Line data    Source code

       1             : /*
       2             :  *
       3             :  *    Copyright (c) 2020 Project CHIP Authors
       4             :  *
       5             :  *    Licensed under the Apache License, Version 2.0 (the "License");
       6             :  *    you may not use this file except in compliance with the License.
       7             :  *    You may obtain a copy of the License at
       8             :  *
       9             :  *        http://www.apache.org/licenses/LICENSE-2.0
      10             :  *
      11             :  *    Unless required by applicable law or agreed to in writing, software
      12             :  *    distributed under the License is distributed on an "AS IS" BASIS,
      13             :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      14             :  *    See the License for the specific language governing permissions and
      15             :  *    limitations under the License.
      16             :  */
      17             : 
      18             : #include "BufferReader.h"
      19             : 
      20             : #include <lib/core/CHIPEncoding.h>
      21             : 
      22             : #include <string.h>
      23             : #include <type_traits>
      24             : 
      25             : namespace chip {
      26             : namespace Encoding {
      27             : namespace LittleEndian {
      28             : 
      29             : namespace {
      30             : 
      31             : // This helper methods return void and put the value being read into an
      32             : // outparam because that allows us to easily overload on the type of the
      33             : // thing being read.
      34           6 : void ReadHelper(const uint8_t * p, bool * dest)
      35             : {
      36           6 :     *dest = (*p != 0);
      37           6 : }
      38             : 
      39             : template <typename T>
      40      152848 : void ReadHelper(const uint8_t * p, T * dest)
      41             : {
      42             :     std::make_unsigned_t<T> result;
      43      152848 :     memcpy(&result, p, sizeof(result));
      44      152848 :     result = chip::Encoding::LittleEndian::HostSwap(result);
      45             : 
      46      152848 :     *dest = static_cast<T>(result);
      47      152848 : }
      48             : 
      49             : } // anonymous namespace
      50             : 
      51             : template <typename T>
      52      153165 : void Reader::RawReadLowLevelBeCareful(T * retval)
      53             : {
      54             :     static_assert(CHAR_BIT == 8, "Our various sizeof checks rely on bytes and octets being the same thing");
      55             :     static_assert((-1 & 3) == 3, "LittleEndian::BufferReader only works with 2's complement architectures.");
      56             : 
      57      153165 :     VerifyOrReturn(IsSuccess());
      58             : 
      59      153159 :     constexpr size_t data_size = sizeof(T);
      60             : 
      61      153159 :     if (mAvailable < data_size)
      62             :     {
      63         305 :         mStatus = CHIP_ERROR_BUFFER_TOO_SMALL;
      64             :         // Ensure that future reads all fail.
      65         305 :         mAvailable = 0;
      66         305 :         return;
      67             :     }
      68             : 
      69      152854 :     ReadHelper(mReadPtr, retval);
      70      152854 :     mReadPtr += data_size;
      71             : 
      72      152854 :     mAvailable = static_cast<uint16_t>(mAvailable - data_size);
      73             : }
      74             : 
      75        4364 : Reader & Reader::ReadBytes(uint8_t * dest, size_t size)
      76             : {
      77             :     static_assert(CHAR_BIT == 8, "Our various sizeof checks rely on bytes and octets being the same thing");
      78             : 
      79        4364 :     if ((size > UINT16_MAX) || (mAvailable < size))
      80             :     {
      81           0 :         mStatus = CHIP_ERROR_BUFFER_TOO_SMALL;
      82             :         // Ensure that future reads all fail.
      83           0 :         mAvailable = 0;
      84           0 :         return *this;
      85             :     }
      86             : 
      87        4364 :     memcpy(dest, mReadPtr, size);
      88             : 
      89        4364 :     mReadPtr += size;
      90        4364 :     mAvailable = static_cast<uint16_t>(mAvailable - size);
      91        4364 :     return *this;
      92             : }
      93             : 
      94             : // Explicit Read instantiations for the data types we want to support.
      95             : template void Reader::RawReadLowLevelBeCareful(char *);
      96             : template void Reader::RawReadLowLevelBeCareful(bool *);
      97             : template void Reader::RawReadLowLevelBeCareful(int8_t *);
      98             : template void Reader::RawReadLowLevelBeCareful(int16_t *);
      99             : template void Reader::RawReadLowLevelBeCareful(int32_t *);
     100             : template void Reader::RawReadLowLevelBeCareful(int64_t *);
     101             : template void Reader::RawReadLowLevelBeCareful(uint8_t *);
     102             : template void Reader::RawReadLowLevelBeCareful(uint16_t *);
     103             : template void Reader::RawReadLowLevelBeCareful(uint32_t *);
     104             : template void Reader::RawReadLowLevelBeCareful(uint64_t *);
     105             : 
     106             : } // namespace LittleEndian
     107             : } // namespace Encoding
     108             : } // namespace chip