1 //
2 // Copyright (C) 2015 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/common/utils.h"
18 #include "update_engine/payload_consumer/xz_extent_writer.h"
19
20 using google::protobuf::RepeatedPtrField;
21
22 namespace chromeos_update_engine {
23
24 namespace {
25 const brillo::Blob::size_type kOutputBufferLength = 16 * 1024;
26
27 // xz uses a variable dictionary size which impacts on the compression ratio
28 // and is required to be reconstructed in RAM during decompression. While we
29 // control the required memory from the compressor side, the decompressor allows
30 // to set a limit on this dictionary size, rejecting compressed streams that
31 // require more than that. "xz -9" requires up to 64 MiB, so a 64 MiB limit
32 // will allow compressed streams up to -9, the maximum compression setting.
33 const uint32_t kXzMaxDictSize = 64 * 1024 * 1024;
34
XzErrorString(enum xz_ret error)35 const char* XzErrorString(enum xz_ret error) {
36 #define __XZ_ERROR_STRING_CASE(code) \
37 case code: \
38 return #code;
39 switch (error) {
40 __XZ_ERROR_STRING_CASE(XZ_OK)
41 __XZ_ERROR_STRING_CASE(XZ_STREAM_END)
42 __XZ_ERROR_STRING_CASE(XZ_UNSUPPORTED_CHECK)
43 __XZ_ERROR_STRING_CASE(XZ_MEM_ERROR)
44 __XZ_ERROR_STRING_CASE(XZ_MEMLIMIT_ERROR)
45 __XZ_ERROR_STRING_CASE(XZ_FORMAT_ERROR)
46 __XZ_ERROR_STRING_CASE(XZ_OPTIONS_ERROR)
47 __XZ_ERROR_STRING_CASE(XZ_DATA_ERROR)
48 __XZ_ERROR_STRING_CASE(XZ_BUF_ERROR)
49 default:
50 return "<unknown xz error>";
51 }
52 #undef __XZ_ERROR_STRING_CASE
53 }
54 } // namespace
55
~XzExtentWriter()56 XzExtentWriter::~XzExtentWriter() {
57 stream_.reset();
58 TEST_AND_RETURN(input_buffer_.empty());
59 }
60
Init(const RepeatedPtrField<Extent> & extents,uint32_t block_size)61 bool XzExtentWriter::Init(const RepeatedPtrField<Extent>& extents,
62 uint32_t block_size) {
63 stream_.reset(xz_dec_init(XZ_DYNALLOC, kXzMaxDictSize));
64 TEST_AND_RETURN_FALSE(stream_ != nullptr);
65 return underlying_writer_->Init(extents, block_size);
66 }
67
Write(const void * bytes,size_t count)68 bool XzExtentWriter::Write(const void* bytes, size_t count) {
69 // Copy the input data into |input_buffer_| only if |input_buffer_| already
70 // contains unconsumed data. Otherwise, process the data directly from the
71 // source.
72 const uint8_t* input = reinterpret_cast<const uint8_t*>(bytes);
73 if (!input_buffer_.empty()) {
74 input_buffer_.insert(input_buffer_.end(), input, input + count);
75 input = input_buffer_.data();
76 count = input_buffer_.size();
77 }
78
79 xz_buf request{};
80 request.in = input;
81 request.in_pos = 0;
82 request.in_size = count;
83
84 brillo::Blob output_buffer(kOutputBufferLength);
85 request.out = output_buffer.data();
86 request.out_size = output_buffer.size();
87 for (;;) {
88 request.out_pos = 0;
89
90 xz_ret ret = xz_dec_run(stream_.get(), &request);
91 if (ret != XZ_OK && ret != XZ_STREAM_END) {
92 LOG(ERROR) << "xz_dec_run returned " << XzErrorString(ret);
93 return false;
94 }
95
96 if (request.out_pos == 0)
97 break;
98
99 TEST_AND_RETURN_FALSE(
100 underlying_writer_->Write(output_buffer.data(), request.out_pos));
101 if (ret == XZ_STREAM_END)
102 CHECK_EQ(request.in_size, request.in_pos);
103 if (request.in_size == request.in_pos)
104 break; // No more input to process.
105 }
106 output_buffer.clear();
107
108 // Store unconsumed data (if any) in |input_buffer_|. Since |input| can point
109 // to the existing |input_buffer_| we create a new one before assigning it.
110 brillo::Blob new_input_buffer(request.in + request.in_pos,
111 request.in + request.in_size);
112 input_buffer_ = std::move(new_input_buffer);
113 return true;
114 }
115
116 } // namespace chromeos_update_engine
117