qlibrary.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

/****************************************************************************
**
** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 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 GNU
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at [e-mail].
**
** 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"

#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>

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

Q_GLOBAL_STATIC(QMutex, qt_library_mutex)

/*!
    \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");
        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)();
        MyPrototype myFunction =
                (MyPrototype) QLibrary::resolve("mylib", "mysymbol");
        if (myFunction)
            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, 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] + 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, bool *debug, QByteArray *key)
{
    QFile file(library);
    if (!file.open(QIODevice::ReadOnly)) {
#if defined(QT_DEBUG_COMPONENT)
        qWarning("%s: %s", (const char*) QFile::encodeName(library),
            qPrintable(qt_error_string(errno)));
#endif
        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 defined(QT_DEBUG_COMPONENT)
        qWarning("mmap: %s", qPrintable(qt_error_string(errno)));
#endif
#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);

#ifdef USE_MMAP
    if (mapaddr != MAP_FAILED && munmap(mapaddr, maplen) != 0) {
#if defined(QT_DEBUG_COMPONENT)
        qWarning("munmap: %s", qPrintable(qt_error_string(errno)));
#endif
    }
#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;