qtipccommon.cpp

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// Copyright (C) 2022 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qtipccommon.h"
#include "qtipccommon_p.h"
 
#include <qcryptographichash.h>
#include <qstandardpaths.h>
#include <qstringconverter.h>
#include <qurl.h>
#include <qurlquery.h>
 
#if defined(Q_OS_DARWIN)
#  include "private/qcore_mac_p.h"
#  if !defined(SHM_NAME_MAX)
     // Based on PSEMNAMLEN in XNU's posix_sem.c, which would
     // indicate the max length is 31, _excluding_ the zero
     // terminator. But in practice (possibly due to an off-
     // by-one bug in the kernel) the usable bytes are only 30.
#    define SHM_NAME_MAX 30
#  endif
#elif defined(Q_OS_WINDOWS)
#  include "qt_windows.h"
#endif
 
#if QT_CONFIG(sharedmemory) || QT_CONFIG(systemsemaphore)
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
static QStringView staticTypeToString(QNativeIpcKey::Type type)
{
    switch (type) {
    case QNativeIpcKey::Type::SystemV:
        return u"systemv";
    case QNativeIpcKey::Type::PosixRealtime:
        return u"posix";
    case QNativeIpcKey::Type::Windows:
        return u"windows";
    }
    return {};
}
 
static QString typeToString(QNativeIpcKey::Type type)
{
    QStringView typeString = staticTypeToString(type);
    switch (type) {
    case QNativeIpcKey::Type::SystemV:
    case QNativeIpcKey::Type::PosixRealtime:
    case QNativeIpcKey::Type::Windows:
        return QString::fromRawData(typeString.constData(), typeString.size());
    }
 
    int value = int(type);
    if (value >= 1 && value <= 0xff) {
        // System V key with id different from 'Q'
        typeString = staticTypeToString(QNativeIpcKey::Type::SystemV);
        return typeString + QString::number(-value);   // negative so it prepends a dash
    }
 
    return QString();       // invalid!
}
 
static QNativeIpcKey::Type stringToType(QStringView typeString)
{
    if (typeString == staticTypeToString(QNativeIpcKey::Type::PosixRealtime))
        return QNativeIpcKey::Type::PosixRealtime;
    if (typeString == staticTypeToString(QNativeIpcKey::Type::Windows))
        return QNativeIpcKey::Type::Windows;
 
    auto fromNumber = [](QStringView number, int low, int high) {
        bool ok;
        int n = -number.toInt(&ok, 10);
        if (!ok || n < low || n > high)
            return QNativeIpcKey::Type{};
        return QNativeIpcKey::Type(n);
    };
 
    QStringView sysv = staticTypeToString(QNativeIpcKey::Type::SystemV);
    if (typeString.startsWith(sysv)) {
        if (typeString.size() == sysv.size())
            return QNativeIpcKey::Type::SystemV;
        return fromNumber(typeString.sliced(sysv.size()), 1, 0xff);
    }
 
    // invalid!
    return QNativeIpcKey::Type{};
}
 
QNativeIpcKey QtIpcCommon::legacyPlatformSafeKey(const QString &key, QtIpcCommon::IpcType ipcType,
                                                 QNativeIpcKey::Type type)
{
    QNativeIpcKey k(type);
    if (key.isEmpty())
        return k;
 
    QByteArray hex = QCryptographicHash::hash(key.toUtf8(), QCryptographicHash::Sha1).toHex();
 
    if (type == QNativeIpcKey::Type::PosixRealtime) {
#if defined(Q_OS_DARWIN)
        if (qt_apple_isSandboxed()) {
            // Sandboxed applications on Apple platforms require the shared memory name
            // to be in the form <application group identifier>/<custom identifier>.
            // Since we don't know which application group identifier the user wants
            // to apply, we instead document that requirement, and use the key directly.
            QNativeIpcKeyPrivate::setNativeAndLegacyKeys(k, key, key);
        } else {
            // The shared memory name limit on Apple platforms is very low (30 characters),
            // so we can't use the logic below of combining the prefix, key, and a hash,
            // to ensure a unique and valid name. Instead we use the first part of the
            // hash, which should still long enough to avoid collisions in practice.
            QString native = u'/' + QLatin1StringView(hex).left(SHM_NAME_MAX - 1);
            QNativeIpcKeyPrivate::setNativeAndLegacyKeys(k, native, key);
        }
        return k;
#endif
    }
 
    QString result;
    result.reserve(1 + 18 + key.size() + 40);
    switch (ipcType) {
    case IpcType::SharedMemory:
        result += "qipc_sharedmemory_"_L1;
        break;
    case IpcType::SystemSemaphore:
        result += "qipc_systemsem_"_L1;
        break;
    }
 
    for (QChar ch : key) {
        if ((ch >= u'a' && ch <= u'z') ||
           (ch >= u'A' && ch <= u'Z'))
           result += ch;
    }
    result.append(QLatin1StringView(hex));
 
    switch (type) {
    case QNativeIpcKey::Type::Windows:
        if (isIpcSupported(ipcType, QNativeIpcKey::Type::Windows))
            QNativeIpcKeyPrivate::setNativeAndLegacyKeys(k, result, key);
        return k;
    case QNativeIpcKey::Type::PosixRealtime:
        result.prepend(u'/');
        if (isIpcSupported(ipcType, QNativeIpcKey::Type::PosixRealtime))
            QNativeIpcKeyPrivate::setNativeAndLegacyKeys(k, result, key);
        return k;
    case QNativeIpcKey::Type::SystemV:
        break;
    }
    if (isIpcSupported(ipcType, QNativeIpcKey::Type::SystemV)) {
        result = QStandardPaths::writableLocation(QStandardPaths::TempLocation) + u'/' + result;
        QNativeIpcKeyPrivate::setNativeAndLegacyKeys(k, result, key);
    }
    return k;
}
 
QNativeIpcKey QtIpcCommon::platformSafeKey(const QString &key, QtIpcCommon::IpcType ipcType,
                                           QNativeIpcKey::Type type)
{
    QNativeIpcKey k(type);
    if (key.isEmpty())
        return k;
 
    switch (type) {
    case QNativeIpcKey::Type::PosixRealtime:
        if (isIpcSupported(ipcType, QNativeIpcKey::Type::PosixRealtime)) {
#ifdef SHM_NAME_MAX
            // The shared memory name limit on Apple platforms is very low (30
            // characters), so we have to cut it down to avoid ENAMETOOLONG. We
            // hope that there won't be too many collisions...
            k.setNativeKey(u'/' + QStringView(key).left(SHM_NAME_MAX - 1));
#else
            k.setNativeKey(u'/' + key);
#endif
        }
        return k;
 
    case QNativeIpcKey::Type::Windows:
        if (isIpcSupported(ipcType, QNativeIpcKey::Type::Windows)) {
            QStringView prefix;
            QStringView payload = key;
            // see https://learn.microsoft.com/en-us/windows/win32/termserv/kernel-object-namespaces
            for (QStringView candidate : { u"Local\\", u"Global\\" }) {
                if (!key.startsWith(candidate))
                    continue;
                prefix = candidate;
                payload = payload.sliced(prefix.size());
                break;
            }
 
            QStringView mid;
            switch (ipcType) {
            case IpcType::SharedMemory:     mid = u"shm_"; break;
            case IpcType::SystemSemaphore:  mid = u"sem_"; break;
            }
 
            QString result = prefix + mid + payload;
#ifdef Q_OS_WINDOWS
            result.truncate(MAX_PATH);
#endif
            k.setNativeKey(result);
        }
        return k;
 
    case QNativeIpcKey::Type::SystemV:
        break;
    }
 
    // System V
    if (isIpcSupported(ipcType, QNativeIpcKey::Type::SystemV)) {
        if (key.startsWith(u'/')) {
            k.setNativeKey(key);
        } else {
            QString baseDir = QStandardPaths::writableLocation(QStandardPaths::RuntimeLocation);
            k.setNativeKey(baseDir + u'/' + key);
        }
    }
    return k;
}
 
#if defined(Q_OS_DARWIN)
QNativeIpcKey::Type QNativeIpcKey::defaultTypeForOs_internal() noexcept
{
    if (qt_apple_isSandboxed())
        return Type::PosixRealtime;
    return Type::SystemV;
}
#endif
 
void QNativeIpcKey::copy_internal(const QNativeIpcKey &other)
{
    d = new QNativeIpcKeyPrivate(*other.d);
}
 
void QNativeIpcKey::move_internal(QNativeIpcKey &&) noexcept
{
    // inline code already moved properly, nothing for us to do here
}
 
QNativeIpcKey &QNativeIpcKey::assign_internal(const QNativeIpcKey &other)
{
    Q_ASSERT(d || other.d);     // only 3 cases to handle
    if (d && !other.d)
        *d = {};
    else if (d)
        *d = *other.d;
    else
        d = new QNativeIpcKeyPrivate(*other.d);
    return *this;
}
 
void QNativeIpcKey::destroy_internal() noexcept
{
    delete d;
}
 
void QNativeIpcKey::setType_internal(Type type)
{
    Q_UNUSED(type);
}
 
void QNativeIpcKey::setNativeKey_internal(const QString &)
{
    d->legacyKey_.clear();
}
 
size_t qHash(const QNativeIpcKey &ipcKey, size_t seed) noexcept
{
    // by *choice*, we're not including d->legacyKey_ in the hash -- it's
    // already partially encoded in the key
    return qHashMulti(seed, ipcKey.key, ipcKey.type());
}
 
int QNativeIpcKey::compare_internal(const QNativeIpcKey &lhs, const QNativeIpcKey &rhs) noexcept
{
    return (QNativeIpcKeyPrivate::legacyKey(lhs) == QNativeIpcKeyPrivate::legacyKey(rhs)) ? 0 : 1;
}
 
QString QNativeIpcKey::toString() const
{
    QString prefix = typeToString(type());
    if (prefix.isEmpty()) {
        Q_ASSERT(prefix.isNull());
        return prefix;
    }
 
    QString copy = nativeKey();
    copy.replace(u'%', "%25"_L1);
    if (copy.startsWith("//"_L1))
        copy.replace(0, 2, u"/%2F"_s);  // ensure it's parsed as a URL path
 
    QUrl u;
    u.setScheme(prefix);
    u.setPath(copy, QUrl::TolerantMode);
    if (isSlowPath()) {
        QUrlQuery q;
        if (!d->legacyKey_.isEmpty())
            q.addQueryItem(u"legacyKey"_s, QString(d->legacyKey_).replace(u'%', "%25"_L1));
        u.setQuery(q);
    }
    return u.toString(QUrl::DecodeReserved);
}
 
QNativeIpcKey QNativeIpcKey::fromString(const QString &text)
{
    QUrl u(text, QUrl::TolerantMode);
    Type invalidType = {};
    Type type = stringToType(u.scheme());
    if (type == invalidType || !u.isValid() || !u.userInfo().isEmpty() || !u.host().isEmpty()
            || u.port() != -1)
        return QNativeIpcKey(invalidType);
 
    QNativeIpcKey result(QString(), type);
    if (result.type() != type)      // range check, just in case
        return QNativeIpcKey(invalidType);
 
    // decode the payload
    result.setNativeKey(u.path());
 
    if (u.hasQuery()) {
        const QList items = QUrlQuery(u).queryItems();
        for (const auto &item : items) {
            if (item.first == u"legacyKey"_s) {
                QString legacyKey = QUrl::fromPercentEncoding(item.second.toUtf8());
                QNativeIpcKeyPrivate::setLegacyKey(result, std::move(legacyKey));
            } else {
                // unknown query item
                return QNativeIpcKey(invalidType);
            }
        }
    }
    return result;
}
 
QT_END_NAMESPACE
 
#include "moc_qtipccommon.cpp"
 
#endif // QT_CONFIG(sharedmemory) || QT_CONFIG(systemsemaphore)