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      1 //
      2 // Copyright (C) 2009 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/hash_calculator.h"
     18 
     19 #include <fcntl.h>
     20 
     21 #include <base/logging.h>
     22 #include <base/posix/eintr_wrapper.h>
     23 
     24 #include "update_engine/common/utils.h"
     25 
     26 using std::string;
     27 
     28 namespace chromeos_update_engine {
     29 
     30 HashCalculator::HashCalculator() : valid_(false) {
     31   valid_ = (SHA256_Init(&ctx_) == 1);
     32   LOG_IF(ERROR, !valid_) << "SHA256_Init failed";
     33 }
     34 
     35 // Update is called with all of the data that should be hashed in order.
     36 // Mostly just passes the data through to OpenSSL's SHA256_Update()
     37 bool HashCalculator::Update(const void* data, size_t length) {
     38   TEST_AND_RETURN_FALSE(valid_);
     39   TEST_AND_RETURN_FALSE(raw_hash_.empty());
     40   static_assert(sizeof(size_t) <= sizeof(unsigned long),  // NOLINT(runtime/int)
     41                 "length param may be truncated in SHA256_Update");
     42   TEST_AND_RETURN_FALSE(SHA256_Update(&ctx_, data, length) == 1);
     43   return true;
     44 }
     45 
     46 off_t HashCalculator::UpdateFile(const string& name, off_t length) {
     47   int fd = HANDLE_EINTR(open(name.c_str(), O_RDONLY));
     48   if (fd < 0) {
     49     return -1;
     50   }
     51 
     52   const int kBufferSize = 128 * 1024;  // 128 KiB
     53   brillo::Blob buffer(kBufferSize);
     54   off_t bytes_processed = 0;
     55   while (length < 0 || bytes_processed < length) {
     56     off_t bytes_to_read = buffer.size();
     57     if (length >= 0 && bytes_to_read > length - bytes_processed) {
     58       bytes_to_read = length - bytes_processed;
     59     }
     60     ssize_t rc = HANDLE_EINTR(read(fd, buffer.data(), bytes_to_read));
     61     if (rc == 0) {  // EOF
     62       break;
     63     }
     64     if (rc < 0 || !Update(buffer.data(), rc)) {
     65       bytes_processed = -1;
     66       break;
     67     }
     68     bytes_processed += rc;
     69   }
     70   IGNORE_EINTR(close(fd));
     71   return bytes_processed;
     72 }
     73 
     74 // Call Finalize() when all data has been passed in. This mostly just
     75 // calls OpenSSL's SHA256_Final().
     76 bool HashCalculator::Finalize() {
     77   TEST_AND_RETURN_FALSE(raw_hash_.empty());
     78   raw_hash_.resize(SHA256_DIGEST_LENGTH);
     79   TEST_AND_RETURN_FALSE(SHA256_Final(raw_hash_.data(), &ctx_) == 1);
     80   return true;
     81 }
     82 
     83 bool HashCalculator::RawHashOfBytes(const void* data,
     84                                     size_t length,
     85                                     brillo::Blob* out_hash) {
     86   HashCalculator calc;
     87   TEST_AND_RETURN_FALSE(calc.Update(data, length));
     88   TEST_AND_RETURN_FALSE(calc.Finalize());
     89   *out_hash = calc.raw_hash();
     90   return true;
     91 }
     92 
     93 bool HashCalculator::RawHashOfData(const brillo::Blob& data,
     94                                    brillo::Blob* out_hash) {
     95   return RawHashOfBytes(data.data(), data.size(), out_hash);
     96 }
     97 
     98 off_t HashCalculator::RawHashOfFile(const string& name, off_t length,
     99                                     brillo::Blob* out_hash) {
    100   HashCalculator calc;
    101   off_t res = calc.UpdateFile(name, length);
    102   if (res < 0) {
    103     return res;
    104   }
    105   if (!calc.Finalize()) {
    106     return -1;
    107   }
    108   *out_hash = calc.raw_hash();
    109   return res;
    110 }
    111 
    112 string HashCalculator::GetContext() const {
    113   return string(reinterpret_cast<const char*>(&ctx_), sizeof(ctx_));
    114 }
    115 
    116 bool HashCalculator::SetContext(const string& context) {
    117   TEST_AND_RETURN_FALSE(context.size() == sizeof(ctx_));
    118   memcpy(&ctx_, context.data(), sizeof(ctx_));
    119   return true;
    120 }
    121 
    122 }  // namespace chromeos_update_engine
    123