Don't read before the beginning of the string

The code did discard the the data, so it wasn't affecting the comparison
result (tests added anyway), but it could cause crashes if the pointer
to the beginning of the data in the first 8 bytes of a page.

Change-Id: I618e68de329b65de34ef8c934934c3e631cc6c9f
Reported-By: Erik Verbruggen
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qstringref/tst_qstringref.cpp b/tests/auto/corelib/tools/qstringref/tst_qstringref.cpp
index 7bbcee8ab2..342abb7ea8 100644
--- a/tests/auto/corelib/tools/qstringref/tst_qstringref.cpp
+++ b/tests/auto/corelib/tools/qstringref/tst_qstringref.cpp
@@ -68,6 +68,8 @@ private slots:
     void isEmpty();
     void compare_data();
     void compare();
+    void compare2_data();
+    void compare2();
     void operator_eqeq_nullstring();
     void toNum();
     void toDouble_data();
@@ -792,11 +794,17 @@ void tst_QStringRef::compare_data()
     QTest::newRow("data3") << QString("abc") << QString("abc") << 0 << 0;
     QTest::newRow("data4") << QString("abC") << QString("abc") << -1 << 0;
     QTest::newRow("data5") << QString("abc") << QString("abC") << 1 << 0;
+    QTest::newRow("data10") << QString("abcdefgh") << QString("abcdefgh") << 0 << 0;
+    QTest::newRow("data11") << QString("abcdefgh") << QString("abCdefgh") << 1 << 0;
+    QTest::newRow("data12") << QString("0123456789012345") << QString("0123456789012345") << 0 << 0;
+    QTest::newRow("data13") << QString("0123556789012345") << QString("0123456789012345") << 1 << 1;
 
     // different length
     QTest::newRow("data6") << QString("abcdef") << QString("abc") << 1 << 1;
     QTest::newRow("data7") << QString("abCdef") << QString("abc") << -1 << 1;
     QTest::newRow("data8") << QString("abc") << QString("abcdef") << -1 << -1;
+    QTest::newRow("data14") << QString("abcdefgh") << QString("abcdefghi") << -1 << -1;
+    QTest::newRow("data15") << QString("01234567890123456") << QString("0123456789012345") << 1 << 1;
 
     QString upper;
     upper += QChar(QChar::highSurrogate(0x10400));
@@ -862,6 +870,46 @@ void tst_QStringRef::compare()
     }
 }
 
+void tst_QStringRef::compare2_data()
+{
+    compare_data();
+}
+
+void tst_QStringRef::compare2()
+{
+    QFETCH(QString, s1);
+    QFETCH(QString, s2);
+    QFETCH(int, csr);
+    QFETCH(int, cir);
+
+    // prepend and append data
+    // we only use Latin1 here so isLatin1 still results true
+    s1.prepend("xyz").append("zyx");
+    s2.prepend("foobar").append("raboof");
+
+    QStringRef r1(&s1, 3, s1.length() - 6);
+    QStringRef r2(&s2, 6, s2.length() - 12);
+
+    QCOMPARE(sign(QStringRef::compare(r1, r2)), csr);
+    QCOMPARE(sign(r1.compare(r2)), csr);
+
+    QCOMPARE(sign(r1.compare(r2, Qt::CaseSensitive)), csr);
+    QCOMPARE(sign(r1.compare(r2, Qt::CaseInsensitive)), cir);
+
+    QCOMPARE(sign(QStringRef::compare(r1, r2, Qt::CaseSensitive)), csr);
+    QCOMPARE(sign(QStringRef::compare(r1, r2, Qt::CaseInsensitive)), cir);
+
+    if (isLatin(s2)) {
+        QCOMPARE(sign(QStringRef::compare(r1, QLatin1String(r2.toLatin1()))), csr);
+        QCOMPARE(sign(QStringRef::compare(r1, QLatin1String(r2.toLatin1()), Qt::CaseInsensitive)), cir);
+    }
+
+    if (isLatin(s1)) {
+        QCOMPARE(sign(QStringRef::compare(r2, QLatin1String(r1.toLatin1()))), -csr);
+        QCOMPARE(sign(QStringRef::compare(r2, QLatin1String(r1.toLatin1()), Qt::CaseInsensitive)), -cir);
+    }
+}
+
 void tst_QStringRef::toNum()
 {
 #define TEST_TO_INT(num, func, type) \