qlibrary.cpp

QT 开发环境里面一个很重要的文件

        if (lib)
            lib->errorString = file.errorString();
        if (qt_debug_component()) {
            qWarning("%s: %s", (const char*) QFile::encodeName(library),
                qPrintable(qt_error_string(errno)));
        }
        return false;
    }

    QByteArray data;
    char *filedata = 0;
    ulong fdlen = 0;

#ifdef USE_MMAP
    char *mapaddr = 0;
    size_t maplen = file.size();
    mapaddr = (char *) mmap(mapaddr, maplen, PROT_READ, MAP_PRIVATE, file.handle(), 0);
    if (mapaddr != MAP_FAILED) {
        // mmap succeeded
        filedata = mapaddr;
        fdlen = maplen;
    } else {
        // mmap failed
        if (qt_debug_component()) {
            qWarning("mmap: %s", qPrintable(qt_error_string(errno)));
        }
        if (lib)
            lib->errorString = QLibrary::tr("Could not mmap '%1': %2")
                .arg(library)
                .arg(qt_error_string());
#endif // USE_MMAP
        // try reading the data into memory instead
        data = file.readAll();
        filedata = data.data();
        fdlen = data.size();
#ifdef USE_MMAP
    }
#endif // USE_MMAP

    // verify that the pattern is present in the plugin
    const char pattern[] = "pattern=QT_PLUGIN_VERIFICATION_DATA";
    const ulong plen = qstrlen(pattern);
    long pos = qt_find_pattern(filedata, fdlen, pattern, plen);

    bool ret = false;
    if (pos >= 0)
        ret = qt_parse_pattern(filedata + pos, version, debug, key);

    if (!ret && lib)
        lib->errorString = QLibrary::tr("Plugin verification data mismatch in '%1'").arg(library);
#ifdef USE_MMAP
    if (mapaddr != MAP_FAILED && munmap(mapaddr, maplen) != 0) {
        if (qt_debug_component())
            qWarning("munmap: %s", qPrintable(qt_error_string(errno)));
        if (lib)
            lib->errorString = QLibrary::tr("Could not unmap '%1': %2")
                .arg(library)
                .arg( qt_error_string() );
    }
#endif // USE_MMAP

    file.close();
    return ret;
}

#endif // Q_OS_UNIX

typedef QMap<QString, QLibraryPrivate*> LibraryMap;
Q_GLOBAL_STATIC(LibraryMap, libraryMap)

QLibraryPrivate::QLibraryPrivate(const QString &canonicalFileName, int verNum)
    :pHnd(0), fileName(canonicalFileName), majorVerNum(verNum), instance(0), qt_version(0),
     libraryRefCount(1), libraryUnloadCount(1), pluginState(MightBeAPlugin)
{ libraryMap()->insert(canonicalFileName, this); }

QLibraryPrivate *QLibraryPrivate::findOrCreate(const QString &fileName, int verNum)
{
    QMutexLocker locker(qt_library_mutex());
    if (QLibraryPrivate *lib = libraryMap()->value(fileName)) {
        lib->libraryUnloadCount.ref();
        lib->libraryRefCount.ref();
        return lib;
    }

    return new QLibraryPrivate(fileName, verNum);
}

QLibraryPrivate::~QLibraryPrivate()
{
    LibraryMap * const map = libraryMap();
    if (map) {
        QLibraryPrivate *that = map->take(fileName);
        Q_ASSERT(this == that);
	Q_UNUSED(that);
    }
}

void *QLibraryPrivate::resolve(const char *symbol)
{
    if (!pHnd)
        return 0;
    return resolve_sys(symbol);
}


bool QLibraryPrivate::load()
{
    if (pHnd)
        return true;
    if (fileName.isEmpty())
        return false;
    return load_sys();
}

bool QLibraryPrivate::unload()
{
    if (!pHnd)
        return true;
    if (!libraryUnloadCount.deref()) // only unload if ALL QLibrary instance wanted to
        if  (unload_sys())
            pHnd = 0;
    return (pHnd == 0);
}

void QLibraryPrivate::release()
{
    QMutexLocker locker(qt_library_mutex());
    if (!libraryRefCount.deref())
        delete this;
}

bool QLibraryPrivate::loadPlugin()
{
    if (instance)
        return true;
    if (load()) {
        instance = (QtPluginInstanceFunction)resolve("qt_plugin_instance");
        return instance;
    }
    return false;
}

/*!
    Returns true if \a fileName has a valid suffix for a loadable
    library; otherwise returns false.

    \table
    \header \i Platform \i Valid suffixes
    \row \i Windows     \i \c .dll
    \row \i Unix/Linux  \i \c .so
    \row \i AIX  \i \c .a
    \row \i HP-UX       \i \c .sl
    \row \i Mac OS X    \i \c .dylib, \c .bundle, \c .so
    \endtable

    Trailing versioning numbers on Unix are ignored.
 */
bool QLibrary::isLibrary(const QString &fileName)
{
#if defined(Q_OS_WIN32)
    return fileName.endsWith(QLatin1String(".dll"));
#else
    QString completeSuffix = QFileInfo(fileName).completeSuffix();
    if (completeSuffix.isEmpty())
        return false;
    QStringList suffixes = completeSuffix.split(QLatin1Char('.'));
    QString suffix = suffixes.first();
# if defined(Q_OS_DARWIN)

    // On Mac, libs look like libmylib.1.0.0.dylib
    const QString lastSuffix = suffixes.at(suffixes.count() - 1);
    const QString firstSuffix = suffixes.at(0);

    bool valid = (lastSuffix == QLatin1String("dylib")
            || firstSuffix == QLatin1String("so")
            || firstSuffix == QLatin1String("bundle"));

    return valid;
# elif defined(Q_OS_HPUX)
/*
    See "HP-UX Linker and Libraries User's Guide", section "Link-time Differences between PA-RISC and IPF":
    "In PA-RISC (PA-32 and PA-64) shared libraries are suffixed with .sl. In IPF (32-bit and 64-bit),
    the shared libraries are suffixed with .so. For compatibility, the IPF linker also supports the .sl suffix."
 */
    bool valid = (suffix == QLatin1String("sl"));
#  if defined __ia64
    valid = valid || (suffix == QLatin1String("so"))
#  endif
# elif defined(Q_OS_AIX)
    bool valid = (suffix == QLatin1String("a") || suffix == QLatin1String("so"));
# elif defined(Q_OS_UNIX)
    bool valid = (suffix == QLatin1String("so"));
# else
    bool valid = false;
# endif

    for (int i = 1; i < suffixes.count() && valid; ++i)
        suffixes.at(i).toInt(&valid);
    return valid;
#endif

}

bool QLibraryPrivate::isPlugin()
{
    if (pluginState != MightBeAPlugin)
        return pluginState == IsAPlugin;

#ifndef QT_NO_PLUGIN_CHECK
    bool debug = !QLIBRARY_AS_DEBUG;
    QByteArray key;
    bool success = false;

    QFileInfo fileinfo(fileName);

#ifndef QT_NO_DATESTRING
    lastModified  = fileinfo.lastModified().toString(Qt::ISODate);
#endif
    QString regkey = QString::fromLatin1("Qt Plugin Cache %1.%2.%3/%4")
                     .arg((QT_VERSION & 0xff0000) >> 16)
                     .arg((QT_VERSION & 0xff00) >> 8)
                     .arg(QLIBRARY_AS_DEBUG ? QLatin1String("debug") : QLatin1String("false"))
                     .arg(fileName);
    QStringList reg;

    QSettings settings(QSettings::UserScope, QLatin1String("Trolltech"));
    reg = settings.value(regkey).toStringList();
    if (reg.count() == 4 && lastModified == reg.at(3)) {
        qt_version = reg.at(0).toUInt(0, 16);
        debug = bool(reg.at(1).toInt());
        key = reg.at(2).toLatin1();
        success = qt_version != 0;
    } else {
#if defined(Q_OS_UNIX)
        if (!pHnd) {
            // use unix shortcut to avoid loading the library
            success = qt_unix_query(fileName, &qt_version, &debug, &key, this);
        } else
#endif
        {
            bool temporary_load = false;
            if (!pHnd)
                temporary_load =  load_sys();
#  ifdef Q_CC_BOR
            typedef const char * __stdcall (*QtPluginQueryVerificationDataFunction)();
#  else
            typedef const char * (*QtPluginQueryVerificationDataFunction)();
#  endif
            QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction =
                (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");

            if (!qtPluginQueryVerificationDataFunction
                || !qt_parse_pattern(qtPluginQueryVerificationDataFunction(), &qt_version, &debug, &key)) {
                qt_version = 0;
                key = "unknown";
                if (temporary_load)
                    unload_sys();
            } else {
                success = true;
            }
        }

        QStringList queried;
        queried << QString::number(qt_version,16)
                << QString::number((int)debug)
                << QLatin1String(key)
                << lastModified;
        settings.setValue(regkey, queried);
    }

    if (!success)
        return false;

    pluginState = IsNotAPlugin; // be pessimistic

    if ((qt_version > QT_VERSION) || ((QT_VERSION & 0xff0000) > (qt_version & 0xff0000))) {
        if (qt_debug_component()) {
            qWarning("In %s:\n"
                 "  Plugin uses incompatible Qt library (%d.%d.%d) [%s]",
                 (const char*) QFile::encodeName(fileName),
                 (qt_version&0xff0000) >> 16, (qt_version&0xff00) >> 8, qt_version&0xff,
                 debug ? "debug" : "release");
        }
        errorString = QLibrary::tr("The plugin '%1' uses incompatible Qt library. (%2.%3.%4) [%5]")
            .arg(fileName)
            .arg((qt_version&0xff0000) >> 16)
            .arg((qt_version&0xff00) >> 8)
            .arg(qt_version&0xff)
            .arg(debug ? QLatin1String("debug") : QLatin1String("release"));
    } else if (key != QT_BUILD_KEY) {
        if (qt_debug_component()) {
            qWarning("In %s:\n"
                 "  Plugin uses incompatible Qt library\n"
                 "  expected build key \"%s\", got \"%s\"",
                 (const char*) QFile::encodeName(fileName),
                 QT_BUILD_KEY,
                 key.isEmpty() ? "<null>" : (const char *) key);
        }
        errorString = QLibrary::tr("The plugin '%1' uses incompatible Qt library."
                 " Expected build key \"%2\", got \"%3\"")
                 .arg(fileName)
                 .arg(QLatin1String(QT_BUILD_KEY))
                 .arg(key.isEmpty() ? QLatin1String("<null>") : QLatin1String((const char *) key));
#ifndef QT_NO_DEBUG_PLUGIN_CHECK
    } else if(debug != QLIBRARY_AS_DEBUG) {
        //don't issue a qWarning since we will hopefully find a non-debug? --Sam
#endif
    } else {
        pluginState = IsAPlugin;
    }

    return pluginState == IsAPlugin;
#else
    return pluginState == MightBeAPlugin;
#endif
}

/*!
    Loads the library and returns true if the library was loaded
    successfully; otherwise returns false. Since resolve() always
    calls this function before resolving any symbols it is not
    necessary to call it explicitly. In some situations you might want
    the library loaded in advance, in which case you would use this
    function.

    \sa unload()
*/
bool QLibrary::load()
{
    if (!d)
        return false;
    if (did_load)
        return d->pHnd;