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tagparser/matroska/ebmlelement.cpp

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#include "./ebmlelement.h"
#include "./ebmlid.h"
#include "./matroskacontainer.h"
#include "./matroskaid.h"
#include "../exceptions.h"
#include "../mediafileinfo.h"
#include <c++utilities/conversion/binaryconversion.h>
#include <c++utilities/io/binaryreader.h>
#include <c++utilities/io/binarywriter.h>
#include <cstdint>
#include <cstring>
#include <memory>
#include <sstream>
#include <string>
using namespace std;
using namespace CppUtilities;
namespace TagParser {
/*!
* \class TagParser::EbmlElement
* \brief The EbmlElement class helps to parse EBML files such as Matroska files.
*/
/*!
* \brief Specifies the number of bytes to be skipped till a valid EBML element is found in the stream.
*/
std::uint64_t EbmlElement::bytesToBeSkipped = 0x4000;
/*!
* \brief Constructs a new top level element with the specified \a container at the specified \a startOffset.
*/
EbmlElement::EbmlElement(MatroskaContainer &container, std::uint64_t startOffset)
: GenericFileElement<EbmlElement>(container, startOffset)
{
}
/*!
* \brief Constructs a new top level element with the specified \a container at the specified \a startOffset.
*/
EbmlElement::EbmlElement(MatroskaContainer &container, std::uint64_t startOffset, std::uint64_t maxSize)
: GenericFileElement<EbmlElement>(container, startOffset, maxSize)
{
}
/*!
* \brief Constructs a new sub level element with the specified \a parent at the specified \a startOffset.
*/
EbmlElement::EbmlElement(EbmlElement &parent, std::uint64_t startOffset)
: GenericFileElement<EbmlElement>(parent, startOffset)
{
}
/*!
* \brief Returns the parsing context.
*/
string EbmlElement::parsingContext() const
{
return ("parsing header of EBML element " % idToString() % " at ") + startOffset();
}
/*!
* \brief Parses the EBML element.
*/
void EbmlElement::internalParse(Diagnostics &diag)
{
static const string context("parsing EBML element header");
for (std::uint64_t skipped = 0; skipped < bytesToBeSkipped; ++m_startOffset, --m_maxSize, ++skipped) {
// check whether max size is valid
if (maxTotalSize() < 2) {
diag.emplace_back(DiagLevel::Critical, argsToString("The EBML element at ", startOffset(), " is truncated or does not exist."), context);
throw TruncatedDataException();
}
stream().seekg(static_cast<streamoff>(startOffset()));
// read ID
char buf[maximumIdLengthSupported() > maximumSizeLengthSupported() ? maximumIdLengthSupported() : maximumSizeLengthSupported()] = { 0 };
std::uint8_t beg = static_cast<std::uint8_t>(stream().peek()), mask = 0x80;
m_idLength = 1;
while (m_idLength <= maximumIdLengthSupported() && (beg & mask) == 0) {
++m_idLength;
mask >>= 1;
}
if (m_idLength > maximumIdLengthSupported()) {
if (!skipped) {
diag.emplace_back(
DiagLevel::Critical, argsToString("EBML ID length at ", startOffset(), " is not supported, trying to skip."), context);
}
continue; // try again
}
if (m_idLength > container().maxIdLength()) {
if (!skipped) {
diag.emplace_back(DiagLevel::Critical, argsToString("EBML ID length at ", startOffset(), " is invalid, trying to skip."), context);
}
continue; // try again
}
reader().read(buf + (maximumIdLengthSupported() - m_idLength), m_idLength);
m_id = BE::toInt<std::uint32_t>(buf);
// check whether this element is actually a sibling of one of its parents rather then a child
// (might be the case if the parent's size is unknown and hence assumed to be the max file size)
if (m_parent && m_parent->m_sizeUnknown) {
// check at which level in the hierarchy the element is supposed to occur using its ID
// (the only chance to find out whether the element belongs higher up in the hierarchy)
const MatroskaElementLevel supposedLevel = matroskaIdLevel(m_id);
const std::uint8_t actualLevel = level();
if (actualLevel > supposedLevel) {
// the file belongs higher up in the hierarchy so find a better parent
if (EbmlElement *betterParent = m_parent->parent(actualLevel - static_cast<std::uint8_t>(supposedLevel))) {
// recompute the parent size (assumption - which was rest of the available space - was wrong)
m_parent->m_dataSize = m_startOffset - m_parent->m_startOffset - m_parent->headerSize();
m_parent->m_sizeUnknown = false;
// detach from ...
if (m_parent->firstChild() == this) {
// ... parent
m_parent->m_firstChild.release();
m_parent->m_firstChild = std::move(m_nextSibling);
} else {
// ... previous sibling
for (EbmlElement *sibling = m_parent->firstChild(); sibling; sibling = sibling->nextSibling()) {
if (sibling->nextSibling() == this) {
sibling->m_nextSibling.release();
sibling->m_nextSibling = std::move(m_nextSibling);
break;
}
}
}
// insert as child of better parent
if (EbmlElement *previousSibling = betterParent->lastChild()) {
previousSibling->m_nextSibling.reset(this);
} else {
betterParent->m_firstChild.reset(this);
}
// update own reference to parent
m_parent = betterParent;
}
}
}
// read size
beg = static_cast<std::uint8_t>(stream().peek());
mask = 0x80;
m_sizeLength = 1;
if ((m_sizeUnknown = (beg == 0xFF))) {
// this indicates that the element size is unknown
// -> just assume the element takes the maximum available size
m_dataSize = maxTotalSize() - headerSize();
} else {
while (m_sizeLength <= maximumSizeLengthSupported() && (beg & mask) == 0) {
++m_sizeLength;
mask >>= 1;
}
if (m_sizeLength > maximumSizeLengthSupported()) {
if (!skipped) {
diag.emplace_back(DiagLevel::Critical, "EBML size length is not supported.", parsingContext());
}
continue; // try again
}
if (m_sizeLength > container().maxSizeLength()) {
if (!skipped) {
diag.emplace_back(DiagLevel::Critical, "EBML size length is invalid.", parsingContext());
}
continue; // try again
}
// read size into buffer
memset(buf, 0, sizeof(DataSizeType)); // reset buffer
reader().read(buf + (maximumSizeLengthSupported() - m_sizeLength), m_sizeLength);
// xor the first byte in buffer which has been read from the file with mask
*(buf + (maximumSizeLengthSupported() - m_sizeLength)) ^= static_cast<char>(mask);
m_dataSize = BE::toInt<std::uint64_t>(buf);
// check if element is truncated
if (totalSize() > maxTotalSize()) {
if (m_idLength + m_sizeLength > maxTotalSize()) { // header truncated
if (!skipped) {
diag.emplace_back(DiagLevel::Critical, "EBML header seems to be truncated.", parsingContext());
}
continue; // try again
} else { // data truncated
diag.emplace_back(DiagLevel::Warning, "Data of EBML element seems to be truncated; unable to parse siblings of that element.",
parsingContext());
m_dataSize = maxTotalSize() - m_idLength - m_sizeLength; // using max size instead
}
}
}
// check if there's a first child
const std::uint64_t firstChildOffset = this->firstChildOffset();
if (firstChildOffset && firstChildOffset < totalSize()) {
m_firstChild.reset(new EbmlElement(static_cast<EbmlElement &>(*this), startOffset() + firstChildOffset));
} else {
m_firstChild.reset();
}
// check if there's a sibling
if (totalSize() < maxTotalSize()) {
if (parent()) {
m_nextSibling.reset(new EbmlElement(*(parent()), startOffset() + totalSize()));
} else {
m_nextSibling.reset(new EbmlElement(container(), startOffset() + totalSize(), maxTotalSize() - totalSize()));
}
} else {
m_nextSibling.reset();
}
// no critical errors occurred
// -> add a warning if bytes have been skipped
if (skipped) {
diag.emplace_back(DiagLevel::Warning, argsToString(skipped, " bytes have been skipped"), parsingContext());
}
// -> don't need another try, return here
return;
}
// critical errors occurred and skipping some bytes wasn't successful
throw InvalidDataException();
}
/*!
* \brief Reads the content of the element as string.
*/
std::string EbmlElement::readString()
{
stream().seekg(static_cast<streamoff>(dataOffset()));
return reader().readString(dataSize());
}
/*!
* \brief Reads the content of the element as unsigned integer.
*
* Reads up to 8 bytes. If the element stores more data the
* additional bytes are ignored.
*/
std::uint64_t EbmlElement::readUInteger()
{
constexpr DataSizeType maxBytesToRead = 8;
char buff[maxBytesToRead] = { 0 };
const auto bytesToSkip = maxBytesToRead - min(dataSize(), maxBytesToRead);
stream().seekg(static_cast<streamoff>(dataOffset()), ios_base::beg);
stream().read(buff + bytesToSkip, static_cast<streamoff>(sizeof(buff) - bytesToSkip));
return BE::toInt<std::uint64_t>(buff);
}
/*!
* \brief Reads the content of the element as float.
* \remarks Reads exactly 4 or 8 bytes. If the element stores more or less data zero is returned.
*/
double EbmlElement::readFloat()
{
stream().seekg(static_cast<streamoff>(dataOffset()));
switch (dataSize()) {
case sizeof(float):
return static_cast<double>(reader().readFloat32BE());
case sizeof(double):
return reader().readFloat64BE();
default:
return 0.0;
}
}
/*!
* \brief Returns the length of the specified \a id in byte.
* \throws Throws InvalidDataException() if \a id can not be represented.
*/
std::uint8_t EbmlElement::calculateIdLength(GenericFileElement::IdentifierType id)
{
if (id <= 0xFF) {
return 1;
} else if (id <= 0x7FFF) {
return 2;
} else if (id <= 0x3FFFFF) {
return 3;
} else if (id <= 0x1FFFFFFF) {
return 4;
} else {
throw InvalidDataException();
}
}
/*!
* \brief Returns the length of the size denotation for the specified \a size in byte.
* \throws Throws InvalidDataException() if \a size can not be represented.
*/
std::uint8_t EbmlElement::calculateSizeDenotationLength(std::uint64_t size)
{
if (size < 126) {
return 1;
} else if (size <= 16382ul) {
return 2;
} else if (size <= 2097150ul) {
return 3;
} else if (size <= 268435454ul) {
return 4;
} else if (size <= 34359738366ul) {
return 5;
} else if (size <= 4398046511102ul) {
return 6;
} else if (size <= 562949953421310ul) {
return 7;
} else if (size <= 72057594037927934ul) {
return 8;
} else {
throw InvalidDataException();
}
}
/*!
* \brief Stores the specified \a id in the specified buffer
* which must be at least 8 bytes long.
* \returns Returns the number of bytes written to \a buff.
* \throws Throws InvalidDataException() if \a id can not be represented.
*/
std::uint8_t EbmlElement::makeId(GenericFileElement::IdentifierType id, char *buff)
{
if (id <= 0xFF) {
*buff = static_cast<char>(id);
return 1;
} else if (id <= 0x7FFF) {
BE::getBytes(static_cast<std::uint16_t>(id), buff);
return 2;
} else if (id <= 0x3FFFFF) {
BE::getBytes(static_cast<std::uint32_t>(id << 0x8), buff);
return 3;
} else if (id <= 0x1FFFFFFF) {
BE::getBytes(static_cast<std::uint32_t>(id), buff);
return 4;
} else {
throw InvalidDataException();
}
}
/*!
* \brief Makes the size denotation for the specified \a size and stores it to \a buff.
* \param size Specifies the size to be denoted.
* \param buff Specifies the buffer to store the denotation. Must be at least 8 bytes long.
* \returns Returns the number of bytes written to \a buff.
* \throws Throws InvalidDataException() if \a size can not be represented.
*/
std::uint8_t EbmlElement::makeSizeDenotation(std::uint64_t size, char *buff)
{
if (size < 126) {
*buff = static_cast<char>(size | 0x80);
return 1;
} else if (size <= 16382ul) {
BE::getBytes(static_cast<std::uint16_t>(size | 0x4000), buff);
return 2;
} else if (size <= 2097150ul) {
BE::getBytes(static_cast<std::uint32_t>((size | 0x200000) << 0x08), buff);
return 3;
} else if (size <= 268435454ul) {
BE::getBytes(static_cast<std::uint32_t>(size | 0x10000000), buff);
return 4;
} else if (size <= 34359738366ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x800000000) << 0x18), buff);
return 5;
} else if (size <= 4398046511102ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x40000000000) << 0x10), buff);
return 6;
} else if (size <= 562949953421310ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x2000000000000) << 0x08), buff);
return 7;
} else if (size <= 72057594037927934ul) {
BE::getBytes(static_cast<std::uint64_t>(size | 0x100000000000000), buff);
return 8;
}
throw InvalidDataException();
}
/*!
* \brief Makes the size denotation for the specified \a size and stores it to \a buff.
* \param size Specifies the size to be denoted.
* \param buff Specifies the buffer to store the denotation. Must be at least 8 bytes long.
* \param minBytes Specifies the minimum number of bytes to use. Might be use allow subsequent element growth.
* \returns Returns the number of bytes written to \a buff. Always in the range of \a minBytes and 8.
* \throws Throws InvalidDataException() if \a size can not be represented.
*/
std::uint8_t EbmlElement::makeSizeDenotation(std::uint64_t size, char *buff, std::uint8_t minBytes)
{
if (minBytes <= 1 && size < 126) {
*buff = static_cast<char>(size | 0x80);
return 1;
} else if (minBytes <= 2 && size <= 16382ul) {
BE::getBytes(static_cast<std::uint16_t>(size | 0x4000), buff);
return 2;
} else if (minBytes <= 3 && size <= 2097150ul) {
BE::getBytes(static_cast<std::uint32_t>((size | 0x200000) << 0x08), buff);
return 3;
} else if (minBytes <= 4 && size <= 268435454ul) {
BE::getBytes(static_cast<std::uint32_t>(size | 0x10000000), buff);
return 4;
} else if (minBytes <= 5 && size <= 34359738366ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x800000000) << 0x18), buff);
return 5;
} else if (minBytes <= 6 && size <= 4398046511102ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x40000000000) << 0x10), buff);
return 6;
} else if (minBytes <= 7 && size <= 562949953421310ul) {
BE::getBytes(static_cast<std::uint64_t>((size | 0x2000000000000) << 0x08), buff);
return 7;
} else if (minBytes <= 8 && size <= 72057594037927934ul) {
BE::getBytes(static_cast<std::uint64_t>(size | 0x100000000000000), buff);
return 8;
}
throw InvalidDataException();
}
/*!
* \brief Returns the length of the specified unsigned \a integer in byte.
* \throws Throws InvalidDataException() if \a integer can not be represented.
*/
std::uint8_t EbmlElement::calculateUIntegerLength(std::uint64_t integer)
{
if (integer <= 0xFFul) {
return 1;
} else if (integer <= 0xFFFFul) {
return 2;
} else if (integer <= 0xFFFFFFul) {
return 3;
} else if (integer <= 0xFFFFFFFFul) {
return 4;
} else if (integer <= 0xFFFFFFFFFFul) {
return 5;
} else if (integer <= 0xFFFFFFFFFFFFul) {
return 6;
} else if (integer <= 0xFFFFFFFFFFFFFFul) {
return 7;
} else {
return 8;
}
}
/*!
* \brief Writes \a value to \a buff.
* \returns Returns the number of bytes written to \a buff.
*/
std::uint8_t EbmlElement::makeUInteger(std::uint64_t value, char *buff)
{
if (value <= 0xFFul) {
*buff = static_cast<char>(value);
return 1;
} else if (value <= 0xFFFFul) {
BE::getBytes(static_cast<std::uint16_t>(value), buff);
return 2;
} else if (value <= 0xFFFFFFul) {
BE::getBytes(static_cast<std::uint32_t>(value << 0x08), buff);
return 3;
} else if (value <= 0xFFFFFFFFul) {
BE::getBytes(static_cast<std::uint32_t>(value), buff);
return 4;
} else if (value <= 0xFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x18), buff);
return 5;
} else if (value <= 0xFFFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x10), buff);
return 6;
} else if (value <= 0xFFFFFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x08), buff);
return 7;
} else {
BE::getBytes(static_cast<std::uint64_t>(value), buff);
return 8;
}
}
/*!
* \brief Writes \a value to \a buff.
* \returns Returns the number of bytes written to \a buff.
* \param value Specifies the value to be written.
* \param buff Specifies the buffer to write to.
* \param minBytes Specifies the minimum number of bytes to use.
* \remarks Regardless of \a minBytes, this function will never make
* more than 8 bytes.
*/
std::uint8_t EbmlElement::makeUInteger(std::uint64_t value, char *buff, std::uint8_t minBytes)
{
if (minBytes <= 1 && value <= 0xFFul) {
*buff = static_cast<char>(value);
return 1;
} else if (minBytes <= 2 && value <= 0xFFFFul) {
BE::getBytes(static_cast<std::uint16_t>(value), buff);
return 2;
} else if (minBytes <= 3 && value <= 0xFFFFFFul) {
BE::getBytes(static_cast<std::uint32_t>(value << 0x08), buff);
return 3;
} else if (minBytes <= 4 && value <= 0xFFFFFFFFul) {
BE::getBytes(static_cast<std::uint32_t>(value), buff);
return 4;
} else if (minBytes <= 5 && value <= 0xFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x18), buff);
return 5;
} else if (minBytes <= 6 && value <= 0xFFFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x10), buff);
return 6;
} else if (minBytes <= 7 && value <= 0xFFFFFFFFFFFFFFul) {
BE::getBytes(static_cast<std::uint64_t>(value << 0x08), buff);
return 7;
} else {
BE::getBytes(static_cast<std::uint64_t>(value), buff);
return 8;
}
}
/*!
* \brief Makes a simple EBML element.
* \param stream Specifies the stream to write the data to.
* \param id Specifies the element ID.
* \param content Specifies the value of the element as unsigned integer.
*/
void EbmlElement::makeSimpleElement(ostream &stream, IdentifierType id, std::uint64_t content)
{
char buff1[8];
char buff2[8];
std::uint8_t sizeLength = EbmlElement::makeId(id, buff1);
stream.write(buff1, sizeLength);
std::uint8_t elementSize = EbmlElement::makeUInteger(content, buff2);
sizeLength = EbmlElement::makeSizeDenotation(elementSize, buff1);
stream.write(buff1, sizeLength);
stream.write(buff2, elementSize);
}
/*!
* \brief Makes a simple EBML element.
* \param stream Specifies the stream to write the data to.
* \param id Specifies the element ID.
* \param content Specifies the value of the element as string.
*/
void EbmlElement::makeSimpleElement(std::ostream &stream, GenericFileElement::IdentifierType id, string_view content)
{
char buff1[8];
std::uint8_t sizeLength = EbmlElement::makeId(id, buff1);
stream.write(buff1, sizeLength);
sizeLength = EbmlElement::makeSizeDenotation(content.size(), buff1);
stream.write(buff1, sizeLength);
stream.write(content.data(), static_cast<std::streamsize>(content.size()));
}
} // namespace TagParser
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