1//
2// impl/read_at.hpp
3// ~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 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_IMPL_READ_AT_HPP
12#define BOOST_ASIO_IMPL_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 <algorithm>
19#include <boost/asio/buffer.hpp>
20#include <boost/asio/completion_condition.hpp>
21#include <boost/asio/detail/array_fwd.hpp>
22#include <boost/asio/detail/base_from_completion_cond.hpp>
23#include <boost/asio/detail/bind_handler.hpp>
24#include <boost/asio/detail/consuming_buffers.hpp>
25#include <boost/asio/detail/dependent_type.hpp>
26#include <boost/asio/detail/handler_alloc_helpers.hpp>
27#include <boost/asio/detail/handler_cont_helpers.hpp>
28#include <boost/asio/detail/handler_invoke_helpers.hpp>
29#include <boost/asio/detail/handler_type_requirements.hpp>
30#include <boost/asio/detail/throw_error.hpp>
31#include <boost/asio/error.hpp>
32
33#include <boost/asio/detail/push_options.hpp>
34
35namespace boost {
36namespace asio {
37
38template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
39 typename CompletionCondition>
40std::size_t read_at(SyncRandomAccessReadDevice& d,
41 uint64_t offset, const MutableBufferSequence& buffers,
42 CompletionCondition completion_condition, boost::system::error_code& ec)
43{
44 ec = boost::system::error_code();
45 boost::asio::detail::consuming_buffers<
46 mutable_buffer, MutableBufferSequence> tmp(buffers);
47 std::size_t total_transferred = 0;
48 tmp.prepare(detail::adapt_completion_condition_result(
49 completion_condition(ec, total_transferred)));
50 while (tmp.begin() != tmp.end())
51 {
52 std::size_t bytes_transferred = d.read_some_at(
53 offset + total_transferred, tmp, ec);
54 tmp.consume(bytes_transferred);
55 total_transferred += bytes_transferred;
56 tmp.prepare(detail::adapt_completion_condition_result(
57 completion_condition(ec, total_transferred)));
58 }
59 return total_transferred;
60}
61
62template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
63inline std::size_t read_at(SyncRandomAccessReadDevice& d,
64 uint64_t offset, const MutableBufferSequence& buffers)
65{
66 boost::system::error_code ec;
67 std::size_t bytes_transferred = read_at(
68 d, offset, buffers, transfer_all(), ec);
69 boost::asio::detail::throw_error(ec, "read_at");
70 return bytes_transferred;
71}
72
73template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
74inline std::size_t read_at(SyncRandomAccessReadDevice& d,
75 uint64_t offset, const MutableBufferSequence& buffers,
76 boost::system::error_code& ec)
77{
78 return read_at(d, offset, buffers, transfer_all(), ec);
79}
80
81template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
82 typename CompletionCondition>
83inline std::size_t read_at(SyncRandomAccessReadDevice& d,
84 uint64_t offset, const MutableBufferSequence& buffers,
85 CompletionCondition completion_condition)
86{
87 boost::system::error_code ec;
88 std::size_t bytes_transferred = read_at(
89 d, offset, buffers, completion_condition, ec);
90 boost::asio::detail::throw_error(ec, "read_at");
91 return bytes_transferred;
92}
93
94#if !defined(BOOST_ASIO_NO_IOSTREAM)
95
96template <typename SyncRandomAccessReadDevice, typename Allocator,
97 typename CompletionCondition>
98std::size_t read_at(SyncRandomAccessReadDevice& d,
99 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b,
100 CompletionCondition completion_condition, boost::system::error_code& ec)
101{
102 ec = boost::system::error_code();
103 std::size_t total_transferred = 0;
104 std::size_t max_size = detail::adapt_completion_condition_result(
105 completion_condition(ec, total_transferred));
106 std::size_t bytes_available = read_size_helper(b, max_size);
107 while (bytes_available > 0)
108 {
109 std::size_t bytes_transferred = d.read_some_at(
110 offset + total_transferred, b.prepare(bytes_available), ec);
111 b.commit(bytes_transferred);
112 total_transferred += bytes_transferred;
113 max_size = detail::adapt_completion_condition_result(
114 completion_condition(ec, total_transferred));
115 bytes_available = read_size_helper(b, max_size);
116 }
117 return total_transferred;
118}
119
120template <typename SyncRandomAccessReadDevice, typename Allocator>
121inline std::size_t read_at(SyncRandomAccessReadDevice& d,
122 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b)
123{
124 boost::system::error_code ec;
125 std::size_t bytes_transferred = read_at(
126 d, offset, b, transfer_all(), ec);
127 boost::asio::detail::throw_error(ec, "read_at");
128 return bytes_transferred;
129}
130
131template <typename SyncRandomAccessReadDevice, typename Allocator>
132inline std::size_t read_at(SyncRandomAccessReadDevice& d,
133 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b,
134 boost::system::error_code& ec)
135{
136 return read_at(d, offset, b, transfer_all(), ec);
137}
138
139template <typename SyncRandomAccessReadDevice, typename Allocator,
140 typename CompletionCondition>
141inline std::size_t read_at(SyncRandomAccessReadDevice& d,
142 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b,
143 CompletionCondition completion_condition)
144{
145 boost::system::error_code ec;
146 std::size_t bytes_transferred = read_at(
147 d, offset, b, completion_condition, ec);
148 boost::asio::detail::throw_error(ec, "read_at");
149 return bytes_transferred;
150}
151
152#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
153
154namespace detail
155{
156 template <typename AsyncRandomAccessReadDevice,
157 typename MutableBufferSequence, typename CompletionCondition,
158 typename ReadHandler>
159 class read_at_op
160 : detail::base_from_completion_cond<CompletionCondition>
161 {
162 public:
163 read_at_op(AsyncRandomAccessReadDevice& device,
164 uint64_t offset, const MutableBufferSequence& buffers,
165 CompletionCondition completion_condition, ReadHandler& handler)
166 : detail::base_from_completion_cond<
167 CompletionCondition>(completion_condition),
168 device_(device),
169 offset_(offset),
170 buffers_(buffers),
171 start_(0),
172 total_transferred_(0),
173 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
174 {
175 }
176
177#if defined(BOOST_ASIO_HAS_MOVE)
178 read_at_op(const read_at_op& other)
179 : detail::base_from_completion_cond<CompletionCondition>(other),
180 device_(other.device_),
181 offset_(other.offset_),
182 buffers_(other.buffers_),
183 start_(other.start_),
184 total_transferred_(other.total_transferred_),
185 handler_(other.handler_)
186 {
187 }
188
189 read_at_op(read_at_op&& other)
190 : detail::base_from_completion_cond<CompletionCondition>(other),
191 device_(other.device_),
192 offset_(other.offset_),
193 buffers_(other.buffers_),
194 start_(other.start_),
195 total_transferred_(other.total_transferred_),
196 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
197 {
198 }
199#endif // defined(BOOST_ASIO_HAS_MOVE)
200
201 void operator()(const boost::system::error_code& ec,
202 std::size_t bytes_transferred, int start = 0)
203 {
204 switch (start_ = start)
205 {
206 case 1:
207 buffers_.prepare(this->check_for_completion(ec, total_transferred_));
208 for (;;)
209 {
210 device_.async_read_some_at(offset_ + total_transferred_,
211 buffers_, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
212 return; default:
213 total_transferred_ += bytes_transferred;
214 buffers_.consume(bytes_transferred);
215 buffers_.prepare(this->check_for_completion(ec, total_transferred_));
216 if ((!ec && bytes_transferred == 0)
217 || buffers_.begin() == buffers_.end())
218 break;
219 }
220
221 handler_(ec, static_cast<const std::size_t&>(total_transferred_));
222 }
223 }
224
225 //private:
226 AsyncRandomAccessReadDevice& device_;
227 uint64_t offset_;
228 boost::asio::detail::consuming_buffers<
229 mutable_buffer, MutableBufferSequence> buffers_;
230 int start_;
231 std::size_t total_transferred_;
232 ReadHandler handler_;
233 };
234
235 template <typename AsyncRandomAccessReadDevice,
236 typename CompletionCondition, typename ReadHandler>
237 class read_at_op<AsyncRandomAccessReadDevice,
238 boost::asio::mutable_buffers_1, CompletionCondition, ReadHandler>
239 : detail::base_from_completion_cond<CompletionCondition>
240 {
241 public:
242 read_at_op(AsyncRandomAccessReadDevice& device,
243 uint64_t offset, const boost::asio::mutable_buffers_1& buffers,
244 CompletionCondition completion_condition, ReadHandler& handler)
245 : detail::base_from_completion_cond<
246 CompletionCondition>(completion_condition),
247 device_(device),
248 offset_(offset),
249 buffer_(buffers),
250 start_(0),
251 total_transferred_(0),
252 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
253 {
254 }
255
256#if defined(BOOST_ASIO_HAS_MOVE)
257 read_at_op(const read_at_op& other)
258 : detail::base_from_completion_cond<CompletionCondition>(other),
259 device_(other.device_),
260 offset_(other.offset_),
261 buffer_(other.buffer_),
262 start_(other.start_),
263 total_transferred_(other.total_transferred_),
264 handler_(other.handler_)
265 {
266 }
267
268 read_at_op(read_at_op&& other)
269 : detail::base_from_completion_cond<CompletionCondition>(other),
270 device_(other.device_),
271 offset_(other.offset_),
272 buffer_(other.buffer_),
273 start_(other.start_),
274 total_transferred_(other.total_transferred_),
275 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
276 {
277 }
278#endif // defined(BOOST_ASIO_HAS_MOVE)
279
280 void operator()(const boost::system::error_code& ec,
281 std::size_t bytes_transferred, int start = 0)
282 {
283 std::size_t n = 0;
284 switch (start_ = start)
285 {
286 case 1:
287 n = this->check_for_completion(ec, total_transferred_);
288 for (;;)
289 {
290 device_.async_read_some_at(offset_ + total_transferred_,
291 boost::asio::buffer(buffer_ + total_transferred_, n),
292 BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
293 return; default:
294 total_transferred_ += bytes_transferred;
295 if ((!ec && bytes_transferred == 0)
296 || (n = this->check_for_completion(ec, total_transferred_)) == 0
297 || total_transferred_ == boost::asio::buffer_size(buffer_))
298 break;
299 }
300
301 handler_(ec, static_cast<const std::size_t&>(total_transferred_));
302 }
303 }
304
305 //private:
306 AsyncRandomAccessReadDevice& device_;
307 uint64_t offset_;
308 boost::asio::mutable_buffer buffer_;
309 int start_;
310 std::size_t total_transferred_;
311 ReadHandler handler_;
312 };
313
314 template <typename AsyncRandomAccessReadDevice, typename Elem,
315 typename CompletionCondition, typename ReadHandler>
316 class read_at_op<AsyncRandomAccessReadDevice, boost::array<Elem, 2>,
317 CompletionCondition, ReadHandler>
318 : detail::base_from_completion_cond<CompletionCondition>
319 {
320 public:
321 read_at_op(AsyncRandomAccessReadDevice& device,
322 uint64_t offset, const boost::array<Elem, 2>& buffers,
323 CompletionCondition completion_condition, ReadHandler& handler)
324 : detail::base_from_completion_cond<
325 CompletionCondition>(completion_condition),
326 device_(device),
327 offset_(offset),
328 buffers_(buffers),
329 start_(0),
330 total_transferred_(0),
331 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
332 {
333 }
334
335#if defined(BOOST_ASIO_HAS_MOVE)
336 read_at_op(const read_at_op& other)
337 : detail::base_from_completion_cond<CompletionCondition>(other),
338 device_(other.device_),
339 offset_(other.offset_),
340 buffers_(other.buffers_),
341 start_(other.start_),
342 total_transferred_(other.total_transferred_),
343 handler_(other.handler_)
344 {
345 }
346
347 read_at_op(read_at_op&& other)
348 : detail::base_from_completion_cond<CompletionCondition>(other),
349 device_(other.device_),
350 offset_(other.offset_),
351 buffers_(other.buffers_),
352 start_(other.start_),
353 total_transferred_(other.total_transferred_),
354 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
355 {
356 }
357#endif // defined(BOOST_ASIO_HAS_MOVE)
358
359 void operator()(const boost::system::error_code& ec,
360 std::size_t bytes_transferred, int start = 0)
361 {
362 typename boost::asio::detail::dependent_type<Elem,
363 boost::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
364 boost::asio::mutable_buffer(buffers_[0]),
365 boost::asio::mutable_buffer(buffers_[1]) }};
366 std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
367 std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
368 std::size_t n = 0;
369 switch (start_ = start)
370 {
371 case 1:
372 n = this->check_for_completion(ec, total_transferred_);
373 for (;;)
374 {
375 bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
376 bufs[1] = boost::asio::buffer(
377 bufs[1] + (total_transferred_ < buffer_size0
378 ? 0 : total_transferred_ - buffer_size0),
379 n - boost::asio::buffer_size(bufs[0]));
380 device_.async_read_some_at(offset_ + total_transferred_,
381 bufs, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
382 return; default:
383 total_transferred_ += bytes_transferred;
384 if ((!ec && bytes_transferred == 0)
385 || (n = this->check_for_completion(ec, total_transferred_)) == 0
386 || total_transferred_ == buffer_size0 + buffer_size1)
387 break;
388 }
389
390 handler_(ec, static_cast<const std::size_t&>(total_transferred_));
391 }
392 }
393
394 //private:
395 AsyncRandomAccessReadDevice& device_;
396 uint64_t offset_;
397 boost::array<Elem, 2> buffers_;
398 int start_;
399 std::size_t total_transferred_;
400 ReadHandler handler_;
401 };
402
403#if defined(BOOST_ASIO_HAS_STD_ARRAY)
404
405 template <typename AsyncRandomAccessReadDevice, typename Elem,
406 typename CompletionCondition, typename ReadHandler>
407 class read_at_op<AsyncRandomAccessReadDevice, std::array<Elem, 2>,
408 CompletionCondition, ReadHandler>
409 : detail::base_from_completion_cond<CompletionCondition>
410 {
411 public:
412 read_at_op(AsyncRandomAccessReadDevice& device,
413 uint64_t offset, const std::array<Elem, 2>& buffers,
414 CompletionCondition completion_condition, ReadHandler& handler)
415 : detail::base_from_completion_cond<
416 CompletionCondition>(completion_condition),
417 device_(device),
418 offset_(offset),
419 buffers_(buffers),
420 start_(0),
421 total_transferred_(0),
422 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
423 {
424 }
425
426#if defined(BOOST_ASIO_HAS_MOVE)
427 read_at_op(const read_at_op& other)
428 : detail::base_from_completion_cond<CompletionCondition>(other),
429 device_(other.device_),
430 offset_(other.offset_),
431 buffers_(other.buffers_),
432 start_(other.start_),
433 total_transferred_(other.total_transferred_),
434 handler_(other.handler_)
435 {
436 }
437
438 read_at_op(read_at_op&& other)
439 : detail::base_from_completion_cond<CompletionCondition>(other),
440 device_(other.device_),
441 offset_(other.offset_),
442 buffers_(other.buffers_),
443 start_(other.start_),
444 total_transferred_(other.total_transferred_),
445 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
446 {
447 }
448#endif // defined(BOOST_ASIO_HAS_MOVE)
449
450 void operator()(const boost::system::error_code& ec,
451 std::size_t bytes_transferred, int start = 0)
452 {
453 typename boost::asio::detail::dependent_type<Elem,
454 std::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
455 boost::asio::mutable_buffer(buffers_[0]),
456 boost::asio::mutable_buffer(buffers_[1]) }};
457 std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
458 std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
459 std::size_t n = 0;
460 switch (start_ = start)
461 {
462 case 1:
463 n = this->check_for_completion(ec, total_transferred_);
464 for (;;)
465 {
466 bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
467 bufs[1] = boost::asio::buffer(
468 bufs[1] + (total_transferred_ < buffer_size0
469 ? 0 : total_transferred_ - buffer_size0),
470 n - boost::asio::buffer_size(bufs[0]));
471 device_.async_read_some_at(offset_ + total_transferred_,
472 bufs, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
473 return; default:
474 total_transferred_ += bytes_transferred;
475 if ((!ec && bytes_transferred == 0)
476 || (n = this->check_for_completion(ec, total_transferred_)) == 0
477 || total_transferred_ == buffer_size0 + buffer_size1)
478 break;
479 }
480
481 handler_(ec, static_cast<const std::size_t&>(total_transferred_));
482 }
483 }
484
485 //private:
486 AsyncRandomAccessReadDevice& device_;
487 uint64_t offset_;
488 std::array<Elem, 2> buffers_;
489 int start_;
490 std::size_t total_transferred_;
491 ReadHandler handler_;
492 };
493
494#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
495
496 template <typename AsyncRandomAccessReadDevice,
497 typename MutableBufferSequence, typename CompletionCondition,
498 typename ReadHandler>
499 inline void* asio_handler_allocate(std::size_t size,
500 read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
501 CompletionCondition, ReadHandler>* this_handler)
502 {
503 return boost_asio_handler_alloc_helpers::allocate(
504 size, this_handler->handler_);
505 }
506
507 template <typename AsyncRandomAccessReadDevice,
508 typename MutableBufferSequence, typename CompletionCondition,
509 typename ReadHandler>
510 inline void asio_handler_deallocate(void* pointer, std::size_t size,
511 read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
512 CompletionCondition, ReadHandler>* this_handler)
513 {
514 boost_asio_handler_alloc_helpers::deallocate(
515 pointer, size, this_handler->handler_);
516 }
517
518 template <typename AsyncRandomAccessReadDevice,
519 typename MutableBufferSequence, typename CompletionCondition,
520 typename ReadHandler>
521 inline bool asio_handler_is_continuation(
522 read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
523 CompletionCondition, ReadHandler>* this_handler)
524 {
525 return this_handler->start_ == 0 ? true
526 : boost_asio_handler_cont_helpers::is_continuation(
527 this_handler->handler_);
528 }
529
530 template <typename Function, typename AsyncRandomAccessReadDevice,
531 typename MutableBufferSequence, typename CompletionCondition,
532 typename ReadHandler>
533 inline void asio_handler_invoke(Function& function,
534 read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
535 CompletionCondition, ReadHandler>* this_handler)
536 {
537 boost_asio_handler_invoke_helpers::invoke(
538 function, this_handler->handler_);
539 }
540
541 template <typename Function, typename AsyncRandomAccessReadDevice,
542 typename MutableBufferSequence, typename CompletionCondition,
543 typename ReadHandler>
544 inline void asio_handler_invoke(const Function& function,
545 read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
546 CompletionCondition, ReadHandler>* this_handler)
547 {
548 boost_asio_handler_invoke_helpers::invoke(
549 function, this_handler->handler_);
550 }
551
552 template <typename AsyncRandomAccessReadDevice,
553 typename MutableBufferSequence, typename CompletionCondition,
554 typename ReadHandler>
555 inline read_at_op<AsyncRandomAccessReadDevice,
556 MutableBufferSequence, CompletionCondition, ReadHandler>
557 make_read_at_op(AsyncRandomAccessReadDevice& d,
558 uint64_t offset, const MutableBufferSequence& buffers,
559 CompletionCondition completion_condition, ReadHandler handler)
560 {
561 return read_at_op<AsyncRandomAccessReadDevice,
562 MutableBufferSequence, CompletionCondition, ReadHandler>(
563 d, offset, buffers, completion_condition, handler);
564 }
565} // namespace detail
566
567template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
568 typename CompletionCondition, typename ReadHandler>
569inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
570 void (boost::system::error_code, std::size_t))
571async_read_at(AsyncRandomAccessReadDevice& d,
572 uint64_t offset, const MutableBufferSequence& buffers,
573 CompletionCondition completion_condition,
574 BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
575{
576 // If you get an error on the following line it means that your handler does
577 // not meet the documented type requirements for a ReadHandler.
578 BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
579
580 detail::async_result_init<
581 ReadHandler, void (boost::system::error_code, std::size_t)> init(
582 BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
583
584 detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
585 CompletionCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
586 void (boost::system::error_code, std::size_t))>(
587 d, offset, buffers, completion_condition, init.handler)(
588 boost::system::error_code(), 0, 1);
589
590 return init.result.get();
591}
592
593template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
594 typename ReadHandler>
595inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
596 void (boost::system::error_code, std::size_t))
597async_read_at(AsyncRandomAccessReadDevice& d,
598 uint64_t offset, const MutableBufferSequence& buffers,
599 BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
600{
601 // If you get an error on the following line it means that your handler does
602 // not meet the documented type requirements for a ReadHandler.
603 BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
604
605 detail::async_result_init<
606 ReadHandler, void (boost::system::error_code, std::size_t)> init(
607 BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
608
609 detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
610 detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
611 void (boost::system::error_code, std::size_t))>(
612 d, offset, buffers, transfer_all(), init.handler)(
613 boost::system::error_code(), 0, 1);
614
615 return init.result.get();
616}
617
618#if !defined(BOOST_ASIO_NO_IOSTREAM)
619
620namespace detail
621{
622 template <typename AsyncRandomAccessReadDevice, typename Allocator,
623 typename CompletionCondition, typename ReadHandler>
624 class read_at_streambuf_op
625 : detail::base_from_completion_cond<CompletionCondition>
626 {
627 public:
628 read_at_streambuf_op(AsyncRandomAccessReadDevice& device,
629 uint64_t offset, basic_streambuf<Allocator>& streambuf,
630 CompletionCondition completion_condition, ReadHandler& handler)
631 : detail::base_from_completion_cond<
632 CompletionCondition>(completion_condition),
633 device_(device),
634 offset_(offset),
635 streambuf_(streambuf),
636 start_(0),
637 total_transferred_(0),
638 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
639 {
640 }
641
642#if defined(BOOST_ASIO_HAS_MOVE)
643 read_at_streambuf_op(const read_at_streambuf_op& other)
644 : detail::base_from_completion_cond<CompletionCondition>(other),
645 device_(other.device_),
646 offset_(other.offset_),
647 streambuf_(other.streambuf_),
648 start_(other.start_),
649 total_transferred_(other.total_transferred_),
650 handler_(other.handler_)
651 {
652 }
653
654 read_at_streambuf_op(read_at_streambuf_op&& other)
655 : detail::base_from_completion_cond<CompletionCondition>(other),
656 device_(other.device_),
657 offset_(other.offset_),
658 streambuf_(other.streambuf_),
659 start_(other.start_),
660 total_transferred_(other.total_transferred_),
661 handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
662 {
663 }
664#endif // defined(BOOST_ASIO_HAS_MOVE)
665
666 void operator()(const boost::system::error_code& ec,
667 std::size_t bytes_transferred, int start = 0)
668 {
669 std::size_t max_size, bytes_available;
670 switch (start_ = start)
671 {
672 case 1:
673 max_size = this->check_for_completion(ec, total_transferred_);
674 bytes_available = read_size_helper(streambuf_, max_size);
675 for (;;)
676 {
677 device_.async_read_some_at(offset_ + total_transferred_,
678 streambuf_.prepare(bytes_available),
679 BOOST_ASIO_MOVE_CAST(read_at_streambuf_op)(*this));
680 return; default:
681 total_transferred_ += bytes_transferred;
682 streambuf_.commit(bytes_transferred);
683 max_size = this->check_for_completion(ec, total_transferred_);
684 bytes_available = read_size_helper(streambuf_, max_size);
685 if ((!ec && bytes_transferred == 0) || bytes_available == 0)
686 break;
687 }
688
689 handler_(ec, static_cast<const std::size_t&>(total_transferred_));
690 }
691 }
692
693 //private:
694 AsyncRandomAccessReadDevice& device_;
695 uint64_t offset_;
696 boost::asio::basic_streambuf<Allocator>& streambuf_;
697 int start_;
698 std::size_t total_transferred_;
699 ReadHandler handler_;
700 };
701
702 template <typename AsyncRandomAccessReadDevice, typename Allocator,
703 typename CompletionCondition, typename ReadHandler>
704 inline void* asio_handler_allocate(std::size_t size,
705 read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
706 CompletionCondition, ReadHandler>* this_handler)
707 {
708 return boost_asio_handler_alloc_helpers::allocate(
709 size, this_handler->handler_);
710 }
711
712 template <typename AsyncRandomAccessReadDevice, typename Allocator,
713 typename CompletionCondition, typename ReadHandler>
714 inline void asio_handler_deallocate(void* pointer, std::size_t size,
715 read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
716 CompletionCondition, ReadHandler>* this_handler)
717 {
718 boost_asio_handler_alloc_helpers::deallocate(
719 pointer, size, this_handler->handler_);
720 }
721
722 template <typename AsyncRandomAccessReadDevice, typename Allocator,
723 typename CompletionCondition, typename ReadHandler>
724 inline bool asio_handler_is_continuation(
725 read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
726 CompletionCondition, ReadHandler>* this_handler)
727 {
728 return this_handler->start_ == 0 ? true
729 : boost_asio_handler_cont_helpers::is_continuation(
730 this_handler->handler_);
731 }
732
733 template <typename Function, typename AsyncRandomAccessReadDevice,
734 typename Allocator, typename CompletionCondition, typename ReadHandler>
735 inline void asio_handler_invoke(Function& function,
736 read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
737 CompletionCondition, ReadHandler>* this_handler)
738 {
739 boost_asio_handler_invoke_helpers::invoke(
740 function, this_handler->handler_);
741 }
742
743 template <typename Function, typename AsyncRandomAccessReadDevice,
744 typename Allocator, typename CompletionCondition, typename ReadHandler>
745 inline void asio_handler_invoke(const Function& function,
746 read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
747 CompletionCondition, ReadHandler>* this_handler)
748 {
749 boost_asio_handler_invoke_helpers::invoke(
750 function, this_handler->handler_);
751 }
752} // namespace detail
753
754template <typename AsyncRandomAccessReadDevice, typename Allocator,
755 typename CompletionCondition, typename ReadHandler>
756inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
757 void (boost::system::error_code, std::size_t))
758async_read_at(AsyncRandomAccessReadDevice& d,
759 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b,
760 CompletionCondition completion_condition,
761 BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
762{
763 // If you get an error on the following line it means that your handler does
764 // not meet the documented type requirements for a ReadHandler.
765 BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
766
767 detail::async_result_init<
768 ReadHandler, void (boost::system::error_code, std::size_t)> init(
769 BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
770
771 detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
772 CompletionCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
773 void (boost::system::error_code, std::size_t))>(
774 d, offset, b, completion_condition, init.handler)(
775 boost::system::error_code(), 0, 1);
776
777 return init.result.get();
778}
779
780template <typename AsyncRandomAccessReadDevice, typename Allocator,
781 typename ReadHandler>
782inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
783 void (boost::system::error_code, std::size_t))
784async_read_at(AsyncRandomAccessReadDevice& d,
785 uint64_t offset, boost::asio::basic_streambuf<Allocator>& b,
786 BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
787{
788 // If you get an error on the following line it means that your handler does
789 // not meet the documented type requirements for a ReadHandler.
790 BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
791
792 detail::async_result_init<
793 ReadHandler, void (boost::system::error_code, std::size_t)> init(
794 BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
795
796 detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
797 detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
798 void (boost::system::error_code, std::size_t))>(
799 d, offset, b, transfer_all(), init.handler)(
800 boost::system::error_code(), 0, 1);
801
802 return init.result.get();
803}
804
805#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
806
807} // namespace asio
808} // namespace boost
809
810#include <boost/asio/detail/pop_options.hpp>
811
812#endif // BOOST_ASIO_IMPL_READ_AT_HPP
813