1 //
2 // Copyright (C) 2020 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16
17 #include "update_engine/payload_consumer/vabc_partition_writer.h"
18
19 #include <memory>
20 #include <string>
21 #include <vector>
22
23 #include <libsnapshot/cow_writer.h>
24
25 #include "update_engine/common/cow_operation_convert.h"
26 #include "update_engine/common/utils.h"
27 #include "update_engine/payload_consumer/extent_writer.h"
28 #include "update_engine/payload_consumer/file_descriptor.h"
29 #include "update_engine/payload_consumer/install_plan.h"
30 #include "update_engine/payload_consumer/partition_writer.h"
31 #include "update_engine/payload_consumer/snapshot_extent_writer.h"
32
33 namespace chromeos_update_engine {
34 // Expected layout of COW file:
35 // === Beginning of Cow Image ===
36 // All Source Copy Operations
37 // ========== Label 0 ==========
38 // Operation 0 in PartitionUpdate
39 // ========== Label 1 ==========
40 // Operation 1 in PartitionUpdate
41 // ========== label 2 ==========
42 // Operation 2 in PartitionUpdate
43 // ========== label 3 ==========
44 // .
45 // .
46 // .
47
48 // When resuming, pass |next_op_index_| as label to
49 // |InitializeWithAppend|.
50 // For example, suppose we finished writing SOURCE_COPY, and we finished writing
51 // operation 2 completely. Update is suspended when we are half way through
52 // operation 3.
53 // |cnext_op_index_| would be 3, so we pass 3 as
54 // label to |InitializeWithAppend|. The CowWriter will retain all data before
55 // label 3, Which contains all operation 2's data, but none of operation 3's
56 // data.
57
Init(const InstallPlan * install_plan,bool source_may_exist,size_t next_op_index)58 bool VABCPartitionWriter::Init(const InstallPlan* install_plan,
59 bool source_may_exist,
60 size_t next_op_index) {
61 TEST_AND_RETURN_FALSE(install_plan != nullptr);
62 TEST_AND_RETURN_FALSE(
63 OpenSourcePartition(install_plan->source_slot, source_may_exist));
64 std::optional<std::string> source_path;
65 if (!install_part_.source_path.empty()) {
66 // TODO(zhangkelvin) Make |source_path| a std::optional<std::string>
67 source_path = install_part_.source_path;
68 }
69 cow_writer_ = dynamic_control_->OpenCowWriter(
70 install_part_.name, source_path, install_plan->is_resume);
71 TEST_AND_RETURN_FALSE(cow_writer_ != nullptr);
72
73 // ===== Resume case handling code goes here ====
74 // It is possible that the SOURCE_COPY are already written but
75 // |next_op_index_| is still 0. In this case we discard previously written
76 // SOURCE_COPY, and start over.
77 if (install_plan->is_resume && next_op_index > 0) {
78 LOG(INFO) << "Resuming update on partition `"
79 << partition_update_.partition_name() << "` op index "
80 << next_op_index;
81 TEST_AND_RETURN_FALSE(cow_writer_->InitializeAppend(next_op_index));
82 return true;
83 } else {
84 TEST_AND_RETURN_FALSE(cow_writer_->Initialize());
85 }
86
87 // ==============================================
88
89 // TODO(zhangkelvin) Rewrite this in C++20 coroutine once that's available.
90 auto converted = ConvertToCowOperations(partition_update_.operations(),
91 partition_update_.merge_operations());
92
93 WriteAllCowOps(block_size_, converted, cow_writer_.get(), source_fd_);
94 return true;
95 }
96
WriteAllCowOps(size_t block_size,const std::vector<CowOperation> & converted,android::snapshot::ICowWriter * cow_writer,FileDescriptorPtr source_fd)97 bool VABCPartitionWriter::WriteAllCowOps(
98 size_t block_size,
99 const std::vector<CowOperation>& converted,
100 android::snapshot::ICowWriter* cow_writer,
101 FileDescriptorPtr source_fd) {
102 std::vector<uint8_t> buffer(block_size);
103
104 for (const auto& cow_op : converted) {
105 switch (cow_op.op) {
106 case CowOperation::CowCopy:
107 if (cow_op.src_block == cow_op.dst_block) {
108 continue;
109 }
110 TEST_AND_RETURN_FALSE(
111 cow_writer->AddCopy(cow_op.dst_block, cow_op.src_block));
112 break;
113 case CowOperation::CowReplace:
114 ssize_t bytes_read = 0;
115 TEST_AND_RETURN_FALSE(utils::ReadAll(source_fd,
116 buffer.data(),
117 block_size,
118 cow_op.src_block * block_size,
119 &bytes_read));
120 if (bytes_read <= 0 || static_cast<size_t>(bytes_read) != block_size) {
121 LOG(ERROR) << "source_fd->Read failed: " << bytes_read;
122 return false;
123 }
124 TEST_AND_RETURN_FALSE(cow_writer->AddRawBlocks(
125 cow_op.dst_block, buffer.data(), block_size));
126 break;
127 }
128 }
129
130 return true;
131 }
132
CreateBaseExtentWriter()133 std::unique_ptr<ExtentWriter> VABCPartitionWriter::CreateBaseExtentWriter() {
134 return std::make_unique<SnapshotExtentWriter>(cow_writer_.get());
135 }
136
PerformZeroOrDiscardOperation(const InstallOperation & operation)137 [[nodiscard]] bool VABCPartitionWriter::PerformZeroOrDiscardOperation(
138 const InstallOperation& operation) {
139 for (const auto& extent : operation.dst_extents()) {
140 TEST_AND_RETURN_FALSE(
141 cow_writer_->AddZeroBlocks(extent.start_block(), extent.num_blocks()));
142 }
143 return true;
144 }
145
PerformSourceCopyOperation(const InstallOperation & operation,ErrorCode * error)146 [[nodiscard]] bool VABCPartitionWriter::PerformSourceCopyOperation(
147 const InstallOperation& operation, ErrorCode* error) {
148 // TODO(zhangkelvin) Probably just ignore SOURCE_COPY? They should be taken
149 // care of during Init();
150 return true;
151 }
152
CheckpointUpdateProgress(size_t next_op_index)153 void VABCPartitionWriter::CheckpointUpdateProgress(size_t next_op_index) {
154 // No need to call fsync/sync, as CowWriter flushes after a label is added
155 // added.
156 // if cow_writer_ failed, that means Init() failed. This function shouldn't be
157 // called if Init() fails.
158 TEST_AND_RETURN(cow_writer_ != nullptr);
159 cow_writer_->AddLabel(next_op_index);
160 }
161
FinishedInstallOps()162 [[nodiscard]] bool VABCPartitionWriter::FinishedInstallOps() {
163 // Add a hardcoded magic label to indicate end of all install ops. This label
164 // is needed by filesystem verification, don't remove.
165 TEST_AND_RETURN_FALSE(cow_writer_ != nullptr);
166 return cow_writer_->AddLabel(kEndOfInstallLabel);
167 }
168
~VABCPartitionWriter()169 VABCPartitionWriter::~VABCPartitionWriter() {
170 if (cow_writer_) {
171 cow_writer_->Finalize();
172 }
173 }
174
175 } // namespace chromeos_update_engine
176