1 //
2 // Copyright (C) 2010 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_generator/bzip.h"
18
19 #include <bzlib.h>
20 #include <stdlib.h>
21
22 #include <algorithm>
23 #include <limits>
24
25 #include "update_engine/common/utils.h"
26
27 namespace chromeos_update_engine {
28
BzipCompress(const brillo::Blob & in,brillo::Blob * out)29 bool BzipCompress(const brillo::Blob& in, brillo::Blob* out) {
30 TEST_AND_RETURN_FALSE(out);
31 out->clear();
32 if (in.size() == 0)
33 return true;
34
35 // We expect a compression ratio of about 35% with bzip2, so we start with
36 // that much output space, which will then be doubled if needed.
37 size_t buf_size = 40 + in.size() * 35 / 100;
38 out->resize(buf_size);
39
40 // Try increasing buffer size until it works
41 for (;;) {
42 if (buf_size > std::numeric_limits<uint32_t>::max())
43 return false;
44 uint32_t data_size = buf_size;
45 int rc = BZ2_bzBuffToBuffCompress(
46 reinterpret_cast<char*>(out->data()),
47 &data_size,
48 reinterpret_cast<char*>(const_cast<uint8_t*>(in.data())),
49 in.size(),
50 9, // Best compression
51 0, // Silent verbosity
52 0); // Default work factor
53 TEST_AND_RETURN_FALSE(rc == BZ_OUTBUFF_FULL || rc == BZ_OK);
54 if (rc == BZ_OK) {
55 // we're done!
56 out->resize(data_size);
57 return true;
58 }
59
60 // Data didn't fit; double the buffer size.
61 buf_size *= 2;
62 out->resize(buf_size);
63 }
64 }
65
66 } // namespace chromeos_update_engine
67