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