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 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