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Apple OS: Handle QSetting strings with embedded zero-bytes

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Saving strings with embedded zero-bytes (\0) as CFStrings would
sometimes fail, and only write the part of the string leading
up to the first zero-byte, instead of all the way to the final
zero-terminator. This bug was revealed by the code-path that
falls back to storing e.g. QTime as strings, via the helper
method QSettingsPrivate::variantToString().

We now use the same approach as on platforms such as Windows
and WinRT, where the string produced by variantToString() is
checked for null-bytes, and if so, stored using a binary
representation instead of as a string. For our case that
means we fall back to CFData when detecting the null-byte.

To separate strings from regular byte arrays, new logic has
been added to variantToString() that wraps the null-byte
strings in @String(). That way we can implement a fast-path
when converting back from CFData, that doesn't go via the
slow and lossy conversion via UTF8, and the resulting QVariant
will be of type QVariant::ByteArray. The reason for using
UTF-8 as the binary representation of the string is that
in the case of storing a QByteArray("@foo") we need to
still be able to convert it back to the same byte array,
which doesn't work if the on-disk format is UTF-16.

Task-number: QTBUG-56124
Change-Id: Iab2f71cf96cf3225de48dc5e71870d74b6dde1e8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Tor Arne Vestbø 2016-10-03 18:41:30 +02:00 committed by Tor Arne Vestbø
parent 483aff406a
commit 764f5bf48c
5 changed files with 73 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/corelib/io/qsettings.cpp
View File

@ -416,7 +416,9 @@ QString QSettingsPrivate::variantToString(const QVariant &v)
case QVariant::Double:
case QVariant::KeySequence: {
result = v.toString();
if (result.startsWith(QLatin1Char('@')))
if (result.contains(QChar::Null))
result = QLatin1String("@String(") + result + QLatin1Char(')');
else if (result.startsWith(QLatin1Char('@')))
result.prepend(QLatin1Char('@'));
break;
}
@ -476,6 +478,8 @@ QVariant QSettingsPrivate::stringToVariant(const QString &s)
if (s.endsWith(QLatin1Char(')'))) {
if (s.startsWith(QLatin1String("@ByteArray("))) {
return QVariant(s.midRef(11, s.size() - 12).toLatin1());
} else if (s.startsWith(QLatin1String("@String("))) {
return QVariant(s.midRef(8, s.size() - 9).toString());
} else if (s.startsWith(QLatin1String("@Variant("))
|| s.startsWith(QLatin1String("@DateTime("))) {
#ifndef QT_NO_DATASTREAM

19
src/corelib/io/qsettings_mac.cpp
View File

@ -214,7 +214,11 @@ static QCFType<CFPropertyListRef> macValue(const QVariant &value)
case QVariant::String:
string_case:
default:
result = QCFString::toCFStringRef(QSettingsPrivate::variantToString(value));
QString string = QSettingsPrivate::variantToString(value);
if (string.contains(QChar::Null))
result = string.toUtf8().toCFData();
else
result = string.toCFString();
}
return result;
}
@ -266,9 +270,16 @@ static QVariant qtValue(CFPropertyListRef cfvalue)
} else if (typeId == CFBooleanGetTypeID()) {
return (bool)CFBooleanGetValue(static_cast<CFBooleanRef>(cfvalue));
} else if (typeId == CFDataGetTypeID()) {
CFDataRef cfdata = static_cast<CFDataRef>(cfvalue);
return QByteArray(reinterpret_cast<const char *>(CFDataGetBytePtr(cfdata)),
CFDataGetLength(cfdata));
QByteArray byteArray = QByteArray::fromRawCFData(static_cast<CFDataRef>(cfvalue));
// Fast-path for QByteArray, so that we don't have to go
// though the expensive and lossy conversion via UTF-8.
if (!byteArray.startsWith('@'))
return byteArray;
const QString str = QString::fromUtf8(byteArray.constData(), byteArray.size());
return QSettingsPrivate::stringToVariant(str);
} else if (typeId == CFDictionaryGetTypeID()) {
CFDictionaryRef cfdict = static_cast<CFDictionaryRef>(cfvalue);
CFTypeID arrayTypeId = CFArrayGetTypeID();

13
src/corelib/io/qsettings_win.cpp
View File

@ -667,15 +667,6 @@ void QWinSettingsPrivate::remove(const QString &uKey)
}
}
static bool stringContainsNullChar(const QString &s)
{
for (int i = 0; i < s.length(); ++i) {
if (s.at(i).unicode() == 0)
return true;
}
return false;
}
void QWinSettingsPrivate::set(const QString &uKey, const QVariant &value)
{
if (writeHandle() == 0) {
@ -704,7 +695,7 @@ void QWinSettingsPrivate::set(const QString &uKey, const QVariant &value)
QStringList l = variantListToStringList(value.toList());
QStringList::const_iterator it = l.constBegin();
for (; it != l.constEnd(); ++it) {
if ((*it).length() == 0 || stringContainsNullChar(*it)) {
if ((*it).length() == 0 || it->contains(QChar::Null)) {
type = REG_BINARY;
break;
}
@ -748,7 +739,7 @@ void QWinSettingsPrivate::set(const QString &uKey, const QVariant &value)
// If the string does not contain '\0', we can use REG_SZ, the native registry
// string type. Otherwise we use REG_BINARY.
QString s = variantToString(value);
type = stringContainsNullChar(s) ? REG_BINARY : REG_SZ;
type = s.contains(QChar::Null) ? REG_BINARY : REG_SZ;
if (type == REG_BINARY) {
regValueBuff = QByteArray((const char*)s.utf16(), s.length() * 2);
} else {

4
src/corelib/io/qsettings_winrt.cpp
View File

@ -402,7 +402,7 @@ void QWinRTSettingsPrivate::set(const QString &uKey, const QVariant &value)
QStringList::const_iterator it = l.constBegin();
bool containsNull = false;
for (; it != l.constEnd(); ++it) {
if ((*it).length() == 0 || it->indexOf(QChar::Null) != -1) {
if ((*it).length() == 0 || it->contains(QChar::Null)) {
// We can only store as binary
containsNull = true;
break;
@ -445,7 +445,7 @@ void QWinRTSettingsPrivate::set(const QString &uKey, const QVariant &value)
break;
default: {
const QString s = variantToString(value);
if (s.indexOf(QChar::Null) != -1) {
if (s.contains(QChar::Null)) {
hr = valueStatics->CreateUInt8Array(s.length() * 2, (BYTE*) s.utf16(), &val);
} else {
HStringReference ref((const wchar_t*)s.utf16(), s.size());

50
tests/auto/corelib/io/qsettings/tst_qsettings.cpp
View File

@ -174,6 +174,8 @@ private slots:
void testByteArray();
void iniCodec();
void bom();
void embeddedZeroByte_data();
void embeddedZeroByte();
private:
void cleanupTestFiles();
@ -643,7 +645,6 @@ void tst_QSettings::testByteArray_data()
#ifndef QT_NO_COMPRESS
QTest::newRow("compressed") << qCompress(bytes);
#endif
QTest::newRow("with \\0") << bytes + '\0' + bytes;
}
void tst_QSettings::testByteArray()
@ -694,6 +695,53 @@ void tst_QSettings::bom()
QVERIFY(allkeys.contains("section2/foo2"));
}
void tst_QSettings::embeddedZeroByte_data()
{
QTest::addColumn<QVariant>("value");
QByteArray bytes("hello\0world", 11);
QTest::newRow("bytearray\\0") << QVariant(bytes);
QTest::newRow("string\\0") << QVariant(QString::fromLatin1(bytes.data(), bytes.size()));
bytes = QByteArray("@String(");
QTest::newRow("@bytearray") << QVariant(bytes);
QTest::newRow("@string") << QVariant(QString(bytes));
bytes = QByteArray("@String(\0test", 13);
QTest::newRow("@bytearray\\0") << QVariant(bytes);
QTest::newRow("@string\\0") << QVariant(QString::fromLatin1(bytes.data(), bytes.size()));
}
void tst_QSettings::embeddedZeroByte()
{
QFETCH(QVariant, value);
{
QSettings settings("QtProject", "tst_qsettings");
settings.setValue(QTest::currentDataTag(), value);
}
{
QSettings settings("QtProject", "tst_qsettings");
QVariant outValue = settings.value(QTest::currentDataTag());
switch (value.type()) {
case QVariant::ByteArray:
QCOMPARE(outValue.toByteArray(), value.toByteArray());
break;
case QVariant::String:
QCOMPARE(outValue.toString(), value.toString());
break;
default:
Q_UNREACHABLE();
}
if (value.toByteArray().contains(QChar::Null))
QVERIFY(outValue.toByteArray().contains(QChar::Null));
}
}
void tst_QSettings::testErrorHandling_data()
{
QTest::addColumn<int>("filePerms"); // -1 means file should not exist