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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/split_file_writer.h" |
| 6 #include <algorithm> |
| 7 |
| 8 using std::min; |
| 9 |
| 10 namespace chromeos_update_engine { |
| 11 |
| 12 int SplitFileWriter::Open(const char* path, int flags, mode_t mode) { |
| 13 int first_result = first_file_writer_->Open(first_path_, |
| 14 first_flags_, |
| 15 first_mode_); |
| 16 if (first_result < 0) { |
| 17 LOG(ERROR) << "Error opening first file " << first_path_; |
| 18 return first_result; |
| 19 } |
| 20 int second_result = second_file_writer_->Open(path, flags, mode); |
| 21 if (second_result < 0) { |
| 22 LOG(ERROR) << "Error opening second file " << path; |
| 23 first_file_writer_->Close(); |
| 24 return second_result; |
| 25 } |
| 26 return second_result; |
| 27 } |
| 28 |
| 29 namespace { |
| 30 ssize_t PerformWrite(FileWriter* writer, const void* bytes, size_t count) { |
| 31 int rc = writer->Write(bytes, count); |
| 32 if (rc < 0) { |
| 33 LOG(ERROR) << "Write failed to file."; |
| 34 return rc; |
| 35 } |
| 36 if (rc != static_cast<int>(count)) { |
| 37 LOG(ERROR) << "Not all bytes successfully written to file."; |
| 38 return -EIO; |
| 39 } |
| 40 return rc; |
| 41 } |
| 42 } |
| 43 |
| 44 ssize_t SplitFileWriter::Write(const void* bytes, size_t count) { |
| 45 const size_t original_count = count; |
| 46 |
| 47 // This first block is trying to read the first sizeof(uint64_t) |
| 48 // bytes, which are the number of bytes that should be written |
| 49 // to the first FileWriter. |
| 50 if (bytes_received_ < static_cast<off_t>(sizeof(uint64_t))) { |
| 51 // Write more to the initial buffer |
| 52 size_t bytes_to_copy = min(count, |
| 53 sizeof(first_length_buf_) - bytes_received_); |
| 54 memcpy(&first_length_buf_[bytes_received_], bytes, bytes_to_copy); |
| 55 bytes_received_ += bytes_to_copy; |
| 56 count -= bytes_to_copy; |
| 57 bytes = static_cast<const void*>( |
| 58 static_cast<const char*>(bytes) + bytes_to_copy); |
| 59 |
| 60 // See if we have all we need |
| 61 if (bytes_received_ == sizeof(first_length_buf_)) { |
| 62 // Parse first number |
| 63 uint64_t big_endian_first_length; |
| 64 memcpy(&big_endian_first_length, first_length_buf_, |
| 65 sizeof(big_endian_first_length)); |
| 66 first_length_ = be64toh(big_endian_first_length); |
| 67 } |
| 68 if (count == 0) |
| 69 return original_count; |
| 70 } |
| 71 CHECK_GE(bytes_received_, static_cast<off_t>(sizeof(uint64_t))); |
| 72 |
| 73 // This block of code is writing to the first FileWriter. |
| 74 if (bytes_received_ - static_cast<off_t>(sizeof(uint64_t)) < first_length_) { |
| 75 // Write to first FileWriter |
| 76 size_t bytes_to_write = min( |
| 77 first_length_ - |
| 78 (bytes_received_ - static_cast<off_t>(sizeof(uint64_t))), |
| 79 static_cast<off_t>(count)); |
| 80 |
| 81 int rc = PerformWrite(first_file_writer_, bytes, bytes_to_write); |
| 82 if (rc != static_cast<int>(bytes_to_write)) |
| 83 return rc; |
| 84 |
| 85 bytes_received_ += bytes_to_write; |
| 86 count -= bytes_to_write; |
| 87 bytes = static_cast<const void*>( |
| 88 static_cast<const char*>(bytes) + bytes_to_write); |
| 89 if (count == 0) |
| 90 return original_count; |
| 91 } |
| 92 |
| 93 CHECK_GE(static_cast<off_t>(bytes_received_), |
| 94 first_length_ + static_cast<off_t>(sizeof(uint64_t))); |
| 95 // Write to second FileWriter |
| 96 int rc = PerformWrite(second_file_writer_, bytes, count); |
| 97 if (rc != static_cast<int>(count)) |
| 98 return rc; |
| 99 return original_count; |
| 100 } |
| 101 |
| 102 int SplitFileWriter::Close() { |
| 103 int first_result = first_file_writer_->Close(); |
| 104 if (first_result < 0) |
| 105 LOG(ERROR) << "Error Close()ing first file."; |
| 106 int second_result = second_file_writer_->Close(); |
| 107 if (second_result < 0) |
| 108 LOG(ERROR) << "Error Close()ing second file."; |
| 109 // Return error if either had returned error. |
| 110 return second_result < 0 ? second_result : first_result; |
| 111 } |
| 112 |
| 113 } // namespace chromeos_update_engine |
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