Implement moving of a single file system entry to the trash

This implements the operation for Windows, macOS, and Unix, for now
only as a private API (since QFileSystemEngine is private). This adds
the capability as a testable function; public API to be agreed on and
added in a separate commit.

The Unix implementation follows the freedesktop.org specification [1]
version 1.0.

[1] https://specifications.freedesktop.org/trash-spec/trashspec-1.0.html

On macOS and Windows, native APIs are used, with each having some
limitations:

* on macOS, the file in the trash won't have a "put back" option,
  as we don't use Finder automation, for the reasons provided in the
  comments
* on Windows, we might not be able to use the modern IFileOperation
  API, e.g. if Qt is built with mingw which doesn't seem to provide
  the interface definition; the fallback doesn't provide access to
  the file name in the trash

The test case creates files and directories, and moves them to the
trash. As part of the cleanup routine, it deletes all file system
entries created. If run on Windows without IFileOperations support,
this will add a file in the trash for each test run, filling up
hard drive space.

Task-number: QTBUG-47703
Change-Id: I5f5f4e578be2f45d7da84f70a03acbe1a12a1231
Reviewed-by: Vitaly Fanaskov <vitaly.fanaskov@qt.io>

7 files changed, 643 insertions, 2 deletions

diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index c4c6f41387..a33ffe75f2 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -183,7 +183,9 @@ win32 {
             SOURCES += io/qstorageinfo_mac.cpp
             qtConfig(processenvironment): \
                 OBJECTIVE_SOURCES += io/qprocess_darwin.mm
-            OBJECTIVE_SOURCES += io/qstandardpaths_mac.mm
+            OBJECTIVE_SOURCES += \
+                io/qstandardpaths_mac.mm \
+                io/qfilesystemengine_mac.mm
             osx {
                 LIBS += -framework DiskArbitration -framework IOKit
             } else {
diff --git a/src/corelib/io/qfilesystemengine_mac.mm b/src/corelib/io/qfilesystemengine_mac.mm
new file mode 100644
index 0000000000..4bbce9e5f6
--- /dev/null
+++ b/src/corelib/io/qfilesystemengine_mac.mm
@@ -0,0 +1,79 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qplatformdefs.h"
+#include "qfilesystemengine_p.h"
+#include "qfile.h"
+#include "qurl.h"
+
+#include <QtCore/private/qcore_mac_p.h>
+#include <CoreFoundation/CoreFoundation.h>
+
+QT_BEGIN_NAMESPACE
+
+/*
+    This implementation does not enable the "put back" option in Finder
+    for the trashed object. The only way to get this is to use Finder automation,
+    which would query the user for permission to access Finder using a modal,
+    blocking dialog - which we definitely can't have in a console application.
+
+    Using Finder would also play the trash sound, which we don't want either in
+    such a core API; applications that want that can play the sound themselves.
+*/
+//static
+bool QFileSystemEngine::moveFileToTrash(const QFileSystemEntry &source,
+                                        QFileSystemEntry &newLocation, QSystemError &error)
+{
+    QFileInfo info(source.filePath());
+    @autoreleasepool {
+        NSString *filepath = info.filePath().toNSString();
+        NSURL *fileurl = [NSURL fileURLWithPath:filepath isDirectory:info.isDir()];
+        NSURL *resultingUrl = nil;
+        NSError *nserror = nil;
+        NSFileManager *fm = [NSFileManager defaultManager];
+        if ([fm trashItemAtURL:fileurl resultingItemURL:&resultingUrl error:&nserror] != YES) {
+            error = QSystemError(nserror.code, QSystemError::NativeError);
+            return false;
+        }
+        newLocation = QFileSystemEntry(QUrl::fromNSURL(resultingUrl).path());
+    }
+    return true;
+}
+
+QT_END_NAMESPACE
diff --git a/src/corelib/io/qfilesystemengine_p.h b/src/corelib/io/qfilesystemengine_p.h
index ecfdc03743..555483a972 100644
--- a/src/corelib/io/qfilesystemengine_p.h
+++ b/src/corelib/io/qfilesystemengine_p.h
@@ -88,7 +88,7 @@ inline bool qIsFilenameBroken(const QFileSystemEntry &entry)
             Q_RETURN_ON_INVALID_FILENAME("Broken filename passed to function", (result)); \
     } while (false)
 
-class QFileSystemEngine
+class Q_AUTOTEST_EXPORT QFileSystemEngine
 {
 public:
     static bool isCaseSensitive()
@@ -155,6 +155,7 @@ public:
     static bool createLink(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error);
 
     static bool copyFile(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error);
+    static bool moveFileToTrash(const QFileSystemEntry &source, QFileSystemEntry &newLocation, QSystemError &error);
     static bool renameFile(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error);
     static bool renameOverwriteFile(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error);
     static bool removeFile(const QFileSystemEntry &entry, QSystemError &error);
diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index 3bbebc7fe9..16901be187 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -42,6 +42,8 @@
 #include "qplatformdefs.h"
 #include "qfilesystemengine_p.h"
 #include "qfile.h"
+#include "qstorageinfo.h"
+#include "qtextstream.h"
 
 #include <QtCore/qoperatingsystemversion.h>
 #include <QtCore/private/qcore_unix_p.h>
@@ -1197,6 +1199,197 @@ bool QFileSystemEngine::createLink(const QFileSystemEntry &source, const QFileSy
     return false;
 }
 
+#ifndef Q_OS_DARWIN
+/*
+    Implementing as per https://specifications.freedesktop.org/trash-spec/trashspec-1.0.html
+*/
+static QString freeDesktopTrashLocation(const QString &sourcePath)
+{
+    auto makeTrashDir = [](const QDir &topDir, const QString &trashDir) -> QString {
+        auto ownerPerms = QFileDevice::ReadOwner
+                        | QFileDevice::WriteOwner
+                        | QFileDevice::ExeOwner;
+        QString targetDir = topDir.filePath(trashDir);
+        if (topDir.mkdir(trashDir))
+            QFile::setPermissions(targetDir, ownerPerms);
+        if (QFileInfo(targetDir).isDir())
+            return targetDir;
+        return QString();
+    };
+    auto isSticky = [](const QFileInfo &fileInfo) -> bool {
+        struct stat st;
+        if (stat(QFile::encodeName(fileInfo.absoluteFilePath()).constData(), &st) == 0)
+            return st.st_mode & S_ISVTX;
+
+        return false;
+    };
+
+    QString trash;
+    const QLatin1String dotTrash(".Trash");
+    const QStorageInfo sourceStorage(sourcePath);
+    const QStorageInfo homeStorage(QDir::home());
+    // We support trashing of files outside the users home partition
+    if (sourceStorage != homeStorage) {
+        QDir topDir(sourceStorage.rootPath());
+        /*
+            Method 1:
+            "An administrator can create an $topdir/.Trash directory. The permissions on this
+            directories should permit all users who can trash files at all to write in it;
+            and the “sticky bit” in the permissions must be set, if the file system supports
+            it.
+            When trashing a file from a non-home partition/device, an implementation
+            (if it supports trashing in top directories) MUST check for the presence
+            of $topdir/.Trash."
+        */
+        const QString userID = QString::number(::getuid());
+        if (topDir.cd(dotTrash)) {
+            const QFileInfo trashInfo(topDir.path());
+
+            // we MUST check that the sticky bit is set, and that it is not a symlink
+            if (trashInfo.isSymLink()) {
+                // we SHOULD report the failed check to the administrator
+                qCritical("Warning: '%s' is a symlink to '%s'",
+                          trashInfo.absoluteFilePath().toLocal8Bit().constData(),
+                          trashInfo.symLinkTarget().toLatin1().constData());
+            } else if (!isSticky(trashInfo)) {
+                // we SHOULD report the failed check to the administrator
+                qCritical("Warning: '%s' doesn't have sticky bit set!",
+                          trashInfo.absoluteFilePath().toLocal8Bit().constData());
+            } else if (trashInfo.isDir()) {
+                /*
+                    "If the directory exists and passes the checks, a subdirectory of the
+                     $topdir/.Trash directory is to be used as the user's trash directory
+                     for this partition/device. The name of this subdirectory is the numeric
+                     identifier of the current user ($topdir/.Trash/$uid).
+                     When trashing a file, if this directory does not exist for the current user,
+                     the implementation MUST immediately create it, without any warnings or
+                     delays for the user."
+                */
+                trash = makeTrashDir(topDir, userID);
+            }
+        }
+        /*
+            Method 2:
+            "If an $topdir/.Trash directory is absent, an $topdir/.Trash-$uid directory is to be
+             used as the user's trash directory for this device/partition. [...] When trashing a
+             file, if an $topdir/.Trash-$uid directory does not exist, the implementation MUST
+             immediately create it, without any warnings or delays for the user."
+        */
+        if (trash.isEmpty()) {
+            topDir = QDir(sourceStorage.rootPath());
+            const QString userTrashDir = dotTrash + QLatin1Char('-') + userID;
+            trash = makeTrashDir(topDir, userTrashDir);
+        }
+    }
+    /*
+        "If both (1) and (2) fail [...], the implementation MUST either trash the
+         file into the user's “home trash” or refuse to trash it."
+
+         We trash the file into the user's home trash.
+    */
+    if (trash.isEmpty()) {
+        QDir topDir = QDir::home();
+        trash = makeTrashDir(topDir, dotTrash);
+        if (!QFileInfo(trash).isDir()) {
+            qWarning("Unable to establish trash directory %s in %s",
+                     dotTrash.latin1(), topDir.path().toLocal8Bit().constData());
+        }
+    }
+
+    return trash;
+}
+
+//static
+bool QFileSystemEngine::moveFileToTrash(const QFileSystemEntry &source,
+                                        QFileSystemEntry &newLocation, QSystemError &error)
+{
+    const QFileInfo sourceInfo(source.filePath());
+    if (!sourceInfo.exists()) {
+        error = QSystemError(ENOENT, QSystemError::StandardLibraryError);
+        return false;
+    }
+    const QString sourcePath = sourceInfo.absoluteFilePath();
+
+    QDir trashDir(freeDesktopTrashLocation(sourcePath));
+    if (!trashDir.exists())
+        return false;
+    /*
+        "A trash directory contains two subdirectories, named info and files."
+    */
+    const QLatin1String filesDir("files");
+    const QLatin1String infoDir("info");
+    trashDir.mkdir(filesDir);
+    int savedErrno = errno;
+    trashDir.mkdir(infoDir);
+    if (!savedErrno)
+        savedErrno = errno;
+    if (!trashDir.exists(filesDir) || !trashDir.exists(infoDir)) {
+        error = QSystemError(savedErrno, QSystemError::StandardLibraryError);
+        return false;
+    }
+    /*
+        "The $trash/files directory contains the files and directories that were trashed.
+         The names of files in this directory are to be determined by the implementation;
+         the only limitation is that they must be unique within the directory. Even if a
+         file with the same name and location gets trashed many times, each subsequent
+         trashing must not overwrite a previous copy."
+    */
+    const QString trashedName = sourceInfo.isDir()
+                              ? QDir(sourcePath).dirName()
+                              : sourceInfo.fileName();
+    QString uniqueTrashedName = QLatin1Char('/') + trashedName;
+    QString infoFileName;
+    int counter = 0;
+    QFile infoFile;
+    do {
+        while (QFile::exists(trashDir.filePath(filesDir) + uniqueTrashedName)) {
+            ++counter;
+            uniqueTrashedName = QString(QLatin1String("/%1-%2"))
+                                        .arg(trashedName)
+                                        .arg(counter, 4, 10, QLatin1Char('0'));
+        }
+        /*
+            "The $trash/info directory contains an "information file" for every file and directory
+             in $trash/files. This file MUST have exactly the same name as the file or directory in
+             $trash/files, plus the extension ".trashinfo"
+             [...]
+             When trashing a file or directory, the implementation MUST create the corresponding
+             file in $trash/info first. Moreover, it MUST try to do this in an atomic fashion,
+             so that if two processes try to trash files with the same filename this will result
+             in two different trash files. On Unix-like systems this is done by generating a
+             filename, and then opening with O_EXCL. If that succeeds the creation was atomic
+             (at least on the same machine), if it fails you need to pick another filename."
+        */
+        infoFileName = trashDir.filePath(infoDir)
+                     + uniqueTrashedName + QLatin1String(".trashinfo");
+        infoFile.setFileName(infoFileName);
+    } while (!infoFile.open(QIODevice::NewOnly | QIODevice::WriteOnly | QIODevice::Text));
+
+    const QString targetPath = trashDir.filePath(filesDir) + uniqueTrashedName;
+    const QFileSystemEntry target(targetPath);
+
+    if (!renameFile(source, target, error)) {
+        infoFile.close();
+        infoFile.remove();
+        error = QSystemError(errno, QSystemError::StandardLibraryError);
+        return false;
+    }
+
+    QTextStream out(&infoFile);
+#if QT_CONFIG(textcodec)
+    out.setCodec("UTF-8");
+#endif
+    out << "[Trash Info]" << Qt::endl;
+    out << "Path=" << sourcePath << Qt::endl;
+    out << "DeletionDate="
+        << QDateTime::currentDateTime().toString(QLatin1String("yyyy-MM-ddThh:mm:ss")) << Qt::endl;
+    infoFile.close();
+
+    newLocation = QFileSystemEntry(targetPath);
+    return true;
+}
+#endif
+
 //static
 bool QFileSystemEngine::copyFile(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error)
 {
diff --git a/src/corelib/io/qfilesystemengine_win.cpp b/src/corelib/io/qfilesystemengine_win.cpp
index 0579872f8d..71a0e36693 100644
--- a/src/corelib/io/qfilesystemengine_win.cpp
+++ b/src/corelib/io/qfilesystemengine_win.cpp
@@ -41,6 +41,7 @@
 #include "qoperatingsystemversion.h"
 #include "qplatformdefs.h"
 #include "qsysinfo.h"
+#include "qscopeguard.h"
 #include "private/qabstractfileengine_p.h"
 #include "private/qfsfileengine_p.h"
 #include <private/qsystemlibrary_p.h>
@@ -59,6 +60,8 @@
 #include <objbase.h>
 #ifndef Q_OS_WINRT
 #  include <shlobj.h>
+#  include <shobjidl.h>
+#  include <shellapi.h>
 #  include <lm.h>
 #  include <accctrl.h>
 #endif
@@ -422,6 +425,104 @@ static inline bool getFindData(QString path, WIN32_FIND_DATA &findData)
     return false;
 }
 
+#if defined(__IFileOperation_INTERFACE_DEFINED__)
+class FileOperationProgressSink : public IFileOperationProgressSink
+{
+public:
+    FileOperationProgressSink()
+    : ref(1)
+    {}
+    virtual ~FileOperationProgressSink() {}
+
+    ULONG STDMETHODCALLTYPE AddRef()
+    {
+        return ++ref;
+    }
+    ULONG STDMETHODCALLTYPE Release()
+    {
+        if (--ref == 0) {
+            delete this;
+            return 0;
+        }
+        return ref;
+    }
+    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void **ppvObject)
+    {
+        if (!ppvObject)
+            return E_POINTER;
+
+        *ppvObject = nullptr;
+
+        if (iid == __uuidof(IUnknown)) {
+            *ppvObject = static_cast<IUnknown*>(this);
+        } else if (iid == __uuidof(IFileOperationProgressSink)) {
+            *ppvObject = static_cast<IFileOperationProgressSink*>(this);
+        }
+
+        if (*ppvObject) {
+            AddRef();
+            return S_OK;
+        }
+
+        return E_NOINTERFACE;
+    }
+
+    HRESULT STDMETHODCALLTYPE StartOperations()
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE FinishOperations(HRESULT)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PreRenameItem(DWORD, IShellItem *, LPCWSTR)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PostRenameItem(DWORD, IShellItem *, LPCWSTR, HRESULT, IShellItem *)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PreMoveItem(DWORD, IShellItem *, IShellItem *, LPCWSTR)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PostMoveItem(DWORD, IShellItem *, IShellItem *, LPCWSTR, HRESULT,
+                                           IShellItem *)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PreCopyItem(DWORD, IShellItem *, IShellItem *, LPCWSTR )
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PostCopyItem(DWORD, IShellItem *, IShellItem *, LPCWSTR, HRESULT,
+                                           IShellItem *)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PreDeleteItem(DWORD dwFlags, IShellItem *)
+    {
+        // stop the operation if the file will be deleted rather than trashed
+        return (dwFlags & TSF_DELETE_RECYCLE_IF_POSSIBLE) ? S_OK : E_FAIL;
+    }
+    HRESULT STDMETHODCALLTYPE PostDeleteItem(DWORD /* dwFlags */, IShellItem * /* psiItem */,
+                                             HRESULT /* hrDelete */, IShellItem *psiNewlyCreated)
+    {
+        if (psiNewlyCreated) {
+            wchar_t *pszName = nullptr;
+            psiNewlyCreated->GetDisplayName(SIGDN_FILESYSPATH, &pszName);
+            if (pszName) {
+                targetPath = QString::fromWCharArray(pszName);
+                CoTaskMemFree(pszName);
+            }
+        }
+        return S_OK;
+    }
+    HRESULT STDMETHODCALLTYPE PreNewItem(DWORD, IShellItem *, LPCWSTR)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PostNewItem(DWORD, IShellItem *, LPCWSTR, LPCWSTR, DWORD, HRESULT,
+                                          IShellItem *)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE UpdateProgress(UINT,UINT)
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE ResetTimer()
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE PauseTimer()
+    { return S_OK; }
+    HRESULT STDMETHODCALLTYPE ResumeTimer()
+    { return S_OK; }
+
+    QString targetPath;
+private:
+    ULONG ref;
+};
+#endif
+
 bool QFileSystemEngine::uncListSharesOnServer(const QString &server, QStringList *list)
 {
     DWORD res = ERROR_NOT_SUPPORTED;
@@ -1431,6 +1532,97 @@ bool QFileSystemEngine::removeFile(const QFileSystemEntry &entry, QSystemError &
     return ret;
 }
 
+/*
+    If possible, we use the IFileOperation implementation, which allows us to determine
+    the location of the object in the trash.
+    If not (likely on mingw), we fall back to the old API, which won't allow us to know
+    that.
+*/
+//static
+bool QFileSystemEngine::moveFileToTrash(const QFileSystemEntry &source,
+                                        QFileSystemEntry &newLocation, QSystemError &error)
+{
+#ifndef Q_OS_WINRT
+    // we need the "display name" of the file, so can't use nativeFilePath
+    const QString sourcePath = QDir::toNativeSeparators(source.filePath());
+
+#  if defined(__IFileOperation_INTERFACE_DEFINED__)
+    CoInitialize(NULL);
+    IFileOperation *pfo = nullptr;
+    IShellItem *deleteItem = nullptr;
+    FileOperationProgressSink *sink = nullptr;
+    HRESULT hres = E_FAIL;
+
+    auto coUninitialize = qScopeGuard([&](){
+        if (sink)
+            sink->Release();
+        if (deleteItem)
+            deleteItem->Release();
+        if (pfo)
+            pfo->Release();
+        CoUninitialize();
+        if (!SUCCEEDED(hres))
+            error = QSystemError(hres, QSystemError::NativeError);
+    });
+
+    hres = CoCreateInstance(CLSID_FileOperation, nullptr, CLSCTX_ALL, IID_PPV_ARGS(&pfo));
+    if (!pfo)
+        return false;
+    pfo->SetOperationFlags(FOF_ALLOWUNDO | FOFX_RECYCLEONDELETE | FOF_NOCONFIRMATION
+                           | FOF_SILENT | FOF_NOERRORUI);
+    hres = SHCreateItemFromParsingName(reinterpret_cast<const wchar_t*>(sourcePath.utf16()),
+                                       nullptr, IID_PPV_ARGS(&deleteItem));
+    if (!deleteItem)
+        return false;
+    sink = new FileOperationProgressSink;
+    hres = pfo->DeleteItem(deleteItem, static_cast<IFileOperationProgressSink*>(sink));
+    if (!SUCCEEDED(hres))
+        return false;
+    hres = pfo->PerformOperations();
+    if (!SUCCEEDED(hres))
+        return false;
+    newLocation = QFileSystemEntry(sink->targetPath);
+
+#  else // no IFileOperation in SDK (mingw, likely) - fall back to SHFileOperation
+
+    // double null termination needed, so can't use QString::utf16
+    QVarLengthArray<wchar_t, MAX_PATH + 1> winFile(sourcePath.length() + 2);
+    sourcePath.toWCharArray(winFile.data());
+    winFile[sourcePath.length()] = wchar_t{};
+    winFile[sourcePath.length() + 1] = wchar_t{};
+
+    SHFILEOPSTRUCTW operation;
+    operation.hwnd = nullptr;
+    operation.wFunc = FO_DELETE;
+    operation.pFrom = winFile.constData();
+    operation.pTo = nullptr;
+    operation.fFlags = FOF_ALLOWUNDO | FOF_NO_UI;
+    operation.fAnyOperationsAborted = FALSE;
+    operation.hNameMappings = nullptr;
+    operation.lpszProgressTitle = nullptr;
+
+    int result = SHFileOperation(&operation);
+    if (result != 0) {
+        error = QSystemError(result, QSystemError::NativeError);
+        return false;
+    }
+    /*
+        This implementation doesn't let us know where the file ended up, even if
+        we would specify FOF_WANTMAPPINGHANDLE | FOF_RENAMEONCOLLISION, as
+        FOF_RENAMEONCOLLISION has no effect unless files are moved, copied, or renamed.
+    */
+    Q_UNUSED(newLocation);
+#  endif // IFileOperation fallback
+    return true;
+
+#else // Q_OS_WINRT
+    Q_UNUSED(source);
+    Q_UNUSED(newLocation);
+    Q_UNUSED(error);
+    return false;
+#endif
+}
+
 //static
 bool QFileSystemEngine::setPermissions(const QFileSystemEntry &entry, QFile::Permissions permissions, QSystemError &error,
                                        QFileSystemMetaData *data)
diff --git a/tests/auto/corelib/io/qfilesystemengine/qfilesystemengine.pro b/tests/auto/corelib/io/qfilesystemengine/qfilesystemengine.pro
new file mode 100644
index 0000000000..ed59b48d5e
--- /dev/null
+++ b/tests/auto/corelib/io/qfilesystemengine/qfilesystemengine.pro
@@ -0,0 +1,6 @@
+CONFIG += testcase
+TARGET = tst_qfilesystemengine
+QT = core-private testlib
+SOURCES = tst_qfilesystemengine.cpp \
+    $$QT_SOURCE_TREE/src/corelib/io/qfilesystementry.cpp
+HEADERS = $$QT_SOURCE_TREE/src/corelib/io/qfilesystementry_p.h
diff --git a/tests/auto/corelib/io/qfilesystemengine/tst_qfilesystemengine.cpp b/tests/auto/corelib/io/qfilesystemengine/tst_qfilesystemengine.cpp
new file mode 100644
index 0000000000..b64852057a
--- /dev/null
+++ b/tests/auto/corelib/io/qfilesystemengine/tst_qfilesystemengine.cpp
@@ -0,0 +1,168 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QtTest>
+#include <QtCore/QTemporaryDir>
+#include <QtCore/QTemporaryFile>
+
+#include <QtCore/private/qfilesystementry_p.h>
+#include <QtCore/private/qfilesystemengine_p.h>
+
+class tst_QFileSystemEngine : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void cleanupTestCase();
+    void moveToTrash_data();
+    void moveToTrash();
+
+private:
+    QStringList createdEntries;
+};
+
+void tst_QFileSystemEngine::cleanupTestCase()
+{
+    for (QString entry : createdEntries) {
+        QFileInfo entryInfo(entry);
+        if (!entryInfo.exists())
+            continue;
+        QDir entryDir(entry);
+        if (entryInfo.isDir()) {
+            if (!entryDir.removeRecursively())
+                qWarning("Failed to remove trashed dir '%s'", entry.toLocal8Bit().constData());
+        } else if (!QFile::remove(entry)) {
+            qWarning("Failed to remove trashed file '%s'", entry.toLocal8Bit().constData());
+        }
+    }
+}
+
+void tst_QFileSystemEngine::moveToTrash_data()
+{
+    QTest::addColumn<QString>("filePath");
+    QTest::addColumn<bool>("create");
+    QTest::addColumn<bool>("success");
+
+    {
+        QTemporaryFile tempFile;
+        tempFile.open();
+        QTest::newRow("temporary file")
+            << tempFile.fileName()
+            << true << true;
+    }
+    {
+        QTemporaryDir tempDir;
+        tempDir.setAutoRemove(false);
+        QTest::newRow("temporary dir")
+            << tempDir.path() + QLatin1Char('/')
+            << true << true;
+    }
+    {
+        QTemporaryDir homeDir(QFileSystemEngine::homePath() + QLatin1String("/XXXXXX"));
+        homeDir.setAutoRemove(false);
+        QTemporaryFile homeFile(homeDir.path()
+                              + QLatin1String("/tst_qfilesystemengine-XXXXXX"));
+        homeFile.open();
+        QTest::newRow("home file")
+            << homeFile.fileName()
+            << true << true;
+
+        QTest::newRow("home dir")
+            << homeDir.path() + QLatin1Char('/')
+            << true << true;
+    }
+
+    QTest::newRow("unmovable")
+        << QFileSystemEngine::rootPath()
+        << false << false;
+    QTest::newRow("no such file")
+        << QString::fromLatin1("no/such/file")
+        << false << false;
+}
+
+void tst_QFileSystemEngine::moveToTrash()
+{
+    QFETCH(QString, filePath);
+    QFETCH(bool, create);
+    QFETCH(bool, success);
+
+#if defined(Q_OS_WINRT)
+    QSKIP("WinRT does not have a trash", SkipAll);
+#endif
+
+    if (create && !QFileInfo::exists(filePath)) {
+        createdEntries << filePath;
+        if (filePath.endsWith(QLatin1Char('/'))) {
+            QDir temp(QFileSystemEngine::rootPath());
+            temp.mkdir(filePath);
+            QFile file(filePath + QLatin1String("test"));
+            if (!file.open(QIODevice::WriteOnly))
+                QSKIP("Couldn't create directory with file");
+        } else {
+            QFile file(filePath);
+            if (!file.open(QIODevice::WriteOnly))
+                QSKIP("Couldn't open file for writing");
+        }
+        QVERIFY(QFileInfo::exists(filePath));
+    }
+
+    QFileSystemEntry entry(filePath);
+    QFileSystemEntry newLocation;
+    QSystemError error;
+
+    bool existed = QFileInfo::exists(filePath);
+    bool result = QFileSystemEngine::moveFileToTrash(entry, newLocation, error);
+    QCOMPARE(result, success);
+    if (result) {
+        QCOMPARE(error.error(), 0);
+        QVERIFY(existed != QFileInfo::exists(filePath));
+        const QString newPath = newLocation.filePath();
+#if defined(Q_OS_WIN)
+        // one of the Windows code paths doesn't provide the location of the object in the trash
+        if (newPath.isEmpty())
+            QEXPECT_FAIL("", "Qt built without IFileOperations support on Windows!", Continue);
+#endif
+        QVERIFY(!newPath.isEmpty());
+        if (!newPath.isEmpty()) {
+            createdEntries << newPath;
+            QFileInfo trashInfo(newPath);
+            QVERIFY(trashInfo.exists());
+#if defined(Q_OS_UNIX) && !defined(Q_OS_DARWIN)
+            QString infoFile = trashInfo.absolutePath() + QLatin1String("/../info/")
+                             + trashInfo.fileName() + QLatin1String(".trashinfo");
+            createdEntries << infoFile;
+#endif
+        }
+    } else {
+        QVERIFY(error.error() != 0);
+        QCOMPARE(existed, QFileInfo::exists(filePath));
+    }
+}
+
+QTEST_MAIN(tst_QFileSystemEngine)
+#include <tst_qfilesystemengine.moc>