**
- * @defgroup async_read_at boost::asio::async_read_at
- *
- * @brief The @c async_read_at function is a composed asynchronous operation
- * that reads a certain amount of data at the specified offset.
- */
- /*@{*/
- /// Start an asynchronous operation to read a certain amount of data at the
- /// specified offset.
- /**
- * This function is used to asynchronously read a certain number of bytes of
- * data from a random access device at the specified offset. The function call
- * 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 device's
- * async_read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the AsyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device. 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 handler is called.
- *
- * @param handler The handler to be called when the read operation completes.
- * Copies will be made of the handler as required. The function signature of the
- * 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 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 Example
- * To read into a single data buffer use the @ref buffer function as follows:
- * @code
- * boost::asio::async_read_at(d, 42, 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_at(
- * d, 42, buffers,
- * boost::asio::transfer_all(),
- * handler); @endcode
- */
- template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
- std::size_t)) ReadHandler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
- typename AsyncRandomAccessReadDevice::executor_type)>
- BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
- void (boost::system::error_code, std::size_t))
- async_read_at(AsyncRandomAccessReadDevice& d, uint64_t offset,
- const MutableBufferSequence& buffers,
- BOOST_ASIO_MOVE_ARG(ReadHandler) handler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
- typename AsyncRandomAccessReadDevice::executor_type));
- /// Start an asynchronous operation to read a certain amount of data at the
- /// specified offset.
- /**
- * This function is used to asynchronously read a certain number of bytes of
- * data from a random access device at the specified offset. The function call
- * 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 d The device from which the data is to be read. The type must support
- * the AsyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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
- * device. 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 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_at 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 device's async_read_some_at function.
- *
- * @param handler The handler to be called when the read operation completes.
- * Copies will be made of the handler as required. The function signature of the
- * 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 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 Example
- * To read into a single data buffer use the @ref buffer function as follows:
- * @code boost::asio::async_read_at(d, 42,
- * 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.
- */
- template <typename AsyncRandomAccessReadDevice,
- typename MutableBufferSequence, typename CompletionCondition,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
- std::size_t)) ReadHandler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
- typename AsyncRandomAccessReadDevice::executor_type)>
- BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
- void (boost::system::error_code, std::size_t))
- async_read_at(AsyncRandomAccessReadDevice& d,
- uint64_t offset, const MutableBufferSequence& buffers,
- CompletionCondition completion_condition,
- BOOST_ASIO_MOVE_ARG(ReadHandler) handler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
- typename AsyncRandomAccessReadDevice::executor_type));
- #if !defined(BOOST_ASIO_NO_EXTENSIONS)
- #if !defined(BOOST_ASIO_NO_IOSTREAM)
- /// Start an asynchronous operation to read a certain amount of data at the
- /// specified offset.
- /**
- * This function is used to asynchronously read a certain number of bytes of
- * data from a random access device at the specified offset. The function call
- * always returns immediately. The asynchronous operation will continue until
- * one of the following conditions is true:
- *
- * @li An error occurred.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * async_read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the AsyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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 handler is called.
- *
- * @param handler The handler to be called when the read operation completes.
- * Copies will be made of the handler as required. The function signature of the
- * 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 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().
- *
- * @note This overload is equivalent to calling:
- * @code boost::asio::async_read_at(
- * d, 42, b,
- * boost::asio::transfer_all(),
- * handler); @endcode
- */
- template <typename AsyncRandomAccessReadDevice, typename Allocator,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
- std::size_t)) ReadHandler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
- typename AsyncRandomAccessReadDevice::executor_type)>
- BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
- void (boost::system::error_code, std::size_t))
- async_read_at(AsyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b,
- BOOST_ASIO_MOVE_ARG(ReadHandler) handler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
- typename AsyncRandomAccessReadDevice::executor_type));
- /// Start an asynchronous operation to read a certain amount of data at the
- /// specified offset.
- /**
- * This function is used to asynchronously read a certain number of bytes of
- * data from a random access device at the specified offset. The function call
- * always returns immediately. The asynchronous operation will continue until
- * one of the following conditions is true:
- *
- * @li The completion_condition function object returns 0.
- *
- * This operation is implemented in terms of zero or more calls to the device's
- * async_read_some_at function.
- *
- * @param d The device from which the data is to be read. The type must support
- * the AsyncRandomAccessReadDevice concept.
- *
- * @param offset The offset at which the data will be read.
- *
- * @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 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_at 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 device's async_read_some_at function.
- *
- * @param handler The handler to be called when the read operation completes.
- * Copies will be made of the handler as required. The function signature of the
- * 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 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().
- */
- template <typename AsyncRandomAccessReadDevice,
- typename Allocator, typename CompletionCondition,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
- std::size_t)) ReadHandler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
- typename AsyncRandomAccessReadDevice::executor_type)>
- BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
- void (boost::system::error_code, std::size_t))
- async_read_at(AsyncRandomAccessReadDevice& d,
- uint64_t offset, basic_streambuf<Allocator>& b,
- CompletionCondition completion_condition,
- BOOST_ASIO_MOVE_ARG(ReadHandler) handler
- BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
- typename AsyncRandomAccessReadDevice::executor_type));
- #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
- #endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
- /*@}*/
- } // namespace asio
- } // namespace boost
- #include <boost/asio/detail/pop_options.hpp>
- #include <boost/asio/impl/read_at.hpp>
- #endif // BOOST_ASIO_READ_AT_HPP
|