src/FruUtils.cpp - openbmc/entity-manager - Gitiles

 /*
 // Copyright (c) 2018 Intel Corporation
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 */
 /// \file FruUtils.cpp

 #include "FruUtils.hpp"

 #include <array>
 #include <cstdint>
 #include <filesystem>
 #include <iostream>
 #include <numeric>
 #include <set>
 #include <string>
 #include <vector>

 extern "C"
 {
 // Include for I2C_SMBUS_BLOCK_MAX
 #include <linux/i2c.h>
 }

 static constexpr bool debug = false;
 constexpr size_t fruVersion = 1; // Current FRU spec version number is 1

 std::tm intelEpoch(void)
 {
     std::tm val = {};
     val.tm_year = 1996 - 1900;
     val.tm_mday = 1;
     return val;
 }

 char sixBitToChar(uint8_t val)
 {
     return static_cast<char>((val & 0x3f) + ' ');
 }

 char bcdPlusToChar(uint8_t val)
 {
     val &= 0xf;
     return (val < 10) ? static_cast<char>(val + '0') : bcdHighChars[val - 10];
 }

 enum FRUDataEncoding
 {
     binary = 0x0,
     bcdPlus = 0x1,
     sixBitASCII = 0x2,
     languageDependent = 0x3,
 };

 /* Decode FRU data into a std::string, given an input iterator and end. If the
  * state returned is fruDataOk, then the resulting string is the decoded FRU
  * data. The input iterator is advanced past the data consumed.
  *
  * On fruDataErr, we have lost synchronisation with the length bytes, so the
  * iterator is no longer usable.
  */
 std::pair<DecodeState, std::string>
     decodeFRUData(std::vector<uint8_t>::const_iterator& iter,
                   const std::vector<uint8_t>::const_iterator& end,
                   bool isLangEng)
 {
     std::string value;
     unsigned int i;

     /* we need at least one byte to decode the type/len header */
     if (iter == end)
     {
         std::cerr << "Truncated FRU data\n";
         return make_pair(DecodeState::err, value);
     }

     uint8_t c = *(iter++);

     /* 0xc1 is the end marker */
     if (c == 0xc1)
     {
         return make_pair(DecodeState::end, value);
     }

     /* decode type/len byte */
     uint8_t type = static_cast<uint8_t>(c >> 6);
     uint8_t len = static_cast<uint8_t>(c & 0x3f);

     /* we should have at least len bytes of data available overall */
     if (iter + len > end)
     {
         std::cerr << "FRU data field extends past end of FRU area data\n";
         return make_pair(DecodeState::err, value);
     }

     switch (type)
     {
         case FRUDataEncoding::binary:
         {
             std::stringstream ss;
             ss << std::hex << std::setfill('0');
             for (i = 0; i < len; i++, iter++)
             {
                 uint8_t val = static_cast<uint8_t>(*iter);
                 ss << std::setw(2) << static_cast<int>(val);
             }
             value = ss.str();
             break;
         }
         case FRUDataEncoding::languageDependent:
             /* For language-code dependent encodings, assume 8-bit ASCII */
             value = std::string(iter, iter + len);
             iter += len;

             /* English text is encoded in 8-bit ASCII + Latin 1. All other
              * languages are required to use 2-byte unicode. FruDevice does not
              * handle unicode.
              */
             if (!isLangEng)
             {
                 std::cerr << "Error: Non english string is not supported \n";
                 return make_pair(DecodeState::err, value);
             }

             break;

         case FRUDataEncoding::bcdPlus:
             value = std::string();
             for (i = 0; i < len; i++, iter++)
             {
                 uint8_t val = *iter;
                 value.push_back(bcdPlusToChar(val >> 4));
                 value.push_back(bcdPlusToChar(val & 0xf));
             }
             break;

         case FRUDataEncoding::sixBitASCII:
         {
             unsigned int accum = 0;
             unsigned int accumBitLen = 0;
             value = std::string();
             for (i = 0; i < len; i++, iter++)
             {
                 accum |= *iter << accumBitLen;
                 accumBitLen += 8;
                 while (accumBitLen >= 6)
                 {
                     value.push_back(sixBitToChar(accum & 0x3f));
                     accum >>= 6;
                     accumBitLen -= 6;
                 }
             }
         }
         break;
     }

     return make_pair(DecodeState::ok, value);
 }

 bool checkLangEng(uint8_t lang)
 {
     // If Lang is not English then the encoding is defined as 2-byte UNICODE,
     // but we don't support that.
     if (lang && lang != 25)
     {
         std::cerr << "Warning: languages other than English is not "
                      "supported\n";
         // Return language flag as non english
         return false;
     }
     return true;
 }

 /* This function verifies for other offsets to check if they are not
  * falling under other field area
  *
  * fruBytes:    Start of Fru data
  * currentArea: Index of current area offset to be compared against all area
  *              offset and it is a multiple of 8 bytes as per specification
  * len:         Length of current area space and it is a multiple of 8 bytes
  *              as per specification
  */
 bool verifyOffset(const std::vector<uint8_t>& fruBytes, fruAreas currentArea,
                   uint8_t len)
 {

     unsigned int fruBytesSize = fruBytes.size();

     // check if Fru data has at least 8 byte header
     if (fruBytesSize <= fruBlockSize)
     {
         std::cerr << "Error: trying to parse empty FRU\n";
         return false;
     }

     // Check range of passed currentArea value
     if (currentArea > fruAreas::fruAreaMultirecord)
     {
         std::cerr << "Error: Fru area is out of range\n";
         return false;
     }

     unsigned int currentAreaIndex = getHeaderAreaFieldOffset(currentArea);
     if (currentAreaIndex > fruBytesSize)
     {
         std::cerr << "Error: Fru area index is out of range\n";
         return false;
     }

     unsigned int start = fruBytes[currentAreaIndex];
     unsigned int end = start + len;

     /* Verify each offset within the range of start and end */
     for (fruAreas area = fruAreas::fruAreaInternal;
          area <= fruAreas::fruAreaMultirecord; ++area)
     {
         // skip the current offset
         if (area == currentArea)
         {
             continue;
         }

         unsigned int areaIndex = getHeaderAreaFieldOffset(area);
         if (areaIndex > fruBytesSize)
         {
             std::cerr << "Error: Fru area index is out of range\n";
             return false;
         }

         unsigned int areaOffset = fruBytes[areaIndex];
         // if areaOffset is 0 means this area is not available so skip
         if (areaOffset == 0)
         {
             continue;
         }

         // check for overlapping of current offset with given areaoffset
         if (areaOffset == start || (areaOffset > start && areaOffset < end))
         {
             std::cerr << getFruAreaName(currentArea)
                       << " offset is overlapping with " << getFruAreaName(area)
                       << " offset\n";
             return false;
         }
     }
     return true;
 }

 resCodes
     formatIPMIFRU(const std::vector<uint8_t>& fruBytes,
                   boost::container::flat_map<std::string, std::string>& result)
 {
     resCodes ret = resCodes::resOK;
     if (fruBytes.size() <= fruBlockSize)
     {
         std::cerr << "Error: trying to parse empty FRU \n";
         return resCodes::resErr;
     }
     result["Common_Format_Version"] =
         std::to_string(static_cast<int>(*fruBytes.begin()));

     const std::vector<std::string>* fruAreaFieldNames;

     // Don't parse Internal and Multirecord areas
     for (fruAreas area = fruAreas::fruAreaChassis;
          area <= fruAreas::fruAreaProduct; ++area)
     {

         size_t offset = *(fruBytes.begin() + getHeaderAreaFieldOffset(area));
         if (offset == 0)
         {
             continue;
         }
         offset *= fruBlockSize;
         std::vector<uint8_t>::const_iterator fruBytesIter =
             fruBytes.begin() + offset;
         if (fruBytesIter + fruBlockSize >= fruBytes.end())
         {
             std::cerr << "Not enough data to parse \n";
             return resCodes::resErr;
         }
         // check for format version 1
         if (*fruBytesIter != 0x01)
         {
             std::cerr << "Unexpected version " << *fruBytesIter << "\n";
             return resCodes::resErr;
         }
         ++fruBytesIter;

         /* Verify other area offset for overlap with current area by passing
          * length of current area offset pointed by *fruBytesIter
          */
         if (!verifyOffset(fruBytes, area, *fruBytesIter))
         {
             return resCodes::resErr;
         }

         size_t fruAreaSize = *fruBytesIter * fruBlockSize;
         std::vector<uint8_t>::const_iterator fruBytesIterEndArea =
             fruBytes.begin() + offset + fruAreaSize - 1;
         ++fruBytesIter;

         uint8_t fruComputedChecksum =
             calculateChecksum(fruBytes.begin() + offset, fruBytesIterEndArea);
         if (fruComputedChecksum != *fruBytesIterEndArea)
         {
             std::stringstream ss;
             ss << std::hex << std::setfill('0');
             ss << "Checksum error in FRU area " << getFruAreaName(area) << "\n";
             ss << "\tComputed checksum: 0x" << std::setw(2)
                << static_cast<int>(fruComputedChecksum) << "\n";
             ss << "\tThe read checksum: 0x" << std::setw(2)
                << static_cast<int>(*fruBytesIterEndArea) << "\n";
             std::cerr << ss.str();
             ret = resCodes::resWarn;
         }

         /* Set default language flag to true as Chassis Fru area are always
          * encoded in English defined in Section 10 of Fru specification
          */

         bool isLangEng = true;
         switch (area)
         {
             case fruAreas::fruAreaChassis:
             {
                 result["CHASSIS_TYPE"] =
                     std::to_string(static_cast<int>(*fruBytesIter));
                 fruBytesIter += 1;
                 fruAreaFieldNames = &chassisFruAreas;
                 break;
             }
             case fruAreas::fruAreaBoard:
             {
                 uint8_t lang = *fruBytesIter;
                 result["BOARD_LANGUAGE_CODE"] =
                     std::to_string(static_cast<int>(lang));
                 isLangEng = checkLangEng(lang);
                 fruBytesIter += 1;

                 unsigned int minutes = *fruBytesIter |
                                        *(fruBytesIter + 1) << 8 |
                                        *(fruBytesIter + 2) << 16;
                 std::tm fruTime = intelEpoch();
                 std::time_t timeValue = std::mktime(&fruTime);
                 timeValue += minutes * 60;
                 fruTime = *std::gmtime(&timeValue);

                 // Tue Nov 20 23:08:00 2018
                 char timeString[32] = {0};
                 auto bytes = std::strftime(timeString, sizeof(timeString),
                                            "%Y-%m-%d - %H:%M:%S", &fruTime);
                 if (bytes == 0)
                 {
                     std::cerr << "invalid time string encountered\n";
                     return resCodes::resErr;
                 }

                 result["BOARD_MANUFACTURE_DATE"] = std::string(timeString);
                 fruBytesIter += 3;
                 fruAreaFieldNames = &boardFruAreas;
                 break;
             }
             case fruAreas::fruAreaProduct:
             {
                 uint8_t lang = *fruBytesIter;
                 result["PRODUCT_LANGUAGE_CODE"] =
                     std::to_string(static_cast<int>(lang));
                 isLangEng = checkLangEng(lang);
                 fruBytesIter += 1;
                 fruAreaFieldNames = &productFruAreas;
                 break;
             }
             default:
             {
                 std::cerr << "Internal error: unexpected FRU area index: "
                           << static_cast<int>(area) << " \n";
                 return resCodes::resErr;
             }
         }
         size_t fieldIndex = 0;
         DecodeState state;
         do
         {
             auto res =
                 decodeFRUData(fruBytesIter, fruBytesIterEndArea, isLangEng);
             state = res.first;
             std::string value = res.second;
             std::string name;
             if (fieldIndex < fruAreaFieldNames->size())
             {
                 name = std::string(getFruAreaName(area)) + "_" +
                        fruAreaFieldNames->at(fieldIndex);
             }
             else
             {
                 name =
                     std::string(getFruAreaName(area)) + "_" +
                     fruCustomFieldName +
                     std::to_string(fieldIndex - fruAreaFieldNames->size() + 1);
             }

             if (state == DecodeState::ok)
             {
                 // Strip non null characters from the end
                 value.erase(std::find_if(value.rbegin(), value.rend(),
                                          [](char ch) { return ch != 0; })
                                 .base(),
                             value.end());

                 result[name] = std::move(value);
                 ++fieldIndex;
             }
             else if (state == DecodeState::err)
             {
                 std::cerr << "Error while parsing " << name << "\n";
                 ret = resCodes::resWarn;
                 // Cancel decoding if failed to parse any of mandatory
                 // fields
                 if (fieldIndex < fruAreaFieldNames->size())
                 {
                     std::cerr << "Failed to parse mandatory field \n";
                     return resCodes::resErr;
                 }
             }
             else
             {
                 if (fieldIndex < fruAreaFieldNames->size())
                 {
                     std::cerr << "Mandatory fields absent in FRU area "
                               << getFruAreaName(area) << " after " << name
                               << "\n";
                     ret = resCodes::resWarn;
                 }
             }
         } while (state == DecodeState::ok);
         for (; fruBytesIter < fruBytesIterEndArea; fruBytesIter++)
         {
             uint8_t c = *fruBytesIter;
             if (c)
             {
                 std::cerr << "Non-zero byte after EndOfFields in FRU area "
                           << getFruAreaName(area) << "\n";
                 ret = resCodes::resWarn;
                 break;
             }
         }
     }

     return ret;
 }

 // Calculate new checksum for fru info area
 uint8_t calculateChecksum(std::vector<uint8_t>::const_iterator iter,
                           std::vector<uint8_t>::const_iterator end)
 {
     constexpr int checksumMod = 256;
     uint8_t sum = std::accumulate(iter, end, static_cast<uint8_t>(0));
     return (checksumMod - sum) % checksumMod;
 }

 uint8_t calculateChecksum(std::vector<uint8_t>& fruAreaData)
 {
     return calculateChecksum(fruAreaData.begin(), fruAreaData.end());
 }

 // Update new fru area length &
 // Update checksum at new checksum location
 // Return the offset of the area checksum byte
 unsigned int updateFRUAreaLenAndChecksum(std::vector<uint8_t>& fruData,
                                          size_t fruAreaStart,
                                          size_t fruAreaEndOfFieldsOffset,
                                          size_t fruAreaEndOffset)
 {
     size_t traverseFRUAreaIndex = fruAreaEndOfFieldsOffset - fruAreaStart;

     // fill zeros for any remaining unused space
     std::fill(fruData.begin() + fruAreaEndOfFieldsOffset,
               fruData.begin() + fruAreaEndOffset, 0);

     size_t mod = traverseFRUAreaIndex % fruBlockSize;
     size_t checksumLoc;
     if (!mod)
     {
         traverseFRUAreaIndex += (fruBlockSize);
         checksumLoc = fruAreaEndOfFieldsOffset + (fruBlockSize - 1);
     }
     else
     {
         traverseFRUAreaIndex += (fruBlockSize - mod);
         checksumLoc = fruAreaEndOfFieldsOffset + (fruBlockSize - mod - 1);
     }

     size_t newFRUAreaLen = (traverseFRUAreaIndex / fruBlockSize) +
                            ((traverseFRUAreaIndex % fruBlockSize) != 0);
     size_t fruAreaLengthLoc = fruAreaStart + 1;
     fruData[fruAreaLengthLoc] = static_cast<uint8_t>(newFRUAreaLen);

     // Calculate new checksum
     std::vector<uint8_t> finalFRUData;
     std::copy_n(fruData.begin() + fruAreaStart, checksumLoc - fruAreaStart,
                 std::back_inserter(finalFRUData));

     fruData[checksumLoc] = calculateChecksum(finalFRUData);
     return checksumLoc;
 }

 ssize_t getFieldLength(uint8_t fruFieldTypeLenValue)
 {
     constexpr uint8_t typeLenMask = 0x3F;
     constexpr uint8_t endOfFields = 0xC1;
     if (fruFieldTypeLenValue == endOfFields)
     {
         return -1;
     }
     return fruFieldTypeLenValue & typeLenMask;
 }

 bool validateHeader(const std::array<uint8_t, I2C_SMBUS_BLOCK_MAX>& blockData)
 {
     // ipmi spec format version number is currently at 1, verify it
     if (blockData[0] != fruVersion)
     {
         if (debug)
         {
             std::cerr << "FRU spec version " << (int)(blockData[0])
                       << " not supported. Supported version is "
                       << (int)(fruVersion) << "\n";
         }
         return false;
     }

     // verify pad is set to 0
     if (blockData[6] != 0x0)
     {
         if (debug)
         {
             std::cerr << "PAD value in header is non zero, value is "
                       << (int)(blockData[6]) << "\n";
         }
         return false;
     }

     // verify offsets are 0, or don't point to another offset
     std::set<uint8_t> foundOffsets;
     for (int ii = 1; ii < 6; ii++)
     {
         if (blockData[ii] == 0)
         {
             continue;
         }
         auto inserted = foundOffsets.insert(blockData[ii]);
         if (!inserted.second)
         {
             return false;
         }
     }

     // validate checksum
     size_t sum = 0;
     for (int jj = 0; jj < 7; jj++)
     {
         sum += blockData[jj];
     }
     sum = (256 - sum) & 0xFF;

     if (sum != blockData[7])
     {
         if (debug)
         {
             std::cerr << "Checksum " << (int)(blockData[7])
                       << " is invalid. calculated checksum is " << (int)(sum)
                       << "\n";
         }
         return false;
     }
     return true;
 }

 bool findFRUHeader(int flag, int file, uint16_t address,
                    const ReadBlockFunc& readBlock, const std::string& errorHelp,
                    std::array<uint8_t, I2C_SMBUS_BLOCK_MAX>& blockData,
                    off_t& baseOffset)
 {
     if (readBlock(flag, file, address, baseOffset, 0x8, blockData.data()) < 0)
     {
         std::cerr << "failed to read " << errorHelp << " base offset "
                   << baseOffset << "\n";
         return false;
     }

     // check the header checksum
     if (validateHeader(blockData))
     {
         return true;
     }

     // only continue the search if we just looked at 0x0.
     if (baseOffset != 0)
     {
         return false;
     }

     // now check for special cases where the IPMI data is at an offset

     // check if blockData starts with tyanHeader
     const std::vector<uint8_t> tyanHeader = {'$', 'T', 'Y', 'A', 'N', '$'};
     if (blockData.size() >= tyanHeader.size() &&
         std::equal(tyanHeader.begin(), tyanHeader.end(), blockData.begin()))
     {
         // look for the FRU header at offset 0x6000
         baseOffset = 0x6000;
         return findFRUHeader(flag, file, address, readBlock, errorHelp,
                              blockData, baseOffset);
     }

     if (debug)
     {
         std::cerr << "Illegal header " << errorHelp << " base offset "
                   << baseOffset << "\n";
     }

     return false;
 }

 std::vector<uint8_t> readFRUContents(int flag, int file, uint16_t address,
                                      const ReadBlockFunc& readBlock,
                                      const std::string& errorHelp)
 {
     std::array<uint8_t, I2C_SMBUS_BLOCK_MAX> blockData;
     off_t baseOffset = 0x0;

     if (!findFRUHeader(flag, file, address, readBlock, errorHelp, blockData,
                        baseOffset))
     {
         return {};
     }

     std::vector<uint8_t> device;
     device.insert(device.end(), blockData.begin(), blockData.begin() + 8);

     bool hasMultiRecords = false;
     size_t fruLength = fruBlockSize; // At least FRU header is present
     unsigned int prevOffset = 0;
     for (fruAreas area = fruAreas::fruAreaInternal;
          area <= fruAreas::fruAreaMultirecord; ++area)
     {
         // Offset value can be 255.
         unsigned int areaOffset = device[getHeaderAreaFieldOffset(area)];
         if (areaOffset == 0)
         {
             continue;
         }

         /* Check for offset order, as per Section 17 of FRU specification, FRU
          * information areas are required to be in order in FRU data layout
          * which means all offset value should be in increasing order or can be
          * 0 if that area is not present
          */
         if (areaOffset <= prevOffset)
         {
             std::cerr << "Fru area offsets are not in required order as per "
                          "Section 17 of Fru specification\n";
             return {};
         }
         prevOffset = areaOffset;

         // MultiRecords are different. area is not tracking section, it's
         // walking the common header.
         if (area == fruAreas::fruAreaMultirecord)
         {
             hasMultiRecords = true;
             break;
         }

         areaOffset *= fruBlockSize;

         if (readBlock(flag, file, address, baseOffset + areaOffset, 0x2,
                       blockData.data()) < 0)
         {
             std::cerr << "failed to read " << errorHelp << " base offset "
                       << baseOffset << "\n";
             return {};
         }

         // Ignore data type (blockData is already unsigned).
         size_t length = blockData[1] * fruBlockSize;
         areaOffset += length;
         fruLength = (areaOffset > fruLength) ? areaOffset : fruLength;
     }

     if (hasMultiRecords)
     {
         // device[area count] is the index to the last area because the 0th
         // entry is not an offset in the common header.
         unsigned int areaOffset =
             device[getHeaderAreaFieldOffset(fruAreas::fruAreaMultirecord)];
         areaOffset *= fruBlockSize;

         // the multi-area record header is 5 bytes long.
         constexpr size_t multiRecordHeaderSize = 5;
         constexpr uint8_t multiRecordEndOfListMask = 0x80;

         // Sanity hard-limit to 64KB.
         while (areaOffset < std::numeric_limits<uint16_t>::max())
         {
             // In multi-area, the area offset points to the 0th record, each
             // record has 3 bytes of the header we care about.
             if (readBlock(flag, file, address, baseOffset + areaOffset, 0x3,
                           blockData.data()) < 0)
             {
                 std::cerr << "failed to read " << errorHelp << " base offset "
                           << baseOffset << "\n";
                 return {};
             }

             // Ok, let's check the record length, which is in bytes (unsigned,
             // up to 255, so blockData should hold uint8_t not char)
             size_t recordLength = blockData[2];
             areaOffset += (recordLength + multiRecordHeaderSize);
             fruLength = (areaOffset > fruLength) ? areaOffset : fruLength;

             // If this is the end of the list bail.
             if ((blockData[1] & multiRecordEndOfListMask))
             {
                 break;
             }
         }
     }

     // You already copied these first 8 bytes (the ipmi fru header size)
     fruLength -= std::min(fruBlockSize, fruLength);

     int readOffset = fruBlockSize;

     while (fruLength > 0)
     {
         size_t requestLength =
             std::min(static_cast<size_t>(I2C_SMBUS_BLOCK_MAX), fruLength);

         if (readBlock(flag, file, address, baseOffset + readOffset,
                       requestLength, blockData.data()) < 0)
         {
             std::cerr << "failed to read " << errorHelp << " base offset "
                       << baseOffset << "\n";
             return {};
         }

         device.insert(device.end(), blockData.begin(),
                       blockData.begin() + requestLength);

         readOffset += requestLength;
         fruLength -= std::min(requestLength, fruLength);
     }

     return device;
 }

 unsigned int getHeaderAreaFieldOffset(fruAreas area)
 {
     return static_cast<unsigned int>(area) + 1;
 }

 std::vector<uint8_t>& getFRUInfo(const uint8_t& bus, const uint8_t& address)
 {
     auto deviceMap = busMap.find(bus);
     if (deviceMap == busMap.end())
     {
         throw std::invalid_argument("Invalid Bus.");
     }
     auto device = deviceMap->second->find(address);
     if (device == deviceMap->second->end())
     {
         throw std::invalid_argument("Invalid Address.");
     }
     std::vector<uint8_t>& ret = device->second;

     return ret;
 }
	/*
	// Copyright (c) 2018 Intel Corporation
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.
	*/
	/// \file FruUtils.cpp

	#include "FruUtils.hpp"

	#include <array>
	#include <cstdint>
	#include <filesystem>
	#include <iostream>
	#include <numeric>
	#include <set>
	#include <string>
	#include <vector>

	extern "C"
	{
	// Include for I2C_SMBUS_BLOCK_MAX
	#include <linux/i2c.h>
	}

	static constexpr bool debug = false;
	constexpr size_t fruVersion = 1; // Current FRU spec version number is 1

	std::tm intelEpoch(void)
	{
	std::tm val = {};
	val.tm_year = 1996 - 1900;
	val.tm_mday = 1;
	return val;
	}

	char sixBitToChar(uint8_t val)
	{
	return static_cast<char>((val & 0x3f) + ' ');
	}

	char bcdPlusToChar(uint8_t val)
	{
	val &= 0xf;
	return (val < 10) ? static_cast<char>(val + '0') : bcdHighChars[val - 10];
	}

	enum FRUDataEncoding
	{
	binary = 0x0,
	bcdPlus = 0x1,
	sixBitASCII = 0x2,
	languageDependent = 0x3,
	};

	/* Decode FRU data into a std::string, given an input iterator and end. If the
	* state returned is fruDataOk, then the resulting string is the decoded FRU
	* data. The input iterator is advanced past the data consumed.
	*
	* On fruDataErr, we have lost synchronisation with the length bytes, so the
	* iterator is no longer usable.
	*/
	std::pair<DecodeState, std::string>
	decodeFRUData(std::vector<uint8_t>::const_iterator& iter,
	const std::vector<uint8_t>::const_iterator& end,
	bool isLangEng)
	{
	std::string value;
	unsigned int i;

	/* we need at least one byte to decode the type/len header */
	if (iter == end)
	{
	std::cerr << "Truncated FRU data\n";
	return make_pair(DecodeState::err, value);
	}

	uint8_t c = *(iter++);

	/* 0xc1 is the end marker */
	if (c == 0xc1)
	{
	return make_pair(DecodeState::end, value);
	}

	/* decode type/len byte */
	uint8_t type = static_cast<uint8_t>(c >> 6);
	uint8_t len = static_cast<uint8_t>(c & 0x3f);

	/* we should have at least len bytes of data available overall */
	if (iter + len > end)
	{
	std::cerr << "FRU data field extends past end of FRU area data\n";
	return make_pair(DecodeState::err, value);
	}

	switch (type)
	{
	case FRUDataEncoding::binary:
	{
	std::stringstream ss;
	ss << std::hex << std::setfill('0');
	for (i = 0; i < len; i++, iter++)
	{
	uint8_t val = static_cast<uint8_t>(*iter);
	ss << std::setw(2) << static_cast<int>(val);
	}
	value = ss.str();
	break;
	}
	case FRUDataEncoding::languageDependent:
	/* For language-code dependent encodings, assume 8-bit ASCII */
	value = std::string(iter, iter + len);
	iter += len;

	/* English text is encoded in 8-bit ASCII + Latin 1. All other
	* languages are required to use 2-byte unicode. FruDevice does not
	* handle unicode.
	*/
	if (!isLangEng)
	{
	std::cerr << "Error: Non english string is not supported \n";
	return make_pair(DecodeState::err, value);
	}

	break;

	case FRUDataEncoding::bcdPlus:
	value = std::string();
	for (i = 0; i < len; i++, iter++)
	{
	uint8_t val = *iter;
	value.push_back(bcdPlusToChar(val >> 4));
	value.push_back(bcdPlusToChar(val & 0xf));
	}
	break;

	case FRUDataEncoding::sixBitASCII:
	{
	unsigned int accum = 0;
	unsigned int accumBitLen = 0;
	value = std::string();
	for (i = 0; i < len; i++, iter++)
	{
	accum \|= *iter << accumBitLen;
	accumBitLen += 8;
	while (accumBitLen >= 6)
	{
	value.push_back(sixBitToChar(accum & 0x3f));
	accum >>= 6;
	accumBitLen -= 6;
	}
	}
	}
	break;
	}

	return make_pair(DecodeState::ok, value);
	}

	bool checkLangEng(uint8_t lang)
	{
	// If Lang is not English then the encoding is defined as 2-byte UNICODE,
	// but we don't support that.
	if (lang && lang != 25)
	{
	std::cerr << "Warning: languages other than English is not "
	"supported\n";
	// Return language flag as non english
	return false;
	}
	return true;
	}

	/* This function verifies for other offsets to check if they are not
	* falling under other field area
	*
	* fruBytes: Start of Fru data
	* currentArea: Index of current area offset to be compared against all area
	* offset and it is a multiple of 8 bytes as per specification
	* len: Length of current area space and it is a multiple of 8 bytes
	* as per specification
	*/
	bool verifyOffset(const std::vector<uint8_t>& fruBytes, fruAreas currentArea,
	uint8_t len)
	{

	unsigned int fruBytesSize = fruBytes.size();

	// check if Fru data has at least 8 byte header
	if (fruBytesSize <= fruBlockSize)
	{
	std::cerr << "Error: trying to parse empty FRU\n";
	return false;
	}

	// Check range of passed currentArea value
	if (currentArea > fruAreas::fruAreaMultirecord)
	{
	std::cerr << "Error: Fru area is out of range\n";
	return false;
	}

	unsigned int currentAreaIndex = getHeaderAreaFieldOffset(currentArea);
	if (currentAreaIndex > fruBytesSize)
	{
	std::cerr << "Error: Fru area index is out of range\n";
	return false;
	}

	unsigned int start = fruBytes[currentAreaIndex];
	unsigned int end = start + len;

	/* Verify each offset within the range of start and end */
	for (fruAreas area = fruAreas::fruAreaInternal;
	area <= fruAreas::fruAreaMultirecord; ++area)
	{
	// skip the current offset
	if (area == currentArea)
	{
	continue;
	}

	unsigned int areaIndex = getHeaderAreaFieldOffset(area);
	if (areaIndex > fruBytesSize)
	{
	std::cerr << "Error: Fru area index is out of range\n";
	return false;
	}

	unsigned int areaOffset = fruBytes[areaIndex];
	// if areaOffset is 0 means this area is not available so skip
	if (areaOffset == 0)
	{
	continue;
	}

	// check for overlapping of current offset with given areaoffset
	if (areaOffset == start \|\| (areaOffset > start && areaOffset < end))
	{
	std::cerr << getFruAreaName(currentArea)
	<< " offset is overlapping with " << getFruAreaName(area)
	<< " offset\n";
	return false;
	}
	}
	return true;
	}

	resCodes
	formatIPMIFRU(const std::vector<uint8_t>& fruBytes,
	boost::container::flat_map<std::string, std::string>& result)
	{
	resCodes ret = resCodes::resOK;
	if (fruBytes.size() <= fruBlockSize)
	{
	std::cerr << "Error: trying to parse empty FRU \n";
	return resCodes::resErr;
	}
	result["Common_Format_Version"] =
	std::to_string(static_cast<int>(*fruBytes.begin()));

	const std::vector<std::string>* fruAreaFieldNames;

	// Don't parse Internal and Multirecord areas
	for (fruAreas area = fruAreas::fruAreaChassis;
	area <= fruAreas::fruAreaProduct; ++area)
	{

	size_t offset = *(fruBytes.begin() + getHeaderAreaFieldOffset(area));
	if (offset == 0)
	{
	continue;
	}
	offset *= fruBlockSize;
	std::vector<uint8_t>::const_iterator fruBytesIter =
	fruBytes.begin() + offset;
	if (fruBytesIter + fruBlockSize >= fruBytes.end())
	{
	std::cerr << "Not enough data to parse \n";
	return resCodes::resErr;
	}
	// check for format version 1
	if (*fruBytesIter != 0x01)
	{
	std::cerr << "Unexpected version " << *fruBytesIter << "\n";
	return resCodes::resErr;
	}
	++fruBytesIter;

	/* Verify other area offset for overlap with current area by passing
	* length of current area offset pointed by *fruBytesIter
	*/
	if (!verifyOffset(fruBytes, area, *fruBytesIter))
	{
	return resCodes::resErr;
	}

	size_t fruAreaSize = fruBytesIter fruBlockSize;
	std::vector<uint8_t>::const_iterator fruBytesIterEndArea =
	fruBytes.begin() + offset + fruAreaSize - 1;
	++fruBytesIter;

	uint8_t fruComputedChecksum =
	calculateChecksum(fruBytes.begin() + offset, fruBytesIterEndArea);
	if (fruComputedChecksum != *fruBytesIterEndArea)
	{
	std::stringstream ss;
	ss << std::hex << std::setfill('0');
	ss << "Checksum error in FRU area " << getFruAreaName(area) << "\n";
	ss << "\tComputed checksum: 0x" << std::setw(2)
	<< static_cast<int>(fruComputedChecksum) << "\n";
	ss << "\tThe read checksum: 0x" << std::setw(2)
	<< static_cast<int>(*fruBytesIterEndArea) << "\n";
	std::cerr << ss.str();
	ret = resCodes::resWarn;
	}

	/* Set default language flag to true as Chassis Fru area are always
	* encoded in English defined in Section 10 of Fru specification
	*/

	bool isLangEng = true;
	switch (area)
	{
	case fruAreas::fruAreaChassis:
	{
	result["CHASSIS_TYPE"] =
	std::to_string(static_cast<int>(*fruBytesIter));
	fruBytesIter += 1;
	fruAreaFieldNames = &chassisFruAreas;
	break;
	}
	case fruAreas::fruAreaBoard:
	{
	uint8_t lang = *fruBytesIter;
	result["BOARD_LANGUAGE_CODE"] =
	std::to_string(static_cast<int>(lang));
	isLangEng = checkLangEng(lang);
	fruBytesIter += 1;

	unsigned int minutes = *fruBytesIter \|
	*(fruBytesIter + 1) << 8 \|
	*(fruBytesIter + 2) << 16;
	std::tm fruTime = intelEpoch();
	std::time_t timeValue = std::mktime(&fruTime);
	timeValue += minutes * 60;
	fruTime = *std::gmtime(&timeValue);

	// Tue Nov 20 23:08:00 2018
	char timeString[32] = {0};
	auto bytes = std::strftime(timeString, sizeof(timeString),
	"%Y-%m-%d - %H:%M:%S", &fruTime);
	if (bytes == 0)
	{
	std::cerr << "invalid time string encountered\n";
	return resCodes::resErr;
	}

	result["BOARD_MANUFACTURE_DATE"] = std::string(timeString);
	fruBytesIter += 3;
	fruAreaFieldNames = &boardFruAreas;
	break;
	}
	case fruAreas::fruAreaProduct:
	{
	uint8_t lang = *fruBytesIter;
	result["PRODUCT_LANGUAGE_CODE"] =
	std::to_string(static_cast<int>(lang));
	isLangEng = checkLangEng(lang);
	fruBytesIter += 1;
	fruAreaFieldNames = &productFruAreas;
	break;
	}
	default:
	{
	std::cerr << "Internal error: unexpected FRU area index: "
	<< static_cast<int>(area) << " \n";
	return resCodes::resErr;
	}
	}
	size_t fieldIndex = 0;
	DecodeState state;
	do
	{
	auto res =
	decodeFRUData(fruBytesIter, fruBytesIterEndArea, isLangEng);
	state = res.first;
	std::string value = res.second;
	std::string name;
	if (fieldIndex < fruAreaFieldNames->size())
	{
	name = std::string(getFruAreaName(area)) + "_" +
	fruAreaFieldNames->at(fieldIndex);
	}
	else
	{
	name =
	std::string(getFruAreaName(area)) + "_" +
	fruCustomFieldName +
	std::to_string(fieldIndex - fruAreaFieldNames->size() + 1);
	}

	if (state == DecodeState::ok)
	{
	// Strip non null characters from the end
	value.erase(std::find_if(value.rbegin(), value.rend(),
	[](char ch) { return ch != 0; })
	.base(),
	value.end());

	result[name] = std::move(value);
	++fieldIndex;
	}
	else if (state == DecodeState::err)
	{
	std::cerr << "Error while parsing " << name << "\n";
	ret = resCodes::resWarn;
	// Cancel decoding if failed to parse any of mandatory
	// fields
	if (fieldIndex < fruAreaFieldNames->size())
	{
	std::cerr << "Failed to parse mandatory field \n";
	return resCodes::resErr;
	}
	}
	else
	{
	if (fieldIndex < fruAreaFieldNames->size())
	{
	std::cerr << "Mandatory fields absent in FRU area "
	<< getFruAreaName(area) << " after " << name
	<< "\n";
	ret = resCodes::resWarn;
	}
	}
	} while (state == DecodeState::ok);
	for (; fruBytesIter < fruBytesIterEndArea; fruBytesIter++)
	{
	uint8_t c = *fruBytesIter;
	if (c)
	{
	std::cerr << "Non-zero byte after EndOfFields in FRU area "
	<< getFruAreaName(area) << "\n";
	ret = resCodes::resWarn;
	break;
	}
	}
	}

	return ret;
	}

	// Calculate new checksum for fru info area
	uint8_t calculateChecksum(std::vector<uint8_t>::const_iterator iter,
	std::vector<uint8_t>::const_iterator end)
	{
	constexpr int checksumMod = 256;
	uint8_t sum = std::accumulate(iter, end, static_cast<uint8_t>(0));
	return (checksumMod - sum) % checksumMod;
	}

	uint8_t calculateChecksum(std::vector<uint8_t>& fruAreaData)
	{
	return calculateChecksum(fruAreaData.begin(), fruAreaData.end());
	}

	// Update new fru area length &
	// Update checksum at new checksum location
	// Return the offset of the area checksum byte
	unsigned int updateFRUAreaLenAndChecksum(std::vector<uint8_t>& fruData,
	size_t fruAreaStart,
	size_t fruAreaEndOfFieldsOffset,
	size_t fruAreaEndOffset)
	{
	size_t traverseFRUAreaIndex = fruAreaEndOfFieldsOffset - fruAreaStart;

	// fill zeros for any remaining unused space
	std::fill(fruData.begin() + fruAreaEndOfFieldsOffset,
	fruData.begin() + fruAreaEndOffset, 0);

	size_t mod = traverseFRUAreaIndex % fruBlockSize;
	size_t checksumLoc;
	if (!mod)
	{
	traverseFRUAreaIndex += (fruBlockSize);
	checksumLoc = fruAreaEndOfFieldsOffset + (fruBlockSize - 1);
	}
	else
	{
	traverseFRUAreaIndex += (fruBlockSize - mod);
	checksumLoc = fruAreaEndOfFieldsOffset + (fruBlockSize - mod - 1);
	}

	size_t newFRUAreaLen = (traverseFRUAreaIndex / fruBlockSize) +
	((traverseFRUAreaIndex % fruBlockSize) != 0);
	size_t fruAreaLengthLoc = fruAreaStart + 1;
	fruData[fruAreaLengthLoc] = static_cast<uint8_t>(newFRUAreaLen);

	// Calculate new checksum
	std::vector<uint8_t> finalFRUData;
	std::copy_n(fruData.begin() + fruAreaStart, checksumLoc - fruAreaStart,
	std::back_inserter(finalFRUData));

	fruData[checksumLoc] = calculateChecksum(finalFRUData);
	return checksumLoc;
	}

	ssize_t getFieldLength(uint8_t fruFieldTypeLenValue)
	{
	constexpr uint8_t typeLenMask = 0x3F;
	constexpr uint8_t endOfFields = 0xC1;
	if (fruFieldTypeLenValue == endOfFields)
	{
	return -1;
	}
	return fruFieldTypeLenValue & typeLenMask;
	}

	bool validateHeader(const std::array<uint8_t, I2C_SMBUS_BLOCK_MAX>& blockData)
	{
	// ipmi spec format version number is currently at 1, verify it
	if (blockData[0] != fruVersion)
	{
	if (debug)
	{
	std::cerr << "FRU spec version " << (int)(blockData[0])
	<< " not supported. Supported version is "
	<< (int)(fruVersion) << "\n";
	}
	return false;
	}

	// verify pad is set to 0
	if (blockData[6] != 0x0)
	{
	if (debug)
	{
	std::cerr << "PAD value in header is non zero, value is "
	<< (int)(blockData[6]) << "\n";
	}
	return false;
	}

	// verify offsets are 0, or don't point to another offset
	std::set<uint8_t> foundOffsets;
	for (int ii = 1; ii < 6; ii++)
	{
	if (blockData[ii] == 0)
	{
	continue;
	}
	auto inserted = foundOffsets.insert(blockData[ii]);
	if (!inserted.second)
	{
	return false;
	}
	}

	// validate checksum
	size_t sum = 0;
	for (int jj = 0; jj < 7; jj++)
	{
	sum += blockData[jj];
	}
	sum = (256 - sum) & 0xFF;

	if (sum != blockData[7])
	{
	if (debug)
	{
	std::cerr << "Checksum " << (int)(blockData[7])
	<< " is invalid. calculated checksum is " << (int)(sum)
	<< "\n";
	}
	return false;
	}
	return true;
	}

	bool findFRUHeader(int flag, int file, uint16_t address,
	const ReadBlockFunc& readBlock, const std::string& errorHelp,
	std::array<uint8_t, I2C_SMBUS_BLOCK_MAX>& blockData,
	off_t& baseOffset)
	{
	if (readBlock(flag, file, address, baseOffset, 0x8, blockData.data()) < 0)
	{
	std::cerr << "failed to read " << errorHelp << " base offset "
	<< baseOffset << "\n";
	return false;
	}

	// check the header checksum
	if (validateHeader(blockData))
	{
	return true;
	}

	// only continue the search if we just looked at 0x0.
	if (baseOffset != 0)
	{
	return false;
	}

	// now check for special cases where the IPMI data is at an offset

	// check if blockData starts with tyanHeader
	const std::vector<uint8_t> tyanHeader = {'$', 'T', 'Y', 'A', 'N', '$'};
	if (blockData.size() >= tyanHeader.size() &&
	std::equal(tyanHeader.begin(), tyanHeader.end(), blockData.begin()))
	{
	// look for the FRU header at offset 0x6000
	baseOffset = 0x6000;
	return findFRUHeader(flag, file, address, readBlock, errorHelp,
	blockData, baseOffset);
	}

	if (debug)
	{
	std::cerr << "Illegal header " << errorHelp << " base offset "
	<< baseOffset << "\n";
	}

	return false;
	}

	std::vector<uint8_t> readFRUContents(int flag, int file, uint16_t address,
	const ReadBlockFunc& readBlock,
	const std::string& errorHelp)
	{
	std::array<uint8_t, I2C_SMBUS_BLOCK_MAX> blockData;
	off_t baseOffset = 0x0;

	if (!findFRUHeader(flag, file, address, readBlock, errorHelp, blockData,
	baseOffset))
	{
	return {};
	}

	std::vector<uint8_t> device;
	device.insert(device.end(), blockData.begin(), blockData.begin() + 8);

	bool hasMultiRecords = false;
	size_t fruLength = fruBlockSize; // At least FRU header is present
	unsigned int prevOffset = 0;
	for (fruAreas area = fruAreas::fruAreaInternal;
	area <= fruAreas::fruAreaMultirecord; ++area)
	{
	// Offset value can be 255.
	unsigned int areaOffset = device[getHeaderAreaFieldOffset(area)];
	if (areaOffset == 0)
	{
	continue;
	}

	/* Check for offset order, as per Section 17 of FRU specification, FRU
	* information areas are required to be in order in FRU data layout
	* which means all offset value should be in increasing order or can be
	* 0 if that area is not present
	*/
	if (areaOffset <= prevOffset)
	{
	std::cerr << "Fru area offsets are not in required order as per "
	"Section 17 of Fru specification\n";
	return {};
	}
	prevOffset = areaOffset;

	// MultiRecords are different. area is not tracking section, it's
	// walking the common header.
	if (area == fruAreas::fruAreaMultirecord)
	{
	hasMultiRecords = true;
	break;
	}

	areaOffset *= fruBlockSize;

	if (readBlock(flag, file, address, baseOffset + areaOffset, 0x2,
	blockData.data()) < 0)
	{
	std::cerr << "failed to read " << errorHelp << " base offset "
	<< baseOffset << "\n";
	return {};
	}

	// Ignore data type (blockData is already unsigned).
	size_t length = blockData[1] * fruBlockSize;
	areaOffset += length;
	fruLength = (areaOffset > fruLength) ? areaOffset : fruLength;
	}

	if (hasMultiRecords)
	{
	// device[area count] is the index to the last area because the 0th
	// entry is not an offset in the common header.
	unsigned int areaOffset =
	device[getHeaderAreaFieldOffset(fruAreas::fruAreaMultirecord)];
	areaOffset *= fruBlockSize;

	// the multi-area record header is 5 bytes long.
	constexpr size_t multiRecordHeaderSize = 5;
	constexpr uint8_t multiRecordEndOfListMask = 0x80;

	// Sanity hard-limit to 64KB.
	while (areaOffset < std::numeric_limits<uint16_t>::max())
	{
	// In multi-area, the area offset points to the 0th record, each
	// record has 3 bytes of the header we care about.
	if (readBlock(flag, file, address, baseOffset + areaOffset, 0x3,
	blockData.data()) < 0)
	{
	std::cerr << "failed to read " << errorHelp << " base offset "
	<< baseOffset << "\n";
	return {};
	}

	// Ok, let's check the record length, which is in bytes (unsigned,
	// up to 255, so blockData should hold uint8_t not char)
	size_t recordLength = blockData[2];
	areaOffset += (recordLength + multiRecordHeaderSize);
	fruLength = (areaOffset > fruLength) ? areaOffset : fruLength;

	// If this is the end of the list bail.
	if ((blockData[1] & multiRecordEndOfListMask))
	{
	break;
	}
	}
	}

	// You already copied these first 8 bytes (the ipmi fru header size)
	fruLength -= std::min(fruBlockSize, fruLength);

	int readOffset = fruBlockSize;

	while (fruLength > 0)
	{
	size_t requestLength =
	std::min(static_cast<size_t>(I2C_SMBUS_BLOCK_MAX), fruLength);

	if (readBlock(flag, file, address, baseOffset + readOffset,
	requestLength, blockData.data()) < 0)
	{
	std::cerr << "failed to read " << errorHelp << " base offset "
	<< baseOffset << "\n";
	return {};
	}

	device.insert(device.end(), blockData.begin(),
	blockData.begin() + requestLength);

	readOffset += requestLength;
	fruLength -= std::min(requestLength, fruLength);
	}

	return device;
	}

	unsigned int getHeaderAreaFieldOffset(fruAreas area)
	{
	return static_cast<unsigned int>(area) + 1;
	}

	std::vector<uint8_t>& getFRUInfo(const uint8_t& bus, const uint8_t& address)
	{
	auto deviceMap = busMap.find(bus);
	if (deviceMap == busMap.end())
	{
	throw std::invalid_argument("Invalid Bus.");
	}
	auto device = deviceMap->second->find(address);
	if (device == deviceMap->second->end())
	{
	throw std::invalid_argument("Invalid Address.");
	}
	std::vector<uint8_t>& ret = device->second;

	return ret;
	}