qlibrary.cpp

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**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtCore module of the Qt Toolkit.
**
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** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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#include "qplatformdefs.h"
#include "qlibrary.h"

#ifndef QT_NO_LIBRARY

#include "qlibrary_p.h"
#include <qstringlist.h>
#include <qfile.h>
#include <qfileinfo.h>
#include <qmutex.h>
#include <qmap.h>
#include <qsettings.h>
#include <qdatetime.h>
#include <private/qcoreapplication_p.h>
#ifdef Q_OS_MAC
#  include <private/qcore_mac_p.h>
#endif
#ifndef NO_ERRNO_H
#include <errno.h>
#endif // NO_ERROR_H
#include <qdebug.h>
#include <qvector.h>
#include <qdir.h>
#include "qelfparser_p.h"

QT_BEGIN_NAMESPACE

#ifdef QT_NO_DEBUG
#  define QLIBRARY_AS_DEBUG false
#else
#  define QLIBRARY_AS_DEBUG true
#endif

#if defined(Q_OS_UNIX) && !defined(Q_OS_MAC)
// We don't use separate debug and release libs on UNIX, so we want
// to allow loading plugins, regardless of how they were built.
#  define QT_NO_DEBUG_PLUGIN_CHECK
#endif

Q_GLOBAL_STATIC(QMutex, qt_library_mutex)


#ifndef QT_NO_PLUGIN_CHECK
struct qt_token_info
{
    qt_token_info(const char *f, const ulong fc)
        : fields(f), field_count(fc), results(fc), lengths(fc)
    {
        results.fill(0);
        lengths.fill(0);
    }

    const char *fields;
    const ulong field_count;

    QVector<const char *> results;
    QVector<ulong> lengths;
};

/*
  return values:
       1 parse ok
       0 eos
      -1 parse error
*/
static int qt_tokenize(const char *s, ulong s_len, ulong *advance,
                        qt_token_info &token_info)
{
    if (!s)
        return -1;

    ulong pos = 0, field = 0, fieldlen = 0;
    char current;
    int ret = -1;
    *advance = 0;
    for (;;) {
        current = s[pos];

        // next char
        ++pos;
        ++fieldlen;
        ++*advance;

        if (! current || pos == s_len + 1) {
            // save result
            token_info.results[(int)field] = s;
            token_info.lengths[(int)field] = fieldlen - 1;

            // end of string
            ret = 0;
            break;
        }

        if (current == token_info.fields[field]) {
            // save result
            token_info.results[(int)field] = s;
            token_info.lengths[(int)field] = fieldlen - 1;

            // end of field
            fieldlen = 0;
            ++field;
            if (field == token_info.field_count - 1) {
                // parse ok
                ret = 1;
            }
            if (field == token_info.field_count) {
                // done parsing
                break;
            }

            // reset string and its length
            s = s + pos;
            s_len -= pos;
            pos = 0;
        }
    }

    return ret;
}

/*
  returns true if the string s was correctly parsed, false otherwise.
*/
static bool qt_parse_pattern(const char *s, uint *version, bool *debug, QByteArray *key)
{
    bool ret = true;

    qt_token_info pinfo("=\n", 2);
    int parse;
    ulong at = 0, advance, parselen = qstrlen(s);
    do {
        parse = qt_tokenize(s + at, parselen, &advance, pinfo);
        if (parse == -1) {
            ret = false;
            break;
        }

        at += advance;
        parselen -= advance;

        if (qstrncmp("version", pinfo.results[0], pinfo.lengths[0]) == 0) {
            // parse version string
            qt_token_info pinfo2("..-", 3);
            if (qt_tokenize(pinfo.results[1], pinfo.lengths[1],
                              &advance, pinfo2) != -1) {
                QByteArray m(pinfo2.results[0], pinfo2.lengths[0]);
                QByteArray n(pinfo2.results[1], pinfo2.lengths[1]);
                QByteArray p(pinfo2.results[2], pinfo2.lengths[2]);
                *version  = (m.toUInt() << 16) | (n.toUInt() << 8) | p.toUInt();
            } else {
                ret = false;
                break;
            }
        } else if (qstrncmp("debug", pinfo.results[0], pinfo.lengths[0]) == 0) {
            *debug = qstrncmp("true", pinfo.results[1], pinfo.lengths[1]) == 0;
        } else if (qstrncmp("buildkey", pinfo.results[0],
                              pinfo.lengths[0]) == 0){
            // save buildkey
            *key = QByteArray(pinfo.results[1], pinfo.lengths[1]);
        }
    } while (parse == 1 && parselen > 0);

    return ret;
}
#endif // QT_NO_PLUGIN_CHECK

#if defined(Q_OS_UNIX) && !defined(Q_OS_MAC) && !defined(Q_OS_SYMBIAN) && !defined(QT_NO_PLUGIN_CHECK)

static long qt_find_pattern(const char *s, ulong s_len,
                             const char *pattern, ulong p_len)
{
    /*
      we search from the end of the file because on the supported
      systems, the read-only data/text segments are placed at the end
      of the file.  HOWEVER, when building with debugging enabled, all
      the debug symbols are placed AFTER the data/text segments.

      what does this mean?  when building in release mode, the search
      is fast because the data we are looking for is at the end of the
      file... when building in debug mode, the search is slower
      because we have to skip over all the debugging symbols first
    */

    if (! s || ! pattern || p_len > s_len) return -1;
    ulong i, hs = 0, hp = 0, delta = s_len - p_len;

    for (i = 0; i < p_len; ++i) {
        hs += s[delta + i];
        hp += pattern[i];
    }
    i = delta;
    for (;;) {
        if (hs == hp && qstrncmp(s + i, pattern, p_len) == 0)
            return i;
        if (i == 0)
            break;
        --i;
        hs -= s[i + p_len];
        hs += s[i];
    }

    return -1;
}

/*
  This opens the specified library, mmaps it into memory, and searches
  for the QT_PLUGIN_VERIFICATION_DATA.  The advantage of this approach is that
  we can get the verification data without have to actually load the library.
  This lets us detect mismatches more safely.

  Returns false if version/key information is not present, or if the
                information could not be read.
  Returns  true if version/key information is present and successfully read.
*/
static bool qt_unix_query(const QString &library, uint *version, bool *debug, QByteArray *key, QLibraryPrivate *lib = 0)
{
    QFile file(library);
    if (!file.open(QIODevice::ReadOnly)) {
        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;
    const char *filedata = 0;
    ulong fdlen = file.size();
    filedata = (char *) file.map(0, fdlen);
    if (filedata == 0) {
        // try reading the data into memory instead
        data = file.readAll();
        filedata = data.constData();
        fdlen = data.size();
    }

    /*
       ELF binaries on GNU, have .qplugin sections.
    */
    long pos = 0;
    const char pattern[] = "pattern=QT_PLUGIN_VERIFICATION_DATA";
    const ulong plen = qstrlen(pattern);
#if defined (Q_OF_ELF) && defined(Q_CC_GNU)
    int r = QElfParser().parse(filedata, fdlen, library, lib, &pos, &fdlen);
    if (r == QElfParser::NoQtSection) {
        if (pos > 0) {
            // find inside .rodata
            long rel = qt_find_pattern(filedata + pos, fdlen, pattern, plen);
            if (rel < 0) {
                pos = -1;
            } else {
                pos += rel;
            }
        } else {
            pos = qt_find_pattern(filedata, fdlen, pattern, plen);
        }
    } else if (r != QElfParser::Ok) {
        if (lib && qt_debug_component()) {
            qWarning("QElfParser: %s",qPrintable(lib->errorString));
        }
        return false;
    }
#else
    pos = qt_find_pattern(filedata, fdlen, pattern, plen);
#endif // defined(Q_OF_ELF) && defined(Q_CC_GNU)
    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);
    file.close();
    return ret;
}

#endif // Q_OS_UNIX && !Q_OS_MAC && !defined(Q_OS_SYMBIAN) && !defined(QT_NO_PLUGIN_CHECK)

typedef QMap<QString, QLibraryPrivate*> LibraryMap;

struct LibraryData {
    LibraryMap libraryMap;
    QSet<QLibraryPrivate*> loadedLibs;
};

Q_GLOBAL_STATIC(LibraryData, libraryData)

static LibraryMap *libraryMap()
{
    LibraryData *data = libraryData();
    return data ? &data->libraryMap : 0;
}

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

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

    return new QLibraryPrivate(fileName, version);
}

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()
{
    libraryUnloadCount.ref();
    if (pHnd)
        return true;
    if (fileName.isEmpty())
        return false;

    bool ret = load_sys();
    if (ret) {
        //when loading a library we add a reference to it so that the QLibraryPrivate won't get deleted
        //this allows to unload the library at a later time
        if (LibraryData *lib = libraryData()) {
            lib->loadedLibs += this;
            libraryRefCount.ref();
        }
    }

    return ret;
}

bool QLibraryPrivate::unload()
{
    if (!pHnd)
        return false;
    if (!libraryUnloadCount.deref()) { // only unload if ALL QLibrary instance wanted to
        delete inst.data();
        if  (unload_sys()) {
            if (qt_debug_component())
                qWarning() << "QLibraryPrivate::unload succeeded on" << fileName;
            //when the library is unloaded, we release the reference on it so that 'this'
            //can get deleted
            if (LibraryData *lib = libraryData()) {
                if (lib->loadedLibs.remove(this))
                    libraryRefCount.deref();
            }
            pHnd = 0;
        }
    }

    return (pHnd == 0);
}

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

bool QLibraryPrivate::loadPlugin()
{
    if (instance) {
        libraryUnloadCount.ref();
        return true;
    }
    if (pluginState == IsNotAPlugin)
        return false;
    if (load()) {
        instance = (QtPluginInstanceFunction)resolve("qt_plugin_instance");
#if defined(Q_OS_SYMBIAN)
        if (!instance) {
            // If resolving with function name failed (i.e. not STDDLL),
            // try resolving using known ordinal, which for
            // qt_plugin_instance function is always "2".
            instance = (QtPluginInstanceFunction)resolve("2");
        }
#endif
        return instance;
    }
    if (qt_debug_component())
        qWarning() << "QLibraryPrivate::loadPlugin failed on" << fileName << ":" << errorString;
    pluginState = IsNotAPlugin;
    return false;
}

bool QLibrary::isLibrary(const QString &fileName)
{
#if defined(Q_OS_WIN32) || defined(Q_OS_WINCE)
    return fileName.endsWith(QLatin1String(".dll"), Qt::CaseInsensitive);
#elif defined(Q_OS_SYMBIAN)
    // Plugin stubs are also considered libraries in Symbian.
    return (fileName.endsWith(QLatin1String(".dll")) ||
            fileName.endsWith(QLatin1String(".qtplugin")));
#else
    QString completeSuffix = QFileInfo(fileName).completeSuffix();
    if (completeSuffix.isEmpty())
        return false;
    QStringList suffixes = completeSuffix.split(QLatin1Char('.'));
# 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;
# else  // Generic Unix
    QStringList validSuffixList;

#  if 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."
 */
    validSuffixList << QLatin1String("sl");
#   if defined __ia64
    validSuffixList << QLatin1String("so");
#   endif
#  elif defined(Q_OS_AIX)
    validSuffixList << QLatin1String("a") << QLatin1String("so");
#  elif defined(Q_OS_UNIX)
    validSuffixList << QLatin1String("so");
#  endif

    // Examples of valid library names:
    //  libfoo.so
    //  libfoo.so.0
    //  libfoo.so.0.3
    //  libfoo-0.3.so
    //  libfoo-0.3.so.0.3.0

    int suffix;
    int suffixPos = -1;
    for (suffix = 0; suffix < validSuffixList.count() && suffixPos == -1; ++suffix)
        suffixPos = suffixes.indexOf(validSuffixList.at(suffix));

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

}

#if defined (Q_OS_WIN) && defined(_MSC_VER) && _MSC_VER >= 1400  && !defined(Q_CC_INTEL)
#define QT_USE_MS_STD_EXCEPTION 1
const char* qt_try_versioninfo(void *pfn, bool *exceptionThrown)
{
    *exceptionThrown = false;
    const char *szData = 0;
    typedef const char * (*VerificationFunction)();
    VerificationFunction func = reinterpret_cast<VerificationFunction>(pfn);
    __try {
        if(func)
            szData =  func();
    } __except(EXCEPTION_EXECUTE_HANDLER) {
        *exceptionThrown = true;
    }
    return szData;
}
#endif

#ifdef Q_CC_BOR
typedef const char * __stdcall (*QtPluginQueryVerificationDataFunction)();
#else
typedef const char * (*QtPluginQueryVerificationDataFunction)();
#endif

bool qt_get_verificationdata(QtPluginQueryVerificationDataFunction pfn, uint *qt_version, bool *debug, QByteArray *key, bool *exceptionThrown)
{
    *exceptionThrown = false;
    const char *szData = 0;
    if (!pfn)
        return false;
#ifdef QT_USE_MS_STD_EXCEPTION
    szData = qt_try_versioninfo((void *)pfn, exceptionThrown);
    if (*exceptionThrown)
        return false;
#else
    szData = pfn();
#endif

#ifdef QT_NO_PLUGIN_CHECK
    return true;
#else
    return qt_parse_pattern(szData, qt_version, debug, key);
#endif
}

bool QLibraryPrivate::isPlugin(QSettings *settings)
{
    errorString.clear();
    if (pluginState != MightBeAPlugin)
        return pluginState == IsAPlugin;

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

#if defined(Q_OS_UNIX) && !defined(Q_OS_MAC)
    if (fileName.endsWith(QLatin1String(".debug"))) {
        // refuse to load a file that ends in .debug
        // these are the debug symbols from the libraries
        // the problem is that they are valid shared library files
        // and dlopen is known to crash while opening them

        // pretend we didn't see the file
        errorString = QLibrary::tr("The shared library was not found.");
        pluginState = IsNotAPlugin;
        return false;
    }
#endif

    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);
#ifdef Q_WS_MAC
    // On Mac, add the application arch to the reg key in order to
    // cache plugin information separately for each arch. This prevents
    // Qt from wrongly caching plugin load failures when the archs
    // don't match.
#if defined(__x86_64__)
    regkey += QLatin1String("-x86_64");
#elif defined(__i386__)
    regkey += QLatin1String("-i386");
#elif defined(__ppc64__)
    regkey += QLatin1String("-ppc64");
#elif defined(__ppc__)
    regkey += QLatin1String("-ppc");
#endif
#endif // Q_WS_MAC

    QStringList reg;
#ifndef QT_NO_SETTINGS
    if (!settings) {
        settings = QCoreApplicationPrivate::trolltechConf();
    }
    reg = settings->value(regkey).toStringList();
#endif
    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) && !defined(Q_OS_MAC) && !defined(Q_OS_SYMBIAN)
        if (!pHnd) {
            // use unix shortcut to avoid loading the library
            success = qt_unix_query(fileName, &qt_version, &debug, &key, this);
        } else
#endif
        {
            bool retryLoadLibrary = false;    // Only used on Windows with MS compiler.(false in other cases)
            do {
                bool temporary_load = false;
#ifdef Q_OS_WIN
                HMODULE hTempModule = 0;
#endif
                if (!pHnd) {
#ifdef Q_OS_WIN
                    DWORD dwFlags = (retryLoadLibrary) ? 0: DONT_RESOLVE_DLL_REFERENCES;
                    //avoid 'Bad Image' message box
                    UINT oldmode = SetErrorMode(SEM_FAILCRITICALERRORS|SEM_NOOPENFILEERRORBOX);
                    hTempModule = ::LoadLibraryEx((wchar_t*)QDir::toNativeSeparators(fileName).utf16(), 0, dwFlags);
                    SetErrorMode(oldmode);
#else
#  if defined(Q_OS_SYMBIAN)
                    //Guard against accidentally trying to load non-plugin libraries by making sure the stub exists
                    if (fileinfo.exists())
#  endif
                        temporary_load =  load_sys();
#endif
                }
#ifdef Q_OS_WIN
                QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = hTempModule ? (QtPluginQueryVerificationDataFunction)
#ifdef Q_OS_WINCE
                        ::GetProcAddress(hTempModule, L"qt_plugin_query_verification_data")
#else
                        ::GetProcAddress(hTempModule, "qt_plugin_query_verification_data")
#endif
                : (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
#else
                QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = NULL;
#  if defined(Q_OS_SYMBIAN)
                if (temporary_load) {
                    qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
                    // If resolving with function name failed (i.e. not STDDLL), try resolving using known ordinal
                    if (!qtPluginQueryVerificationDataFunction)
                        qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("1");
                }
#  else
                qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
#  endif
#endif
                bool exceptionThrown = false;
                bool ret = qt_get_verificationdata(qtPluginQueryVerificationDataFunction,
                                                   &qt_version, &debug, &key, &exceptionThrown);
                if (!exceptionThrown) {
                    if (!ret) {
                        qt_version = 0;
                        key = "unknown";
                        if (temporary_load)
                            unload_sys();
                    } else {
                        success = true;
                    }
                    retryLoadLibrary = false;
                }
#ifdef QT_USE_MS_STD_EXCEPTION
                else {
                    // An exception was thrown when calling qt_plugin_query_verification_data().
                    // This usually happens when plugin is compiled with the /clr compiler flag,
                    // & will only work if the dependencies are loaded & DLLMain() is called.
                    // LoadLibrary() will do this, try once with this & if it fails don't load.
                    retryLoadLibrary = !retryLoadLibrary;
                }
#endif
#ifdef Q_OS_WIN
                if (hTempModule) {
                    BOOL ok = ::FreeLibrary(hTempModule);
                    if (ok) {
                        hTempModule = 0;
                    }

                }
#endif
            } while(retryLoadLibrary);  // Will be 'false' in all cases other than when an
                                        // exception is thrown(will happen only when using a MS compiler)
        }

        // Qt 4.5 compatibility: stl doesn't affect binary compatibility
        key.replace(" no-stl", "");

#ifndef QT_NO_SETTINGS
        QStringList queried;
        queried << QString::number(qt_version,16)
                << QString::number((int)debug)
                << QLatin1String(key)
                << lastModified;
        settings->setValue(regkey, queried);
#endif
    }

    if (!success) {
        if (errorString.isEmpty()){
            if (fileName.isEmpty())
                errorString = QLibrary::tr("The shared library was not found.");
            else
                errorString = QLibrary::tr("The file '%1' is not a valid Qt plugin.").arg(fileName);
        }
        return false;
    }

    pluginState = IsNotAPlugin; // be pessimistic

    if ((qt_version & 0x00ff00) > (QT_VERSION & 0x00ff00) || (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
               // we may have some compatibility keys, try them too:
#ifdef QT_BUILD_KEY_COMPAT
               && key != QT_BUILD_KEY_COMPAT
#endif
#ifdef QT_BUILD_KEY_COMPAT2
               && key != QT_BUILD_KEY_COMPAT2
#endif
#ifdef QT_BUILD_KEY_COMPAT3
               && key != QT_BUILD_KEY_COMPAT3
#endif
               ) {
        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
        errorString = QLibrary::tr("The plugin '%1' uses incompatible Qt library."
                 " (Cannot mix debug and release libraries.)").arg(fileName);
#endif
    } else {
        pluginState = IsAPlugin;
    }

    return pluginState == IsAPlugin;
#else
    Q_UNUSED(settings);
    return pluginState == MightBeAPlugin;
#endif
}

bool QLibrary::load()
{
    if (!d)
        return false;
    if (did_load)
        return d->pHnd;
    did_load = true;
    return d->load();
}

bool QLibrary::unload()
{
    if (did_load) {
        did_load = false;
        return d->unload();
    }
    return false;
}

bool QLibrary::isLoaded() const
{
    return d && d->pHnd;
}


QLibrary::QLibrary(QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
}


QLibrary::QLibrary(const QString& fileName, QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
    setFileName(fileName);
}


QLibrary::QLibrary(const QString& fileName, int verNum, QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
    setFileNameAndVersion(fileName, verNum);
}

QLibrary::QLibrary(const QString& fileName, const QString &version, QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
    setFileNameAndVersion(fileName, version);
}

QLibrary::~QLibrary()
{
    if (d)
        d->release();
}


void QLibrary::setFileName(const QString &fileName)
{
    QLibrary::LoadHints lh;
    if (d) {
        lh = d->loadHints;
        d->release();
        d = 0;
        did_load = false;
    }
    d = QLibraryPrivate::findOrCreate(fileName);
    d->loadHints = lh;
}

QString QLibrary::fileName() const
{
    if (d)
        return d->qualifiedFileName.isEmpty() ? d->fileName : d->qualifiedFileName;
    return QString();
}

void QLibrary::setFileNameAndVersion(const QString &fileName, int verNum)
{
    QLibrary::LoadHints lh;
    if (d) {
        lh = d->loadHints;
        d->release();
        d = 0;
        did_load = false;
    }
    d = QLibraryPrivate::findOrCreate(fileName, verNum >= 0 ? QString::number(verNum) : QString());
    d->loadHints = lh;
}

void QLibrary::setFileNameAndVersion(const QString &fileName, const QString &version)
{
    QLibrary::LoadHints lh;
    if (d) {
        lh = d->loadHints;
        d->release();
        d = 0;
        did_load = false;
    }
    d = QLibraryPrivate::findOrCreate(fileName, version);
    d->loadHints = lh;
}

void *QLibrary::resolve(const char *symbol)
{
    if (!isLoaded() && !load())
        return 0;
    return d->resolve(symbol);
}

void *QLibrary::resolve(const QString &fileName, const char *symbol)
{
    QLibrary library(fileName);
    return library.resolve(symbol);
}

void *QLibrary::resolve(const QString &fileName, int verNum, const char *symbol)
{
    QLibrary library(fileName, verNum);
    return library.resolve(symbol);
}

void *QLibrary::resolve(const QString &fileName, const QString &version, const char *symbol)
{
    QLibrary library(fileName, version);
    return library.resolve(symbol);
}

QString QLibrary::errorString() const
{
    return (!d || d->errorString.isEmpty()) ? tr("Unknown error") : d->errorString;
}

void QLibrary::setLoadHints(LoadHints hints)
{
    if (!d) {
        d = QLibraryPrivate::findOrCreate(QString());   // ugly, but we need a d-ptr
        d->errorString.clear();
    }
    d->loadHints = hints;
}

QLibrary::LoadHints QLibrary::loadHints() const
{
    return d ? d->loadHints : (QLibrary::LoadHints)0;
}

/* Internal, for debugging */
bool qt_debug_component()
{
    static int debug_env = -1;
    if (debug_env == -1)
       debug_env = QT_PREPEND_NAMESPACE(qgetenv)("QT_DEBUG_PLUGINS").toInt();

    return debug_env != 0;
}

QT_END_NAMESPACE

#endif // QT_NO_LIBRARY