diff options
author | Giuseppe D'Angelo <giuseppe.dangelo@kdab.com> | 2022-07-06 02:20:38 +0200 |
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committer | Giuseppe D'Angelo <giuseppe.dangelo@kdab.com> | 2022-07-10 23:40:24 +0200 |
commit | 6f852935e0c847f91c7d6ffca455a74307ebe26d (patch) | |
tree | 037cd5c792abf48ef86535f7a249bffef84e5913 /src/corelib/text/qstring.cpp | |
parent | 54b276be0b5885bbaee2c38f472eb39731fd684a (diff) |
QString: fix lifetime issues with QRegularExpression APIs
QString has several functions taking a QRegularExpression: indexOf(),
contains(), and so on. Some of those have an out-argument of type
QRegularExpressionMatch, to report the details of the match (if any).
For instance:
QRegularExpression re(...);
QRegularExpressionMatch match;
if (string.contains(re, &match))
use(match);
The code used to route the implementation of these functions through
QStringView (which has the very same functions). This however opens
up a lifetime problem with temporary strings:
if (getString().contains(re, &match))
use(match); // match is dangling
Here `match` is dangling because it is referencing data into the
destroyed temporary -- nothing is keeping the string alive. This is
against the rules we've decided for Qt, and it's also asymmetric with
the corresponding code that uses QRegularExpression directly instead:
match = re.match(getString());
if (match.hasMatch())
use(match); // not dangling
... although we've documented not to do this. (In light of the decision
we've made w.r.t. temporaries, the documentation is wrong anyways.)
Here QRE takes a copy of the string and stores it in the match object,
thus keeping it alive.
Hence, extend the implementation of the QString functions to keep a
(shallow) copy of the string. To keep the code shared as much as
possible with QStringView, in theory one could have a function taking a
std::variant<QString, QStringView> and that uses the currently active
member. However I've found that std::variant here creates some abysmal
codegen, so instead I went for a simpler approach -- pass a QStringView
and an optional pointer to a QString. Use the latter if it's loaded.
QStringView has some inline code that calls into exported functions, so
I can't change the signature of them without breaking BC; I'm instead
adding new unexported functions and a Qt 7 note to unify them.
Change-Id: I7c65885a84069d0fbb902dcc96ddff543ca84562
Fixes: QTBUG-103940
Pick-to: 6.2 6.3 6.4
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src/corelib/text/qstring.cpp')
-rw-r--r-- | src/corelib/text/qstring.cpp | 41 |
1 files changed, 31 insertions, 10 deletions
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp index 1694ea8dbe..c569bf627d 100644 --- a/src/corelib/text/qstring.cpp +++ b/src/corelib/text/qstring.cpp @@ -4560,7 +4560,7 @@ qsizetype QString::count(QStringView str, Qt::CaseSensitivity cs) const */ qsizetype QString::indexOf(const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) const { - return QtPrivate::indexOf(QStringView(*this), re, from, rmatch); + return QtPrivate::indexOf(QStringView(*this), this, re, from, rmatch); } /*! @@ -4594,7 +4594,7 @@ qsizetype QString::indexOf(const QRegularExpression &re, qsizetype from, QRegula */ qsizetype QString::lastIndexOf(const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) const { - return QtPrivate::lastIndexOf(QStringView(*this), re, from, rmatch); + return QtPrivate::lastIndexOf(QStringView(*this), this, re, from, rmatch); } /*! @@ -4633,7 +4633,7 @@ qsizetype QString::lastIndexOf(const QRegularExpression &re, qsizetype from, QRe bool QString::contains(const QRegularExpression &re, QRegularExpressionMatch *rmatch) const { - return QtPrivate::contains(QStringView(*this), re, rmatch); + return QtPrivate::contains(QStringView(*this), this, re, rmatch); } /*! @@ -10798,14 +10798,16 @@ qsizetype QtPrivate::lastIndexOf(QLatin1StringView haystack, qsizetype from, QLa } #if QT_CONFIG(regularexpression) -qsizetype QtPrivate::indexOf(QStringView haystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) +qsizetype QtPrivate::indexOf(QStringView viewHaystack, const QString *stringHaystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) { if (!re.isValid()) { qtWarnAboutInvalidRegularExpression(re.pattern(), "QString(View)::indexOf"); return -1; } - QRegularExpressionMatch match = re.match(haystack, from); + QRegularExpressionMatch match = stringHaystack + ? re.match(*stringHaystack, from) + : re.match(viewHaystack, from); if (match.hasMatch()) { const qsizetype ret = match.capturedStart(); if (rmatch) @@ -10816,15 +10818,22 @@ qsizetype QtPrivate::indexOf(QStringView haystack, const QRegularExpression &re, return -1; } -qsizetype QtPrivate::lastIndexOf(QStringView haystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) +qsizetype QtPrivate::indexOf(QStringView haystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) +{ + return indexOf(haystack, nullptr, re, from, rmatch); +} + +qsizetype QtPrivate::lastIndexOf(QStringView viewHaystack, const QString *stringHaystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) { if (!re.isValid()) { qtWarnAboutInvalidRegularExpression(re.pattern(), "QString(View)::lastIndexOf"); return -1; } - qsizetype endpos = (from < 0) ? (haystack.size() + from + 1) : (from + 1); - QRegularExpressionMatchIterator iterator = re.globalMatch(haystack); + qsizetype endpos = (from < 0) ? (viewHaystack.size() + from + 1) : (from + 1); + QRegularExpressionMatchIterator iterator = stringHaystack + ? re.globalMatch(*stringHaystack) + : re.globalMatch(viewHaystack); qsizetype lastIndex = -1; while (iterator.hasNext()) { QRegularExpressionMatch match = iterator.next(); @@ -10841,19 +10850,31 @@ qsizetype QtPrivate::lastIndexOf(QStringView haystack, const QRegularExpression return lastIndex; } -bool QtPrivate::contains(QStringView haystack, const QRegularExpression &re, QRegularExpressionMatch *rmatch) +qsizetype QtPrivate::lastIndexOf(QStringView haystack, const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) +{ + return lastIndexOf(haystack, nullptr, re, from, rmatch); +} + +bool QtPrivate::contains(QStringView viewHaystack, const QString *stringHaystack, const QRegularExpression &re, QRegularExpressionMatch *rmatch) { if (!re.isValid()) { qtWarnAboutInvalidRegularExpression(re.pattern(), "QString(View)::contains"); return false; } - QRegularExpressionMatch m = re.match(haystack); + QRegularExpressionMatch m = stringHaystack + ? re.match(*stringHaystack) + : re.match(viewHaystack); bool hasMatch = m.hasMatch(); if (hasMatch && rmatch) *rmatch = std::move(m); return hasMatch; } +bool QtPrivate::contains(QStringView haystack, const QRegularExpression &re, QRegularExpressionMatch *rmatch) +{ + return contains(haystack, nullptr, re, rmatch); +} + qsizetype QtPrivate::count(QStringView haystack, const QRegularExpression &re) { if (!re.isValid()) { |