569 lines
22 KiB
C++
569 lines
22 KiB
C++
//
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// read_at.hpp
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// ~~~~~~~~~~~
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//
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// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_READ_AT_HPP
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#define ASIO_READ_AT_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/push_options.hpp"
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#include "asio/detail/push_options.hpp"
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#include <cstddef>
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#include <boost/config.hpp>
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#include <boost/cstdint.hpp>
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#include "asio/detail/pop_options.hpp"
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#include "asio/basic_streambuf.hpp"
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#include "asio/error.hpp"
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namespace asio {
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/**
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* @defgroup read_at asio::read_at
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*
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* @brief Attempt to read a certain amount of data at the specified offset
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* before returning.
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*/
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/*@{*/
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li The supplied buffers are full. That is, the bytes transferred is equal to
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* the sum of the buffer sizes.
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*
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* @li An error occurred.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param buffers One or more buffers into which the data will be read. The sum
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* of the buffer sizes indicates the maximum number of bytes to read from the
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* device.
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*
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* @returns The number of bytes transferred.
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*
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* @throws asio::system_error Thrown on failure.
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*
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* @par Example
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* To read into a single data buffer use the @ref buffer function as follows:
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* @code asio::read_at(d, 42, asio::buffer(data, size)); @endcode
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* See the @ref buffer documentation for information on reading into multiple
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* buffers in one go, and how to use it with arrays, boost::array or
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* std::vector.
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*
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* @note This overload is equivalent to calling:
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* @code asio::read_at(
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* d, 42, buffers,
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* asio::transfer_all()); @endcode
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*/
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template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, const MutableBufferSequence& buffers);
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li The supplied buffers are full. That is, the bytes transferred is equal to
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* the sum of the buffer sizes.
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*
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* @li The completion_condition function object returns true.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param buffers One or more buffers into which the data will be read. The sum
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* of the buffer sizes indicates the maximum number of bytes to read from the
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* device.
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*
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* @param completion_condition The function object to be called to determine
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* whether the read operation is complete. The signature of the function object
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* must be:
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* @code std::size_t completion_condition(
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* // Result of latest read_some_at operation.
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* const asio::error_code& error,
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*
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* // Number of bytes transferred so far.
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* std::size_t bytes_transferred
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* ); @endcode
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* A return value of 0 indicates that the read operation is complete. A non-zero
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* return value indicates the maximum number of bytes to be read on the next
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* call to the device's read_some_at function.
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*
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* @returns The number of bytes transferred.
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*
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* @throws asio::system_error Thrown on failure.
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*
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* @par Example
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* To read into a single data buffer use the @ref buffer function as follows:
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* @code asio::read_at(d, 42, asio::buffer(data, size),
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* asio::transfer_at_least(32)); @endcode
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* See the @ref buffer documentation for information on reading into multiple
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* buffers in one go, and how to use it with arrays, boost::array or
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* std::vector.
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*/
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template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
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typename CompletionCondition>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, const MutableBufferSequence& buffers,
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CompletionCondition completion_condition);
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li The supplied buffers are full. That is, the bytes transferred is equal to
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* the sum of the buffer sizes.
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*
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* @li The completion_condition function object returns true.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param buffers One or more buffers into which the data will be read. The sum
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* of the buffer sizes indicates the maximum number of bytes to read from the
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* device.
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*
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* @param completion_condition The function object to be called to determine
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* whether the read operation is complete. The signature of the function object
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* must be:
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* @code std::size_t completion_condition(
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* // Result of latest read_some_at operation.
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* const asio::error_code& error,
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*
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* // Number of bytes transferred so far.
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* std::size_t bytes_transferred
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* ); @endcode
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* A return value of 0 indicates that the read operation is complete. A non-zero
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* return value indicates the maximum number of bytes to be read on the next
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* call to the device's read_some_at function.
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*
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* @param ec Set to indicate what error occurred, if any.
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*
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* @returns The number of bytes read. If an error occurs, returns the total
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* number of bytes successfully transferred prior to the error.
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*/
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template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
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typename CompletionCondition>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, const MutableBufferSequence& buffers,
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CompletionCondition completion_condition, asio::error_code& ec);
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li An error occurred.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param b The basic_streambuf object into which the data will be read.
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*
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* @returns The number of bytes transferred.
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*
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* @throws asio::system_error Thrown on failure.
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*
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* @note This overload is equivalent to calling:
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* @code asio::read_at(
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* d, 42, b,
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* asio::transfer_all()); @endcode
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*/
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template <typename SyncRandomAccessReadDevice, typename Allocator>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, basic_streambuf<Allocator>& b);
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li The completion_condition function object returns true.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param b The basic_streambuf object into which the data will be read.
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*
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* @param completion_condition The function object to be called to determine
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* whether the read operation is complete. The signature of the function object
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* must be:
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* @code std::size_t completion_condition(
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* // Result of latest read_some_at operation.
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* const asio::error_code& error,
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*
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* // Number of bytes transferred so far.
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* std::size_t bytes_transferred
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* ); @endcode
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* A return value of 0 indicates that the read operation is complete. A non-zero
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* return value indicates the maximum number of bytes to be read on the next
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* call to the device's read_some_at function.
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*
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* @returns The number of bytes transferred.
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*
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* @throws asio::system_error Thrown on failure.
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*/
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template <typename SyncRandomAccessReadDevice, typename Allocator,
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typename CompletionCondition>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, basic_streambuf<Allocator>& b,
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CompletionCondition completion_condition);
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/// Attempt to read a certain amount of data at the specified offset before
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/// returning.
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/**
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* This function is used to read a certain number of bytes of data from a
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* random access device at the specified offset. The call will block until one
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* of the following conditions is true:
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*
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* @li The completion_condition function object returns true.
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*
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* This operation is implemented in terms of zero or more calls to the device's
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* read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the SyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param b The basic_streambuf object into which the data will be read.
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*
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* @param completion_condition The function object to be called to determine
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* whether the read operation is complete. The signature of the function object
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* must be:
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* @code std::size_t completion_condition(
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* // Result of latest read_some_at operation.
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* const asio::error_code& error,
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*
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* // Number of bytes transferred so far.
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* std::size_t bytes_transferred
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* ); @endcode
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* A return value of 0 indicates that the read operation is complete. A non-zero
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* return value indicates the maximum number of bytes to be read on the next
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* call to the device's read_some_at function.
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*
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* @param ec Set to indicate what error occurred, if any.
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*
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* @returns The number of bytes read. If an error occurs, returns the total
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* number of bytes successfully transferred prior to the error.
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*/
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template <typename SyncRandomAccessReadDevice, typename Allocator,
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typename CompletionCondition>
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std::size_t read_at(SyncRandomAccessReadDevice& d,
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boost::uint64_t offset, basic_streambuf<Allocator>& b,
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CompletionCondition completion_condition, asio::error_code& ec);
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/*@}*/
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/**
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* @defgroup async_read_at asio::async_read_at
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*
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* @brief Start an asynchronous operation to read a certain amount of data at
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* the specified offset.
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*/
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/*@{*/
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/// Start an asynchronous operation to read a certain amount of data at the
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/// specified offset.
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/**
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* This function is used to asynchronously read a certain number of bytes of
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* data from a random access device at the specified offset. The function call
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* always returns immediately. The asynchronous operation will continue until
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* one of the following conditions is true:
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*
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* @li The supplied buffers are full. That is, the bytes transferred is equal to
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* the sum of the buffer sizes.
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*
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* @li An error occurred.
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*
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* This operation is implemented in terms of zero or more calls to the device's
|
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* async_read_some_at function.
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*
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* @param d The device from which the data is to be read. The type must support
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* the AsyncRandomAccessReadDevice concept.
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*
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* @param offset The offset at which the data will be read.
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*
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* @param buffers One or more buffers into which the data will be read. The sum
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|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
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* device. Although the buffers object may be copied as necessary, ownership of
|
|
* the underlying memory blocks is retained by the caller, which must guarantee
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* that they remain valid until the handler is called.
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*
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* @param handler The handler to be called when the read operation completes.
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* Copies will be made of the handler as required. The function signature of the
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* handler must be:
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* @code void handler(
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* // Result of operation.
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* const asio::error_code& error,
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*
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* // Number of bytes copied into the buffers. If an error
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* // occurred, this will be the number of bytes successfully
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* // transferred prior to the error.
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* std::size_t bytes_transferred
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* ); @endcode
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* Regardless of whether the asynchronous operation completes immediately or
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* not, the handler will not be invoked from within this function. Invocation of
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* the handler will be performed in a manner equivalent to using
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* asio::io_service::post().
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*
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* @par Example
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* To read into a single data buffer use the @ref buffer function as follows:
|
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* @code
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* asio::async_read_at(d, 42, asio::buffer(data, size), handler);
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* @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.
|
|
*
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|
* @note This overload is equivalent to calling:
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* @code asio::async_read_at(
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* d, 42, buffers,
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* asio::transfer_all(),
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* handler); @endcode
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*/
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template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
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typename ReadHandler>
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void async_read_at(AsyncRandomAccessReadDevice& d, boost::uint64_t offset,
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const MutableBufferSequence& buffers, ReadHandler handler);
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|
|
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/// 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 true.
|
|
*
|
|
* @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. Invocation of
|
|
* the handler will be performed in a manner equivalent to using
|
|
* asio::io_service::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, typename ReadHandler>
|
|
void async_read_at(AsyncRandomAccessReadDevice& d,
|
|
boost::uint64_t offset, const MutableBufferSequence& buffers,
|
|
CompletionCondition completion_condition, ReadHandler handler);
|
|
|
|
/// 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.
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|
* std::size_t bytes_transferred
|
|
* ); @endcode
|
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* Regardless of whether the asynchronous operation completes immediately or
|
|
* not, the handler will not be invoked from within this function. Invocation of
|
|
* the handler will be performed in a manner equivalent to using
|
|
* asio::io_service::post().
|
|
*
|
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* @note This overload is equivalent to calling:
|
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* @code asio::async_read_at(
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|
* d, 42, b,
|
|
* asio::transfer_all(),
|
|
* handler); @endcode
|
|
*/
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|
template <typename AsyncRandomAccessReadDevice, typename Allocator,
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|
typename ReadHandler>
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void async_read_at(AsyncRandomAccessReadDevice& d, boost::uint64_t offset,
|
|
basic_streambuf<Allocator>& b, ReadHandler handler);
|
|
|
|
/// 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 true.
|
|
*
|
|
* 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. Invocation of
|
|
* the handler will be performed in a manner equivalent to using
|
|
* asio::io_service::post().
|
|
*/
|
|
template <typename AsyncRandomAccessReadDevice, typename Allocator,
|
|
typename CompletionCondition, typename ReadHandler>
|
|
void async_read_at(AsyncRandomAccessReadDevice& d,
|
|
boost::uint64_t offset, basic_streambuf<Allocator>& b,
|
|
CompletionCondition completion_condition, ReadHandler handler);
|
|
|
|
/*@}*/
|
|
|
|
} // namespace asio
|
|
|
|
#include "asio/impl/read_at.ipp"
|
|
|
|
#include "asio/detail/pop_options.hpp"
|
|
|
|
#endif // ASIO_READ_AT_HPP
|