Fix bug in IAB channel code mapping

[cjee21]

As mentioned at the end of #2105 (comment), Cppcheck found an array access that is out of bounds:

Id: arrayIndexOutOfBoundsCond
CWE: 788
Either the condition 'Code>=0x80' is redundant or the array 'Iab_Channel_Values[34]' is accessed at index 104, which is out of bounds.

MediaInfoLib/Source/MediaInfo/Audio/File_Iab.cpp

Lines 117 to 118 in dbed027

	if (Code>=0x80 && Code<sizeof(Iab_Channel_Values)/sizeof(const char*)-0x18)
	return Iab_Channel_Values[Code-0x18];

Upon further inspection and looking at the IAB specs, I concluded that there is indeed a bug.
Since I do not have an IAB test file to test, I wrote a test based on pages 31 and 32 of https://pub.smpte.org/doc/st2098-2/20220525-pub/st2098-2-2022.pdf to test it and confirmed that this PR is needed. The fixed version is also validated with Visual Studio Code Analysis and Cppcheck.

Test Code:

Test.cpp

#include <string>
#include <iostream>
#include <cassert>

typedef unsigned int int32u;
const char* Iab_Channel(int32u Code)
{
    static const char* Iab_Channel_Values[] =
    {
        "L",
        "Lc",
        "C",
        "Rc",
        "R",
        "Lss",
        "Ls",
        "Lb",
        "Rb",
        "Rss",
        "Rs",
        "Tsl",
        "Tsr",
        "LFE",
        "Left Height",
        "Right Height",
        "Center Height",
        "Left Surround Height",
        "Right Surround Height",
        "Left Side Surround Height",
        "Right Side Surround Height",
        "Left Rear Surround Height",
        "Right Rear Surround Height",
        "Tc",
        //0x18-0x7F reserved
        "Tfl",
        "Tfr",
        "Tbl",
        "Tbr",
        "Tsl",
        "Tsr",
        "LFE1",
        "LFE2",
        "Lw",
        "Rw",
    };
    if (Code < 0x18)
        return Iab_Channel_Values[Code];
    if (Code >= 0x80 && Code < sizeof(Iab_Channel_Values) / sizeof(const char*) + 0x68)
        return Iab_Channel_Values[Code - 0x68];
    return "";
}

const char* Iab_Channel_OLD(int32u Code)
{
    static const char* Iab_Channel_Values[] =
    {
        "L",
        "Lc",
        "C",
        "Rc",
        "R",
        "Lss",
        "Ls",
        "Lb",
        "Rb",
        "Rss",
        "Rs",
        "Tsl",
        "Tsr",
        "LFE",
        "Left Height",
        "Right Height",
        "Center Height",
        "Left Surround Height",
        "Right Surround Height",
        "Left Side Surround Height",
        "Right Side Surround Height",
        "Left Rear Surround Height",
        "Right Rear Surround Height",
        "Tc",
        //0x18-0x7F reserved
        "Tfl",
        "Tfr",
        "Tbl",
        "Tbr",
        "Tsl",
        "Tsr",
        "LFE1",
        "LFE2",
        "Lw",
        "Rw",
    };
    if (Code < 0x18)
        return Iab_Channel_Values[Code];
    if (Code >= 0x80 && Code < sizeof(Iab_Channel_Values) / sizeof(const char*) - 0x18)
        return Iab_Channel_Values[Code - 0x18];
    return "";
}

struct ChannelIDMap {
    unsigned int ChannelID;
    const char* Channel_Name;
};

int main() {

    // ChannelID and DestinationChannelID Codes
    // From Pages 31 and 32 of SMPTE ST 2098-2:2022
    ChannelIDMap Iab_Channel_Values_Map[] = {

        //0x0-0x17 SMPTE ST 428-12:2013 and SMPTE ST 2098-5:2018 Channel Name
        {0x00, "L"},
        {0x01, "Lc"},
        {0x02, "C"},
        {0x03, "Rc"},
        {0x04, "R"},
        {0x05, "Lss"},
        {0x06, "Ls"},
        {0x07, "Lb"},
        {0x08, "Rb"},
        {0x09, "Rss"},
        {0x0A, "Rs"},
        {0x0B, "Tsl"},
        {0x0C, "Tsr"},
        {0x0D, "LFE"},
        {0x0E, "Left Height"},
        {0x0F, "Right Height"},
        {0x10, "Center Height"},
        {0x11, "Left Surround Height"},
        {0x12, "Right Surround Height"},
        {0x13, "Left Side Surround Height"},
        {0x14, "Right Side Surround Height"},
        {0x15, "Left Rear Surround Height"},
        {0x16, "Right Rear Surround Height"},
        {0x17, "Tc"},

        //0x18-0x7F Reserved for D-Cinema

        //0x80-0x89 ITU-R BS.2051-2 Channel Name / System
        {0x80, "Tfl" },
        {0x81, "Tfr"},
        {0x82, "Tbl"},
        {0x83, "Tbr"},
        {0x84, "Tsl"},
        {0x85, "Tsr"},
        {0x86, "LFE1"},
        {0x87, "LFE2"},
        {0x88, "Lw"},
        {0x89, "Rw"}

    };

    // Test fixed Iab_Channel_Values_Map()
    std::cout << "\nTesting Iab_Channel_Values_Map()\n";
    for (unsigned int i = 0x0; i < sizeof(Iab_Channel_Values_Map) / sizeof(ChannelIDMap); ++i) {
        std::cout << "Testing " << std::hex << Iab_Channel_Values_Map[i].ChannelID << " - " << Iab_Channel_Values_Map[i].Channel_Name << "  ";
        assert(Iab_Channel(Iab_Channel_Values_Map[i].ChannelID) == Iab_Channel_Values_Map[i].Channel_Name);
        std::cout << "PASS\n";
    }

    // Test previous Iab_Channel_Values_Map()
    std::cout << "\nTesting OLD Iab_Channel_Values_Map()\n";
    for (unsigned int i = 0x0; i < sizeof(Iab_Channel_Values_Map) / sizeof(ChannelIDMap); ++i) {
        std::cout << "Testing 0x" << std::hex << Iab_Channel_Values_Map[i].ChannelID << " - " << Iab_Channel_Values_Map[i].Channel_Name << "  ";
        assert(Iab_Channel_OLD(Iab_Channel_Values_Map[i].ChannelID) == Iab_Channel_Values_Map[i].Channel_Name);
        std::cout << "PASS\n";
    }

    return 0;
}

Results:

Test Output

Testing Iab_Channel_Values_Map()
Testing 0x0 - L  PASS
Testing 0x1 - Lc  PASS
Testing 0x2 - C  PASS
Testing 0x3 - Rc  PASS
Testing 0x4 - R  PASS
Testing 0x5 - Lss  PASS
Testing 0x6 - Ls  PASS
Testing 0x7 - Lb  PASS
Testing 0x8 - Rb  PASS
Testing 0x9 - Rss  PASS
Testing 0xa - Rs  PASS
Testing 0xb - Tsl  PASS
Testing 0xc - Tsr  PASS
Testing 0xd - LFE  PASS
Testing 0xe - Left Height  PASS
Testing 0xf - Right Height  PASS
Testing 0x10 - Center Height  PASS
Testing 0x11 - Left Surround Height  PASS
Testing 0x12 - Right Surround Height  PASS
Testing 0x13 - Left Side Surround Height  PASS
Testing 0x14 - Right Side Surround Height  PASS
Testing 0x15 - Left Rear Surround Height  PASS
Testing 0x16 - Right Rear Surround Height  PASS
Testing 0x17 - Tc  PASS
Testing 0x80 - Tfl  PASS
Testing 0x81 - Tfr  PASS
Testing 0x82 - Tbl  PASS
Testing 0x83 - Tbr  PASS
Testing 0x84 - Tsl  PASS
Testing 0x85 - Tsr  PASS
Testing 0x86 - LFE1  PASS
Testing 0x87 - LFE2  PASS
Testing 0x88 - Lw  PASS
Testing 0x89 - Rw  PASS

Testing OLD Iab_Channel_Values_Map()
Testing 0x0 - L  PASS
Testing 0x1 - Lc  PASS
Testing 0x2 - C  PASS
Testing 0x3 - Rc  PASS
Testing 0x4 - R  PASS
Testing 0x5 - Lss  PASS
Testing 0x6 - Ls  PASS
Testing 0x7 - Lb  PASS
Testing 0x8 - Rb  PASS
Testing 0x9 - Rss  PASS
Testing 0xa - Rs  PASS
Testing 0xb - Tsl  PASS
Testing 0xc - Tsr  PASS
Testing 0xd - LFE  PASS
Testing 0xe - Left Height  PASS
Testing 0xf - Right Height  PASS
Testing 0x10 - Center Height  PASS
Testing 0x11 - Left Surround Height  PASS
Testing 0x12 - Right Surround Height  PASS
Testing 0x13 - Left Side Surround Height  PASS
Testing 0x14 - Right Side Surround Height  PASS
Testing 0x15 - Left Rear Surround Height  PASS
Testing 0x16 - Right Rear Surround Height  PASS
Testing 0x17 - Tc  PASS
Testing 0x80 - Tfl  Assertion failed: Iab_Channel_OLD(Iab_Channel_Values_Map[i].ChannelID) == Iab_Channel_Values_Map[i].Channel_Name, file Test.cpp, line 165

[JeromeMartinez]

Right!