/****************************************************************************
**
** Copyright (C) 1992-2004 Trolltech AS. All rights reserved.
**
** This file is part of the core module of the Qt Toolkit.
**
** Licensees holding valid Qt Preview licenses may use this file in
** accordance with the Qt Preview License Agreement provided with the
** Software.
**
** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
** information about Qt Commercial License Agreements.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "qplatformdefs.h"
#include "qlibrary.h"
#include "qlibrary_p.h"
#include <qstringlist.h>
#include <qfile.h>
#include <qfileinfo.h>
#include <qmutex.h>
#include <qmap.h>
#include <qcoresettings.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>

/*!
    \class QLibrary
    \reentrant
    \brief The QLibrary class loads shared libraries at runtime.

    \mainclass
    \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. 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.

    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.

    \code
    QLibrary myLib("mylib"); // mylib.dll or mylib.so or mylib.dylib etc
    typedef void (*MyPrototype)();
    MyPrototype myFunction = (MyPrototype) myLib.resolve("mysymbol");
    if (myFunction) {
        myFunction();
    }
    \endcode

    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:

    \code
    typedef void (*MyPrototype)();
    if (MyPrototype myFunction = (MyPrototype) QLibrary::resolve("mylib", "mysymbol"))
        myFunction();
    \endcode

    \sa QPluginLoader

*/

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, 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("buildkey", pinfo.results[0],
                              pinfo.lengths[0]) == 0){
            // save buildkey
            *key = QByteArray(pinfo.results[1], pinfo.lengths[1] + 1);
        }
    } while (parse == 1 && parselen > 0);

    return ret;
}

#if defined(Q_OS_UNIX)

#if defined(Q_OS_FREEBSD) || defined(Q_OS_LINUX)
#  define USE_MMAP
#  include <sys/types.h>
#  include <sys/mman.h>
#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, QByteArray *key)
{
    QFile file(library);
    if (! file.open(IO_ReadOnly)) {
        qWarning("%s: %s", (const char*) QFile::encodeName(library),
            strerror(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
        qWarning("mmap: %s", strerror(errno));
#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, key);
    }

#ifdef USE_MMAP
    if (mapaddr != MAP_FAILED && munmap(mapaddr, maplen) != 0) {
        qWarning("munmap: %s", strerror(errno));
    }
#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)
    :pHnd(0), fileName(canonicalFileName), instance(0), qt_version(0), pluginState(MightBeAPlugin)
{
    libraryRefCount = 1;
    libraryUnloadCount = 1;
    libraryMap()->insert(canonicalFileName, this);
}

QLibraryPrivate *QLibraryPrivate::findOrCreate(const QString &fileName)
{
    if (QLibraryPrivate *lib = libraryMap()->value(fileName)) {
        ++lib->libraryUnloadCount;
        ++lib->libraryRefCount;
        return lib;
    }
    return new QLibraryPrivate(fileName);
}

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) // only unload if ALL QLibrary instance wanted to
        if  (unload_sys())
            pHnd = 0;
    return (pHnd == 0);
}

void QLibraryPrivate::release()
{
    if (!--libraryRefCount)
        delete this;
}

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

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

    QByteArray key;
    bool success = false;

    QFileInfo fileinfo(fileName);
    lastModified  = fileinfo.lastModified().toString(Qt::ISODate);
    QString regkey = QString::fromLatin1("Qt Plugin Cache %1.%2/%3")
                     .arg((QT_VERSION & 0xff0000) >> 16)
                     .arg((QT_VERSION & 0xff00) >> 8)
                     .arg(fileName);
    QStringList reg;

    QCoreSettings settings(Qt::UserScope, QLatin1String("trolltech.com"));
    reg = settings.value(regkey).toStringList();
    if (reg.count() == 3 &&lastModified == reg[2]) {
        qt_version = reg[0].toUInt(0, 16);
        key = reg[1].latin1();
        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, &key);
        } else
#endif
        {
            bool temporary_load = false;
            if (!pHnd)
                temporary_load =  load_sys();
#  ifdef Q_CC_BOR
            typedef const char * __stdcall (*QtPluginQueryVerificationDataFn)();
#  else
            typedef const char * (*QtPluginQueryVerificationDataFn)();
#  endif
            QtPluginQueryVerificationDataFn qtPluginQueryVerificationDataFn =
                (QtPluginQueryVerificationDataFn) resolve("qt_plugin_query_verification_data");

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

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

    if (!success) {
        qWarning("In %s:\n Not a plugin", QFile::encodeName(fileName).constData());
        return false;
    }

    pluginState = IsNotAPlugin; // be pessimistic

    bool warn = true;
    if ((qt_version > QT_VERSION) ||
                ((QT_VERSION & 0xff0000) > (qt_version & 0xff0000))) {
        if (warn)
            qWarning("In %s:\n"
                      "  Plugin uses incompatible Qt library (%d.%d.%d)",
                      (const char*) QFile::encodeName(fileName),
                      (qt_version&0xff0000) >> 16, (qt_version&0xff00) >> 8, qt_version&0xff);
    } else if (key != QT_BUILD_KEY) {
        if (warn)
            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);
    } else {
        pluginState = IsAPlugin;
    }

    return pluginState == IsAPlugin;
}

/*!
    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.

    On Darwin and Mac OS X this function uses code from dlcompat, part of the
    OpenDarwin project.

    \sa unload()

    \legalese

    Copyright (c) 2002 Jorge Acereda and Peter O'Gorman

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
bool QLibrary::load()
{
    if (!d)
        return false;
    if (did_load)
        return d->pHnd;
    did_load = true;
    return d->load();
}

/*!
    Unloads the library and returns true if the library could be
    unloaded; otherwise returns false.

    This happens automatically on application termination, so you
    shouldn't normally need to call this function.

    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().

    Note that on Mac OS X, dynamic libraries cannot be unloaded.

    \sa resolve(), load()
*/
bool QLibrary::unload()
{
    if (did_load) {
        did_load = false;
        return d->unload();
    }
    return false;
}

/*!
    Returns true if the library is loaded; otherwise returns false.

    \sa load()
 */
bool QLibrary::isLoaded() const
{
    return d && d->pHnd;
}


/*!
    Constructs a library with the given \a parent.
 */
QLibrary::QLibrary(QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
}


/*!
    Constructs a library object with the given \a parent that will
    load the library specified by \a fileName.

    We recommend omitting the file's suffix in \a fileName, since
    QLibrary will automatically look for the file with the appropriate
    suffix in accordance with the platform, e.g. ".so" on Unix,
    ".dylib" on Mac OS X, and ".dll" on Windows. (See \l{fileName}.)
 */
QLibrary::QLibrary(const QString& fileName, QObject *parent)
    :QObject(parent), d(0), did_load(false)
{
    setFileName(fileName);
}

/*!
    Destroys the QLibrary object.

    Unless unload() was called explicitly, the library stays in memory
    until the application terminates.

    \sa isLoaded(), unload()
*/
QLibrary::~QLibrary()
{
    if (d)
        d->release();
}


/*!
    \property QLibrary::fileName
    \brief the file name of the library

    We recommend omitting the file's suffix in the file name, since
    QLibrary will automatically look for the file with the appropriate
    suffix in accordance with the following list:

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

    When loading the library, QLibrary searches in all system-specific
    library locations (e.g. \c LD_LIBRARY_PATH on Unix), unless the
    file name has an absolute path.
*/

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

}

QString QLibrary::fileName() const
{
    if (d)
        return d->fileName;
    return QString();
}


/*!
    Returns the address of the exported symbol \a symbol. The library is
    loaded if necessary. The function returns 0 if the symbol could
    not be resolved or if the library could not be loaded.

    Example:
    \code
    typedef int (*avgProc)(int, int);

    avgProc avg = (avgProc) library->resolve("avg");
    if (avg)
        return avg(5, 8);
    else
        return -1;
    \endcode

    The symbol must be exported as a C-function from the library. This
    means that the function must be wrapped in an \c{extern "C"} if
    the library is compiled with a C++ compiler. On Windows you must
    also explicitly export the function from the DLL using the
    \c{__declspec(dllexport)} compiler directive, for example:

    \code
    extern "C" MY_EXPORT int avg(int a, int b)
    {
        return (a + b) / 2;
    }
    \endcode

    with \c MY_EXPORT defined as

    \code
    #ifdef Q_WS_WIN
    # define MY_EXPORT __declspec(dllexport)
    #else
    # define MY_EXPORT
    #endif
    \endcode

    On Darwin and Mac OS X this function uses code from dlcompat, part of the
    OpenDarwin project.

    \legalese

    Copyright (c) 2002 Jorge Acereda and Peter O'Gorman

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
void *QLibrary::resolve(const char *symbol)
{
    if (!d)
        return 0;
    if (!d->pHnd)
        d->load();
    return d->resolve(symbol);
}

/*!
    \overload

    Loads the library \a fileName and returns the address of the
    exported symbol \a symbol. Note that \a fileName should not
    include the platform-specific file suffix; (see \l{fileName}). The
    library remains loaded until the application exits.

    The function returns 0 if the symbol could not be resolved or if
    the library could not be loaded.

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

/*!
    \fn QString QLibrary::library() const

    Use fileName() instead.
*/

/*!
    \fn void QLibrary::setAutoUnload( bool b )

    Use load(), isLoaded(), and unload() as necessary instead.
*/

