| // |
| // read_at.hpp |
| // ~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| // |
| |
| #ifndef ASIO_READ_AT_HPP |
| #define ASIO_READ_AT_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| # pragma once |
| #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
| |
| #include "asio/detail/config.hpp" |
| #include <cstddef> |
| #include "asio/async_result.hpp" |
| #include "asio/detail/cstdint.hpp" |
| #include "asio/error.hpp" |
| |
| #if !defined(ASIO_NO_EXTENSIONS) |
| # include "asio/basic_streambuf_fwd.hpp" |
| #endif // !defined(ASIO_NO_EXTENSIONS) |
| |
| #include "asio/detail/push_options.hpp" |
| |
| namespace asio { |
| |
| /** |
| * @defgroup read_at 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 asio::system_error Thrown on failure. |
| * |
| * @par Example |
| * To read into a single data buffer use the @ref buffer function as follows: |
| * @code asio::read_at(d, 42, 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 asio::read_at( |
| * d, 42, buffers, |
| * 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 asio::read_at(d, 42, |
| * 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 asio::read_at( |
| * d, 42, buffers, |
| * asio::transfer_all(), ec); @endcode |
| */ |
| template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence> |
| std::size_t read_at(SyncRandomAccessReadDevice& d, |
| uint64_t offset, const MutableBufferSequence& buffers, |
| asio::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 asio::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 asio::system_error Thrown on failure. |
| * |
| * @par Example |
| * To read into a single data buffer use the @ref buffer function as follows: |
| * @code asio::read_at(d, 42, asio::buffer(data, size), |
| * 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 asio::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, asio::error_code& ec); |
| |
| #if !defined(ASIO_NO_EXTENSIONS) |
| #if !defined(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 asio::system_error Thrown on failure. |
| * |
| * @note This overload is equivalent to calling: |
| * @code asio::read_at( |
| * d, 42, b, |
| * 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 asio::read_at( |
| * d, 42, b, |
| * asio::transfer_all(), ec); @endcode |
| */ |
| template <typename SyncRandomAccessReadDevice, typename Allocator> |
| std::size_t read_at(SyncRandomAccessReadDevice& d, |
| uint64_t offset, basic_streambuf<Allocator>& b, |
| asio::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 asio::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 asio::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 asio::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, asio::error_code& ec); |
| |
| #endif // !defined(ASIO_NO_IOSTREAM) |
| #endif // !defined(ASIO_NO_EXTENSIONS) |
| |
| /*@}*/ |
| /** |
| * @defgroup async_read_at 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 asio::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 asio::post(). |
| * |
| * @par Example |
| * To read into a single data buffer use the @ref buffer function as follows: |
| * @code |
| * asio::async_read_at(d, 42, 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 asio::async_read_at( |
| * d, 42, buffers, |
| * asio::transfer_all(), |
| * handler); @endcode |
| */ |
| template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence, |
| ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code, |
| std::size_t)) ReadHandler |
| ASIO_DEFAULT_COMPLETION_TOKEN_TYPE( |
| typename AsyncRandomAccessReadDevice::executor_type)> |
| ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler, |
| void (asio::error_code, std::size_t)) |
| async_read_at(AsyncRandomAccessReadDevice& d, uint64_t offset, |
| const MutableBufferSequence& buffers, |
| ASIO_MOVE_ARG(ReadHandler) handler |
| 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 asio::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 asio::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 asio::post(). |
| * |
| * @par Example |
| * To read into a single data buffer use the @ref buffer function as follows: |
| * @code asio::async_read_at(d, 42, |
| * asio::buffer(data, size), |
| * 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, |
| ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code, |
| std::size_t)) ReadHandler |
| ASIO_DEFAULT_COMPLETION_TOKEN_TYPE( |
| typename AsyncRandomAccessReadDevice::executor_type)> |
| ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler, |
| void (asio::error_code, std::size_t)) |
| async_read_at(AsyncRandomAccessReadDevice& d, |
| uint64_t offset, const MutableBufferSequence& buffers, |
| CompletionCondition completion_condition, |
| ASIO_MOVE_ARG(ReadHandler) handler |
| ASIO_DEFAULT_COMPLETION_TOKEN( |
| typename AsyncRandomAccessReadDevice::executor_type)); |
| |
| #if !defined(ASIO_NO_EXTENSIONS) |
| #if !defined(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 asio::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 asio::post(). |
| * |
| * @note This overload is equivalent to calling: |
| * @code asio::async_read_at( |
| * d, 42, b, |
| * asio::transfer_all(), |
| * handler); @endcode |
| */ |
| template <typename AsyncRandomAccessReadDevice, typename Allocator, |
| ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code, |
| std::size_t)) ReadHandler |
| ASIO_DEFAULT_COMPLETION_TOKEN_TYPE( |
| typename AsyncRandomAccessReadDevice::executor_type)> |
| ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler, |
| void (asio::error_code, std::size_t)) |
| async_read_at(AsyncRandomAccessReadDevice& d, |
| uint64_t offset, basic_streambuf<Allocator>& b, |
| ASIO_MOVE_ARG(ReadHandler) handler |
| 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 asio::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 asio::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 asio::post(). |
| */ |
| template <typename AsyncRandomAccessReadDevice, |
| typename Allocator, typename CompletionCondition, |
| ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code, |
| std::size_t)) ReadHandler |
| ASIO_DEFAULT_COMPLETION_TOKEN_TYPE( |
| typename AsyncRandomAccessReadDevice::executor_type)> |
| ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler, |
| void (asio::error_code, std::size_t)) |
| async_read_at(AsyncRandomAccessReadDevice& d, |
| uint64_t offset, basic_streambuf<Allocator>& b, |
| CompletionCondition completion_condition, |
| ASIO_MOVE_ARG(ReadHandler) handler |
| ASIO_DEFAULT_COMPLETION_TOKEN( |
| typename AsyncRandomAccessReadDevice::executor_type)); |
| |
| #endif // !defined(ASIO_NO_IOSTREAM) |
| #endif // !defined(ASIO_NO_EXTENSIONS) |
| |
| /*@}*/ |
| |
| } // namespace asio |
| |
| #include "asio/detail/pop_options.hpp" |
| |
| #include "asio/impl/read_at.hpp" |
| |
| #endif // ASIO_READ_AT_HPP |