// 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 "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_