/****************************************************************************

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

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** This file is part of the QtCore module of the Qt Toolkit.

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** No Commercial Usage

** This file contains pre-release code and may not be distributed.

** You may use this file in accordance with the terms and conditions

** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, this file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** 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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**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

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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>

#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>

QT_BEGIN_NAMESPACE

//#define QT_DEBUG_COMPONENT

#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)

/*!

    \class QLibrary

    \reentrant

    \brief The QLibrary class loads shared libraries at runtime.

    \ingroup plugins

    An instance of a QLibrary object operates on a single shared

    object file (which we call a "library", but is also known as a

    "DLL"). A QLibrary provides access to the functionality in the

    library in a platform independent way. You can either pass a file

    name in the constructor, or set it explicitly with setFileName().

    When loading the library, QLibrary searches in all the

    system-specific library locations (e.g. \c LD_LIBRARY_PATH on

    Unix), unless the file name has an absolute path. If the file

    cannot be found, QLibrary tries the name with different

    platform-specific file suffixes, like ".so" on Unix, ".dylib" on

    the Mac, or ".dll" on Windows and Symbian. This makes it possible

    to specify shared libraries that are only identified by their

    basename (i.e. without their suffix), so the same code will work

    on different operating systems.

    The most important functions are load() to dynamically load the

    library file, isLoaded() to check whether loading was successful,

    and resolve() to resolve a symbol in the library. The resolve()

    function implicitly tries to load the library if it has not been

    loaded yet. Multiple instances of QLibrary can be used to access

    the same physical library. Once loaded, libraries remain in memory

    until the application terminates. You can attempt to unload a

    library using unload(), but if other instances of QLibrary are

    using the same library, the call will fail, and unloading will

    only happen when every instance has called unload().

    A typical use of QLibrary is to resolve an exported symbol in a

    library, and to call the C function that this symbol represents.

    This is called "explicit linking" in contrast to "implicit

    linking", which is done by the link step in the build process when

    linking an executable against a library.

    Note: In Symbian resolving symbols using their names is supported

    only if the library is built as STDDLL. Otherwise ordinals must

    be used. Also, in Symbian the path of the library is ignored and

    system default library location is always used.

    The following code snippet loads a library, resolves the symbol

    "mysymbol", and calls the function if everything succeeded. If

    something goes wrong, e.g. the library file does not exist or the

    symbol is not defined, the function pointer will be 0 and won't be

    called.

    \snippet doc/src/snippets/code/src_corelib_plugin_qlibrary.cpp 0

    The symbol must be exported as a C function from the library for

    resolve() to work. This means that the function must be wrapped in

    an \c{extern "C"} block if the library is compiled with a C++

    compiler. On Windows, this also requires the use of a \c dllexport

    macro; see resolve() for the details of how this is done. For

    convenience, there is a static resolve() function which you can

    use if you just want to call a function in a library without

    explicitly loading the library first:

    \snippet doc/src/snippets/code/src_corelib_plugin_qlibrary.cpp 1

    \sa QPluginLoader

*/

/*!

    \enum QLibrary::LoadHint

    This enum describes the possible hints that can be used to change the way

    libraries are handled when they are loaded. These values indicate how

    symbols are resolved when libraries are loaded, and are specified using

    the setLoadHints() function.

    \value ResolveAllSymbolsHint

    Causes all symbols in a library to be resolved when it is loaded, not

    simply when resolve() is called.

    \value ExportExternalSymbolsHint

    Exports unresolved and external symbols in the library so that they can be

    resolved in other dynamically-loaded libraries loaded later.

    \value LoadArchiveMemberHint

    Allows the file name of the library to specify a particular object file

    within an archive file.

    If this hint is given, the filename of the library consists of

    a path, which is a reference to an archive file, followed by

    a reference to the archive member.

    \sa loadHints

*/

#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)

{

    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)

#if defined(Q_OS_FREEBSD) || defined(Q_OS_LINUX)

#  define USE_MMAP

QT_BEGIN_INCLUDE_NAMESPACE

#  include <sys/types.h>

#  include <sys/mman.h>

QT_END_INCLUDE_NAMESPACE

#endif // Q_OS_FREEBSD || Q_OS_LINUX

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;

    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 && !Q_OS_MAC && !defined(Q_OS_SYMBIAN) && !defined(QT_NO_PLUGIN_CHECK)

typedef QMap<QString, QLibraryPrivate*> LibraryMap;

struct LibraryData {

    LibraryData() : settings(0) { }

    ~LibraryData() {

        delete settings;

    }

    QSettings *settings;

    LibraryMap libraryMap;

};

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;

    return load_sys();

}

bool QLibraryPrivate::unload()

{

    if (!pHnd)

        return false;

    if (!libraryUnloadCount.deref()) { // only unload if ALL QLibrary instance wanted to

        if (instance)

            delete instance();

        if  (unload_sys()) {

            instance = 0;

            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 (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;

    }

    return false;