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/*
* Copyright (C) by Daniel Molkentin <danimo@owncloud.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include <QDir>
#include <QScopeGuard>
#include <QThread>
#include "common/asserts.h"
#include "common/utility.h"
#include "filesystem.h"
#include "folderwatcher.h"
#include "folderwatcher_win.h"
#include <stdlib.h>
#include <stdio.h>
#include <tchar.h>
namespace OCC {
WatcherThread::WatchChanges WatcherThread::watchChanges(size_t fileNotifyBufferSize)
{
_directory = CreateFileW(
reinterpret_cast<const wchar_t *>(_longPath.utf16()), // QString stores UTF-16 internally, so use that here.
FILE_LIST_DIRECTORY,
FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE,
NULL,
OPEN_EXISTING,
FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
NULL);
if (_directory == INVALID_HANDLE_VALUE) {
const auto error = GetLastError();
qCWarning(lcFolderWatcher) << "Failed to create handle for" << _path << ", error:" << Utility::formatWinError(error);
_directory = 0;
return WatchChanges::Error;
}
QScopeGuard todoBeforeReturn([this]() {
CancelIo(_directory);
closeHandle();
});
OVERLAPPED overlapped;
overlapped.hEvent = _resultEvent;
// QVarLengthArray ensures the stack-buffer is aligned like double and qint64.
QVarLengthArray<char, 4096 * 10> fileNotifyBuffer;
fileNotifyBuffer.resize(static_cast<int>(fileNotifyBufferSize));
while (true) {
ResetEvent(_resultEvent);
FILE_NOTIFY_INFORMATION *pFileNotifyBuffer =
reinterpret_cast<FILE_NOTIFY_INFORMATION *>(fileNotifyBuffer.data());
DWORD dwBytesReturned = 0;
if (!ReadDirectoryChangesW(_directory, pFileNotifyBuffer,
static_cast<DWORD>(fileNotifyBufferSize), true,
FILE_NOTIFY_CHANGE_FILE_NAME
| FILE_NOTIFY_CHANGE_DIR_NAME
| FILE_NOTIFY_CHANGE_LAST_WRITE
| FILE_NOTIFY_CHANGE_ATTRIBUTES, // attributes are for vfs pin state changes
&dwBytesReturned, &overlapped, nullptr)) {
const DWORD errorCode = GetLastError();
if (errorCode == ERROR_NOTIFY_ENUM_DIR) {
qCDebug(lcFolderWatcher) << "The buffer for changes overflowed! Triggering a generic change and resizing";
emit changed(_path);
return WatchChanges::NeedBiggerBuffer;
} else {
qCWarning(lcFolderWatcher) << "ReadDirectoryChangesW error" << Utility::formatWinError(errorCode);
return WatchChanges::Error;
}
}
emit ready();
HANDLE handles[] = { _resultEvent, _stopEvent };
DWORD result = WaitForMultipleObjects(
2, handles,
false, // awake once one of them arrives
INFINITE);
const auto error = GetLastError();
if (result == 1) {
qCDebug(lcFolderWatcher) << "Received stop event, aborting folder watcher thread";
return WatchChanges::Done;
}
if (result != 0) {
qCWarning(lcFolderWatcher) << "WaitForMultipleObjects failed" << result << Utility::formatWinError(error);
return WatchChanges::Error;
}
bool ok = GetOverlappedResult(_directory, &overlapped, &dwBytesReturned, false);
if (!ok) {
const DWORD errorCode = GetLastError();
if (errorCode == ERROR_NOTIFY_ENUM_DIR) {
qCDebug(lcFolderWatcher) << "The buffer for changes overflowed! Triggering a generic change and resizing";
emit lostChanges();
emit changed(_path);
return WatchChanges::NeedBiggerBuffer;
} else {
qCWarning(lcFolderWatcher) << "GetOverlappedResult error" << Utility::formatWinError(errorCode);
return WatchChanges::Error;
}
}
processEntries(pFileNotifyBuffer);
}
}
void WatcherThread::processEntries(FILE_NOTIFY_INFORMATION *curEntry)
{
while (curEntry) {
const size_t fileNameBufferSize = 4096;
TCHAR fileNameBuffer[fileNameBufferSize];
const int len = curEntry->FileNameLength / sizeof(wchar_t);
QString longfile = _longPath + QString::fromWCharArray(curEntry->FileName, len);
// Unless the file was removed or renamed, get its full long name
// TODO: We could still try expanding the path in the tricky cases...
if (curEntry->Action != FILE_ACTION_REMOVED && curEntry->Action != FILE_ACTION_RENAMED_OLD_NAME) {
const auto wfile = longfile.toStdWString();
const int longNameSize = GetLongPathNameW(wfile.data(), fileNameBuffer, fileNameBufferSize);
const auto error = GetLastError();
if (longNameSize > 0) {
longfile = QString::fromWCharArray(fileNameBuffer, longNameSize);
} else {
qCWarning(lcFolderWatcher) << "Error converting file name" << longfile << "to full length, keeping original name." << Utility::formatWinError(error);
}
}
#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
// The prefix is needed for native Windows functions before Windows 10, version 1607
const bool hasLongPathPrefix = longPath.startsWith(QStringLiteral("\\\\?\\"));
if (hasLongPathPrefix) {
longfile.remove(0, 4);
}
#endif
longfile = QDir::cleanPath(longfile);
// Skip modifications of folders: One of these is triggered for changes
// and new files in a folder, probably because of the folder's mtime
// changing. We don't need them.
const bool skip = curEntry->Action == FILE_ACTION_MODIFIED && QFileInfo(longfile).isDir();
if (!skip) {
emit changed(longfile);
}
if (curEntry->NextEntryOffset == 0) {
return;
}
// FILE_NOTIFY_INFORMATION has no fixed size and the offset is in bytes therefor we first need to cast to char
curEntry = reinterpret_cast<FILE_NOTIFY_INFORMATION *>(reinterpret_cast<char *>(curEntry) + curEntry->NextEntryOffset);
}
}
void WatcherThread::closeHandle()
{
if (_directory) {
CloseHandle(_directory);
_directory = NULL;
}
}
void WatcherThread::run()
{
_resultEvent = CreateEvent(NULL, true, false, NULL);
_stopEvent = CreateEvent(NULL, true, false, NULL);
// If this buffer fills up before we've extracted its data we will lose
// change information. Therefore start big.
size_t bufferSize = 4096 * 10;
const size_t maxBuffer = 64 * 1024;
while (true) {
switch (watchChanges(bufferSize)) {
case WatchChanges::NeedBiggerBuffer:
bufferSize = qMin(bufferSize * 2, maxBuffer);
continue;
case WatchChanges::Done:
return;
case WatchChanges::Error:
// Other errors shouldn't actually happen,
// so sleep a bit to avoid running into the same error case in a
// tight loop.
sleep(2);
default:
Q_UNREACHABLE();
}
}
}
WatcherThread::WatcherThread(const QString &path)
: QThread()
, _path(path + (path.endsWith(QLatin1Char('/')) ? QString() : QStringLiteral("/")))
, _longPath(FileSystem::longWinPath(_path))
, _directory(0)
, _resultEvent(0)
, _stopEvent(0)
{
}
WatcherThread::~WatcherThread()
{
closeHandle();
}
void WatcherThread::stop()
{
SetEvent(_stopEvent);
}
FolderWatcherPrivate::FolderWatcherPrivate(FolderWatcher *p, const QString &path)
: _parent(p)
{
_thread.reset(new WatcherThread(path));
connect(_thread.get(), &WatcherThread::changed, _parent, qOverload<const QString &>(&FolderWatcher::changeDetected));
connect(_thread.get(), &WatcherThread::lostChanges, _parent, &FolderWatcher::lostChanges);
connect(_thread.get(), &WatcherThread::ready, this, [this]() { _ready = 1; });
_thread->start();
}
FolderWatcherPrivate::~FolderWatcherPrivate()
{
_thread->stop();
_thread->wait();
}
} // namespace OCC
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