From 96a7118d05ada8eca1eaee06d76a93cf02f21761 Mon Sep 17 00:00:00 2001
From: Daniel Molkentin <danimo@owncloud.com>
Date: Thu, 6 Nov 2014 00:36:04 +0100
Subject: [PATCH] WiP: switch to ReadDirectoryChangesW

---
 src/mirall/folderwatcher_win.cpp | 87 ++++++++++++++++++++------------
 1 file changed, 54 insertions(+), 33 deletions(-)

diff --git a/src/mirall/folderwatcher_win.cpp b/src/mirall/folderwatcher_win.cpp
index c6c8242fa9..b4b8f7fdc3 100644
--- a/src/mirall/folderwatcher_win.cpp
+++ b/src/mirall/folderwatcher_win.cpp
@@ -25,42 +25,63 @@ namespace Mirall {
 
 void WatcherThread::run()
 {
-    _handle = FindFirstChangeNotification((wchar_t*)_path.utf16(),
-                                         true, // recursive watch
-                                         FILE_NOTIFY_CHANGE_FILE_NAME |
-                                         FILE_NOTIFY_CHANGE_DIR_NAME |
-                                         FILE_NOTIFY_CHANGE_LAST_WRITE);
-
-    if (_handle == INVALID_HANDLE_VALUE)
-    {
-        qDebug() << Q_FUNC_INFO << "FindFirstChangeNotification function failed, stopping watcher!";
-        FindCloseChangeNotification(_handle);
-        _handle = 0;
-        return;
-    }
-
-    if (_handle == NULL)
-    {
-        qDebug() << Q_FUNC_INFO << "FindFirstChangeNotification returned null, stopping watcher!";
-        FindCloseChangeNotification(_handle);
-        _handle = 0;
-        return;
-    }
+    _handle = CreateFileW(
+        (wchar_t*)_path.utf16(),
+        FILE_LIST_DIRECTORY,
+        FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE,
+        NULL,
+        OPEN_EXISTING,
+        FILE_FLAG_BACKUP_SEMANTICS,
+        NULL
+        );
 
+    size_t bufsize = 4096;
+    size_t maxlen = 4096;
     while(true) {
-        switch(WaitForSingleObject(_handle, /*wait*/ INFINITE)) {
-        case WAIT_OBJECT_0:
-            if (FindNextChangeNotification(_handle) == false) {
-                qDebug() << Q_FUNC_INFO << "FindFirstChangeNotification returned FALSE, stopping watcher!";
-                FindCloseChangeNotification(_handle);
-                _handle = 0;
-                return;
+        char fileNotify[bufsize];
+        // TODO: handle CreateFileW failure
+        FILE_NOTIFY_INFORMATION *pFileNotify =
+                (FILE_NOTIFY_INFORMATION*)fileNotify;
+        DWORD dwBytesReturned = 0;
+        SecureZeroMemory(pFileNotify, bufsize);
+        if(ReadDirectoryChangesW( _handle, (LPVOID)pFileNotify,
+                                  bufsize, true,
+                                  FILE_NOTIFY_CHANGE_LAST_WRITE |
+                                  FILE_NOTIFY_CHANGE_DIR_NAME |
+                                  FILE_NOTIFY_CHANGE_LAST_WRITE,
+                                  &dwBytesReturned, NULL, NULL))
+        {
+            FILE_NOTIFY_INFORMATION *curEntry = pFileNotify;
+            while(true) {
+                size_t len = pFileNotify->FileNameLength / 2;
+                QString file = _path + "\\" + QString::fromWCharArray(pFileNotify->FileName, len);
+
+                QScopedArrayPointer<TCHAR> buffer(new TCHAR[maxlen]);
+                if (GetLongPathNameW(reinterpret_cast<LPCWSTR>(file.utf16()), buffer.data(), maxlen) == 0) {
+                    qDebug() << "Error converting file name to full length";
+                }
+                const QString longfile = QString::fromUtf16(reinterpret_cast<const ushort *>(buffer.data()), maxlen-1);
+
+                qDebug() << Q_FUNC_INFO << "Found change in" << file;
+                emit changed(longfile);
+                if (curEntry->NextEntryOffset == 0) {
+                    break;
+                }
+                curEntry = (FILE_NOTIFY_INFORMATION*)
+                                (char*)curEntry + curEntry->NextEntryOffset;
+            }
+        } else {
+            switch(GetLastError()) {
+            case ERROR_NOTIFY_ENUM_DIR:
+                qDebug() << Q_FUNC_INFO << "Too many events for buffer, resizing";
+                bufsize *= 2;
+                break;
+            default:
+                qDebug() << Q_FUNC_INFO << "General error while watching. Exiting.";
+                CloseHandle(_handle);
+                _handle = NULL;
+                break;
             }
-            // qDebug() << Q_FUNC_INFO << "Change detected in" << _path << "from" << QThread::currentThread    ();
-            emit changed(_path);
-            break;
-        default:
-            qDebug()  << Q_FUNC_INFO << "Error while watching";
         }
     }
 }