Implement an FSEvents-based QFileSystemWatcherEngine

This has been around for a while and really should have been put in
earlier. Mac OS X (client) has a much lower ulimit for open files than
what some other Unix-like OS's have (in defense it does save memory).
However, if you start watching a lot of files, it will start to fall
down. You can adjust the ulimit, but it's a bit inconvenient. FSEvents
watches the directory and notifies you of changes that happen in that
directory (and below, but we don't really use it). It also can be
adjusted for latency so that performance isn't affected by heavy file
system use (but Qt doesn't use that either at the moment). The other
thing is that it doesn't require any open files, so it's much better for
our number of open files. This feature is only on Leopard and up, so
people wanting to deploy Tiger will still have the "open files" problem
to deal with.

There are still some optimizations available in this code. For example,
we could coalesce things down to watch only one high-level directory
without changing much of the implementation. The current implementation
has some very simplistic ways of handling things, but this simplicity
works well. I documented it, so you can see that, yes, I really
meant to do that.

Task-Id: 164068 (and others)
Reviewed-by: Denis

5 files changed, 687 insertions, 2 deletions

diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index 5033b21..bd41f5e 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -65,7 +65,10 @@ win32 {
         SOURCES += io/qfsfileengine_unix.cpp
         SOURCES += io/qfsfileengine_iterator_unix.cpp
         SOURCES += io/qprocess_unix.cpp
-        mac:SOURCES += io/qsettings_mac.cpp
+        macx-*: {
+            HEADERS += io/qfilesystemwatcher_fsevents_p.h
+            SOURCES += io/qsettings_mac.cpp io/qfilesystemwatcher_fsevents.cpp
+        }
 
         linux-*:{
             SOURCES += \
diff --git a/src/corelib/io/qfilesystemwatcher.cpp b/src/corelib/io/qfilesystemwatcher.cpp
index b321644..902e240 100644
--- a/src/corelib/io/qfilesystemwatcher.cpp
+++ b/src/corelib/io/qfilesystemwatcher.cpp
@@ -58,6 +58,9 @@
 #  include "qfilesystemwatcher_inotify_p.h"
 #  include "qfilesystemwatcher_dnotify_p.h"
 #elif defined(Q_OS_FREEBSD) || defined(Q_OS_MAC)
+#  if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
+#  include "qfilesystemwatcher_fsevents_p.h"
+#  endif //MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
 #  include "qfilesystemwatcher_kqueue_p.h"
 #endif
 
@@ -243,7 +246,12 @@ QFileSystemWatcherEngine *QFileSystemWatcherPrivate::createNativeEngine()
         eng = QDnotifyFileSystemWatcherEngine::create();
     return eng;
 #elif defined(Q_OS_FREEBSD) || defined(Q_OS_MAC)
-    return QKqueueFileSystemWatcherEngine::create();
+#  if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
+    if (QSysInfo::MacintoshVersion >= QSysInfo::MV_10_5)
+        return QFSEventsFileSystemWatcherEngine::create();
+    else
+#  endif
+        return QKqueueFileSystemWatcherEngine::create();
 #else
     return 0;
 #endif
diff --git a/src/corelib/io/qfilesystemwatcher_fsevents.cpp b/src/corelib/io/qfilesystemwatcher_fsevents.cpp
new file mode 100644
index 0000000..3e0aee8
--- /dev/null
+++ b/src/corelib/io/qfilesystemwatcher_fsevents.cpp
@@ -0,0 +1,467 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://www.qtsoftware.com/contact.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#include <qplatformdefs.h>
+
+#include "qfilesystemwatcher.h"
+#include "qfilesystemwatcher_fsevents_p.h"
+
+#include <qdebug.h>
+#include <qfile.h>
+#include <qdatetime.h>
+#include <qfileinfo.h>
+#include <qvarlengtharray.h>
+
+#include <mach/mach.h>
+#include <sys/types.h>
+#include <CoreFoundation/CFRunLoop.h>
+#include <CoreFoundation/CFUUID.h>
+#include <CoreServices/CoreServices.h>
+#include <AvailabilityMacros.h>
+#include <private/qcore_mac_p.h>
+
+QT_BEGIN_NAMESPACE
+
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+// Static operator overloading so for the sake of some convieniece.
+// They only live in this compilation unit to avoid polluting Qt in general.
+static bool operator==(const struct ::timespec &left, const struct ::timespec &right)
+{
+    return left.tv_sec == right.tv_sec
+            && left.tv_nsec == right.tv_nsec;
+}
+
+static bool operator==(const struct ::stat64 &left, const struct ::stat64 &right)
+{
+    return left.st_dev == right.st_dev
+            && left.st_mode == right.st_mode
+            && left.st_size == right.st_size
+            && left.st_ino == right.st_ino
+            && left.st_uid == right.st_uid
+            && left.st_gid == right.st_gid
+            && left.st_mtimespec == right.st_mtimespec
+            && left.st_ctimespec == right.st_ctimespec
+            && left.st_flags == right.st_flags;
+}
+
+static bool operator!=(const struct ::stat64 &left, const struct ::stat64 &right)
+{
+    return !(operator==(left, right));
+}
+
+
+static void addPathToHash(PathHash &pathHash, const QString &key, const QFileInfo &fileInfo,
+                          const QString &path)
+{
+    PathInfoList &list = pathHash[key];
+    list.push_back(PathInfo(path,
+                            fileInfo.absoluteFilePath().normalized(QString::NormalizationForm_D).toUtf8()));
+    pathHash.insert(key, list);
+}
+
+static void removePathFromHash(PathHash &pathHash, const QString &key, const QString &path)
+{
+    PathInfoList &list = pathHash[key];
+    // We make the assumption that the list contains unique paths
+    PathInfoList::iterator End = list.end();
+    PathInfoList::iterator it = list.begin();
+    while (it != End) {
+        if (it->originalPath == path) {
+            list.erase(it);
+            break;
+        }
+        ++it;
+    }
+    if (list.isEmpty())
+        pathHash.remove(key);
+}
+
+static void stopFSStream(FSEventStreamRef stream)
+{
+    if (stream) {
+        FSEventStreamStop(stream);
+        FSEventStreamInvalidate(stream);
+    }
+}
+
+static QString createFSStreamPath(const QString &absolutePath)
+{
+    // The path returned has a trailing slash, so ensure that here.
+    QString string = absolutePath;
+    string.reserve(string.size() + 1);
+    string.append(QLatin1Char('/'));
+    return string;
+}
+
+static void cleanupFSStream(FSEventStreamRef stream)
+{
+    if (stream)
+        FSEventStreamRelease(stream);
+}
+
+const FSEventStreamCreateFlags QtFSEventFlags = (kFSEventStreamCreateFlagUseCFTypes | kFSEventStreamCreateFlagNoDefer /* | kFSEventStreamCreateFlagWatchRoot*/);
+
+const CFTimeInterval Latency = 0.033; // This will do updates 30 times a second which is probably more than you need.
+#endif
+
+QFSEventsFileSystemWatcherEngine::QFSEventsFileSystemWatcherEngine()
+    : fsStream(0), pathsToWatch(0), threadsRunLoop(0)
+{
+}
+
+QFSEventsFileSystemWatcherEngine::~QFSEventsFileSystemWatcherEngine()
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    // I assume that at this point, QFileSystemWatcher has already called stop
+    // on me, so I don't need to invalidate or stop my stream, simply
+    // release it.
+    cleanupFSStream(fsStream);
+    if (pathsToWatch)
+        CFRelease(pathsToWatch);
+#endif
+}
+
+QFSEventsFileSystemWatcherEngine *QFSEventsFileSystemWatcherEngine::create()
+{
+    return new QFSEventsFileSystemWatcherEngine();
+}
+
+QStringList QFSEventsFileSystemWatcherEngine::addPaths(const QStringList &paths,
+                                                       QStringList *files,
+                                                       QStringList *directories)
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    stop();
+    QMutexLocker locker(&mutex);
+    QStringList failedToAdd;
+    // if we have a running FSStreamEvent, we have to kill it, we'll re-add the stream soon.
+    FSEventStreamEventId idToCheck;
+    if (fsStream) {
+        idToCheck = FSEventStreamGetLatestEventId(fsStream);
+        cleanupFSStream(fsStream);
+    } else {
+        idToCheck = kFSEventStreamEventIdSinceNow;
+    }
+
+    // Brain-dead approach, but works. FSEvents actually can already read sub-trees, but since it's
+    // work to figure out if we are doing a double register, we just register it twice as FSEvents
+    // seems smart enough to only deliver one event. We also duplicate directory entries in here
+    // (e.g., if you watch five files in the same directory, you get that directory included in the
+    // array 5 times). This stupidity also makes remove work correctly though. I'll freely admit
+    // that we could make this a bit smarter. If you do, check the auto-tests, they should catch at
+    // least a couple of the issues.
+    QCFType<CFMutableArrayRef> tmpArray = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);
+    for (int i = 0; i < paths.size(); ++i) {
+        const QString &path = paths.at(i);
+
+        QFileInfo fileInfo(path);
+        if (!fileInfo.exists()) {
+            failedToAdd.append(path);
+            continue;
+        }
+
+        if (fileInfo.isDir()) {
+            if (directories->contains(path)) {
+                failedToAdd.append(path);
+                continue;
+            } else {
+                directories->append(path);
+                // Full file path for dirs.
+                QCFString cfpath(createFSStreamPath(fileInfo.absoluteFilePath()));
+                addPathToHash(dirPathInfoHash, cfpath, fileInfo, path);
+                CFArrayAppendValue(tmpArray, cfpath);
+            }
+        } else {
+            if (files->contains(path)) {
+                failedToAdd.append(path);
+                continue;
+            } else {
+                // Just the absolute path (minus it's filename) for files.
+                QCFString cfpath(createFSStreamPath(fileInfo.absolutePath()));
+                files->append(path);
+                addPathToHash(filePathInfoHash, cfpath, fileInfo, path);
+                CFArrayAppendValue(tmpArray, cfpath);
+            }
+        }
+    }
+    if (CFArrayGetCount(tmpArray) > 0) {
+        if (pathsToWatch) {
+            CFArrayAppendArray(tmpArray, pathsToWatch, CFRangeMake(0, CFArrayGetCount(pathsToWatch)));
+            CFRelease(pathsToWatch);
+        }
+        pathsToWatch = CFArrayCreateCopy(kCFAllocatorDefault, tmpArray);
+    }
+    FSEventStreamContext context = { 0, this, 0, 0, 0 };
+    fsStream = FSEventStreamCreate(kCFAllocatorDefault,
+                                   QFSEventsFileSystemWatcherEngine::fseventsCallback,
+                                   &context, pathsToWatch,
+                                   idToCheck, Latency, QtFSEventFlags);
+    warmUpFSEvents();
+
+    return failedToAdd;
+#else
+    Q_UNUSED(paths);
+    Q_UNUSED(files);
+    Q_UNUSED(directories);
+    return QStringList();
+#endif
+}
+
+void QFSEventsFileSystemWatcherEngine::warmUpFSEvents()
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    // This function assumes that the mutex has already been grabbed before calling it.
+    // It exits with the mutex still locked (Q_ASSERT(mutex.isLocked()) ;-).
+    start();
+    waitCondition.wait(&mutex);
+#endif
+}
+
+QStringList QFSEventsFileSystemWatcherEngine::removePaths(const QStringList &paths,
+                                                          QStringList *files,
+                                                          QStringList *directories)
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    stop();
+    QMutexLocker locker(&mutex);
+    // short circuit for smarties that call remove before add and we have nothing.
+    if (pathsToWatch == 0)
+        return paths;
+    QStringList failedToRemove;
+    // if we have a running FSStreamEvent, we have to stop it, we'll re-add the stream soon.
+    FSEventStreamEventId idToCheck;
+    if (fsStream) {
+        idToCheck = FSEventStreamGetLatestEventId(fsStream);
+        cleanupFSStream(fsStream);
+        fsStream = 0;
+    } else {
+        idToCheck = kFSEventStreamEventIdSinceNow;
+    }
+
+    CFIndex itemCount = CFArrayGetCount(pathsToWatch);
+    QCFType<CFMutableArrayRef> tmpArray = CFArrayCreateMutableCopy(kCFAllocatorDefault, itemCount,
+                                                                   pathsToWatch);
+    CFRelease(pathsToWatch);
+    pathsToWatch = 0;
+    for (int i = 0; i < paths.size(); ++i) {
+        // Get the itemCount at the beginning to avoid any overruns during the iteration.
+        itemCount = CFArrayGetCount(tmpArray);
+        const QString &path = paths.at(i);
+        QFileInfo fi(path);
+        QCFString cfpath(createFSStreamPath(fi.absolutePath()));
+
+        CFIndex index = CFArrayGetFirstIndexOfValue(tmpArray, CFRangeMake(0, itemCount), cfpath);
+        if (index != -1) {
+            CFArrayRemoveValueAtIndex(tmpArray, index);
+            files->removeAll(path);
+            removePathFromHash(filePathInfoHash, cfpath, path);
+        } else {
+            // Could be a directory we are watching instead.
+            QCFString cfdirpath(createFSStreamPath(fi.absoluteFilePath()));
+            index = CFArrayGetFirstIndexOfValue(tmpArray, CFRangeMake(0, itemCount), cfdirpath);
+            if (index != -1) {
+                CFArrayRemoveValueAtIndex(tmpArray, index);
+                directories->removeAll(path);
+                removePathFromHash(dirPathInfoHash, cfpath, path);
+            } else {
+                failedToRemove.append(path);
+            }
+        }
+    }
+    itemCount = CFArrayGetCount(tmpArray);
+    if (itemCount != 0) {
+        pathsToWatch = CFArrayCreateCopy(kCFAllocatorDefault, tmpArray);
+
+        FSEventStreamContext context = { 0, this, 0, 0, 0 };
+        fsStream = FSEventStreamCreate(kCFAllocatorDefault,
+                                       QFSEventsFileSystemWatcherEngine::fseventsCallback,
+                                       &context, pathsToWatch, idToCheck, Latency, QtFSEventFlags);
+        warmUpFSEvents();
+    }
+    return failedToRemove;
+#else
+    Q_UNUSED(paths);
+    Q_UNUSED(files);
+    Q_UNUSED(directories);
+    return QStringList();
+#endif
+}
+
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+void QFSEventsFileSystemWatcherEngine::updateList(PathInfoList &list, bool directory, bool emitSignals)
+{
+    PathInfoList::iterator End = list.end();
+    PathInfoList::iterator it = list.begin();
+    while (it != End) {
+        struct ::stat64 newInfo;
+        if (::stat64(it->absolutePath, &newInfo) == 0) {
+            if (emitSignals) {
+                if (newInfo != it->savedInfo) {
+                    it->savedInfo = newInfo;
+                    if (directory)
+                        emit directoryChanged(it->originalPath, false);
+                    else
+                        emit fileChanged(it->originalPath, false);
+                }
+            } else {
+                it->savedInfo = newInfo;
+            }
+        } else {
+            if (errno == ENOENT) {
+                if (emitSignals) {
+                    if (directory)
+                        emit directoryChanged(it->originalPath, true);
+                    else
+                        emit fileChanged(it->originalPath, true);
+                }
+                it = list.erase(it);
+                continue;
+            } else {
+                qWarning("%s:%d:QFSEventsFileSystemWatcherEngine: stat error on %s:%s",
+                         __FILE__, __LINE__, qPrintable(it->originalPath), strerror(errno));
+
+            }
+        }
+        ++it;
+    }
+}
+
+void QFSEventsFileSystemWatcherEngine::updateHash(PathHash &pathHash)
+{
+    PathHash::iterator HashEnd = pathHash.end();
+    PathHash::iterator it = pathHash.begin();
+    const bool IsDirectory = (&pathHash == &dirPathInfoHash);
+    while (it != HashEnd) {
+        updateList(it.value(), IsDirectory, false);
+        if (it.value().isEmpty())
+            it = pathHash.erase(it);
+        else
+            ++it;
+    }
+}
+#endif
+
+void QFSEventsFileSystemWatcherEngine::fseventsCallback(ConstFSEventStreamRef ,
+                                                        void *clientCallBackInfo, size_t numEvents,
+                                                        void *eventPaths,
+                                                        const FSEventStreamEventFlags eventFlags[],
+                                                        const FSEventStreamEventId [])
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    QFSEventsFileSystemWatcherEngine *watcher = static_cast<QFSEventsFileSystemWatcherEngine *>(clientCallBackInfo);
+    QMutexLocker locker(&watcher->mutex);
+    CFArrayRef paths = static_cast<CFArrayRef>(eventPaths);
+    for (size_t i = 0; i < numEvents; ++i) {
+        const QString path = QCFString::toQString(
+                                    static_cast<CFStringRef>(CFArrayGetValueAtIndex(paths, i)));
+        const FSEventStreamEventFlags pathFlags = eventFlags[i];
+        // There are several flags that may be passed, but we really don't care about them ATM.
+        // Here they are and why we don't care.
+        // kFSEventStreamEventFlagHistoryDone--(very unlikely to be gotten, but even then, not much changes).
+        // kFSEventStreamEventFlagMustScanSubDirs--Likely means the data is very much out of date, we
+        //            aren't coalescing our directories, so again not so much of an issue
+        // kFSEventStreamEventFlagRootChanged | kFSEventStreamEventFlagMount | kFSEventStreamEventFlagUnmount--
+        // These three flags indicate something has changed, but the stat will likely show this, so
+        // there's not really much to worry about.
+        // (btw, FSEvents is not the correct way of checking for mounts/unmounts,
+        //  there are real CarbonCore events for that.)
+        Q_UNUSED(pathFlags);
+        if (watcher->filePathInfoHash.contains(path))
+            watcher->updateList(watcher->filePathInfoHash[path], false, true);
+
+        if (watcher->dirPathInfoHash.contains(path))
+            watcher->updateList(watcher->dirPathInfoHash[path], true, true);
+    }
+#else
+    Q_UNUSED(clientCallBackInfo);
+    Q_UNUSED(numEvents);
+    Q_UNUSED(eventPaths);
+    Q_UNUSED(eventFlags);
+#endif
+}
+
+void QFSEventsFileSystemWatcherEngine::stop()
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    stopFSStream(fsStream);
+    if (threadsRunLoop)
+        CFRunLoopStop(threadsRunLoop);
+#endif
+}
+
+void QFSEventsFileSystemWatcherEngine::updateFiles()
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    QMutexLocker locker(&mutex);
+    updateHash(filePathInfoHash);
+    updateHash(dirPathInfoHash);
+    if (filePathInfoHash.isEmpty() && dirPathInfoHash.isEmpty()) {
+        // Everything disappeared before we got to start, don't bother.
+        stop();
+        cleanupFSStream(fsStream);
+    }
+    waitCondition.wakeAll();
+#endif
+}
+
+void QFSEventsFileSystemWatcherEngine::run()
+{
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    threadsRunLoop = CFRunLoopGetCurrent();
+    FSEventStreamScheduleWithRunLoop(fsStream, threadsRunLoop, kCFRunLoopDefaultMode);
+    bool startedOK = FSEventStreamStart(fsStream);
+    // It's recommended by Apple that you only update the files after you've started
+    // the stream, because otherwise you might miss an update in between starting it.
+    updateFiles();
+#ifdef QT_NO_DEBUG
+    Q_UNUSED(startedOK);
+#else
+    Q_ASSERT(startedOK);
+#endif
+    // If for some reason we called stop up above (and invalidated our stream), this call will return
+    // immediately.
+    CFRunLoopRun();
+    threadsRunLoop = 0;
+#endif
+}
+
+QT_END_NAMESPACE
diff --git a/src/corelib/io/qfilesystemwatcher_fsevents_p.h b/src/corelib/io/qfilesystemwatcher_fsevents_p.h
new file mode 100644
index 0000000..2e8b788
--- /dev/null
+++ b/src/corelib/io/qfilesystemwatcher_fsevents_p.h
@@ -0,0 +1,127 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://www.qtsoftware.com/contact.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#ifndef FILEWATCHER_FSEVENTS_P_H
+#define FILEWATCHER_FSEVENTS_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of the QLibrary class.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qfilesystemwatcher_p.h"
+
+#include <QtCore/qmutex.h>
+#include <QtCore/qwaitcondition.h>
+#include <QtCore/qthread.h>
+#include <QtCore/QHash>
+#include <QtCore/QLinkedList>
+#include <private/qcore_mac_p.h>
+#include <sys/stat.h>
+
+typedef struct __FSEventStream *FSEventStreamRef;
+typedef const struct __FSEventStream *ConstFSEventStreamRef;
+typedef const struct __CFArray *CFArrayRef;
+typedef uint FSEventStreamEventFlags;
+typedef uint64_t FSEventStreamEventId;
+
+QT_BEGIN_NAMESPACE
+
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+// Yes, I use a stat64 element here. QFileInfo requires too much knowledge about implementation
+// details to be used as a long-standing record. Since I'm going to have to store this information, I can
+// do the stat myself too.
+struct PathInfo {
+    PathInfo(const QString &path, const QByteArray &absPath)
+            : originalPath(path), absolutePath(absPath) {}
+    QString originalPath; // The path we need to emit
+    QByteArray absolutePath; // The path we need to stat.
+    struct ::stat64 savedInfo;  // All the info for the path so we can compare it.
+};
+typedef QLinkedList<PathInfo> PathInfoList;
+typedef QHash<QString, PathInfoList> PathHash;
+#endif
+
+class QFSEventsFileSystemWatcherEngine : public QFileSystemWatcherEngine
+{
+    Q_OBJECT
+public:
+    ~QFSEventsFileSystemWatcherEngine();
+
+    static QFSEventsFileSystemWatcherEngine *create();
+
+    QStringList addPaths(const QStringList &paths, QStringList *files, QStringList *directories);
+    QStringList removePaths(const QStringList &paths, QStringList *files, QStringList *directories);
+
+    void stop();
+
+private:
+    QFSEventsFileSystemWatcherEngine();
+    void warmUpFSEvents();
+    void updateFiles();
+
+    static void fseventsCallback(ConstFSEventStreamRef streamRef, void *clientCallBackInfo, size_t numEvents,
+                                  void *eventPaths, const FSEventStreamEventFlags eventFlags[],
+                                  const FSEventStreamEventId eventIds[]);
+    void run();
+    FSEventStreamRef fsStream;
+    CFArrayRef pathsToWatch;
+    CFRunLoopRef threadsRunLoop;
+    QMutex mutex;
+    QWaitCondition waitCondition;
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+    PathHash filePathInfoHash;
+    PathHash dirPathInfoHash;
+    void updateHash(PathHash &pathHash);
+    void updateList(PathInfoList &list, bool directory, bool emitSignals);
+#endif
+};
+
+#endif
+
+QT_END_NAMESPACE
diff --git a/tests/auto/qfilesystemwatcher/tst_qfilesystemwatcher.cpp b/tests/auto/qfilesystemwatcher/tst_qfilesystemwatcher.cpp
index da06742..c883c63 100644
--- a/tests/auto/qfilesystemwatcher/tst_qfilesystemwatcher.cpp
+++ b/tests/auto/qfilesystemwatcher/tst_qfilesystemwatcher.cpp
@@ -73,6 +73,8 @@ private slots:
     void removePath();
     void addPaths();
     void removePaths();
+    void watchFileAndItsDirectory();
+    void watchFileAndItsDirectory_data() { basicTest_data(); }
 
 private:
     QStringList do_force_engines;
@@ -397,5 +399,83 @@ void tst_QFileSystemWatcher::removePaths()
     watcher.removePaths(paths);
 }
 
+void tst_QFileSystemWatcher::watchFileAndItsDirectory()
+{
+    QFETCH(QString, backend);
+    QDir().mkdir("testDir");
+    QDir testDir("testDir");
+
+    QString testFileName = testDir.filePath("testFile.txt");
+    QString secondFileName = testDir.filePath("testFile2.txt");
+    QFile::remove(secondFileName);
+
+    QFile testFile(testFileName);
+    testFile.setPermissions(QFile::ReadOwner | QFile::WriteOwner);
+    testFile.remove();
+
+    QVERIFY(testFile.open(QIODevice::WriteOnly | QIODevice::Truncate));
+    testFile.write(QByteArray("hello"));
+    testFile.close();
+
+    QFileSystemWatcher watcher;
+    watcher.setObjectName(QLatin1String("_qt_autotest_force_engine_") + backend);
+
+    watcher.addPath(testDir.dirName());
+    watcher.addPath(testFileName);
+
+    QSignalSpy fileChangedSpy(&watcher, SIGNAL(fileChanged(const QString &)));
+    QSignalSpy dirChangedSpy(&watcher, SIGNAL(directoryChanged(const QString &)));
+    QEventLoop eventLoop;
+    QTimer timer;
+    connect(&timer, SIGNAL(timeout()), &eventLoop, SLOT(quit()));
+
+    // resolution of the modification time is system dependent, but it's at most 1 second when using
+    // the polling engine. From what I know, FAT32 has a 2 second resolution. So we have to
+    // wait before modifying the directory...
+    QTest::qWait(2000);
+
+    QVERIFY(testFile.open(QIODevice::WriteOnly | QIODevice::Truncate));
+    testFile.write(QByteArray("hello again"));
+    testFile.close();
+
+    timer.start(3000);
+    eventLoop.exec();
+    QCOMPARE(fileChangedSpy.count(), 1);
+    QCOMPARE(dirChangedSpy.count(), 0);
+
+    fileChangedSpy.clear();
+    QFile secondFile(secondFileName);
+    secondFile.open(QIODevice::WriteOnly | QIODevice::Truncate);
+    secondFile.write("Foo");
+    secondFile.close();
+
+    timer.start(3000);
+    eventLoop.exec();
+    QCOMPARE(fileChangedSpy.count(), 0);
+    QCOMPARE(dirChangedSpy.count(), 1);
+
+    dirChangedSpy.clear();
+
+    QFile::remove(testFileName);
+
+    timer.start(3000);
+    eventLoop.exec();
+    QCOMPARE(fileChangedSpy.count(), 1);
+    QCOMPARE(dirChangedSpy.count(), 1);
+
+    fileChangedSpy.clear();
+    dirChangedSpy.clear();
+
+    watcher.removePath(testFileName);
+    QFile::remove(secondFileName);
+
+    timer.start(3000);
+    eventLoop.exec();
+    QCOMPARE(fileChangedSpy.count(), 0);
+    QCOMPARE(dirChangedSpy.count(), 1);
+
+    QVERIFY(QDir().rmdir("testDir"));
+}
+
 QTEST_MAIN(tst_QFileSystemWatcher)
 #include "tst_qfilesystemwatcher.moc"