. /include/boost/corosio /random_access_file.hpp
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1   // 1   //
2   // Copyright (c) 2026 Michael Vandeberg 2   // Copyright (c) 2026 Michael Vandeberg
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 4   // Distributed under the Boost Software License, Version 1.0. (See accompanying
5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/corosio 7   // Official repository: https://github.com/cppalliance/corosio
8   // 8   //
9   9  
10   #ifndef BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP 10   #ifndef BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP
11   #define BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP 11   #define BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP
12   12  
13   #include <boost/corosio/detail/config.hpp> 13   #include <boost/corosio/detail/config.hpp>
14   #include <boost/corosio/detail/platform.hpp> 14   #include <boost/corosio/detail/platform.hpp>
15   #include <boost/corosio/detail/except.hpp> 15   #include <boost/corosio/detail/except.hpp>
16   #include <boost/corosio/detail/native_handle.hpp> 16   #include <boost/corosio/detail/native_handle.hpp>
17   #include <boost/corosio/detail/buffer_param.hpp> 17   #include <boost/corosio/detail/buffer_param.hpp>
18   #include <boost/corosio/file_base.hpp> 18   #include <boost/corosio/file_base.hpp>
19   #include <boost/corosio/io/io_object.hpp> 19   #include <boost/corosio/io/io_object.hpp>
20   #include <boost/capy/io_result.hpp> 20   #include <boost/capy/io_result.hpp>
21   #include <boost/capy/ex/executor_ref.hpp> 21   #include <boost/capy/ex/executor_ref.hpp>
22   #include <boost/capy/ex/execution_context.hpp> 22   #include <boost/capy/ex/execution_context.hpp>
23   #include <boost/capy/ex/io_env.hpp> 23   #include <boost/capy/ex/io_env.hpp>
24   #include <boost/capy/concept/executor.hpp> 24   #include <boost/capy/concept/executor.hpp>
25   #include <boost/capy/buffers.hpp> 25   #include <boost/capy/buffers.hpp>
26   26  
27   #include <concepts> 27   #include <concepts>
28   #include <coroutine> 28   #include <coroutine>
29   #include <cstddef> 29   #include <cstddef>
30   #include <cstdint> 30   #include <cstdint>
31   #include <type_traits> 31   #include <type_traits>
32   #include <filesystem> 32   #include <filesystem>
33   #include <stop_token> 33   #include <stop_token>
34   #include <system_error> 34   #include <system_error>
35   35  
36   namespace boost::corosio { 36   namespace boost::corosio {
37   37  
38   /** An asynchronous random-access file for coroutine I/O. 38   /** An asynchronous random-access file for coroutine I/O.
39   39  
40   Provides asynchronous read and write operations at explicit 40   Provides asynchronous read and write operations at explicit
41   byte offsets, without maintaining an implicit file position. 41   byte offsets, without maintaining an implicit file position.
42   42  
43   On POSIX platforms, file I/O is dispatched to a thread pool 43   On POSIX platforms, file I/O is dispatched to a thread pool
44   (blocking `preadv`/`pwritev`) with completion posted back to 44   (blocking `preadv`/`pwritev`) with completion posted back to
45   the scheduler. On Windows, true overlapped I/O is used via IOCP. 45   the scheduler. On Windows, true overlapped I/O is used via IOCP.
46   46  
47   @par Thread Safety 47   @par Thread Safety
48   Distinct objects: Safe.@n 48   Distinct objects: Safe.@n
49   Shared objects: Unsafe. Multiple concurrent reads and writes 49   Shared objects: Unsafe. Multiple concurrent reads and writes
50   are supported from coroutines sharing the same file object, 50   are supported from coroutines sharing the same file object,
51   but external synchronization is required for non-async 51   but external synchronization is required for non-async
52   operations (open, close, size, resize, etc.). 52   operations (open, close, size, resize, etc.).
53   53  
54   @par Example 54   @par Example
55   @par !example random_access_file 55   @par !example random_access_file
56   */ 56   */
57   class BOOST_COROSIO_DECL random_access_file : public io_object 57   class BOOST_COROSIO_DECL random_access_file : public io_object
58   { 58   {
59   public: 59   public:
60   /** Platform-specific random-access file implementation interface. 60   /** Platform-specific random-access file implementation interface.
61   61  
62   Backends derive from this to provide offset-based file I/O. 62   Backends derive from this to provide offset-based file I/O.
63   */ 63   */
64   struct implementation : io_object::implementation 64   struct implementation : io_object::implementation
65   { 65   {
66   /** Initiate a read at the given offset. 66   /** Initiate a read at the given offset.
67   67  
68   @param offset Byte offset into the file. 68   @param offset Byte offset into the file.
69   @param h Coroutine handle to resume on completion. 69   @param h Coroutine handle to resume on completion.
70   @param ex Executor for dispatching the completion. 70   @param ex Executor for dispatching the completion.
71   @param buf The buffer to read into. 71   @param buf The buffer to read into.
72   @param token Stop token for cancellation. 72   @param token Stop token for cancellation.
73   @param ec Output error code. 73   @param ec Output error code.
74   @param bytes_out Output bytes transferred. 74   @param bytes_out Output bytes transferred.
75   @return Coroutine handle to resume immediately. 75   @return Coroutine handle to resume immediately.
76   */ 76   */
77   virtual std::coroutine_handle<> read_some_at( 77   virtual std::coroutine_handle<> read_some_at(
78   std::uint64_t offset, 78   std::uint64_t offset,
79   std::coroutine_handle<> h, 79   std::coroutine_handle<> h,
80   capy::executor_ref ex, 80   capy::executor_ref ex,
81   buffer_param buf, 81   buffer_param buf,
82   std::stop_token token, 82   std::stop_token token,
83   std::error_code* ec, 83   std::error_code* ec,
84   std::size_t* bytes_out) = 0; 84   std::size_t* bytes_out) = 0;
85   85  
86   /** Initiate a write at the given offset. 86   /** Initiate a write at the given offset.
87   87  
88   @param offset Byte offset into the file. 88   @param offset Byte offset into the file.
89   @param h Coroutine handle to resume on completion. 89   @param h Coroutine handle to resume on completion.
90   @param ex Executor for dispatching the completion. 90   @param ex Executor for dispatching the completion.
91   @param buf The buffer to write from. 91   @param buf The buffer to write from.
92   @param token Stop token for cancellation. 92   @param token Stop token for cancellation.
93   @param ec Output error code. 93   @param ec Output error code.
94   @param bytes_out Output bytes transferred. 94   @param bytes_out Output bytes transferred.
95   @return Coroutine handle to resume immediately. 95   @return Coroutine handle to resume immediately.
96   */ 96   */
97   virtual std::coroutine_handle<> write_some_at( 97   virtual std::coroutine_handle<> write_some_at(
98   std::uint64_t offset, 98   std::uint64_t offset,
99   std::coroutine_handle<> h, 99   std::coroutine_handle<> h,
100   capy::executor_ref ex, 100   capy::executor_ref ex,
101   buffer_param buf, 101   buffer_param buf,
102   std::stop_token token, 102   std::stop_token token,
103   std::error_code* ec, 103   std::error_code* ec,
104   std::size_t* bytes_out) = 0; 104   std::size_t* bytes_out) = 0;
105   105  
106   /// Return the platform file descriptor or handle. 106   /// Return the platform file descriptor or handle.
107   virtual native_handle_type native_handle() const noexcept = 0; 107   virtual native_handle_type native_handle() const noexcept = 0;
108   108  
109   /// Cancel pending asynchronous operations. 109   /// Cancel pending asynchronous operations.
110   virtual void cancel() noexcept = 0; 110   virtual void cancel() noexcept = 0;
111   111  
112   /// Return the file size in bytes. 112   /// Return the file size in bytes.
113   virtual std::uint64_t size() const = 0; 113   virtual std::uint64_t size() const = 0;
114   114  
115   /// Resize the file to @p new_size bytes. 115   /// Resize the file to @p new_size bytes.
116   virtual std::error_code resize(std::uint64_t new_size) noexcept = 0; 116   virtual std::error_code resize(std::uint64_t new_size) noexcept = 0;
117   117  
118   /// Synchronize file data to stable storage. 118   /// Synchronize file data to stable storage.
119   virtual std::error_code sync_data() noexcept = 0; 119   virtual std::error_code sync_data() noexcept = 0;
120   120  
121   /// Synchronize file data and metadata to stable storage. 121   /// Synchronize file data and metadata to stable storage.
122   virtual std::error_code sync_all() noexcept = 0; 122   virtual std::error_code sync_all() noexcept = 0;
123   123  
124   /// Release ownership of the native handle. 124   /// Release ownership of the native handle.
125   virtual native_handle_type release() = 0; 125   virtual native_handle_type release() = 0;
126   126  
127   /// Adopt an existing native handle. 127   /// Adopt an existing native handle.
128   virtual std::error_code assign(native_handle_type handle) noexcept = 0; 128   virtual std::error_code assign(native_handle_type handle) noexcept = 0;
129   }; 129   };
130   130  
131   /** Awaitable for async read-at operations. */ 131   /** Awaitable for async read-at operations. */
132   template<class MutableBufferSequence> 132   template<class MutableBufferSequence>
133   struct read_some_at_awaitable 133   struct read_some_at_awaitable
134   { 134   {
135   random_access_file& f_; 135   random_access_file& f_;
136   std::uint64_t offset_; 136   std::uint64_t offset_;
137   MutableBufferSequence buffers_; 137   MutableBufferSequence buffers_;
138   std::stop_token token_; 138   std::stop_token token_;
139   mutable std::error_code ec_; 139   mutable std::error_code ec_;
140   mutable std::size_t bytes_ = 0; 140   mutable std::size_t bytes_ = 0;
141   141  
HITCBC 142   293 read_some_at_awaitable( 142   293 read_some_at_awaitable(
143   random_access_file& f, 143   random_access_file& f,
144   std::uint64_t offset, 144   std::uint64_t offset,
145 - MutableBufferSequence 145 + MutableBufferSequence buffers)
146 - buffers) noexcept(std:: 146 + noexcept(std::is_nothrow_move_constructible_v<MutableBufferSequence>)
147 - is_nothrow_move_constructible_v<  
148 - MutableBufferSequence>)  
HITCBC 149   293 : f_(f) 147   293 : f_(f)
HITCBC 150   293 , offset_(offset) 148   293 , offset_(offset)
HITCBC 151   293 , buffers_(std::move(buffers)) 149   293 , buffers_(std::move(buffers))
152   { 150   {
HITCBC 153   293 } 151   293 }
154   152  
HITCBC 155   293 bool await_ready() const noexcept 153   293 bool await_ready() const noexcept
156   { 154   {
157   // A pre-set ec_ means the initiator failed before 155   // A pre-set ec_ means the initiator failed before
158   // dispatch (e.g. a closed object). 156   // dispatch (e.g. a closed object).
HITCBC 159   293 return static_cast<bool>(ec_) || token_.stop_requested(); 157   293 return static_cast<bool>(ec_) || token_.stop_requested();
160   } 158   }
161   159  
HITCBC 162   291 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept 160   291 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
163   { 161   {
HITCBC 164   291 if (token_.stop_requested()) 162   291 if (token_.stop_requested())
HITCBC 165   4 return {make_error_code(std::errc::operation_canceled), 0}; 163   4 return {make_error_code(std::errc::operation_canceled), 0};
HITCBC 166   287 return {ec_, bytes_}; 164   287 return {ec_, bytes_};
167   } 165   }
168   166  
HITCBC 169   291 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env) 167   291 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
170   -> std::coroutine_handle<> 168   -> std::coroutine_handle<>
171   { 169   {
HITCBC 172   291 token_ = env->stop_token; 170   291 token_ = env->stop_token;
HITCBC 173   873 return f_.get().read_some_at( 171   873 return f_.get().read_some_at(
HITCBC 174   873 offset_, h, env->executor, buffers_, token_, &ec_, &bytes_); 172   873 offset_, h, env->executor, buffers_, token_, &ec_, &bytes_);
175   } 173   }
176   }; 174   };
177   175  
178   /** Awaitable for async write-at operations. */ 176   /** Awaitable for async write-at operations. */
179   template<class ConstBufferSequence> 177   template<class ConstBufferSequence>
180   struct write_some_at_awaitable 178   struct write_some_at_awaitable
181   { 179   {
182   random_access_file& f_; 180   random_access_file& f_;
183   std::uint64_t offset_; 181   std::uint64_t offset_;
184   ConstBufferSequence buffers_; 182   ConstBufferSequence buffers_;
185   std::stop_token token_; 183   std::stop_token token_;
186   mutable std::error_code ec_; 184   mutable std::error_code ec_;
187   mutable std::size_t bytes_ = 0; 185   mutable std::size_t bytes_ = 0;
188   186  
HITCBC 189   43 write_some_at_awaitable( 187   43 write_some_at_awaitable(
190   random_access_file& f, 188   random_access_file& f,
191   std::uint64_t offset, 189   std::uint64_t offset,
192 - ConstBufferSequence 190 + ConstBufferSequence buffers)
193 - buffers) noexcept(std:: 191 + noexcept(std::is_nothrow_move_constructible_v<ConstBufferSequence>)
194 - is_nothrow_move_constructible_v<  
195 - ConstBufferSequence>)  
HITCBC 196   43 : f_(f) 192   43 : f_(f)
HITCBC 197   43 , offset_(offset) 193   43 , offset_(offset)
HITCBC 198   43 , buffers_(std::move(buffers)) 194   43 , buffers_(std::move(buffers))
199   { 195   {
HITCBC 200   43 } 196   43 }
201   197  
HITCBC 202   43 bool await_ready() const noexcept 198   43 bool await_ready() const noexcept
203   { 199   {
204   // A pre-set ec_ means the initiator failed before 200   // A pre-set ec_ means the initiator failed before
205   // dispatch (e.g. a closed object). 201   // dispatch (e.g. a closed object).
HITCBC 206   43 return static_cast<bool>(ec_) || token_.stop_requested(); 202   43 return static_cast<bool>(ec_) || token_.stop_requested();
207   } 203   }
208   204  
HITCBC 209   43 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept 205   43 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
210   { 206   {
HITCBC 211   43 if (token_.stop_requested()) 207   43 if (token_.stop_requested())
HITCBC 212   2 return {make_error_code(std::errc::operation_canceled), 0}; 208   2 return {make_error_code(std::errc::operation_canceled), 0};
HITCBC 213   41 return {ec_, bytes_}; 209   41 return {ec_, bytes_};
214   } 210   }
215   211  
HITCBC 216   41 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env) 212   41 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
217   -> std::coroutine_handle<> 213   -> std::coroutine_handle<>
218   { 214   {
HITCBC 219   41 token_ = env->stop_token; 215   41 token_ = env->stop_token;
HITCBC 220   123 return f_.get().write_some_at( 216   123 return f_.get().write_some_at(
HITCBC 221   123 offset_, h, env->executor, buffers_, token_, &ec_, &bytes_); 217   123 offset_, h, env->executor, buffers_, token_, &ec_, &bytes_);
222   } 218   }
223   }; 219   };
224   220  
225   public: 221   public:
226   /** Destructor. 222   /** Destructor.
227   223  
228   Closes the file if open, cancelling any pending operations. 224   Closes the file if open, cancelling any pending operations.
229   */ 225   */
230   ~random_access_file() override; 226   ~random_access_file() override;
231   227  
232   /** Construct from an execution context. 228   /** Construct from an execution context.
233   229  
234   @param ctx The execution context that will own this file. 230   @param ctx The execution context that will own this file.
235   */ 231   */
236   explicit random_access_file(capy::execution_context& ctx); 232   explicit random_access_file(capy::execution_context& ctx);
237   233  
238   /** Construct from an executor. 234   /** Construct from an executor.
239   235  
240   @param ex The executor whose context will own this file. 236   @param ex The executor whose context will own this file.
241   */ 237   */
242   template<class Ex> 238   template<class Ex>
243   requires(!std::same_as<std::remove_cvref_t<Ex>, random_access_file>) && 239   requires(!std::same_as<std::remove_cvref_t<Ex>, random_access_file>) &&
244   capy::Executor<Ex> 240   capy::Executor<Ex>
HITCBC 245   2 explicit random_access_file(Ex const& ex) : random_access_file(ex.context()) 241   2 explicit random_access_file(Ex const& ex) : random_access_file(ex.context())
246   { 242   {
HITCBC 247   2 } 243   2 }
248   244  
249   /** Move constructor. */ 245   /** Move constructor. */
HITCBC 250   2 random_access_file(random_access_file&& other) noexcept 246   2 random_access_file(random_access_file&& other) noexcept
HITCBC 251   2 : io_object(std::move(other)) 247   2 : io_object(std::move(other))
252   { 248   {
HITCBC 253   2 } 249   2 }
254   250  
255   /** Move assignment operator. */ 251   /** Move assignment operator. */
256   random_access_file& operator=(random_access_file&& other) noexcept 252   random_access_file& operator=(random_access_file&& other) noexcept
257   { 253   {
258   if (this != &other) 254   if (this != &other)
259   { 255   {
260   close(); 256   close();
261   h_ = std::move(other.h_); 257   h_ = std::move(other.h_);
262   } 258   }
263   return *this; 259   return *this;
264   } 260   }
265   261  
266   random_access_file(random_access_file const&) = delete; 262   random_access_file(random_access_file const&) = delete;
267   random_access_file& operator=(random_access_file const&) = delete; 263   random_access_file& operator=(random_access_file const&) = delete;
268   264  
269   /** Open a file. 265   /** Open a file.
270   266  
271   Failures such as a missing file or insufficient permissions 267   Failures such as a missing file or insufficient permissions
272   are expected runtime conditions and are reported through the 268   are expected runtime conditions and are reported through the
273   returned error code. If the file is already open, it is 269   returned error code. If the file is already open, it is
274   closed first. 270   closed first.
275   271  
276   @param path The filesystem path to open. 272   @param path The filesystem path to open.
277   @param mode Bitmask of @ref file_base::flags specifying 273   @param mode Bitmask of @ref file_base::flags specifying
278   access mode and creation behavior. 274   access mode and creation behavior.
279   275  
280   @return The error code, empty on success. 276   @return The error code, empty on success.
281   */ 277   */
282   [[nodiscard]] std::error_code open( 278   [[nodiscard]] std::error_code open(
283   std::filesystem::path const& path, 279   std::filesystem::path const& path,
284   file_base::flags mode = file_base::read_only) noexcept; 280   file_base::flags mode = file_base::read_only) noexcept;
285   281  
286   /** Close the file. 282   /** Close the file.
287   283  
288   Releases file resources. Any pending operations complete 284   Releases file resources. Any pending operations complete
289   with `errc::operation_canceled`. 285   with `errc::operation_canceled`.
290   */ 286   */
291   void close() noexcept; 287   void close() noexcept;
292   288  
293   /** Check if the file is open. */ 289   /** Check if the file is open. */
HITCBC 294   682 bool is_open() const noexcept 290   682 bool is_open() const noexcept
295   { 291   {
296   #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS) 292   #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
297   return h_ && get().native_handle() != ~native_handle_type(0); 293   return h_ && get().native_handle() != ~native_handle_type(0);
298   #else 294   #else
HITCBC 299   682 return h_ && get().native_handle() >= 0; 295   682 return h_ && get().native_handle() >= 0;
300   #endif 296   #endif
301   } 297   }
302   298  
303   /** Read data at the given offset. 299   /** Read data at the given offset.
304   300  
305   @param offset Byte offset into the file. 301   @param offset Byte offset into the file.
306   @param buffers The buffer sequence to read into. 302   @param buffers The buffer sequence to read into.
307   303  
308   @return An awaitable yielding `(error_code, std::size_t)`. 304   @return An awaitable yielding `(error_code, std::size_t)`.
309   305  
310   A closed file reports `errc::bad_file_descriptor`. 306   A closed file reports `errc::bad_file_descriptor`.
311   */ 307   */
312   template<capy::MutableBufferSequence MB> 308   template<capy::MutableBufferSequence MB>
HITCBC 313   293 [[nodiscard]] auto read_some_at(std::uint64_t offset, MB const& buffers) 309   293 [[nodiscard]] auto read_some_at(std::uint64_t offset, MB const& buffers)
314   { 310   {
HITCBC 315   293 read_some_at_awaitable<MB> aw(*this, offset, buffers); 311   293 read_some_at_awaitable<MB> aw(*this, offset, buffers);
HITCBC 316   293 if (!is_open()) 312   293 if (!is_open())
HITCBC 317   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor); 313   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor);
HITCBC 318   293 return aw; 314   293 return aw;
319   } 315   }
320   316  
321   /** Write data at the given offset. 317   /** Write data at the given offset.
322   318  
323   @param offset Byte offset into the file. 319   @param offset Byte offset into the file.
324   @param buffers The buffer sequence to write from. 320   @param buffers The buffer sequence to write from.
325   321  
326   @return An awaitable yielding `(error_code, std::size_t)`. 322   @return An awaitable yielding `(error_code, std::size_t)`.
327   323  
328   A closed file reports `errc::bad_file_descriptor`. 324   A closed file reports `errc::bad_file_descriptor`.
329   */ 325   */
330   template<capy::ConstBufferSequence CB> 326   template<capy::ConstBufferSequence CB>
HITCBC 331   43 [[nodiscard]] auto write_some_at(std::uint64_t offset, CB const& buffers) 327   43 [[nodiscard]] auto write_some_at(std::uint64_t offset, CB const& buffers)
332   { 328   {
HITCBC 333   43 write_some_at_awaitable<CB> aw(*this, offset, buffers); 329   43 write_some_at_awaitable<CB> aw(*this, offset, buffers);
HITCBC 334   43 if (!is_open()) 330   43 if (!is_open())
HITCBC 335   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor); 331   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor);
HITCBC 336   43 return aw; 332   43 return aw;
337   } 333   }
338   334  
339   /** Cancel pending asynchronous operations. */ 335   /** Cancel pending asynchronous operations. */
340   void cancel() noexcept; 336   void cancel() noexcept;
341   337  
342   /** Get the native file descriptor or handle. */ 338   /** Get the native file descriptor or handle. */
343   native_handle_type native_handle() const noexcept; 339   native_handle_type native_handle() const noexcept;
344   340  
345   /** Return the file size in bytes. 341   /** Return the file size in bytes.
346   342  
347   @throws std::system_error If the file is not open, or if the 343   @throws std::system_error If the file is not open, or if the
348   underlying size query fails. 344   underlying size query fails.
349   */ 345   */
350   std::uint64_t size() const; 346   std::uint64_t size() const;
351   347  
352   /** Resize the file to @p new_size bytes. 348   /** Resize the file to @p new_size bytes.
353   349  
354   Failures such as insufficient disk space are reported 350   Failures such as insufficient disk space are reported
355   through the returned error code. A closed file reports 351   through the returned error code. A closed file reports
356   `errc::bad_file_descriptor`. 352   `errc::bad_file_descriptor`.
357   353  
358   @param new_size The new file size. 354   @param new_size The new file size.
359   355  
360   @return The error code, empty on success. 356   @return The error code, empty on success.
361   */ 357   */
362   [[nodiscard]] std::error_code resize(std::uint64_t new_size) noexcept; 358   [[nodiscard]] std::error_code resize(std::uint64_t new_size) noexcept;
363   359  
364   /** Synchronize file data to stable storage. 360   /** Synchronize file data to stable storage.
365   361  
366   Write-back failures such as device I/O errors surface here 362   Write-back failures such as device I/O errors surface here
367   and are reported through the returned error code. A closed 363   and are reported through the returned error code. A closed
368   file reports `errc::bad_file_descriptor`. 364   file reports `errc::bad_file_descriptor`.
369   365  
370   @return The error code, empty on success. 366   @return The error code, empty on success.
371   */ 367   */
372   [[nodiscard]] std::error_code sync_data() noexcept; 368   [[nodiscard]] std::error_code sync_data() noexcept;
373   369  
374   /** Synchronize file data and metadata to stable storage. 370   /** Synchronize file data and metadata to stable storage.
375   371  
376   Write-back failures such as device I/O errors surface here 372   Write-back failures such as device I/O errors surface here
377   and are reported through the returned error code. A closed 373   and are reported through the returned error code. A closed
378   file reports `errc::bad_file_descriptor`. 374   file reports `errc::bad_file_descriptor`.
379   375  
380   @return The error code, empty on success. 376   @return The error code, empty on success.
381   */ 377   */
382   [[nodiscard]] std::error_code sync_all() noexcept; 378   [[nodiscard]] std::error_code sync_all() noexcept;
383   379  
384   /** Release ownership of the native handle. 380   /** Release ownership of the native handle.
385   381  
386   The file object becomes not-open. The caller is 382   The file object becomes not-open. The caller is
387   responsible for closing the returned handle. 383   responsible for closing the returned handle.
388   384  
389   @return The native file descriptor or handle. 385   @return The native file descriptor or handle.
390   386  
391   @throws std::system_error `errc::bad_file_descriptor` if the 387   @throws std::system_error `errc::bad_file_descriptor` if the
392   file is not open. 388   file is not open.
393   */ 389   */
394   native_handle_type release(); 390   native_handle_type release();
395   391  
396   /** Adopt an existing native handle. 392   /** Adopt an existing native handle.
397   393  
398   Closes any currently open file before adopting. 394   Closes any currently open file before adopting.
399   The file object takes ownership of the handle. Handles 395   The file object takes ownership of the handle. Handles
400   created elsewhere may be unsuitable for asynchronous I/O; 396   created elsewhere may be unsuitable for asynchronous I/O;
401   such failures are reported through the returned error code. 397   such failures are reported through the returned error code.
402   398  
403   @param handle The native file descriptor or handle. 399   @param handle The native file descriptor or handle.
404   400  
405   @return The error code, empty on success. 401   @return The error code, empty on success.
406   */ 402   */
407   [[nodiscard]] std::error_code assign(native_handle_type handle) noexcept; 403   [[nodiscard]] std::error_code assign(native_handle_type handle) noexcept;
408   404  
409   protected: 405   protected:
410   /// Construct from a pre-built handle (for native_random_access_file). 406   /// Construct from a pre-built handle (for native_random_access_file).
HITCBC 411   16 explicit random_access_file(handle h) noexcept : io_object(std::move(h)) {} 407   16 explicit random_access_file(handle h) noexcept : io_object(std::move(h)) {}
412   408  
413   private: 409   private:
HITCBC 414   1171 inline implementation& get() const noexcept 410   1171 inline implementation& get() const noexcept
415   { 411   {
HITCBC 416   1171 return *static_cast<implementation*>(h_.get()); 412   1171 return *static_cast<implementation*>(h_.get());
417   } 413   }
418   }; 414   };
419   415  
420   } // namespace boost::corosio 416   } // namespace boost::corosio
421   417  
422   #endif // BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP 418   #endif // BOOST_COROSIO_RANDOM_ACCESS_FILE_HPP