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| 1 // Copyright (c) 2010 The Chromium OS 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 "update_engine/buffered_file_writer.h" |
| 6 |
| 7 namespace chromeos_update_engine { |
| 8 |
| 9 BufferedFileWriter::BufferedFileWriter(FileWriter* next, size_t buffer_size) |
| 10 : next_(next), |
| 11 buffer_(new char[buffer_size]), |
| 12 buffer_size_(buffer_size), |
| 13 buffered_bytes_(0) {} |
| 14 |
| 15 BufferedFileWriter::~BufferedFileWriter() {} |
| 16 |
| 17 int BufferedFileWriter::Open(const char* path, int flags, mode_t mode) { |
| 18 return next_->Open(path, flags, mode); |
| 19 } |
| 20 |
| 21 ssize_t BufferedFileWriter::Write(const void* bytes, size_t count) { |
| 22 size_t copied_bytes = 0; |
| 23 while (copied_bytes < count) { |
| 24 // Buffers as many bytes as possible. |
| 25 size_t remaining_free = buffer_size_ - buffered_bytes_; |
| 26 size_t copy_bytes = count - copied_bytes; |
| 27 if (copy_bytes > remaining_free) { |
| 28 copy_bytes = remaining_free; |
| 29 } |
| 30 const char* char_bytes = reinterpret_cast<const char*>(bytes); |
| 31 memcpy(&buffer_[buffered_bytes_], char_bytes + copied_bytes, copy_bytes); |
| 32 buffered_bytes_ += copy_bytes; |
| 33 copied_bytes += copy_bytes; |
| 34 |
| 35 // If full, sends the buffer to the next FileWriter. |
| 36 if (buffered_bytes_ == buffer_size_) { |
| 37 ssize_t rc = WriteBuffer(); |
| 38 if (rc < 0) |
| 39 return rc; |
| 40 } |
| 41 } |
| 42 return count; |
| 43 } |
| 44 |
| 45 int BufferedFileWriter::Close() { |
| 46 // Flushes the buffer first, then closes the next FileWriter. |
| 47 ssize_t rc_write = WriteBuffer(); |
| 48 int rc_close = next_->Close(); |
| 49 return (rc_write < 0) ? rc_write : rc_close; |
| 50 } |
| 51 |
| 52 ssize_t BufferedFileWriter::WriteBuffer() { |
| 53 if (buffered_bytes_ == 0) |
| 54 return 0; |
| 55 ssize_t rc = next_->Write(&buffer_[0], buffered_bytes_); |
| 56 buffered_bytes_ = 0; |
| 57 return rc; |
| 58 } |
| 59 |
| 60 } // namespace chromeos_update_engine |
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