boost/asio/read_at.hpp

   1 //
   2 // read_at.hpp
   3 // ~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef BOOST_ASIO_READ_AT_HPP
  12 #define BOOST_ASIO_READ_AT_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/push_options.hpp>
  19
  20 #include <boost/asio/detail/push_options.hpp>
  21 #include <cstddef>
  22 #include <boost/config.hpp>
  23 #include <boost/cstdint.hpp>
  24 #include <boost/asio/detail/pop_options.hpp>
  25
  26 #include <boost/asio/basic_streambuf.hpp>
  27 #include <boost/asio/error.hpp>
  28
  29 namespace boost {
  30 namespace asio {
  31
  32 /**
  33  * @defgroup read_at boost::asio::read_at
  34  *
  35  * @brief Attempt to read a certain amount of data at the specified offset
  36  * before returning.
  37  */
  38 /*@{*/
  39
  40 /// Attempt to read a certain amount of data at the specified offset before
  41 /// returning.
  42 /**
  43  * This function is used to read a certain number of bytes of data from a
  44  * random access device at the specified offset. The call will block until one
  45  * of the following conditions is true:
  46  *
  47  * @li The supplied buffers are full. That is, the bytes transferred is equal to
  48  * the sum of the buffer sizes.
  49  *
  50  * @li An error occurred.
  51  *
  52  * This operation is implemented in terms of zero or more calls to the device's
  53  * read_some_at function.
  54  *
  55  * @param d The device from which the data is to be read. The type must support
  56  * the SyncRandomAccessReadDevice concept.
  57  *
  58  * @param offset The offset at which the data will be read.
  59  *
  60  * @param buffers One or more buffers into which the data will be read. The sum
  61  * of the buffer sizes indicates the maximum number of bytes to read from the
  62  * device.
  63  *
  64  * @returns The number of bytes transferred.
  65  *
  66  * @throws boost::system::system_error Thrown on failure.
  67  *
  68  * @par Example
  69  * To read into a single data buffer use the @ref buffer function as follows:
  70  * @code boost::asio::read_at(d, 42, boost::asio::buffer(data, size)); @endcode
  71  * See the @ref buffer documentation for information on reading into multiple
  72  * buffers in one go, and how to use it with arrays, boost::array or
  73  * std::vector.
  74  *
  75  * @note This overload is equivalent to calling:
  76  * @code boost::asio::read_at(
  77  *     d, 42, buffers,
  78  *     boost::asio::transfer_all()); @endcode
  79  */
  80 template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
  81 std::size_t read_at(SyncRandomAccessReadDevice& d,
  82     boost::uint64_t offset, const MutableBufferSequence& buffers);
  83
  84 /// Attempt to read a certain amount of data at the specified offset before
  85 /// returning.
  86 /**
  87  * This function is used to read a certain number of bytes of data from a
  88  * random access device at the specified offset. The call will block until one
  89  * of the following conditions is true:
  90  *
  91  * @li The supplied buffers are full. That is, the bytes transferred is equal to
  92  * the sum of the buffer sizes.
  93  *
  94  * @li The completion_condition function object returns 0.
  95  *
  96  * This operation is implemented in terms of zero or more calls to the device's
  97  * read_some_at function.
  98  *
  99  * @param d The device from which the data is to be read. The type must support
 100  * the SyncRandomAccessReadDevice concept.
 101  *
 102  * @param offset The offset at which the data will be read.
 103  *
 104  * @param buffers One or more buffers into which the data will be read. The sum
 105  * of the buffer sizes indicates the maximum number of bytes to read from the
 106  * device.
 107  *
 108  * @param completion_condition The function object to be called to determine
 109  * whether the read operation is complete. The signature of the function object
 110  * must be:
 111  * @code std::size_t completion_condition(
 112  *   // Result of latest read_some_at operation.
 113  *   const boost::system::error_code& error,
 114  *
 115  *   // Number of bytes transferred so far.
 116  *   std::size_t bytes_transferred
 117  * ); @endcode
 118  * A return value of 0 indicates that the read operation is complete. A non-zero
 119  * return value indicates the maximum number of bytes to be read on the next
 120  * call to the device's read_some_at function.
 121  *
 122  * @returns The number of bytes transferred.
 123  *
 124  * @throws boost::system::system_error Thrown on failure.
 125  *
 126  * @par Example
 127  * To read into a single data buffer use the @ref buffer function as follows:
 128  * @code boost::asio::read_at(d, 42, boost::asio::buffer(data, size),
 129  *     boost::asio::transfer_at_least(32)); @endcode
 130  * See the @ref buffer documentation for information on reading into multiple
 131  * buffers in one go, and how to use it with arrays, boost::array or
 132  * std::vector.
 133  */
 134 template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
 135     typename CompletionCondition>
 136 std::size_t read_at(SyncRandomAccessReadDevice& d,
 137     boost::uint64_t offset, const MutableBufferSequence& buffers,
 138     CompletionCondition completion_condition);
 139
 140 /// Attempt to read a certain amount of data at the specified offset before
 141 /// returning.
 142 /**
 143  * This function is used to read a certain number of bytes of data from a
 144  * random access device at the specified offset. The call will block until one
 145  * of the following conditions is true:
 146  *
 147  * @li The supplied buffers are full. That is, the bytes transferred is equal to
 148  * the sum of the buffer sizes.
 149  *
 150  * @li The completion_condition function object returns 0.
 151  *
 152  * This operation is implemented in terms of zero or more calls to the device's
 153  * read_some_at function.
 154  *
 155  * @param d The device from which the data is to be read. The type must support
 156  * the SyncRandomAccessReadDevice concept.
 157  *
 158  * @param offset The offset at which the data will be read.
 159  *
 160  * @param buffers One or more buffers into which the data will be read. The sum
 161  * of the buffer sizes indicates the maximum number of bytes to read from the
 162  * device.
 163  *
 164  * @param completion_condition The function object to be called to determine
 165  * whether the read operation is complete. The signature of the function object
 166  * must be:
 167  * @code std::size_t completion_condition(
 168  *   // Result of latest read_some_at operation.
 169  *   const boost::system::error_code& error,
 170  *
 171  *   // Number of bytes transferred so far.
 172  *   std::size_t bytes_transferred
 173  * ); @endcode
 174  * A return value of 0 indicates that the read operation is complete. A non-zero
 175  * return value indicates the maximum number of bytes to be read on the next
 176  * call to the device's read_some_at function.
 177  *
 178  * @param ec Set to indicate what error occurred, if any.
 179  *
 180  * @returns The number of bytes read. If an error occurs, returns the total
 181  * number of bytes successfully transferred prior to the error.
 182  */
 183 template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
 184     typename CompletionCondition>
 185 std::size_t read_at(SyncRandomAccessReadDevice& d,
 186     boost::uint64_t offset, const MutableBufferSequence& buffers,
 187     CompletionCondition completion_condition, boost::system::error_code& ec);
 188
 189 /// Attempt to read a certain amount of data at the specified offset before
 190 /// returning.
 191 /**
 192  * This function is used to read a certain number of bytes of data from a
 193  * random access device at the specified offset. The call will block until one
 194  * of the following conditions is true:
 195  *
 196  * @li An error occurred.
 197  *
 198  * This operation is implemented in terms of zero or more calls to the device's
 199  * read_some_at function.
 200  *
 201  * @param d The device from which the data is to be read. The type must support
 202  * the SyncRandomAccessReadDevice concept.
 203  *
 204  * @param offset The offset at which the data will be read.
 205  *
 206  * @param b The basic_streambuf object into which the data will be read.
 207  *
 208  * @returns The number of bytes transferred.
 209  *
 210  * @throws boost::system::system_error Thrown on failure.
 211  *
 212  * @note This overload is equivalent to calling:
 213  * @code boost::asio::read_at(
 214  *     d, 42, b,
 215  *     boost::asio::transfer_all()); @endcode
 216  */
 217 template <typename SyncRandomAccessReadDevice, typename Allocator>
 218 std::size_t read_at(SyncRandomAccessReadDevice& d,
 219     boost::uint64_t offset, basic_streambuf<Allocator>& b);
 220
 221 /// Attempt to read a certain amount of data at the specified offset before
 222 /// returning.
 223 /**
 224  * This function is used to read a certain number of bytes of data from a
 225  * random access device at the specified offset. The call will block until one
 226  * of the following conditions is true:
 227  *
 228  * @li The completion_condition function object returns 0.
 229  *
 230  * This operation is implemented in terms of zero or more calls to the device's
 231  * read_some_at function.
 232  *
 233  * @param d The device from which the data is to be read. The type must support
 234  * the SyncRandomAccessReadDevice concept.
 235  *
 236  * @param offset The offset at which the data will be read.
 237  *
 238  * @param b The basic_streambuf object into which the data will be read.
 239  *
 240  * @param completion_condition The function object to be called to determine
 241  * whether the read operation is complete. The signature of the function object
 242  * must be:
 243  * @code std::size_t completion_condition(
 244  *   // Result of latest read_some_at operation.
 245  *   const boost::system::error_code& error,
 246  *
 247  *   // Number of bytes transferred so far.
 248  *   std::size_t bytes_transferred
 249  * ); @endcode
 250  * A return value of 0 indicates that the read operation is complete. A non-zero
 251  * return value indicates the maximum number of bytes to be read on the next
 252  * call to the device's read_some_at function.
 253  *
 254  * @returns The number of bytes transferred.
 255  *
 256  * @throws boost::system::system_error Thrown on failure.
 257  */
 258 template <typename SyncRandomAccessReadDevice, typename Allocator,
 259     typename CompletionCondition>
 260 std::size_t read_at(SyncRandomAccessReadDevice& d,
 261     boost::uint64_t offset, basic_streambuf<Allocator>& b,
 262     CompletionCondition completion_condition);
 263
 264 /// Attempt to read a certain amount of data at the specified offset before
 265 /// returning.
 266 /**
 267  * This function is used to read a certain number of bytes of data from a
 268  * random access device at the specified offset. The call will block until one
 269  * of the following conditions is true:
 270  *
 271  * @li The completion_condition function object returns 0.
 272  *
 273  * This operation is implemented in terms of zero or more calls to the device's
 274  * read_some_at function.
 275  *
 276  * @param d The device from which the data is to be read. The type must support
 277  * the SyncRandomAccessReadDevice concept.
 278  *
 279  * @param offset The offset at which the data will be read.
 280  *
 281  * @param b The basic_streambuf object into which the data will be read.
 282  *
 283  * @param completion_condition The function object to be called to determine
 284  * whether the read operation is complete. The signature of the function object
 285  * must be:
 286  * @code std::size_t completion_condition(
 287  *   // Result of latest read_some_at operation.
 288  *   const boost::system::error_code& error,
 289  *
 290  *   // Number of bytes transferred so far.
 291  *   std::size_t bytes_transferred
 292  * ); @endcode
 293  * A return value of 0 indicates that the read operation is complete. A non-zero
 294  * return value indicates the maximum number of bytes to be read on the next
 295  * call to the device's read_some_at function.
 296  *
 297  * @param ec Set to indicate what error occurred, if any.
 298  *
 299  * @returns The number of bytes read. If an error occurs, returns the total
 300  * number of bytes successfully transferred prior to the error.
 301  */
 302 template <typename SyncRandomAccessReadDevice, typename Allocator,
 303     typename CompletionCondition>
 304 std::size_t read_at(SyncRandomAccessReadDevice& d,
 305     boost::uint64_t offset, basic_streambuf<Allocator>& b,
 306     CompletionCondition completion_condition, boost::system::error_code& ec);
 307
 308 /*@}*/
 309 /**
 310  * @defgroup async_read_at boost::asio::async_read_at
 311  *
 312  * @brief Start an asynchronous operation to read a certain amount of data at
 313  * the specified offset.
 314  */
 315 /*@{*/
 316
 317 /// Start an asynchronous operation to read a certain amount of data at the
 318 /// specified offset.
 319 /**
 320  * This function is used to asynchronously read a certain number of bytes of
 321  * data from a random access device at the specified offset. The function call
 322  * always returns immediately. The asynchronous operation will continue until
 323  * one of the following conditions is true:
 324  *
 325  * @li The supplied buffers are full. That is, the bytes transferred is equal to
 326  * the sum of the buffer sizes.
 327  *
 328  * @li An error occurred.
 329  *
 330  * This operation is implemented in terms of zero or more calls to the device's
 331  * async_read_some_at function.
 332  *
 333  * @param d The device from which the data is to be read. The type must support
 334  * the AsyncRandomAccessReadDevice concept.
 335  *
 336  * @param offset The offset at which the data will be read.
 337  *
 338  * @param buffers One or more buffers into which the data will be read. The sum
 339  * of the buffer sizes indicates the maximum number of bytes to read from the
 340  * device. Although the buffers object may be copied as necessary, ownership of
 341  * the underlying memory blocks is retained by the caller, which must guarantee
 342  * that they remain valid until the handler is called.
 343  *
 344  * @param handler The handler to be called when the read operation completes.
 345  * Copies will be made of the handler as required. The function signature of the
 346  * handler must be:
 347  * @code void handler(
 348  *   // Result of operation.
 349  *   const boost::system::error_code& error,
 350  *
 351  *   // Number of bytes copied into the buffers. If an error
 352  *   // occurred, this will be the number of bytes successfully
 353  *   // transferred prior to the error.
 354  *   std::size_t bytes_transferred
 355  * ); @endcode
 356  * Regardless of whether the asynchronous operation completes immediately or
 357  * not, the handler will not be invoked from within this function. Invocation of
 358  * the handler will be performed in a manner equivalent to using
 359  * boost::asio::io_service::post().
 360  *
 361  * @par Example
 362  * To read into a single data buffer use the @ref buffer function as follows:
 363  * @code
 364  * boost::asio::async_read_at(d, 42, boost::asio::buffer(data, size), handler);
 365  * @endcode
 366  * See the @ref buffer documentation for information on reading into multiple
 367  * buffers in one go, and how to use it with arrays, boost::array or
 368  * std::vector.
 369  *
 370  * @note This overload is equivalent to calling:
 371  * @code boost::asio::async_read_at(
 372  *     d, 42, buffers,
 373  *     boost::asio::transfer_all(),
 374  *     handler); @endcode
 375  */
 376 template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
 377     typename ReadHandler>
 378 void async_read_at(AsyncRandomAccessReadDevice& d, boost::uint64_t offset,
 379     const MutableBufferSequence& buffers, ReadHandler handler);
 380
 381 /// Start an asynchronous operation to read a certain amount of data at the
 382 /// specified offset.
 383 /**
 384  * This function is used to asynchronously read a certain number of bytes of
 385  * data from a random access device at the specified offset. The function call
 386  * always returns immediately. The asynchronous operation will continue until
 387  * one of the following conditions is true:
 388  *
 389  * @li The supplied buffers are full. That is, the bytes transferred is equal to
 390  * the sum of the buffer sizes.
 391  *
 392  * @li The completion_condition function object returns 0.
 393  *
 394  * @param d The device from which the data is to be read. The type must support
 395  * the AsyncRandomAccessReadDevice concept.
 396  *
 397  * @param offset The offset at which the data will be read.
 398  *
 399  * @param buffers One or more buffers into which the data will be read. The sum
 400  * of the buffer sizes indicates the maximum number of bytes to read from the
 401  * device. Although the buffers object may be copied as necessary, ownership of
 402  * the underlying memory blocks is retained by the caller, which must guarantee
 403  * that they remain valid until the handler is called.
 404  *
 405  * @param completion_condition The function object to be called to determine
 406  * whether the read operation is complete. The signature of the function object
 407  * must be:
 408  * @code std::size_t completion_condition(
 409  *   // Result of latest async_read_some_at operation.
 410  *   const boost::system::error_code& error,
 411  *
 412  *   // Number of bytes transferred so far.
 413  *   std::size_t bytes_transferred
 414  * ); @endcode
 415  * A return value of 0 indicates that the read operation is complete. A non-zero
 416  * return value indicates the maximum number of bytes to be read on the next
 417  * call to the device's async_read_some_at function.
 418  *
 419  * @param handler The handler to be called when the read operation completes.
 420  * Copies will be made of the handler as required. The function signature of the
 421  * handler must be:
 422  * @code void handler(
 423  *   // Result of operation.
 424  *   const boost::system::error_code& error,
 425  *
 426  *   // Number of bytes copied into the buffers. If an error
 427  *   // occurred, this will be the number of bytes successfully
 428  *   // transferred prior to the error.
 429  *   std::size_t bytes_transferred
 430  * ); @endcode
 431  * Regardless of whether the asynchronous operation completes immediately or
 432  * not, the handler will not be invoked from within this function. Invocation of
 433  * the handler will be performed in a manner equivalent to using
 434  * boost::asio::io_service::post().
 435  *
 436  * @par Example
 437  * To read into a single data buffer use the @ref buffer function as follows:
 438  * @code boost::asio::async_read_at(d, 42,
 439  *     boost::asio::buffer(data, size),
 440  *     boost::asio::transfer_at_least(32),
 441  *     handler); @endcode
 442  * See the @ref buffer documentation for information on reading into multiple
 443  * buffers in one go, and how to use it with arrays, boost::array or
 444  * std::vector.
 445  */
 446 template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
 447     typename CompletionCondition, typename ReadHandler>
 448 void async_read_at(AsyncRandomAccessReadDevice& d,
 449     boost::uint64_t offset, const MutableBufferSequence& buffers,
 450     CompletionCondition completion_condition, ReadHandler handler);
 451
 452 /// Start an asynchronous operation to read a certain amount of data at the
 453 /// specified offset.
 454 /**
 455  * This function is used to asynchronously read a certain number of bytes of
 456  * data from a random access device at the specified offset. The function call
 457  * always returns immediately. The asynchronous operation will continue until
 458  * one of the following conditions is true:
 459  *
 460  * @li An error occurred.
 461  *
 462  * This operation is implemented in terms of zero or more calls to the device's
 463  * async_read_some_at function.
 464  *
 465  * @param d The device from which the data is to be read. The type must support
 466  * the AsyncRandomAccessReadDevice concept.
 467  *
 468  * @param offset The offset at which the data will be read.
 469  *
 470  * @param b A basic_streambuf object into which the data will be read. Ownership
 471  * of the streambuf is retained by the caller, which must guarantee that it
 472  * remains valid until the handler is called.
 473  *
 474  * @param handler The handler to be called when the read operation completes.
 475  * Copies will be made of the handler as required. The function signature of the
 476  * handler must be:
 477  * @code void handler(
 478  *   // Result of operation.
 479  *   const boost::system::error_code& error,
 480  *
 481  *   // Number of bytes copied into the buffers. If an error
 482  *   // occurred, this will be the number of bytes successfully
 483  *   // transferred prior to the error.
 484  *   std::size_t bytes_transferred
 485  * ); @endcode
 486  * Regardless of whether the asynchronous operation completes immediately or
 487  * not, the handler will not be invoked from within this function. Invocation of
 488  * the handler will be performed in a manner equivalent to using
 489  * boost::asio::io_service::post().
 490  *
 491  * @note This overload is equivalent to calling:
 492  * @code boost::asio::async_read_at(
 493  *     d, 42, b,
 494  *     boost::asio::transfer_all(),
 495  *     handler); @endcode
 496  */
 497 template <typename AsyncRandomAccessReadDevice, typename Allocator,
 498     typename ReadHandler>
 499 void async_read_at(AsyncRandomAccessReadDevice& d, boost::uint64_t offset,
 500     basic_streambuf<Allocator>& b, ReadHandler handler);
 501
 502 /// Start an asynchronous operation to read a certain amount of data at the
 503 /// specified offset.
 504 /**
 505  * This function is used to asynchronously read a certain number of bytes of
 506  * data from a random access device at the specified offset. The function call
 507  * always returns immediately. The asynchronous operation will continue until
 508  * one of the following conditions is true:
 509  *
 510  * @li The completion_condition function object returns 0.
 511  *
 512  * This operation is implemented in terms of zero or more calls to the device's
 513  * async_read_some_at function.
 514  *
 515  * @param d The device from which the data is to be read. The type must support
 516  * the AsyncRandomAccessReadDevice concept.
 517  *
 518  * @param offset The offset at which the data will be read.
 519  *
 520  * @param b A basic_streambuf object into which the data will be read. Ownership
 521  * of the streambuf is retained by the caller, which must guarantee that it
 522  * remains valid until the handler is called.
 523  *
 524  * @param completion_condition The function object to be called to determine
 525  * whether the read operation is complete. The signature of the function object
 526  * must be:
 527  * @code std::size_t completion_condition(
 528  *   // Result of latest async_read_some_at operation.
 529  *   const boost::system::error_code& error,
 530  *
 531  *   // Number of bytes transferred so far.
 532  *   std::size_t bytes_transferred
 533  * ); @endcode
 534  * A return value of 0 indicates that the read operation is complete. A non-zero
 535  * return value indicates the maximum number of bytes to be read on the next
 536  * call to the device's async_read_some_at function.
 537  *
 538  * @param handler The handler to be called when the read operation completes.
 539  * Copies will be made of the handler as required. The function signature of the
 540  * handler must be:
 541  * @code void handler(
 542  *   // Result of operation.
 543  *   const boost::system::error_code& error,
 544  *
 545  *   // Number of bytes copied into the buffers. If an error
 546  *   // occurred, this will be the number of bytes successfully
 547  *   // transferred prior to the error.
 548  *   std::size_t bytes_transferred
 549  * ); @endcode
 550  * Regardless of whether the asynchronous operation completes immediately or
 551  * not, the handler will not be invoked from within this function. Invocation of
 552  * the handler will be performed in a manner equivalent to using
 553  * boost::asio::io_service::post().
 554  */
 555 template <typename AsyncRandomAccessReadDevice, typename Allocator,
 556     typename CompletionCondition, typename ReadHandler>
 557 void async_read_at(AsyncRandomAccessReadDevice& d,
 558     boost::uint64_t offset, basic_streambuf<Allocator>& b,
 559     CompletionCondition completion_condition, ReadHandler handler);
 560
 561 /*@}*/
 562
 563 } // namespace asio
 564 } // namespace boost
 565
 566 #include <boost/asio/impl/read_at.ipp>
 567
 568 #include <boost/asio/detail/pop_options.hpp>
 569
 570 #endif // BOOST_ASIO_READ_AT_HPP