From a5025efccfa877426dcdf31d91cacb1a6c52b276 Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@qt.io>
Date: Mon, 6 Jul 2020 09:36:32 +0200
Subject: [PATCH] Fix a crash in QClipBoard when copying utf16 data

Properly use the new QStringConverter API and not an internal
qFromUtfEncoded method that was buggy after the changes.

Take the oppportunity to clean up and remove qFromUtfEncoded, as
QClipboard was its only user.

Fixes: QTBUG-85417
Change-Id: I8540d12056bf3f448c1f628ce0bd0ad462a6447d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
---
 src/corelib/text/qstringconverter.cpp | 20 --------------------
 src/corelib/text/qstringconverter_p.h |  6 ------
 src/gui/kernel/qclipboard.cpp         |  5 ++++-
 3 files changed, 4 insertions(+), 27 deletions(-)

diff --git a/src/corelib/text/qstringconverter.cpp b/src/corelib/text/qstringconverter.cpp
index 30da0add8f6..511f2d7810e 100644
--- a/src/corelib/text/qstringconverter.cpp
+++ b/src/corelib/text/qstringconverter.cpp
@@ -1067,26 +1067,6 @@ QChar *QUtf32::convertToUnicode(QChar *out, const char *chars, qsizetype len, QS
     return out;
 }
 
-QString qFromUtfEncoded(const QByteArray &ba)
-{
-    const qsizetype arraySize = ba.size();
-    const uchar *buf = reinterpret_cast<const uchar *>(ba.constData());
-    const uint bom = 0xfeff;
-
-    if (arraySize > 3) {
-        uint uc = qFromUnaligned<uint>(buf);
-        if (uc == qToBigEndian(bom) || uc == qToLittleEndian(bom))
-            return QUtf32::convertToUnicode(ba.constData(), ba.length(), nullptr); // utf-32
-    }
-
-    if (arraySize > 1) {
-        ushort uc = qFromUnaligned<ushort>(buf);
-        if (uc == qToBigEndian(ushort(bom)) || qToLittleEndian(ushort(bom)))
-            return QUtf16::convertToUnicode(ba.constData(), ba.length(), nullptr); // utf-16
-    }
-    return QUtf8::convertToUnicode(ba.constData(), ba.length());
-}
-
 #if defined(Q_OS_WIN) && !defined(QT_BOOTSTRAPPED)
 static QString convertToUnicodeCharByChar(const char *chars, qsizetype length, QStringConverter::State *state)
 {
diff --git a/src/corelib/text/qstringconverter_p.h b/src/corelib/text/qstringconverter_p.h
index 83ffb889cb1..2e897c47eb1 100644
--- a/src/corelib/text/qstringconverter_p.h
+++ b/src/corelib/text/qstringconverter_p.h
@@ -331,12 +331,6 @@ struct Q_CORE_EXPORT QLocal8Bit
 #endif
 };
 
-/*
- Converts from different utf encodings looking at a possible byte order mark at the
- beginning of the string. If no BOM exists, utf-8 is assumed.
- */
-Q_CORE_EXPORT QString qFromUtfEncoded(const QByteArray &ba);
-
 QT_END_NAMESPACE
 
 #endif // QSTRINGCONVERTER_P_H
diff --git a/src/gui/kernel/qclipboard.cpp b/src/gui/kernel/qclipboard.cpp
index eb6c2af6d13..d51c356970d 100644
--- a/src/gui/kernel/qclipboard.cpp
+++ b/src/gui/kernel/qclipboard.cpp
@@ -286,7 +286,10 @@ QString QClipboard::text(QString &subtype, Mode mode) const
     }
 
     const QByteArray rawData = data->data(QLatin1String("text/") + subtype);
-    return qFromUtfEncoded(rawData);
+    auto encoding = QStringConverter::encodingForData(rawData.constData(), rawData.size());
+    if (!encoding)
+        encoding = QStringConverter::Utf8;
+    return QStringDecoder(*encoding).decode(rawData);
 }
 
 /*!