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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "content/browser/fileapi/upload_file_system_file_element_reader.h"
      6 
      7 #include <algorithm>
      8 
      9 #include "base/bind.h"
     10 #include "net/base/net_errors.h"
     11 #include "webkit/browser/blob/file_stream_reader.h"
     12 #include "webkit/browser/fileapi/file_system_context.h"
     13 #include "webkit/browser/fileapi/file_system_url.h"
     14 
     15 namespace content {
     16 
     17 UploadFileSystemFileElementReader::UploadFileSystemFileElementReader(
     18     fileapi::FileSystemContext* file_system_context,
     19     const GURL& url,
     20     uint64 range_offset,
     21     uint64 range_length,
     22     const base::Time& expected_modification_time)
     23     : file_system_context_(file_system_context),
     24       url_(url),
     25       range_offset_(range_offset),
     26       range_length_(range_length),
     27       expected_modification_time_(expected_modification_time),
     28       stream_length_(0),
     29       position_(0),
     30       weak_ptr_factory_(this) {
     31 }
     32 
     33 UploadFileSystemFileElementReader::~UploadFileSystemFileElementReader() {
     34 }
     35 
     36 int UploadFileSystemFileElementReader::Init(
     37     const net::CompletionCallback& callback) {
     38   // Reset states.
     39   weak_ptr_factory_.InvalidateWeakPtrs();
     40   stream_length_ = 0;
     41   position_ = 0;
     42 
     43   // Initialize the stream reader and the length.
     44   stream_reader_ =
     45       file_system_context_->CreateFileStreamReader(
     46           file_system_context_->CrackURL(url_),
     47           range_offset_,
     48           expected_modification_time_);
     49   DCHECK(stream_reader_);
     50 
     51   const int64 result = stream_reader_->GetLength(
     52       base::Bind(&UploadFileSystemFileElementReader::OnGetLength,
     53                  weak_ptr_factory_.GetWeakPtr(),
     54                  callback));
     55   if (result >= 0) {
     56     stream_length_ = result;
     57     return net::OK;
     58   }
     59 
     60   // The error code can be casted to int.
     61   return static_cast<int>(result);
     62 }
     63 
     64 uint64 UploadFileSystemFileElementReader::GetContentLength() const {
     65   return std::min(stream_length_, range_length_);
     66 }
     67 
     68 uint64 UploadFileSystemFileElementReader::BytesRemaining() const {
     69   return GetContentLength() - position_;
     70 }
     71 
     72 int UploadFileSystemFileElementReader::Read(
     73     net::IOBuffer* buf,
     74     int buf_length,
     75     const net::CompletionCallback& callback) {
     76   DCHECK_LT(0, buf_length);
     77   DCHECK(stream_reader_);
     78 
     79   const uint64 num_bytes_to_read =
     80       std::min(BytesRemaining(), static_cast<uint64>(buf_length));
     81 
     82   if (num_bytes_to_read == 0)
     83     return 0;
     84 
     85   const int result = stream_reader_->Read(
     86       buf, num_bytes_to_read,
     87       base::Bind(&UploadFileSystemFileElementReader::OnRead,
     88                  weak_ptr_factory_.GetWeakPtr(),
     89                  callback));
     90   if (result >= 0)
     91     OnRead(net::CompletionCallback(), result);
     92   return result;
     93 }
     94 
     95 void UploadFileSystemFileElementReader::OnGetLength(
     96     const net::CompletionCallback& callback,
     97     int64 result) {
     98   if (result >= 0) {
     99     stream_length_ = result;
    100     callback.Run(net::OK);
    101     return;
    102   }
    103   callback.Run(result);
    104 }
    105 
    106 void UploadFileSystemFileElementReader::OnRead(
    107     const net::CompletionCallback& callback,
    108     int result) {
    109   if (result > 0) {
    110     position_ += result;
    111     DCHECK_LE(position_, GetContentLength());
    112   }
    113   if (!callback.is_null())
    114     callback.Run(result);
    115 }
    116 
    117 }  // namespace content
    118