Optimize plugin loading on ELF platforms

This is equal to 3c2a43f91e0225bde8d6e6d6076dfe2cddbc2f8e
except the alignment checks have been relaxed.

Reviewed-by: janarve

4 files changed, 365 insertions, 6 deletions

diff --git a/src/corelib/plugin/plugin.pri b/src/corelib/plugin/plugin.pri
index 2e986ec..2e7db5d 100644
--- a/src/corelib/plugin/plugin.pri
+++ b/src/corelib/plugin/plugin.pri
@@ -7,13 +7,15 @@ HEADERS += \
 	plugin/qlibrary_p.h \
 	plugin/qplugin.h \
 	plugin/quuid.h \
-	plugin/qfactoryloader_p.h
+	plugin/qfactoryloader_p.h \
+	plugin/qelfparser_p.h
 
 SOURCES += \
 	plugin/qpluginloader.cpp \
 	plugin/qfactoryloader.cpp \
 	plugin/quuid.cpp \
-	plugin/qlibrary.cpp
+	plugin/qlibrary.cpp \
+	plugin/qelfparser_p.cpp
 
 win32 {
 	SOURCES += plugin/qlibrary_win.cpp
diff --git a/src/corelib/plugin/qelfparser_p.cpp b/src/corelib/plugin/qelfparser_p.cpp
new file mode 100644
index 0000000..2e77ae7
--- /dev/null
+++ b/src/corelib/plugin/qelfparser_p.cpp
@@ -0,0 +1,234 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qlibrary_p.h"
+#include "qelfparser_p.h"
+#include <qdebug.h>
+
+QT_BEGIN_NAMESPACE
+
+// #define QELFPARSER_DEBUG 1
+
+const char *QElfParser::parseSectionHeader(const char *data, ElfSectionHeader *sh)
+{
+    sh->name = read<qelfword_t>(data);
+    data += sizeof(qelfword_t); // sh_name
+    sh->type = read<qelfword_t>(data);
+    data += sizeof(qelfword_t)  // sh_type
+         + sizeof(qelfaddr_t)   // sh_flags
+         + sizeof(qelfaddr_t);  // sh_addr
+    sh->offset = read<qelfoff_t>(data);
+    data += sizeof(qelfoff_t);  // sh_offset
+    sh->size = read<qelfword_t>(data);
+    data += sizeof(qelfword_t); // sh_size
+    return data;
+}
+
+int QElfParser::parse(const char *dataStart, ulong fdlen, const QString &library, QLibraryPrivate *lib, long *pos, ulong *sectionlen)
+{
+#if defined(QELFPARSER_DEBUG)
+    qDebug() << "QElfParser::parse " << library;
+#endif
+
+    if (fdlen < 64){
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is not an ELF object (%2)").arg(library).arg(QLatin1String("file too small"));
+        return NotElf;
+    }
+    const char *data = dataStart;
+    if (qstrncmp(data, "\177ELF", 4) != 0) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is not an ELF object").arg(library);
+        return NotElf;
+    }
+    // 32 or 64 bit
+    if (data[4] != 1 && data[4] != 2) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library).arg(QLatin1String("odd cpu architecture"));
+        return Corrupt;
+    }
+    m_bits = (data[4] << 5);
+
+    /*  If you remove this check, to read ELF objects of a different arch, please make sure you modify the typedefs
+        to match the _plugin_ architecture.
+    */
+    if ((sizeof(void*) == 4 && m_bits != 32) || (sizeof(void*) == 8 && m_bits != 64)) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library).arg(QLatin1String("wrong cpu architecture"));
+        return Corrupt;
+    }
+    // endian
+    if (data[5] == 0) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library).arg(QLatin1String("odd endianess"));
+        return Corrupt;
+    }
+    m_endian = (data[5] == 1 ? ElfLittleEndian : ElfBigEndian);
+
+    data += 16                  // e_ident
+         +  sizeof(qelfhalf_t)  // e_type
+         +  sizeof(qelfhalf_t)  // e_machine
+         +  sizeof(qelfword_t)  // e_version
+         +  sizeof(qelfaddr_t)  // e_entry
+         +  sizeof(qelfoff_t);  // e_phoff
+
+    qelfoff_t e_shoff = read<qelfoff_t> (data);
+    data += sizeof(qelfoff_t)    // e_shoff
+         +  sizeof(qelfword_t);  // e_flags
+
+    qelfhalf_t e_shsize = read<qelfhalf_t> (data);
+
+    if (e_shsize > fdlen) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library).arg(QLatin1String("unexpected e_shsize"));
+        return Corrupt;
+    }
+
+    data += sizeof(qelfhalf_t)  // e_ehsize
+         +  sizeof(qelfhalf_t)  // e_phentsize
+         +  sizeof(qelfhalf_t); // e_phnum
+
+    qelfhalf_t e_shentsize = read<qelfhalf_t> (data);
+
+    if (e_shentsize % 4){
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library).arg(QLatin1String("unexpected e_shentsize"));
+        return Corrupt;
+    }
+    data += sizeof(qelfhalf_t); // e_shentsize
+    qelfhalf_t e_shnum     = read<qelfhalf_t> (data);
+    data += sizeof(qelfhalf_t); // e_shnum
+    qelfhalf_t e_shtrndx   = read<qelfhalf_t> (data);
+    data += sizeof(qelfhalf_t); // e_shtrndx
+
+    if ((e_shnum * e_shentsize) > fdlen) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                               .arg(QLatin1String("announced %2 sections, each %3 bytes, exceed file size"))
+                               .arg(e_shnum).arg(e_shentsize);
+        return Corrupt;
+    }
+
+#if defined(QELFPARSER_DEBUG)
+    qDebug() << e_shnum << "sections starting at " << ("0x" + QByteArray::number(e_shoff, 16)).data() << "each" << e_shentsize << "bytes";
+#endif
+
+    ElfSectionHeader strtab;
+    qulonglong soff = e_shoff + e_shentsize * (e_shtrndx);
+
+    if ((soff + e_shentsize) > fdlen || soff % 4 || soff == 0) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                               .arg(QLatin1String("shstrtab section header seems to be at %1"))
+                               .arg(QString::number(soff, 16));
+        return Corrupt;
+    }
+
+    parseSectionHeader(dataStart + soff, &strtab);
+    m_stringTableFileOffset = strtab.offset;
+
+    if ((m_stringTableFileOffset + e_shentsize) >= fdlen || m_stringTableFileOffset == 0) {
+        if (lib)
+            lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                               .arg(QLatin1String("string table seems to be at %1"))
+                               .arg(QString::number(soff, 16));
+        return Corrupt;
+    }
+
+#if defined(QELFPARSER_DEBUG)
+    qDebug(".shstrtab at 0x%s", QByteArray::number(m_stringTableFileOffset, 16).data());
+#endif
+
+    const char *s = dataStart + e_shoff;
+    for (int i = 0; i < e_shnum; ++i) {
+        ElfSectionHeader sh;
+        parseSectionHeader(s, &sh);
+        if (sh.name == 0) {
+            s += e_shentsize;
+            continue;
+        }
+        const char *shnam = dataStart + m_stringTableFileOffset + sh.name;
+
+        if (m_stringTableFileOffset + sh.name > fdlen) {
+            if (lib)
+                lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                                  .arg(QLatin1String("section name %2 of %3 behind end of file"))
+                                  .arg(i).arg(e_shnum);
+            return Corrupt;
+        }
+
+#if defined(QELFPARSER_DEBUG)
+        qDebug() << "++++" << i << shnam;
+#endif
+
+        if (qstrcmp(shnam, ".qtplugin") == 0 || qstrcmp(shnam, ".rodata") == 0) {
+            if (!(sh.type & 0x1)) {
+                if (shnam[1] == 'r') {
+                    if (lib)
+                        lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                            .arg(QLatin1String("empty .rodata. not a library."));
+                    return Corrupt;
+                }
+#if defined(QELFPARSER_DEBUG)
+                qDebug()<<"section is not program data. skipped.";
+#endif
+                s += e_shentsize;
+                continue;
+            }
+
+            if (sh.offset == 0 || (sh.offset + sh.size) > fdlen) {
+                if (lib)
+                    lib->errorString = QLibrary::tr("'%1' is an invalid ELF object (%2)").arg(library)
+                                      .arg(QLatin1String("missing section data. This is not a library."));
+                return Corrupt;
+            }
+            *pos = sh.offset;
+            *sectionlen = sh.size - 1;
+            if (shnam[1] == 'q')
+                return Ok;
+        }
+        s += e_shentsize;
+    }
+    return NoQtSection;
+}
+
+QT_END_NAMESPACE
+
diff --git a/src/corelib/plugin/qelfparser_p.h b/src/corelib/plugin/qelfparser_p.h
new file mode 100644
index 0000000..380d5a1
--- /dev/null
+++ b/src/corelib/plugin/qelfparser_p.h
@@ -0,0 +1,103 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QELFPARSER_P_H
+#define QELFPARSER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <qendian.h>
+#include <qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+class QString;
+class QLibraryPrivate;
+
+typedef quint16  qelfhalf_t;
+typedef quint32  qelfword_t;
+typedef quintptr qelfoff_t;
+typedef quintptr qelfaddr_t;
+
+class QElfParser
+{
+public:
+    enum {Ok = 0, NotElf = 1, NoQtSection = 2, Corrupt = 3};
+    enum {ElfLittleEndian = 0, ElfBigEndian = 1};
+
+    struct ElfSectionHeader
+    {
+        qelfword_t name;
+        qelfword_t type;
+        qelfoff_t  offset;
+        qelfword_t size;
+    };
+
+    int m_endian;
+    int m_bits;
+    int m_stringTableFileOffset;
+
+    template <typename T>
+    T read(const char *s)
+    {
+        if (m_endian == ElfBigEndian)
+            return qFromBigEndian<T>(reinterpret_cast<const uchar *>(s));
+        else
+            return qFromLittleEndian<T>(reinterpret_cast<const uchar *>(s));
+    }
+
+    const char *parseSectionHeader(const char* s, ElfSectionHeader *sh);
+    int parse(const char *m_s, ulong fdlen, const QString &library, QLibraryPrivate *lib, long *pos, ulong *sectionlen);
+};
+
+QT_END_NAMESPACE
+
+#endif // QELFPARSER_P_H
+
diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index 1ca9d70..8f82cc4 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -38,7 +38,6 @@
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/
-
 #include "qplatformdefs.h"
 #include "qlibrary.h"
 
@@ -61,6 +60,7 @@
 #include <qdebug.h>
 #include <qvector.h>
 #include <qdir.h>
+#include "qelfparser_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -365,11 +365,31 @@ static bool qt_unix_query(const QString &library, uint *version, bool *debug, QB
         fdlen = data.size();
     }
 
-    // verify that the pattern is present in the plugin
+    /*
+       ELF binaries on GNU, have .qplugin sections.
+    */
+    long pos = 0;
     const char pattern[] = "pattern=QT_PLUGIN_VERIFICATION_DATA";
     const ulong plen = qstrlen(pattern);
-    long pos = qt_find_pattern(filedata, fdlen, pattern, plen);
-
+#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)
+        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);