treewide: comply with the OpenBMC style guidelines

The guidelines say cpp source code filenames should be lower_snake_case:
https://github.com/openbmc/docs/blob/master/cpp-style-and-conventions.md#files

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Change-Id: Ia04017b0eb9a65ce1303af5b6dc36e730410fd91
diff --git a/src/fru_utils.cpp b/src/fru_utils.cpp
new file mode 100644
index 0000000..62390c6
--- /dev/null
+++ b/src/fru_utils.cpp
@@ -0,0 +1,789 @@
+/*
+// 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 fru_utils.cpp
+
+#include "fru_utils.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;
+}