From 16e7366b5ce61418a69ba13a74996514b69dac37 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Fri, 10 Sep 2021 18:00:46 -0700
Subject: [PATCH] QPlugin: use one global metadata magic string

And use QByteArrayView where applicable.

Change-Id: I2de1b4dfacd443148279fffd16a39ec22908f75f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/corelib/plugin/qfactoryloader.cpp | 37 ++++++++++-----------------
 src/corelib/plugin/qlibrary.cpp       | 17 +++++-------
 2 files changed, 20 insertions(+), 34 deletions(-)

diff --git a/src/corelib/plugin/qfactoryloader.cpp b/src/corelib/plugin/qfactoryloader.cpp
index 17844353714..5a2b9e7758c 100644
--- a/src/corelib/plugin/qfactoryloader.cpp
+++ b/src/corelib/plugin/qfactoryloader.cpp
@@ -48,7 +48,6 @@
 #include "private/qobject_p.h"
 #include "qcbormap.h"
 #include "qcborvalue.h"
-#include "qendian.h"
 #include "qjsonarray.h"
 #include "qjsondocument.h"
 #include "qjsonobject.h"
@@ -65,24 +64,23 @@
 
 QT_BEGIN_NAMESPACE
 
-static inline int metaDataSignatureLength()
+QJsonDocument qJsonFromRawLibraryMetaData(const char *raw, qsizetype size, QString *errMsg)
 {
-    return sizeof("QTMETADATA  ") - 1;
-}
+    Q_ASSERT(size >= qsizetype(sizeof(QPluginMetaData::MagicString)));
+    raw += sizeof(QPluginMetaData::MagicString);
+    size -= sizeof(QPluginMetaData::MagicString);
 
-static QJsonDocument jsonFromCborMetaData(const char *raw, qsizetype size, QString *errMsg)
-{
     // extract the keys not stored in CBOR
-    int qt_metadataVersion = quint8(raw[0]);
-    int qt_version = qFromBigEndian<quint16>(raw + 1);
-    int qt_archRequirements = quint8(raw[3]);
-    if (Q_UNLIKELY(raw[-1] != '!' || qt_metadataVersion != 0)) {
+    QPluginMetaData::Header header;
+    Q_ASSERT(size >= qsizetype(sizeof(header)));
+    memcpy(&header, raw, sizeof(header));
+    if (Q_UNLIKELY(header.version > QPluginMetaData::CurrentMetaDataVersion)) {
         *errMsg = QStringLiteral("Invalid metadata version");
         return QJsonDocument();
     }
 
-    raw += 4;
-    size -= 4;
+    raw += sizeof(header);
+    size -= sizeof(header);
     QByteArray ba = QByteArray::fromRawData(raw, int(size));
     QCborParserError err;
     QCborValue metadata = QCborValue::fromCbor(ba, &err);
@@ -98,9 +96,10 @@ static QJsonDocument jsonFromCborMetaData(const char *raw, qsizetype size, QStri
     }
 
     QJsonObject o;
-    o.insert(QLatin1String("version"), qt_version << 8);
-    o.insert(QLatin1String("debug"), bool(qt_archRequirements & 1));
-    o.insert(QLatin1String("archreq"), qt_archRequirements);
+    o.insert(QLatin1String("version"),
+             QT_VERSION_CHECK(header.qt_major_version, header.qt_minor_version, 0));
+    o.insert(QLatin1String("debug"), bool(header.plugin_arch_requirements & 1));
+    o.insert(QLatin1String("archreq"), header.plugin_arch_requirements);
 
     // convert the top-level map integer keys
     for (auto it : metadata.toMap()) {
@@ -128,14 +127,6 @@ static QJsonDocument jsonFromCborMetaData(const char *raw, qsizetype size, QStri
     return QJsonDocument(o);
 }
 
-QJsonDocument qJsonFromRawLibraryMetaData(const char *raw, qsizetype sectionSize, QString *errMsg)
-{
-    raw += metaDataSignatureLength();
-    sectionSize -= metaDataSignatureLength();
-
-    return jsonFromCborMetaData(raw, sectionSize, errMsg);
-}
-
 class QFactoryLoaderPrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QFactoryLoader)
diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index ee81b32bfb8..befe784c05a 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
-** Copyright (C) 2018 Intel Corporation.
+** Copyright (C) 2020 The Qt Company Ltd.
+** Copyright (C) 2021 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -182,9 +182,7 @@ QT_BEGIN_NAMESPACE
     \sa loadHints
 */
 
-
-static qsizetype qt_find_pattern(const char *s, qsizetype s_len,
-                             const char *pattern, ulong p_len)
+static qsizetype qt_find_pattern(const char *s, qsizetype s_len)
 {
     /*
       We used to search from the end of the file so we'd skip the code and find
@@ -195,8 +193,8 @@ static qsizetype qt_find_pattern(const char *s, qsizetype s_len,
       More importantly, the pattern string may exist in the debug information due
       to it being used in the plugin in the first place.
     */
-
-    static const QByteArrayMatcher matcher(QByteArray(pattern, p_len));
+    QByteArrayView pattern = QPluginMetaData::MagicString;
+    static const QByteArrayMatcher matcher(pattern.toByteArray());
     return matcher.indexIn(s, s_len);
 }
 
@@ -278,10 +276,7 @@ static bool findPatternUnloaded(const QString &library, QLibraryPrivate *lib)
     }
 #endif // defined(Q_OF_ELF) && defined(Q_CC_GNU)
 
-    char pattern[] = "qTMETADATA ";
-    pattern[0] = 'Q'; // Ensure the pattern "QTMETADATA" is not found in this library should QPluginLoader ever encounter it.
-    const ulong plen = ulong(qstrlen(pattern));
-    if (qsizetype rel = qt_find_pattern(filedata + r.pos, r.length, pattern, plen);
+    if (qsizetype rel = qt_find_pattern(filedata + r.pos, r.length);
             rel >= 0) {
         const char *data = filedata + r.pos + rel;
         QString errMsg;