Plugins: store the metadata in CBOR instead of binary JSON

In preparation for Qt 6 deprecating the binary JSON format. Also reduces
the size of the metadata a little: for the xcb platform plugin, it went
down from 264 bytes to 138; for the jpeg image plugin, it went from 320
to 135.

I've had to change the signature so older versions of Qt won't try to
parse the CBOR data as Binary JSON. Unfortunately, before QJsonDocument
could get a chance to reject it, qJsonFromRawLibraryMetaData() needed to
allocate memory and that causes crashes with Qt < 5.11.2.

Change-Id: Ieb48f7c0dd0e4e0fb35efffd153bee34e16ce347
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 113 insertions, 45 deletions

diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index a3ef1147d6..e5154b779b 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -2,6 +2,7 @@
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
 ** Copyright (C) 2013 Olivier Goffart <ogoffart@woboq.com>
+** Copyright (C) 2018 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the tools applications of the Qt Toolkit.
@@ -28,6 +29,7 @@
 ****************************************************************************/
 
 #include "generator.h"
+#include "cbordevice.h"
 #include "outputrevision.h"
 #include "utils.h"
 #include <QtCore/qmetatype.h>
@@ -36,9 +38,13 @@
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qjsonarray.h>
 #include <QtCore/qplugin.h>
+#include <QtCore/qstringview.h>
+
+#include <math.h>
 #include <stdio.h>
 
 #include <private/qmetaobject_p.h> //for the flags.
+#include <private/qplugin_p.h> //for the flags.
 
 QT_BEGIN_NAMESPACE
 
@@ -1560,31 +1566,56 @@ void Generator::generateSignal(FunctionDef *def,int index)
     fprintf(out, "}\n");
 }
 
-static void writePluginMetaData(FILE *out, const QJsonObject &data)
+static CborError jsonValueToCbor(CborEncoder *parent, const QJsonValue &v);
+static CborError jsonObjectToCbor(CborEncoder *parent, const QJsonObject &o)
 {
-    const QJsonDocument doc(data);
+    auto it = o.constBegin();
+    auto end = o.constEnd();
+    CborEncoder map;
+    cbor_encoder_create_map(parent, &map, o.size());
+
+    for ( ; it != end; ++it) {
+        QByteArray key = it.key().toUtf8();
+        cbor_encode_text_string(&map, key.constData(), key.size());
+        jsonValueToCbor(&map, it.value());
+    }
+    return cbor_encoder_close_container(parent, &map);
+}
 
-    fputs("\nQT_PLUGIN_METADATA_SECTION\n"
-          "static const unsigned char qt_pluginMetaData[] = {\n"
-          "    'Q', 'T', 'M', 'E', 'T', 'A', 'D', 'A', 'T', 'A', ' ', ' ',\n   ", out);
-#if 0
-    fprintf(out, "\"%s\";\n", doc.toJson().constData());
-#else
-    const QByteArray binary = doc.toBinaryData();
-    const int last = binary.size() - 1;
-    for (int i = 0; i < last; ++i) {
-        uchar c = (uchar)binary.at(i);
-        if (c < 0x20 || c >= 0x7f)
-            fprintf(out, " 0x%02x,", c);
-        else if (c == '\'' || c == '\\')
-            fprintf(out, " '\\%c',", c);
-        else
-            fprintf(out, " '%c', ", c);
-        if (!((i + 1) % 8))
-            fputs("\n   ", out);
+static CborError jsonArrayToCbor(CborEncoder *parent, const QJsonArray &a)
+{
+    CborEncoder array;
+    cbor_encoder_create_array(parent, &array, a.size());
+    for (const QJsonValue &v : a)
+        jsonValueToCbor(&array, v);
+    return cbor_encoder_close_container(parent, &array);
+}
+
+static CborError jsonValueToCbor(CborEncoder *parent, const QJsonValue &v)
+{
+    switch (v.type()) {
+    case QJsonValue::Null:
+    case QJsonValue::Undefined:
+        return cbor_encode_null(parent);
+    case QJsonValue::Bool:
+        return cbor_encode_boolean(parent, v.toBool());
+    case QJsonValue::Array:
+        return jsonArrayToCbor(parent, v.toArray());
+    case QJsonValue::Object:
+        return jsonObjectToCbor(parent, v.toObject());
+    case QJsonValue::String: {
+        QByteArray s = v.toString().toUtf8();
+        return cbor_encode_text_string(parent, s.constData(), s.size());
     }
-    fprintf(out, " 0x%02x\n};\n", (uchar)binary.at(last));
-#endif
+    case QJsonValue::Double: {
+        double d = v.toDouble();
+        if (d == floor(d) && fabs(d) <= (Q_INT64_C(1) << std::numeric_limits<double>::digits))
+            return cbor_encode_int(parent, qint64(d));
+        return cbor_encode_double(parent, d);
+    }
+    }
+    Q_UNREACHABLE();
+    return CborUnknownError;
 }
 
 void Generator::generatePluginMetaData()
@@ -1592,32 +1623,59 @@ void Generator::generatePluginMetaData()
     if (cdef->pluginData.iid.isEmpty())
         return;
 
-    // Write plugin meta data #ifdefed QT_NO_DEBUG with debug=false,
-    // true, respectively.
-
-    QJsonObject data;
-    const QString debugKey = QStringLiteral("debug");
-    data.insert(QStringLiteral("IID"), QLatin1String(cdef->pluginData.iid.constData()));
-    data.insert(QStringLiteral("className"), QLatin1String(cdef->classname.constData()));
-    data.insert(QStringLiteral("version"), (int)QT_VERSION);
-    data.insert(debugKey, QJsonValue(false));
-    data.insert(QStringLiteral("MetaData"), cdef->pluginData.metaData.object());
+    fputs("\nQT_PLUGIN_METADATA_SECTION\n"
+          "static const unsigned char qt_pluginMetaData[] = {\n"
+          "    'Q', 'T', 'M', 'E', 'T', 'A', 'D', 'A', 'T', 'A', ' ', '!',", out);
+
+    CborDevice dev(out);
+    CborEncoder enc;
+    cbor_encoder_init_writer(&enc, CborDevice::callback, &dev);
+
+    CborEncoder map;
+    cbor_encoder_create_map(&enc, &map, CborIndefiniteLength);
+
+    dev.nextItem("\"version\"");
+    cbor_encode_int(&map, int(QtPluginMetaDataKeys::QtVersion));
+    cbor_encode_int(&map, QT_VERSION);
+
+    fputs("\n#ifdef QT_NO_DEBUG", out);
+    dev.nextItem("\"debug\" = false");
+    cbor_encode_int(&map, int(QtPluginMetaDataKeys::Debug));
+    cbor_encode_boolean(&map, false);
+    fputs("\n#else", out);
+    dev.nextItem("\"debug\" = true");
+    cbor_encode_int(&map, int(QtPluginMetaDataKeys::Debug));
+    cbor_encode_boolean(&map, true);
+    fputs("\n#endif", out);
+
+    dev.nextItem("\"IID\"");
+    cbor_encode_int(&map, int(QtPluginMetaDataKeys::IID));
+    cbor_encode_text_string(&map, cdef->pluginData.iid.constData(), cdef->pluginData.iid.size());
+
+    dev.nextItem("\"className\"");
+    cbor_encode_int(&map, int(QtPluginMetaDataKeys::ClassName));
+    cbor_encode_text_string(&map, cdef->classname.constData(), cdef->classname.size());
+
+    QJsonObject o = cdef->pluginData.metaData.object();
+    if (!o.isEmpty()) {
+        dev.nextItem("\"MetaData\"");
+        cbor_encode_int(&map, int(QtPluginMetaDataKeys::MetaData));
+        jsonObjectToCbor(&map, o);
+    }
 
     // Add -M args from the command line:
-    for (auto it = cdef->pluginData.metaArgs.cbegin(), end = cdef->pluginData.metaArgs.cend(); it != end; ++it)
-        data.insert(it.key(), it.value());
-
-    fputs("\nQT_PLUGIN_METADATA_SECTION const uint qt_section_alignment_dummy = 42;\n\n"
-          "#ifdef QT_NO_DEBUG\n", out);
-    writePluginMetaData(out, data);
-
-    fputs("\n#else // QT_NO_DEBUG\n", out);
-
-    data.remove(debugKey);
-    data.insert(debugKey, QJsonValue(true));
-    writePluginMetaData(out, data);
+    for (auto it = cdef->pluginData.metaArgs.cbegin(), end = cdef->pluginData.metaArgs.cend(); it != end; ++it) {
+        const QJsonArray &a = it.value();
+        QByteArray key = it.key().toUtf8();
+        dev.nextItem(QByteArray("command-line \"" + key + "\"").constData());
+        cbor_encode_text_string(&map, key.constData(), key.size());
+        jsonArrayToCbor(&map, a);
+    }
 
-    fputs("#endif // QT_NO_DEBUG\n\n", out);
+    // Close the CBOR map manually
+    dev.nextItem();
+    cbor_encoder_close_container(&enc, &map);
+    fputs("\n};\n", out);
 
     // 'Use' all namespaces.
     int pos = cdef->qualified.indexOf("::");
@@ -1627,4 +1685,14 @@ void Generator::generatePluginMetaData()
             cdef->qualified.constData(), cdef->classname.constData());
 }
 
+QT_WARNING_DISABLE_GCC("-Wunused-function")
+QT_WARNING_DISABLE_CLANG("-Wunused-function")
+QT_WARNING_DISABLE_CLANG("-Wundefined-internal")
+QT_WARNING_DISABLE_MSVC(4334) // '<<': result of 32-bit shift implicitly converted to 64 bits (was 64-bit shift intended?)
+
+#define CBOR_ENCODER_WRITER_CONTROL     1
+#define CBOR_ENCODER_WRITE_FUNCTION     CborDevice::callback
+
 QT_END_NAMESPACE
+
+#include "cborencoder.c"