| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef PPAPI_CPP_FILE_IO_H_ |
| #define PPAPI_CPP_FILE_IO_H_ |
| |
| #include <stdint.h> |
| |
| #include "ppapi/c/pp_time.h" |
| #include "ppapi/cpp/completion_callback.h" |
| #include "ppapi/cpp/resource.h" |
| |
| /// @file |
| /// This file defines the API to create a file i/o object. |
| |
| struct PP_FileInfo; |
| |
| namespace pp { |
| |
| class FileRef; |
| class InstanceHandle; |
| |
| /// The <code>FileIO</code> class represents a regular file. |
| class FileIO : public Resource { |
| public: |
| /// Default constructor for creating an is_null() <code>FileIO</code> |
| /// object. |
| FileIO(); |
| |
| /// A constructor used to create a <code>FileIO</code> and associate it with |
| /// the provided <code>Instance</code>. |
| /// |
| /// @param[in] instance The instance with which this resource will be |
| /// associated. |
| explicit FileIO(const InstanceHandle& instance); |
| |
| /// The copy constructor for <code>FileIO</code>. |
| /// |
| /// @param[in] other A reference to a <code>FileIO</code>. |
| FileIO(const FileIO& other); |
| |
| /// Open() opens the specified regular file for I/O according to the given |
| /// open flags, which is a bit-mask of the PP_FileOpenFlags values. Upon |
| /// success, the corresponding file is classified as "in use" by this FileIO |
| /// object until such time as the FileIO object is closed or destroyed. |
| /// |
| /// @param[in] file_ref A <code>PP_Resource</code> corresponding to a file |
| /// reference. |
| /// |
| /// @param[in] open_flags A bit-mask of the <code>PP_FileOpenFlags</code> |
| /// values. Valid values are: |
| /// - PP_FILEOPENFLAG_READ |
| /// - PP_FILEOPENFLAG_WRITE |
| /// - PP_FILEOPENFLAG_CREATE |
| /// - PP_FILEOPENFLAG_TRUNCATE |
| /// - PP_FILEOPENFLAG_EXCLUSIVE |
| /// See <code>PP_FileOpenFlags</code> in <code>ppb_file_io.h</code> for more |
| /// details on these flags. |
| /// |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Open(). |
| /// |
| /// @return An int32_t containing an error code from |
| /// <code>pp_errors.h</code>. |
| int32_t Open(const FileRef& file_ref, |
| int32_t open_flags, |
| const CompletionCallback& cc); |
| |
| /// Query() queries info about the file opened by this FileIO object. This |
| /// function will fail if the FileIO object has not been opened. |
| /// |
| /// @param[in] result_buf The <code>PP_FileInfo</code> structure representing |
| /// all information about the file. |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Query(). <code>result_buf</code> must remain valid until |
| /// after the callback runs. If you pass a blocking callback, |
| /// <code>result_buf</code> must remain valid until after Query() returns. |
| /// |
| /// @return An int32_t containing an error code from |
| /// <code>pp_errors.h</code>. |
| int32_t Query(PP_FileInfo* result_buf, |
| const CompletionCallback& cc); |
| |
| /// Touch() Updates time stamps for the file opened by this FileIO object. |
| /// This function will fail if the FileIO object has not been opened. |
| /// |
| /// @param[in] last_access_time The last time the FileIO was accessed. |
| /// @param[in] last_modified_time The last time the FileIO was modified. |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Touch(). |
| /// |
| /// @return An int32_t containing an error code from |
| /// <code>pp_errors.h</code>. |
| int32_t Touch(PP_Time last_access_time, |
| PP_Time last_modified_time, |
| const CompletionCallback& cc); |
| |
| /// Reads from an offset in the file. |
| /// |
| /// The size of the buffer must be large enough to hold the specified number |
| /// of bytes to read. This function might perform a partial read, meaning |
| /// that all the requested bytes might not be returned, even if the end of the |
| /// file has not been reached. |
| /// |
| /// This function reads into a buffer that the caller supplies. This buffer |
| /// must remain valid as long as the FileIO resource is alive. If you use |
| /// a completion callback factory and it goes out of scope, it will not issue |
| /// the callback on your class, BUT the callback factory can NOT cancel |
| /// the request from the browser's perspective. This means that the browser |
| /// will still try to write to your buffer even if the callback factory is |
| /// destroyed! |
| /// |
| /// So you must ensure that your buffer outlives the FileIO resource. If you |
| /// have one class and use the FileIO resource exclusively from that class |
| /// and never make any copies, this will be fine: the resource will be |
| /// destroyed when your class is. But keep in mind that copying a pp::FileIO |
| /// object just creates a second reference to the original resource. For |
| /// example, if you have a function like this: |
| /// pp::FileIO MyClass::GetFileIO(); |
| /// where a copy of your FileIO resource could outlive your class, the |
| /// callback will still be pending when your class goes out of scope, creating |
| /// the possibility of writing into invalid memory. So it's recommended to |
| /// keep your FileIO resource and any output buffers tightly controlled in |
| /// the same scope. |
| /// |
| /// <strong>Caveat:</strong> This Read() is potentially unsafe if you're using |
| /// a CompletionCallbackFactory to scope callbacks to the lifetime of your |
| /// class. When your class goes out of scope, the callback factory will not |
| /// actually cancel the callback, but will rather just skip issuing the |
| /// callback on your class. This means that if the FileIO object outlives |
| /// your class (if you made a copy saved somewhere else, for example), then |
| /// the browser will still try to write into your buffer when the |
| /// asynchronous read completes, potentially causing a crash. |
| /// |
| /// See the other version of Read() which avoids this problem by writing into |
| /// CompletionCallbackWithOutput, where the output buffer is automatically |
| /// managed by the callback. |
| /// |
| /// @param[in] offset The offset into the file. |
| /// @param[in] buffer The buffer to hold the specified number of bytes read. |
| /// @param[in] bytes_to_read The number of bytes to read from |
| /// <code>offset</code>. |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Read(). <code>buffer</code> must remain valid until after |
| /// the callback runs. If you pass a blocking callback, <code>buffer</code> |
| /// must remain valid until after Read() returns. |
| /// |
| /// @return An The number of bytes read an error code from |
| /// <code>pp_errors.h</code>. If the return value is 0, then end-of-file was |
| /// reached. It is valid to call Read() multiple times with a completion |
| /// callback to queue up parallel reads from the file at different offsets. |
| int32_t Read(int64_t offset, |
| char* buffer, |
| int32_t bytes_to_read, |
| const CompletionCallback& cc); |
| |
| /// Read() reads from an offset in the file. A PP_ArrayOutput must be |
| /// provided so that output will be stored in its allocated buffer. This |
| /// function might perform a partial read. |
| /// |
| /// @param[in] file_io A <code>PP_Resource</code> corresponding to a file |
| /// FileIO. |
| /// @param[in] offset The offset into the file. |
| /// @param[in] max_read_length The maximum number of bytes to read from |
| /// <code>offset</code>. |
| /// @param[in] output A <code>PP_ArrayOutput</code> to hold the output data. |
| /// @param[in] callback A <code>PP_CompletionCallback</code> to be called upon |
| /// completion of Read(). |
| /// |
| /// @return The number of bytes read or an error code from |
| /// <code>pp_errors.h</code>. If the return value is 0, then end-of-file was |
| /// reached. It is valid to call Read() multiple times with a completion |
| /// callback to queue up parallel reads from the file, but pending reads |
| /// cannot be interleaved with other operations. |
| int32_t Read(int32_t offset, |
| int32_t max_read_length, |
| const CompletionCallbackWithOutput< std::vector<char> >& cc); |
| |
| /// Write() writes to an offset in the file. This function might perform a |
| /// partial write. The FileIO object must have been opened with write access. |
| /// |
| /// @param[in] offset The offset into the file. |
| /// @param[in] buffer The buffer to hold the specified number of bytes read. |
| /// @param[in] bytes_to_write The number of bytes to write to |
| /// <code>offset</code>. |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Write(). |
| /// |
| /// @return An The number of bytes written or an error code from |
| /// <code>pp_errors.h</code>. If the return value is 0, then end-of-file was |
| /// reached. It is valid to call Write() multiple times with a completion |
| /// callback to queue up parallel writes to the file at different offsets. |
| int32_t Write(int64_t offset, |
| const char* buffer, |
| int32_t bytes_to_write, |
| const CompletionCallback& cc); |
| |
| /// SetLength() sets the length of the file. If the file size is extended, |
| /// then the extended area of the file is zero-filled. The FileIO object must |
| /// have been opened with write access. |
| /// |
| /// @param[in] length The length of the file to be set. |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of SetLength(). |
| /// |
| /// @return An int32_t containing an error code from |
| /// <code>pp_errors.h</code>. |
| int32_t SetLength(int64_t length, |
| const CompletionCallback& cc); |
| |
| /// Flush() flushes changes to disk. This call can be very expensive! |
| /// |
| /// @param[in] cc A <code>CompletionCallback</code> to be called upon |
| /// completion of Flush(). |
| /// |
| /// @return An int32_t containing an error code from |
| /// <code>pp_errors.h</code>. |
| int32_t Flush(const CompletionCallback& cc); |
| |
| /// Close() cancels any IO that may be pending, and closes the FileIO object. |
| /// Any pending callbacks will still run, reporting |
| /// <code>PP_ERROR_ABORTED</code> if pending IO was interrupted. It is not |
| /// valid to call Open() again after a call to this method. |
| /// |
| /// <strong>Note:</strong> If the FileIO object is destroyed, and it is still |
| /// open, then it will be implicitly closed, so you are not required to call |
| /// Close(). |
| void Close(); |
| |
| private: |
| struct CallbackData1_0 { |
| PP_ArrayOutput output; |
| char* temp_buffer; |
| PP_CompletionCallback original_callback; |
| }; |
| |
| // Provide backwards-compatibility for older Read versions. Converts the |
| // old-style "char*" output buffer of 1.0 to the new "PP_ArrayOutput" |
| // interface in 1.1. |
| // |
| // This takes a heap-allocated CallbackData1_0 struct passed as the user data |
| // and deletes it when the call completes. |
| static void CallbackConverter(void* user_data, int32_t result); |
| }; |
| |
| } // namespace pp |
| |
| #endif // PPAPI_CPP_FILE_IO_H_ |