okular/generators/chm/lib/ebook_epub.cpp

/*
    Kchmviewer - a CHM and EPUB file viewer with broad language support
    SPDX-FileCopyrightText: 2004-2014 George Yunaev gyunaev@ulduzsoft.com

    SPDX-License-Identifier: GPL-3.0-or-later
*/

#if defined(WIN32)
#include <io.h> // dup
#else
#include <unistd.h>
#endif

#include <KLocalizedString>
#include <QMessageBox>
#include <QXmlSimpleReader>

#include "ebook_epub.h"
#include "helperxmlhandler_epubcontainer.h"
#include "helperxmlhandler_epubcontent.h"
#include "helperxmlhandler_epubtoc.h"

static const char *URL_SCHEME_EPUB = "epub";

EBook_EPUB::EBook_EPUB()
    : EBook()
{
    m_zipFile = nullptr;
}

EBook_EPUB::~EBook_EPUB()
{
    close();
}

bool EBook_EPUB::load(const QString &archiveName)
{
    close();

    // We use QFile and zip_fdopen instead of zip_open because latter does not support Unicode file names
    m_epubFile.setFileName(archiveName);

    if (!m_epubFile.open(QIODevice::ReadOnly)) {
        qWarning("Could not open file %s: %s", qPrintable(archiveName), qPrintable(m_epubFile.errorString()));
        return false;
    }

    // Open the ZIP archive: http://www.nih.at/libzip/zip_fdopen.html
    // Note that zip_fdopen takes control over the passed descriptor,
    // so we need to pass a duplicate of it for this to work correctly
    int fdcopy = dup(m_epubFile.handle());

    if (fdcopy < 0) {
        qWarning("Could not duplicate descriptor");
        return false;
    }

    int errcode;
    m_zipFile = zip_fdopen(fdcopy, 0, &errcode);

    if (!m_zipFile) {
        qWarning("Could not open file %s: error %d", qPrintable(archiveName), errcode);
        return false;
    }

    // Parse the book descriptor file
    if (!parseBookinfo())
        return false;

    return true;
}

void EBook_EPUB::close()
{
    if (m_zipFile) {
        zip_close(m_zipFile);
        m_zipFile = nullptr;
    }

    // if ( m_epubFile.isOpen() )
    //	m_epubFile.close();
}

bool EBook_EPUB::getFileContentAsString(QString &str, const QUrl &url) const
{
    return getFileAsString(str, urlToPath(url));
}

bool EBook_EPUB::getFileContentAsBinary(QByteArray &data, const QUrl &url) const
{
    return getFileAsBinary(data, urlToPath(url));
}

bool EBook_EPUB::enumerateFiles(QList<QUrl> &files)
{
    files = m_ebookManifest;
    return true;
}

QString EBook_EPUB::title() const
{
    return m_title;
}

QUrl EBook_EPUB::homeUrl() const
{
    return m_tocEntries[0].url;
}

bool EBook_EPUB::hasFeature(EBook::Feature code) const
{
    switch (code) {
    case FEATURE_TOC:
        return true;

    case FEATURE_INDEX:
        return false;

    case FEATURE_ENCODING:
        return false;
    }

    return false;
}

bool EBook_EPUB::getTableOfContents(QList<EBookTocEntry> &toc) const
{
    toc = m_tocEntries;
    return true;
}

bool EBook_EPUB::getIndex(QList<EBookIndexEntry> &) const
{
    return false;
}

QString EBook_EPUB::getTopicByUrl(const QUrl &url)
{
    if (m_urlTitleMap.contains(url))
        return m_urlTitleMap[url];

    return QLatin1String("");
}

QString EBook_EPUB::currentEncoding() const
{
    return QStringLiteral("UTF-8");
}

bool EBook_EPUB::setCurrentEncoding(const char *)
{
    abort();
}

bool EBook_EPUB::isSupportedUrl(const QUrl &url)
{
    return url.scheme() == URL_SCHEME_EPUB;
}

bool EBook_EPUB::parseXML(const QString &uri, QXmlDefaultHandler *parser)
{
    QByteArray container;

    if (!getFileAsBinary(container, uri)) {
        qDebug("Failed to retrieve XML file %s", qPrintable(uri));
        return false;
    }

    // Use it as XML source
    QXmlInputSource source;
    source.setData(container);

    // Init the reader
    QXmlSimpleReader reader;
    reader.setContentHandler(parser);
    reader.setErrorHandler(parser);

    return reader.parse(source);
}

bool EBook_EPUB::parseBookinfo()
{
    // Parse the container.xml to find the content descriptor
    HelperXmlHandler_EpubContainer container_parser;

    if (!parseXML(QStringLiteral("META-INF/container.xml"), &container_parser) || container_parser.contentPath.isEmpty())
        return false;

    // Parse the content.opf
    HelperXmlHandler_EpubContent content_parser;

    if (!parseXML(container_parser.contentPath, &content_parser))
        return false;

    // At least title and the TOC must be present
    if (!content_parser.metadata.contains(QStringLiteral("title")) || content_parser.tocname.isEmpty())
        return false;

    // All the files, including TOC, are relative to the container_parser.contentPath
    m_documentRoot.clear();
    int sep = container_parser.contentPath.lastIndexOf('/');

    if (sep != -1)
        m_documentRoot = container_parser.contentPath.left(sep + 1); // Keep the trailing slash

    // Parse the TOC
    HelperXmlHandler_EpubTOC toc_parser(this);

    if (!parseXML(content_parser.tocname, &toc_parser))
        return false;

    // Get the data
    m_title = content_parser.metadata[QStringLiteral("title")];

    // Move the manifest entries into the list
    for (const QString &f : qAsConst(content_parser.manifest))
        m_ebookManifest.push_back(pathToUrl(f));

    // Copy the manifest information and fill up the other maps if we have it
    if (!toc_parser.entries.isEmpty()) {
        for (const EBookTocEntry &e : qAsConst(toc_parser.entries)) {
            // Add into url-title map
            m_urlTitleMap[e.url] = e.name;
            m_tocEntries.push_back(e);
        }
    } else {
        // Copy them from spine
        for (QString url : qAsConst(content_parser.spine)) {
            EBookTocEntry e;

            if (content_parser.manifest.contains(url))
                url = content_parser.manifest[url];

            e.name = url;
            e.url = pathToUrl(url);
            e.iconid = EBookTocEntry::IMAGE_NONE;
            e.indent = 0;

            // Add into url-title map
            m_urlTitleMap[pathToUrl(url)] = url;
            m_tocEntries.push_back(e);
        }
    }

    // EPub with an empty TOC is not valid
    if (m_tocEntries.isEmpty())
        return false;

    return true;
}

QUrl EBook_EPUB::pathToUrl(const QString &link) const
{
    QUrl url;
    url.setScheme(URL_SCHEME_EPUB);
    url.setHost(URL_SCHEME_EPUB);

    // Does the link contain the fragment as well?
    int off = link.indexOf('#');
    QString path;

    if (off != -1) {
        path = link.left(off);
        url.setFragment(link.mid(off + 1));
    } else
        path = link;

    if (!path.startsWith('/'))
        path.prepend('/');

    url.setPath(QUrl::fromPercentEncoding(path.toUtf8()));

    return url;
}

QString EBook_EPUB::urlToPath(const QUrl &link) const
{
    if (link.scheme() == URL_SCHEME_EPUB)
        return link.path();

    return QLatin1String("");
}

bool EBook_EPUB::getFileAsString(QString &str, const QString &path) const
{
    QByteArray data;

    if (!getFileAsBinary(data, path))
        return false;

    // I have never seen yet an UTF16 epub
    if (data.startsWith("<?xml")) {
        int endxmltag = data.indexOf("?>");
        int utf16 = data.indexOf("UTF-16");

        if (utf16 > 0 && utf16 < endxmltag) {
            QMessageBox::critical(nullptr, i18n("Unsupported encoding"), i18n("The encoding of this ebook is not supported yet. Please open a bug in https://bugs.kde.org for support to be added"));
            return false;
        }
    }

    str = QString::fromUtf8(data);
    return true;
}

bool EBook_EPUB::getFileAsBinary(QByteArray &data, const QString &path) const
{
    // Retrieve the file size
    struct zip_stat fileinfo;
    QString completeUrl;

    if (!path.isEmpty() && path[0] == '/')
        completeUrl = m_documentRoot + path.mid(1);
    else
        completeUrl = m_documentRoot + path;

    // qDebug("URL requested: %s (%s)", qPrintable(path), qPrintable(completeUrl));

    // http://www.nih.at/libzip/zip_stat.html
    if (zip_stat(m_zipFile, completeUrl.toUtf8().constData(), 0, &fileinfo) != 0) {
        qDebug("File %s is not found in the archive", qPrintable(completeUrl));
        return false;
    }

    // Make sure the size field is valid
    if ((fileinfo.valid & ZIP_STAT_SIZE) == 0 || (fileinfo.valid & ZIP_STAT_INDEX) == 0)
        return false;

    // Open the file
    struct zip_file *file = zip_fopen_index(m_zipFile, fileinfo.index, 0);

    if (!file)
        return false;

    // Allocate the memory and read the file
    data.resize(fileinfo.size);

    // Could it return a positive number but not fileinfo.size???
    int ret = zip_fread(file, data.data(), fileinfo.size);
    if (ret != (int)fileinfo.size) {
        zip_fclose(file);
        return false;
    }

    zip_fclose(file);
    return true;
}