JD2022-TU1/main/extern/libwebm/custom/mkvparser/ebmlheader.cpp

#include "ebmlheader.hpp"
#include "imkvreader.hpp"
#include "ebmlreadhelpers.hpp"
#include "mkvprofiler.hpp"

#include <stddef.h>
#include <assert.h>

namespace mkvparser
{

EBMLHeader::EBMLHeader() :
    m_docType(NULL)
{
    Init();
}

EBMLHeader::~EBMLHeader()
{
    mem::Free(m_docType);
}

void EBMLHeader::Init()
{
    m_version = 1;
    m_readVersion = 1;
    m_maxIdLength = 4;
    m_maxSizeLength = 8;

    if (m_docType)
    {
        mem::Free(m_docType);
        m_docType = NULL;
    }

    m_docTypeVersion = 1;
    m_docTypeReadVersion = 1;
}

long long EBMLHeader::Parse(
    IMkvReader* pReader,
    long long& pos)
{
    PROFILER_SCOPED_EVENT("webm::EBMLHeader::Parse");

    assert(pReader);

    long long total, available;

    long status = pReader->Length(&total, &available);

    if (status < 0)  //error
        return status;

    pos = 0;
    long long end = (available >= 1024) ? 1024 : available;

    for (;;)
    {
        unsigned char b = 0;

        while (pos < end)
        {
            status = pReader->Read(pos, 1, &b);

            if (status < 0)  //error
                return status;

            if (b == 0x1A)
                break;

            ++pos;
        }

        if (b != 0x1A)
        {
            if (pos >= 1024)
                return E_FILE_FORMAT_INVALID;  //don't bother looking anymore

            if ((total >= 0) && ((total - available) < 5))
                return E_FILE_FORMAT_INVALID;

            return available + 5;  //5 = 4-byte ID + 1st byte of size
        }

        if ((total >= 0) && ((total - pos) < 5))
            return E_FILE_FORMAT_INVALID;

        if ((available - pos) < 5)
            return pos + 5;  //try again later

        long len;

        const long long result = ReadUInt(pReader, pos, len);

        if (result < 0)  //error
            return result;

        if (result == 0x0A45DFA3)  //EBML Header ID
        {
            pos += len;  //consume ID
            break;
        }

        ++pos;  //throw away just the 0x1A byte, and try again
    }

    //pos designates start of size field

    //get length of size field

    long len;
    long long result = GetUIntLength(pReader, pos, len);

    if (result < 0)  //error
        return result;

    if (result > 0)  //need more data
        return result;

    assert(len > 0);
    assert(len <= 8);

    if ((total >= 0) && ((total -  pos) < len))
        return E_FILE_FORMAT_INVALID;

    if ((available - pos) < len)
        return pos + len;  //try again later

    //get the EBML header size

    result = ReadUInt(pReader, pos, len);

    if (result < 0)  //error
        return result;

    pos += len;  //consume size field

    //pos now designates start of payload

    if ((total >= 0) && ((total - pos) < result))
        return E_FILE_FORMAT_INVALID;

    if ((available - pos) < result)
        return pos + result;

    end = pos + result;

    Init();

    while (pos < end)
    {
        long long id, size;

        status = ParseElementHeader(
                    pReader,
                    pos,
                    end,
                    id,
                    size);

        if (status < 0) //error
            return status;

        if (size == 0)  //weird
            return E_FILE_FORMAT_INVALID;

        if (id == 0x0286)  //version
        {
            m_version = UnserializeUInt(pReader, pos, size);

            if (m_version <= 0)
                return E_FILE_FORMAT_INVALID;
        }
        else if (id == 0x02F7)  //read version
        {
            m_readVersion = UnserializeUInt(pReader, pos, size);

            if (m_readVersion <= 0)
                return E_FILE_FORMAT_INVALID;
        }
        else if (id == 0x02F2)  //max id length
        {
            m_maxIdLength = UnserializeUInt(pReader, pos, size);

            if (m_maxIdLength <= 0)
                return E_FILE_FORMAT_INVALID;
        }
        else if (id == 0x02F3)  //max size length
        {
            m_maxSizeLength = UnserializeUInt(pReader, pos, size);

            if (m_maxSizeLength <= 0)
                return E_FILE_FORMAT_INVALID;
        }
        else if (id == 0x0282)  //doctype
        {
            if (m_docType)
                return E_FILE_FORMAT_INVALID;

            status = UnserializeString(pReader, pos, size, m_docType);

            if (status)  //error
                return status;
        }
        else if (id == 0x0287)  //doctype version
        {
            m_docTypeVersion = UnserializeUInt(pReader, pos, size);

            if (m_docTypeVersion <= 0)
                return E_FILE_FORMAT_INVALID;
        }
        else if (id == 0x0285)  //doctype read version
        {
            m_docTypeReadVersion = UnserializeUInt(pReader, pos, size);

            if (m_docTypeReadVersion <= 0)
                return E_FILE_FORMAT_INVALID;
        }

        pos += size;
    }

    assert(pos == end);
    return 0;
}


} // namespace mkvparser