exiv2/src/crwimage_int.cpp

// SPDX-License-Identifier: GPL-2.0-or-later

#include "crwimage_int.hpp"
#include "canonmn_int.hpp"
#include "i18n.h"                // NLS support.
#include "unused.h"
#include "error.hpp"
#include "enforce.hpp"

#include <cassert>
#include <ctime>
#include <iostream>

// *****************************************************************************
// local declarations
namespace {
    //! Helper class to map Exif orientation values to CRW rotation degrees
    class RotationMap {
    public:
        //! Get the orientation number for a degree value
        static uint16_t orientation(int32_t degrees);
        //! Get the degree value for an orientation number
        static int32_t  degrees(uint16_t orientation);
    private:
        //! Helper structure for the mapping list
        struct OmList {
            uint16_t orientation; //!< Exif orientation value
            int32_t  degrees;     //!< CRW Rotation degrees
        };
        // DATA
        static const OmList omList_[];
    }; // class RotationMap
}  // namespace

// *****************************************************************************
// local definitions
namespace {
    constexpr RotationMap::OmList RotationMap::omList_[] = {
        { 1,    0 },
        { 3,  180 },
        { 3, -180 },
        { 6,   90 },
        { 6, -270 },
        { 8,  270 },
        { 8,  -90 },
    };

    uint16_t RotationMap::orientation(int32_t degrees)
    {
        uint16_t o = 1;
        for (auto&& om : omList_) {
            if (om.degrees == degrees) {
                o = om.orientation;
                break;
            }
        }
        return o;
    }

    int32_t RotationMap::degrees(uint16_t orientation)
    {
        int32_t d = 0;
        for (auto&& om : omList_) {
            if (om.orientation == orientation) {
                d = om.degrees;
                break;
            }
        }
        return d;
    }
}  // namespace

namespace Exiv2 {
    namespace Internal {

    /*
      Mapping table used to decode and encode CIFF tags to/from Exif tags.  Only
      a subset of the Exif tags can be mapped to known tags found in CRW files
      and not all CIFF tags in the CRW files have a corresponding Exif tag. Tags
      which are not mapped in the table below are ignored.

      When decoding, each CIFF tag/directory pair in the CRW image is looked up
      in the table and if it has an entry, the corresponding decode function is
      called (CrwMap::decode). This function may or may not make use of the
      other parameters in the structure (such as the Exif tag and Ifd id).

      Encoding is done in a loop over the mapping table (CrwMap::encode). For
      each entry, the encode function is called, which looks up the (Exif)
      metadata to encode in the image. This function may or may not make use of
      the other parameters in the mapping structure.
    */
    const CrwMapping CrwMap::crwMapping_[] = {
        //         CrwTag  CrwDir  Size ExifTag IfdId    decodeFct     encodeFct
        //         ------  ------  ---- ------- -----    ---------     ---------
        CrwMapping(0x0805, 0x300a,   0, 0,      canonId, decode0x0805, encode0x0805),
        CrwMapping(0x080a, 0x2807,   0, 0,      canonId, decode0x080a, encode0x080a),
        CrwMapping(0x080b, 0x3004,   0, 0x0007, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x0810, 0x2807,   0, 0x0009, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x0815, 0x2804,   0, 0x0006, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x1029, 0x300b,   0, 0x0002, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x102a, 0x300b,   0, 0x0004, canonId, decodeArray,  encodeArray),
        CrwMapping(0x102d, 0x300b,   0, 0x0001, canonId, decodeArray,  encodeArray),
        CrwMapping(0x1033, 0x300b,   0, 0x000f, canonId, decodeArray,  encodeArray),
        CrwMapping(0x1038, 0x300b,   0, 0x0012, canonId, decodeArray,  encodeArray),
        CrwMapping(0x10a9, 0x300b,   0, 0x00a9, canonId, decodeBasic,  encodeBasic),
        // Mapped to Exif.Photo.ColorSpace instead (see below)
        //CrwMapping(0x10b4, 0x300b,   0, 0x00b4, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x10b4, 0x300b,   0, 0xa001, exifId,  decodeBasic,  encodeBasic),
        CrwMapping(0x10b5, 0x300b,   0, 0x00b5, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x10c0, 0x300b,   0, 0x00c0, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x10c1, 0x300b,   0, 0x00c1, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x1807, 0x3002,   0, 0x9206, exifId,  decodeBasic,  encodeBasic),
        CrwMapping(0x180b, 0x3004,   0, 0x000c, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x180e, 0x300a,   0, 0x9003, exifId,  decode0x180e, encode0x180e),
        CrwMapping(0x1810, 0x300a,   0, 0xa002, exifId,  decode0x1810, encode0x1810),
        CrwMapping(0x1817, 0x300a,   4, 0x0008, canonId, decodeBasic,  encodeBasic),
        //CrwMapping(0x1818, 0x3002,   0, 0x9204, exifId, decodeBasic,  encodeBasic),
        CrwMapping(0x183b, 0x300b,   0, 0x0015, canonId, decodeBasic,  encodeBasic),
        CrwMapping(0x2008, 0x0000,   0, 0,      ifd1Id,  decode0x2008, encode0x2008),
    }; // CrwMap::crwMapping_[]

    /*
      CIFF directory hierarchy

                root
                 |
                300a
                 |
       +----+----+----+----+
       |    |    |    |    |
      2804 2807 3002 3003 300b
            |
           3004

      The array is arranged bottom-up so that starting with a directory at the
      bottom, the (unique) path to root can be determined in a single loop.
    */
    const CrwSubDir CrwMap::crwSubDir_[] = {
        // dir,   parent
        { 0x3004, 0x2807 },
        { 0x300b, 0x300a },
        { 0x3003, 0x300a },
        { 0x3002, 0x300a },
        { 0x2807, 0x300a },
        { 0x2804, 0x300a },
        { 0x300a, 0x0000 },
        { 0x0000, 0xffff },
    };

    const char CiffHeader::signature_[] = "HEAPCCDR";

    CiffHeader::~CiffHeader()
    {
    }

    CiffDirectory::~CiffDirectory()
    {
        for (auto&& component : components_) {
            delete component;
        }
    }

    void CiffComponent::add(UniquePtr component)
    {
        doAdd(std::move(component));
    }

    void CiffEntry::doAdd(UniquePtr /*component*/)
    {
        throw Error(kerFunctionNotSupported, "CiffEntry::add");
    } // CiffEntry::doAdd

    void CiffDirectory::doAdd(UniquePtr component)
    {
        components_.push_back(component.release());
    } // CiffDirectory::doAdd

    void CiffHeader::read(const byte* pData, uint32_t size)
    {
        if (size < 14) throw Error(kerNotACrwImage);

        if (pData[0] == 'I' && pData[0] == pData[1]) {
            byteOrder_ = littleEndian;
        }
        else if (pData[0] == 'M' && pData[0] == pData[1]) {
            byteOrder_ = bigEndian;
        }
        else {
            throw Error(kerNotACrwImage);
        }
        offset_ = getULong(pData + 2, byteOrder_);
        if (offset_ < 14 || offset_ > size) throw Error(kerNotACrwImage);
        if (std::memcmp(pData + 6, signature(), 8) != 0) {
            throw Error(kerNotACrwImage);
        }

        pPadding_.clear();
        pPadding_.resize(offset_ - 14);
        padded_ = offset_ - 14;
        std::copy_n(pData+14, padded_, pPadding_.begin());

        pRootDir_ = std::make_unique<CiffDirectory>();
        pRootDir_->readDirectory(pData + offset_, size - offset_, byteOrder_);
    } // CiffHeader::read

    void CiffComponent::read(const byte* pData,
                             uint32_t    size,
                             uint32_t    start,
                             ByteOrder   byteOrder)
    {
        doRead(pData, size, start, byteOrder);
    }

    void CiffComponent::doRead(const byte* pData,
                               uint32_t    size,
                               uint32_t    start,
                               ByteOrder   byteOrder)
    {
        // We're going read 10 bytes. Make sure they won't be out-of-bounds.
        enforce(size >= 10 && start <= size - 10, kerNotACrwImage);
        tag_ = getUShort(pData + start, byteOrder);

        DataLocId dl = dataLocation();
        assert(dl == directoryData || dl == valueData);

        if (dl == valueData) {
            size_   = getULong(pData + start + 2, byteOrder);
            offset_ = getULong(pData + start + 6, byteOrder);

            // Make sure that the sub-region does not overlap with the 10 bytes
            // that we just read. (Otherwise a malicious file could cause an
            // infinite recursion.) There are two cases two consider because
            // the sub-region is allowed to be either before or after the 10
            // bytes in memory.
            if (offset_ < start) {
              // Sub-region is before in memory.
              enforce(size_ <= start - offset_, kerOffsetOutOfRange);
            } else {
              // Sub-region is after in memory.
              enforce(offset_ >= start + 10, kerOffsetOutOfRange);
              enforce(offset_ <= size, kerOffsetOutOfRange);
              enforce(size_ <= size - offset_, kerOffsetOutOfRange);
            }
        }
        if (dl == directoryData) {
            size_ = 8;
            offset_ = start + 2;
        }
        pData_ = pData + offset_;
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "  Entry for tag 0x"
                  << std::hex << tagId() << " (0x" << tag()
                  << "), " << std::dec << size_
                  << " Bytes, Offset is " << offset_ << "\n";
#endif

    } // CiffComponent::doRead

    void CiffDirectory::doRead(const byte* pData,
                               uint32_t    size,
                               uint32_t    start,
                               ByteOrder   byteOrder)
    {
        CiffComponent::doRead(pData, size, start, byteOrder);
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "Reading directory 0x" << std::hex << tag() << "\n";
#endif
        if (this->offset() + this->size() > size)
            throw Error(kerOffsetOutOfRange);

        readDirectory(pData + offset(), this->size(), byteOrder);
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "<---- 0x" << std::hex << tag() << "\n";
#endif
    } // CiffDirectory::doRead

    void CiffDirectory::readDirectory(const byte* pData,
                                      uint32_t    size,
                                      ByteOrder   byteOrder)
    {
        if (size < 4)
            throw Error(kerCorruptedMetadata);
        uint32_t o = getULong(pData + size - 4, byteOrder);
        if ( o > size-2 )
            throw Error(kerCorruptedMetadata);
        uint16_t count = getUShort(pData + o, byteOrder);
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "Directory at offset " << std::dec << o
                  <<", " << count << " entries \n";
#endif
        o += 2;
        if ( static_cast<uint32_t>(count) * 10 > size-o )
            throw Error(kerCorruptedMetadata);

        for (uint16_t i = 0; i < count; ++i) {
            uint16_t tag = getUShort(pData + o, byteOrder);
            std::unique_ptr<CiffComponent> m;
            switch (CiffComponent::typeId(tag)) {
            case directory: m = std::make_unique<CiffDirectory>(); break;
            default: m = std::make_unique<CiffEntry>(); break;
            }
            m->setDir(this->tag());
            m->read(pData, size, o, byteOrder);
            add(std::move(m));
            o += 10;
        }
    }  // CiffDirectory::readDirectory

    void CiffHeader::decode(Image& image) const
    {
        // Nothing to decode from the header itself, just add correct byte order
        if (pRootDir_)
            pRootDir_->decode(image, byteOrder_);
    }

    void CiffComponent::decode(Image& image, ByteOrder byteOrder) const
    {
        doDecode(image, byteOrder);
    }

    void CiffEntry::doDecode(Image& image, ByteOrder byteOrder) const
    {
        CrwMap::decode(*this, image, byteOrder);
    } // CiffEntry::doDecode

    void CiffDirectory::doDecode(Image& image, ByteOrder byteOrder) const
    {
        for (auto&& component : components_) {
            component->decode(image, byteOrder);
        }
    } // CiffDirectory::doDecode

    void CiffHeader::write(Blob& blob) const
    {
        assert(   byteOrder_ == littleEndian
               || byteOrder_ == bigEndian);
        if (byteOrder_ == littleEndian) {
            blob.push_back('I');
            blob.push_back('I');
        }
        else {
            blob.push_back('M');
            blob.push_back('M');
        }
        uint32_t o = 2;
        byte buf[4];
        ul2Data(buf, offset_, byteOrder_);
        append(blob, buf, 4);
        o += 4;
        append(blob, reinterpret_cast<const byte*>(signature_), 8);
        o += 8;
        // Pad as needed
        if (pPadding_.empty() == false) {
            assert(padded_ == offset_ - o);
            append(blob, pPadding_.data(), padded_);
        }
        else {
            for (uint32_t i = o; i < offset_; ++i) {
                blob.push_back(0);
                ++o;
            }
        }
        if (pRootDir_) {
            pRootDir_->write(blob, byteOrder_, offset_);
        }
    }

    uint32_t CiffComponent::write(Blob&     blob,
                                  ByteOrder byteOrder,
                                  uint32_t  offset)
    {
        return doWrite(blob, byteOrder, offset);
    }

    uint32_t CiffEntry::doWrite(Blob&     blob,
                                ByteOrder /*byteOrder*/,
                                uint32_t  offset)
    {
        return writeValueData(blob, offset);
    } // CiffEntry::doWrite

    uint32_t CiffComponent::writeValueData(Blob& blob, uint32_t offset)
    {
        if (dataLocation() == valueData) {
#ifdef EXIV2_DEBUG_MESSAGES
            std::cout << "  Data for tag 0x" << std::hex << tagId()
                      << ", " << std::dec << size_ << " Bytes\n";
#endif
            offset_ = offset;
            append(blob, pData_, size_);
            offset += size_;
            // Pad the value to an even number of bytes
            if (size_ % 2 == 1) {
                blob.push_back(0);
                ++offset;
            }
        }
        return offset;
    } // CiffComponent::writeValueData

    uint32_t CiffDirectory::doWrite(Blob&     blob,
                                    ByteOrder byteOrder,
                                    uint32_t  offset)
    {
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "Writing directory 0x" << std::hex << tag() << "---->\n";
#endif
        // Ciff offsets are relative to the start of the directory
        uint32_t dirOffset = 0;

        // Value data
        for (auto&& component : components_) {
            dirOffset = component->write(blob, byteOrder, dirOffset);
        }
        const uint32_t dirStart = dirOffset;

        // Number of directory entries
        byte buf[4];
        us2Data(buf, static_cast<uint16_t>(components_.size()), byteOrder);
        append(blob, buf, 2);
        dirOffset += 2;

        // Directory entries
        for (auto&& component : components_) {
            component->writeDirEntry(blob, byteOrder);
            dirOffset += 10;
        }

        // Offset of directory
        ul2Data(buf, dirStart, byteOrder);
        append(blob, buf, 4);
        dirOffset += 4;

        // Update directory entry
        setOffset(offset);
        setSize(dirOffset);

#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "Directory is at offset " << std::dec << dirStart
                  << ", " << components_.size() << " entries\n"
                  << "<---- 0x" << std::hex << tag() << "\n";
#endif
        return offset + dirOffset;
    } // CiffDirectory::doWrite

    void CiffComponent::writeDirEntry(Blob& blob, ByteOrder byteOrder) const
    {
#ifdef EXIV2_DEBUG_MESSAGES
        std::cout << "  Directory entry for tag 0x"
                  << std::hex << tagId() << " (0x" << tag()
                  << "), " << std::dec << size_
                  << " Bytes, Offset is " << offset_ << "\n";
#endif
        byte buf[4];

        DataLocId dl = dataLocation();
        assert(dl == directoryData || dl == valueData);

        if (dl == valueData) {
            us2Data(buf, tag_, byteOrder);
            append(blob, buf, 2);

            ul2Data(buf, size_, byteOrder);
            append(blob, buf, 4);

            ul2Data(buf, offset_, byteOrder);
            append(blob, buf, 4);
        }

        if (dl == directoryData) {
            // Only 8 bytes fit in the directory entry
            assert(size_ <= 8);

            us2Data(buf, tag_, byteOrder);
            append(blob, buf, 2);
            // Copy value instead of size and offset
            append(blob, pData_, size_);
            // Pad with 0s
            for (uint32_t i = size_; i < 8; ++i) {
                blob.push_back(0);
            }
        }
    } // CiffComponent::writeDirEntry

    void CiffComponent::print(std::ostream&      os,
                              ByteOrder          byteOrder,
                              const std::string& prefix) const
    {
        doPrint(os, byteOrder, prefix);
    }

    void CiffComponent::doPrint(std::ostream&      os,
                                ByteOrder          byteOrder,
                                const std::string& prefix) const
    {
        os << prefix
           << _("tag") << " = 0x" << std::setw(4) << std::setfill('0')
           << std::hex << std::right << tagId()
           << ", " << _("dir") << " = 0x" << std::setw(4) << std::setfill('0')
           << std::hex << std::right << dir()
           << ", " << _("type") << " = " << TypeInfo::typeName(typeId())
           << ", " << _("size") << " = " << std::dec << size_
           << ", " << _("offset") << " = " << offset_ << "\n";

        if (typeId() != directory) {
            auto value = Value::create(typeId());
            value->read(pData_, size_, byteOrder);
            if (value->size() < 100) {
                os << prefix << *value << "\n";
            }
        }
    } // CiffComponent::doPrint

    void CiffDirectory::doPrint(std::ostream&      os,
                                ByteOrder          byteOrder,
                                const std::string& prefix) const
    {
        CiffComponent::doPrint(os, byteOrder, prefix);
        for (auto&& component : components_) {
            component->print(os, byteOrder, prefix + "   ");
        }
    } // CiffDirectory::doPrint

    void CiffComponent::setValue(DataBuf&& buf)
    {
        storage_ = std::move(buf);
        pData_ = storage_.c_data();
        size_  = static_cast<uint32_t>(storage_.size());
        if (size_ > 8 && dataLocation() == directoryData) {
            tag_ &= 0x3fff;
        }
    } // CiffComponent::setValue

    TypeId CiffComponent::typeId(uint16_t tag)
    {
        TypeId ti = invalidTypeId;
        switch (tag & 0x3800) {
        case 0x0000: ti = unsignedByte; break;
        case 0x0800: ti = asciiString; break;
        case 0x1000: ti = unsignedShort; break;
        case 0x1800: ti = unsignedLong; break;
        case 0x2000: ti = undefined; break;
        case 0x2800: // fallthrough
        case 0x3000: ti = directory; break;
        }
        return ti;
    } // CiffComponent::typeId

    DataLocId CiffComponent::dataLocation(uint16_t tag)
    {
        switch (tag & 0xc000) {
        case 0x0000: return valueData;
        case 0x4000: return directoryData;
        default: throw Error(kerCorruptedMetadata);
        }
    } // CiffComponent::dataLocation

    /*!
      @brief Finds \em crwTagId in directory \em crwDir, returning a pointer to
             the component or 0 if not found.

     */
    CiffComponent* CiffHeader::findComponent(uint16_t crwTagId,
                                             uint16_t crwDir) const
    {
        if (pRootDir_ == nullptr)
            return nullptr;
        return pRootDir_->findComponent(crwTagId, crwDir);
    } // CiffHeader::findComponent

    CiffComponent* CiffComponent::findComponent(uint16_t crwTagId,
                                                uint16_t crwDir) const
    {
        return doFindComponent(crwTagId, crwDir);
    } // CiffComponent::findComponent

    CiffComponent* CiffComponent::doFindComponent(uint16_t crwTagId,
                                                  uint16_t crwDir) const
    {
        if (tagId() == crwTagId && dir() == crwDir) {
            return const_cast<CiffComponent*>(this);
        }
        return nullptr;
    } // CiffComponent::doFindComponent

    CiffComponent* CiffDirectory::doFindComponent(uint16_t crwTagId,
                                                  uint16_t crwDir) const
    {
        for (auto&& component : components_) {
            auto cc = component->findComponent(crwTagId, crwDir);
            if (cc)
                return cc;
        }
        return nullptr;
    } // CiffDirectory::doFindComponent

    void CiffHeader::add(uint16_t crwTagId, uint16_t crwDir, DataBuf&& buf)
    {
        CrwDirs crwDirs;
        CrwMap::loadStack(crwDirs, crwDir);
        uint16_t rootDirectory = crwDirs.top().crwDir_;
        UNUSED(rootDirectory);
        assert(rootDirectory == 0x0000);
        crwDirs.pop();
        if (!pRootDir_) {
            pRootDir_ = std::make_unique<CiffDirectory>();
        }
        CiffComponent* child = pRootDir_->add(crwDirs, crwTagId);
        if (child) {
            child->setValue(std::move(buf));
        }
    }  // CiffHeader::add

    CiffComponent* CiffComponent::add(CrwDirs& crwDirs, uint16_t crwTagId)
    {
        return doAdd(crwDirs, crwTagId);
    } // CiffComponent::add

    CiffComponent* CiffComponent::doAdd(CrwDirs& /*crwDirs*/, uint16_t /*crwTagId*/)
    {
        return nullptr;
    } // CiffComponent::doAdd

    CiffComponent* CiffDirectory::doAdd(CrwDirs& crwDirs, uint16_t crwTagId)
    {
        /*
          add()
            if stack not empty
              pop from stack
              find dir among components
              if not found, create it
              add()
            else
              find tag among components
              if not found, create it
              set value
        */
        if (!crwDirs.empty()) {
            CrwSubDir csd = crwDirs.top();
            crwDirs.pop();
            // Find the directory
            for (auto&& component : components_) {
                if (component->tag() == csd.crwDir_) {
                    cc_ = component;
                    break;
                }
            }
            if (cc_ == nullptr) {
                // Directory doesn't exist yet, add it
                m_ = std::make_unique<CiffDirectory>(csd.crwDir_, csd.parent_);
                cc_ = m_.get();
                add(std::move(m_));
            }
            // Recursive call to next lower level directory
            cc_ = cc_->add(crwDirs, crwTagId);
        }
        else {
            // Find the tag
            for (auto&& component : components_) {
                if (component->tagId() == crwTagId) {
                    cc_ = component;
                    break;
                }
            }
            if (cc_ == nullptr) {
                // Tag doesn't exist yet, add it
                m_ = std::make_unique<CiffEntry>(crwTagId, tag());
                cc_ = m_.get();
                add(std::move(m_));
            }
        }
        return cc_;
    } // CiffDirectory::doAdd

    void CiffHeader::remove(uint16_t crwTagId, uint16_t crwDir)
    {
        if (pRootDir_) {
            CrwDirs crwDirs;
            CrwMap::loadStack(crwDirs, crwDir);
            uint16_t rootDirectory = crwDirs.top().crwDir_;
            UNUSED(rootDirectory);
            assert(rootDirectory == 0x0000);
            crwDirs.pop();
            pRootDir_->remove(crwDirs, crwTagId);
        }
    } // CiffHeader::remove

    void CiffComponent::remove(CrwDirs& crwDirs, uint16_t crwTagId)
    {
        return doRemove(crwDirs, crwTagId);
    } // CiffComponent::remove

    void CiffComponent::doRemove(CrwDirs& /*crwDirs*/, uint16_t /*crwTagId*/)
    {
        // do nothing
    } // CiffComponent::doRemove

    void CiffDirectory::doRemove(CrwDirs& crwDirs, uint16_t crwTagId)
    {
        if (!crwDirs.empty()) {
            CrwSubDir csd = crwDirs.top();
            crwDirs.pop();
            // Find the directory
            for (auto i = components_.begin(); i != components_.end(); ++i) {
                if ((*i)->tag() == csd.crwDir_) {
                    // Recursive call to next lower level directory
                    (*i)->remove(crwDirs, crwTagId);
                    if ((*i)->empty()) components_.erase(i);
                    break;
                }
            }
        }
        else {
            // Find the tag
            for (auto i = components_.begin(); i != components_.end(); ++i) {
                if ((*i)->tagId() == crwTagId) {
                    // Remove the entry and abort the loop
                    delete *i;
                    components_.erase(i);
                    break;
                }
            }
        }
    } // CiffDirectory::doRemove

    bool CiffComponent::empty() const
    {
        return doEmpty();
    }

    bool CiffComponent::doEmpty() const
    {
        return size_ == 0;
    }

    bool CiffDirectory::doEmpty() const
    {
        return components_.empty();
    }

    void CrwMap::decode(const CiffComponent& ciffComponent,
                        Image&               image,
                        ByteOrder            byteOrder)
    {
        const CrwMapping* cmi = crwMapping(ciffComponent.dir(),
                                           ciffComponent.tagId());
        if (cmi && cmi->toExif_) {
            cmi->toExif_(ciffComponent, cmi, image, byteOrder);
        }
    } // CrwMap::decode

    const CrwMapping* CrwMap::crwMapping(uint16_t crwDir, uint16_t crwTagId)
    {
        for (auto&& crw : crwMapping_) {
            if (crw.crwDir_ == crwDir && crw.crwTagId_ == crwTagId) {
                return &crw;
            }
        }
        return nullptr;
    } // CrwMap::crwMapping

    void CrwMap::decode0x0805(const CiffComponent& ciffComponent,
                              const CrwMapping*    /*pCrwMapping*/,
                                    Image&         image,
                                    ByteOrder      /*byteOrder*/)
    {
        std::string s(reinterpret_cast<const char*>(ciffComponent.pData()));
        image.setComment(s);
    } // CrwMap::decode0x0805

    void CrwMap::decode0x080a(const CiffComponent& ciffComponent,
                              const CrwMapping*    /*pCrwMapping*/,
                                    Image&         image,
                                    ByteOrder      byteOrder)
    {
        if (ciffComponent.typeId() != asciiString) return;

        // Make
        ExifKey key1("Exif.Image.Make");
        auto value1 = Value::create(ciffComponent.typeId());
        uint32_t i = 0;
        while (i < ciffComponent.size() && ciffComponent.pData()[i++] != '\0') {
            // empty
        }
        value1->read(ciffComponent.pData(), i, byteOrder);
        image.exifData().add(key1, value1.get());

        // Model
        ExifKey key2("Exif.Image.Model");
        auto value2 = Value::create(ciffComponent.typeId());
        uint32_t j = i;
        while (i < ciffComponent.size() && ciffComponent.pData()[i++] != '\0') {
            // empty
        }
        value2->read(ciffComponent.pData() + j, i - j, byteOrder);
        image.exifData().add(key2, value2.get());
    } // CrwMap::decode0x080a

    void CrwMap::decodeArray(const CiffComponent& ciffComponent,
                             const CrwMapping*    pCrwMapping,
                                   Image&         image,
                                   ByteOrder      byteOrder)
    {
        if (ciffComponent.typeId() != unsignedShort) {
            return decodeBasic(ciffComponent, pCrwMapping, image, byteOrder);
        }

        int64_t aperture = 0;
        int64_t shutterSpeed = 0;

        IfdId ifdId = ifdIdNotSet;
        switch (pCrwMapping->tag_) {
        case 0x0001: ifdId = canonCsId; break;
        case 0x0004: ifdId = canonSiId; break;
        case 0x000f: ifdId = canonCfId; break;
        case 0x0012: ifdId = canonPiId; break;
        }
        assert(ifdId != ifdIdNotSet);

        std::string groupName(Internal::groupName(ifdId));
        const uint32_t component_size = ciffComponent.size();
        enforce(component_size % 2 == 0, kerCorruptedMetadata);
        enforce(component_size/2 <= static_cast<uint32_t>(std::numeric_limits<uint16_t>::max()), kerCorruptedMetadata);
        const uint16_t num_components = static_cast<uint16_t>(component_size/2);
        uint16_t c = 1;
        while (c < num_components) {
            uint16_t n = 1;
            ExifKey key(c, groupName);
            UShortValue value;
            if (ifdId == canonCsId && c == 23 && component_size >= 52) n = 3;
            value.read(ciffComponent.pData() + c*2, n*2, byteOrder);
            image.exifData().add(key, &value);
            if (ifdId == canonSiId && c == 21) aperture = value.toInt64();
            if (ifdId == canonSiId && c == 22) shutterSpeed = value.toInt64();
            c += n;
        }

        if (ifdId == canonSiId) {
            // Exif.Photo.FNumber
            float f = fnumber(canonEv(aperture));
            Rational r = floatToRationalCast(f);
            URational ur(r.first, r.second);
            URationalValue fn;
            fn.value_.push_back(ur);
            image.exifData().add(ExifKey("Exif.Photo.FNumber"), &fn);

            // Exif.Photo.ExposureTime
            ur = exposureTime(canonEv(shutterSpeed));
            URationalValue et;
            et.value_.push_back(ur);
            image.exifData().add(ExifKey("Exif.Photo.ExposureTime"), &et);
        }
    } // CrwMap::decodeArray

    void CrwMap::decode0x180e(const CiffComponent& ciffComponent,
                              const CrwMapping*    pCrwMapping,
                                    Image&         image,
                                    ByteOrder      byteOrder)
    {
        if (ciffComponent.size() < 8 || ciffComponent.typeId() != unsignedLong) {
            return decodeBasic(ciffComponent, pCrwMapping, image, byteOrder);
        }
        assert(pCrwMapping != 0);
        ULongValue v;
        v.read(ciffComponent.pData(), 8, byteOrder);
        time_t t = v.value_.at(0);
        struct tm* tm = std::localtime(&t);
        if (tm) {
            const size_t m = 20;
            char s[m];
            std::strftime(s, m, "%Y:%m:%d %H:%M:%S", tm);

            ExifKey key(pCrwMapping->tag_, Internal::groupName(pCrwMapping->ifdId_));
            AsciiValue value;
            value.read(std::string(s));
            image.exifData().add(key, &value);
        }
    } // CrwMap::decode0x180e

    void CrwMap::decode0x1810(const CiffComponent& ciffComponent,
                              const CrwMapping*    pCrwMapping,
                                    Image&         image,
                                    ByteOrder      byteOrder)
    {
        if (ciffComponent.typeId() != unsignedLong || ciffComponent.size() < 28) {
            return decodeBasic(ciffComponent, pCrwMapping, image, byteOrder);
        }

        ExifKey key1("Exif.Photo.PixelXDimension");
        ULongValue value1;
        value1.read(ciffComponent.pData(), 4, byteOrder);
        image.exifData().add(key1, &value1);

        ExifKey key2("Exif.Photo.PixelYDimension");
        ULongValue value2;
        value2.read(ciffComponent.pData() + 4, 4, byteOrder);
        image.exifData().add(key2, &value2);

        int32_t r = getLong(ciffComponent.pData() + 12, byteOrder);
        uint16_t o = RotationMap::orientation(r);
        image.exifData()["Exif.Image.Orientation"] = o;

    } // CrwMap::decode0x1810

    void CrwMap::decode0x2008(const CiffComponent& ciffComponent,
                              const CrwMapping*    /*pCrwMapping*/,
                                    Image&         image,
                                    ByteOrder      /*byteOrder*/)
    {
        ExifThumb exifThumb(image.exifData());
        exifThumb.setJpegThumbnail(ciffComponent.pData(), ciffComponent.size());
    } // CrwMap::decode0x2008

    void CrwMap::decodeBasic(const CiffComponent& ciffComponent,
                             const CrwMapping*    pCrwMapping,
                                   Image&         image,
                                   ByteOrder      byteOrder)
    {
        assert(pCrwMapping != 0);
        // create a key and value pair
        ExifKey key(pCrwMapping->tag_, Internal::groupName(pCrwMapping->ifdId_));
        std::unique_ptr<Value> value;
        if (ciffComponent.typeId() != directory) {
            value = Value::create(ciffComponent.typeId());
            uint32_t size = 0;
            if (pCrwMapping->size_ != 0) {
                // size in the mapping table overrides all
                size = pCrwMapping->size_;
            }
            else if (ciffComponent.typeId() == asciiString) {
                // determine size from the data, by looking for the first 0
                uint32_t i = 0;
                while (i < ciffComponent.size() && ciffComponent.pData()[i++] != '\0') {
                    // empty
                }
                size = i;
            }
            else {
                // by default, use the size from the directory entry
                size = ciffComponent.size();
            }
            value->read(ciffComponent.pData(), size, byteOrder);
        }
        // Add metadatum to exif data
        image.exifData().add(key, value.get());
    } // CrwMap::decodeBasic

    void CrwMap::loadStack(CrwDirs& crwDirs, uint16_t crwDir)
    {
        for (auto&& crw : crwSubDir_) {
            if (crw.crwDir_ == crwDir) {
                crwDirs.push(crw);
                crwDir = crw.parent_;
            }
        }
    } // CrwMap::loadStack

    void CrwMap::encode(CiffHeader* pHead, const Image& image)
    {
        for (auto&& crw : crwMapping_) {
            if (crw.fromExif_ != nullptr) {
                crw.fromExif_(image, &crw, pHead);
            }
        }
    } // CrwMap::encode

    void CrwMap::encodeBasic(const Image&      image,
                             const CrwMapping* pCrwMapping,
                                   CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        // Determine the source Exif metadatum
        ExifKey ek(pCrwMapping->tag_, Internal::groupName(pCrwMapping->ifdId_));
        auto ed = image.exifData().findKey(ek);

        // Set the new value or remove the entry
        if (ed != image.exifData().end()) {
            DataBuf buf(ed->size());
            ed->copy(buf.data(), pHead->byteOrder());
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encodeBasic

    void CrwMap::encode0x0805(const Image&      image,
                              const CrwMapping* pCrwMapping,
                                    CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        std::string comment = image.comment();

        CiffComponent* cc = pHead->findComponent(pCrwMapping->crwTagId_,
                                                 pCrwMapping->crwDir_);
        if (!comment.empty()) {
            auto size = static_cast<uint32_t>(comment.size());
            if (cc && cc->size() > size) size = cc->size();
            DataBuf buf(size);
            buf.copyBytes(0, comment.data(), comment.size());
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            if (cc) {
                // Just delete the value, do not remove the tag
                DataBuf buf(cc->size());
                cc->setValue(std::move(buf));
            }
        }
    } // CrwMap::encode0x0805

    void CrwMap::encode0x080a(const Image&      image,
                              const CrwMapping* pCrwMapping,
                                    CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        const ExifKey k1("Exif.Image.Make");
        const ExifKey k2("Exif.Image.Model");
        const auto ed1 = image.exifData().findKey(k1);
        const auto ed2 = image.exifData().findKey(k2);
        const auto edEnd = image.exifData().end();

        long size = 0;
        if (ed1 != edEnd) size += ed1->size();
        if (ed2 != edEnd) size += ed2->size();
        if (size != 0) {
            DataBuf buf(size);
            long pos = 0;
            if (ed1 != edEnd) {
                ed1->copy(buf.data(), pHead->byteOrder());
                pos += ed1->size();
            }
            if (ed2 != edEnd) {
                ed2->copy(buf.data(pos), pHead->byteOrder());
                pos += ed2->size();
            }
            assert(pos == size);
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encode0x080a

    void CrwMap::encodeArray(const Image&      image,
                             const CrwMapping* pCrwMapping,
                                   CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        IfdId ifdId = ifdIdNotSet;
        switch (pCrwMapping->tag_) {
        case 0x0001: ifdId = canonCsId; break;
        case 0x0004: ifdId = canonSiId; break;
        case 0x000f: ifdId = canonCfId; break;
        case 0x0012: ifdId = canonPiId; break;
        }
        assert(ifdId != ifdIdNotSet);
        DataBuf buf = packIfdId(image.exifData(), ifdId, pHead->byteOrder());
        if (buf.empty()) {
            // Try the undecoded tag
            encodeBasic(image, pCrwMapping, pHead);
        }
        if (buf.size() > 0) {
            // Write the number of shorts to the beginning of buf
            buf.write_uint16(0, static_cast<uint16_t>(buf.size()), pHead->byteOrder());
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encodeArray

    void CrwMap::encode0x180e(const Image&      image,
                              const CrwMapping* pCrwMapping,
                                    CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        time_t t = 0;
        const ExifKey key(pCrwMapping->tag_, Internal::groupName(pCrwMapping->ifdId_));
        const auto ed = image.exifData().findKey(key);
        if (ed != image.exifData().end()) {
            struct tm tm;
            std::memset(&tm, 0x0, sizeof(tm));
            if ( exifTime(ed->toString().c_str(), &tm) == 0 ) {
                t=::mktime(&tm);
            }
        }
        if (t != 0) {
            DataBuf buf(12);
            buf.write_uint32(0, static_cast<uint32_t>(t), pHead->byteOrder());
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encode0x180e

    void CrwMap::encode0x1810(const Image&      image,
                              const CrwMapping* pCrwMapping,
                                    CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        const ExifKey kX("Exif.Photo.PixelXDimension");
        const ExifKey kY("Exif.Photo.PixelYDimension");
        const ExifKey kO("Exif.Image.Orientation");
        const ExifData &exivData = image.exifData();
        const auto edX = exivData.findKey(kX);
        const auto edY = exivData.findKey(kY);
        const auto edO = exivData.findKey(kO);
        const auto edEnd = exivData.end();

        CiffComponent* cc = pHead->findComponent(pCrwMapping->crwTagId_,
                                                 pCrwMapping->crwDir_);
        if (edX != edEnd || edY != edEnd || edO != edEnd) {
            uint32_t size = 28;
            if (cc) {
              if (cc->size() < size)
                throw Error(kerCorruptedMetadata);
              size = cc->size();
            }
            DataBuf buf(size);
            if (cc) buf.copyBytes(8, cc->pData() + 8, cc->size() - 8);
            if (edX != edEnd && edX->size() == 4) {
                edX->copy(buf.data(), pHead->byteOrder());
            }
            if (edY != edEnd && edY->size() == 4) {
                edY->copy(buf.data(4), pHead->byteOrder());
            }
            int32_t d = 0;
            if (edO != edEnd && edO->count() > 0 && edO->typeId() == unsignedShort) {
                d = RotationMap::degrees(static_cast<uint16_t>(edO->toInt64()));
            }
            buf.write_uint32(12, d, pHead->byteOrder());
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encode0x1810

    void CrwMap::encode0x2008(const Image&      image,
                              const CrwMapping* pCrwMapping,
                                    CiffHeader* pHead)
    {
        assert(pCrwMapping != 0);
        assert(pHead != 0);

        ExifThumbC exifThumb(image.exifData());
        DataBuf buf = exifThumb.copy();
        if (buf.size() != 0) {
            pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));
        }
        else {
            pHead->remove(pCrwMapping->crwTagId_, pCrwMapping->crwDir_);
        }
    } // CrwMap::encode0x2008

    // *************************************************************************
    // free functions
    DataBuf packIfdId(const ExifData& exifData,
                            IfdId     ifdId,
                            ByteOrder byteOrder)
    {
        const uint16_t size = 1024;
        DataBuf buf(size);

        uint16_t len = 0;

        for (auto&& exif : exifData) {
            if (exif.ifdId() != ifdId)
                continue;
            const uint16_t s = exif.tag() * 2 + static_cast<uint16_t>(exif.size());
            if (s <= size) {
                if (len < s) len = s;
                exif.copy(buf.data(exif.tag() * 2), byteOrder);
            } else {
                EXV_ERROR << "packIfdId out-of-bounds error: s = " << std::dec << s << "\n";
            }
        }
        // Round the size to make it even.
        buf.resize(len + len%2);
        return buf;
    }

    }  // namespace Internal
}  // namespace Exiv2