QTemporaryFile: Add support for Linux's O_TMPFILE

That means a file is never created, unless you ask for the name. There's
no chance of left-over temporary files being left behind. QSaveFile also
benefits from this, since the save file is not present on disk until
commit(). Unfortunately, QSaveFile must go through a temporary name
because linkat(2) cannot overwrite -- we need rename(2) for that (for
now).

[ChangeLog][Important Behavior Changes][QTemporaryFile] On Linux,
QTemporaryFile will attempt to create unnamed temporary files. If that
succeeds, open() will return true but exists() will be false. If you
call fileName() or any function that calls it, QTemporaryFile will give
the file a name, so most applications will not see a difference.

Change-Id: I1eba2b016de74620bfc8fffd14cc843e5b0919d0
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 76 insertions, 5 deletions

diff --git a/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp b/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
index 4481def214..11c24ca86f 100644
--- a/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
+++ b/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the test suite of the Qt Toolkit.
@@ -32,6 +33,7 @@
 #include <qtemporarydir.h>
 #include <qtemporaryfile.h>
 #include <qfile.h>
+#include <qdatetime.h>
 #include <qdir.h>
 #include <qset.h>
 #include <qtextcodec.h>
@@ -63,7 +65,7 @@ private slots:
     void fileNameIsEmpty();
     void autoRemove();
     void nonWritableCurrentDir();
-    void write();
+    void io();
     void openCloseOpenClose();
     void removeAndReOpen();
     void size();
@@ -286,6 +288,18 @@ void tst_QTemporaryFile::autoRemove()
         fileName = file.fileName();
         file.close();
     }
+    QVERIFY(!fileName.isEmpty());
+    QVERIFY(!QFile::exists(fileName));
+
+    // same, but gets the file name after closing
+    {
+        QTemporaryFile file("tempXXXXXX");
+        file.setAutoRemove(true);
+        QVERIFY(file.open());
+        file.close();
+        fileName = file.fileName();
+    }
+    QVERIFY(!fileName.isEmpty());
     QVERIFY(!QFile::exists(fileName));
 
     // Test if disabling auto remove works.
@@ -296,6 +310,19 @@ void tst_QTemporaryFile::autoRemove()
         fileName = file.fileName();
         file.close();
     }
+    QVERIFY(!fileName.isEmpty());
+    QVERIFY(QFile::exists(fileName));
+    QVERIFY(QFile::remove(fileName));
+
+    // same, but gets the file name after closing
+    {
+        QTemporaryFile file("tempXXXXXX");
+        file.setAutoRemove(false);
+        QVERIFY(file.open());
+        file.close();
+        fileName = file.fileName();
+    }
+    QVERIFY(!fileName.isEmpty());
     QVERIFY(QFile::exists(fileName));
     QVERIFY(QFile::remove(fileName));
 
@@ -346,17 +373,51 @@ void tst_QTemporaryFile::nonWritableCurrentDir()
 #endif
 }
 
-void tst_QTemporaryFile::write()
+void tst_QTemporaryFile::io()
 {
     QByteArray data("OLE\nOLE\nOLE");
     QTemporaryFile file;
+    QDateTime before = QDateTime::currentDateTimeUtc().addMSecs(-250);
+
+    // discard msec component (round down) - not all FSs and OSs support them
+    before.setSecsSinceEpoch(before.toSecsSinceEpoch());
+
     QVERIFY(file.open());
+    QVERIFY(file.readLink().isEmpty()); // it's not a link!
+    QFile::Permissions perm = file.permissions();
+    QVERIFY(perm & QFile::ReadOwner);
+    QVERIFY(file.setPermissions(perm));
+
+    QCOMPARE(int(file.size()), 0);
+    QVERIFY(file.resize(data.size()));
+    QCOMPARE(int(file.size()), data.size());
     QCOMPARE((int)file.write(data), data.size());
+    QCOMPARE(int(file.size()), data.size());
+
+    QDateTime mtime = file.fileTime(QFile::FileModificationTime).toUTC();
+    QDateTime btime = file.fileTime(QFile::FileBirthTime).toUTC();
+    QDateTime ctime = file.fileTime(QFile::FileMetadataChangeTime).toUTC();
+    QDateTime atime = file.fileTime(QFile::FileAccessTime).toUTC();
+
+    QDateTime after = QDateTime::currentDateTimeUtc().toUTC().addMSecs(250);
+    // round msecs up
+    after.setSecsSinceEpoch(after.toSecsSinceEpoch() + 1);
+
+    // mtime must be valid, the rest could fail
+    QVERIFY(mtime <= after && mtime >= before);
+    QVERIFY(!btime.isValid() || (btime <= after && btime >= before));
+    QVERIFY(!ctime.isValid() || (ctime <= after && ctime >= before));
+    QVERIFY(!btime.isValid() || (btime <= after && btime >= before));
+
+    QVERIFY(file.setFileTime(before.addSecs(-10), QFile::FileModificationTime));
+    mtime = file.fileTime(QFile::FileModificationTime).toUTC();
+    QCOMPARE(mtime, before.addSecs(-10));
+
     file.reset();
     QFile compare(file.fileName());
     compare.open(QIODevice::ReadOnly);
     QCOMPARE(compare.readAll() , data);
-    file.close();
+    QCOMPARE(compare.fileTime(QFile::FileModificationTime), mtime);
 }
 
 void tst_QTemporaryFile::openCloseOpenClose()
@@ -407,17 +468,19 @@ void tst_QTemporaryFile::size()
 {
     QTemporaryFile file;
     QVERIFY(file.open());
-    QVERIFY(file.exists());
     QVERIFY(!file.isSequential());
     QByteArray str("foobar");
     file.write(str);
-    QVERIFY(QFile::exists(file.fileName()));
+
     // On CE it takes more time for the filesystem to update
     // the information. Usually you have to close it or seek
     // to get latest information. flush() does not help either.
     QCOMPARE(file.size(), qint64(6));
     file.seek(0);
     QCOMPARE(file.size(), qint64(6));
+
+    QVERIFY(QFile::exists(file.fileName()));
+    QVERIFY(file.exists());
 }
 
 void tst_QTemporaryFile::resize()
@@ -814,6 +877,14 @@ void tst_QTemporaryFile::QTBUG_4796()
         QCOMPARE(file5.open(), openResult);
         QCOMPARE(file6.open(), openResult);
 
+        // force the files to exist, if they are supposed to
+        QCOMPARE(!file1.fileName().isEmpty(), openResult);
+        QCOMPARE(!file2.fileName().isEmpty(), openResult);
+        QCOMPARE(!file3.fileName().isEmpty(), openResult);
+        QCOMPARE(!file4.fileName().isEmpty(), openResult);
+        QCOMPARE(!file5.fileName().isEmpty(), openResult);
+        QCOMPARE(!file6.fileName().isEmpty(), openResult);
+
         QCOMPARE(file1.exists(), openResult);
         QCOMPARE(file2.exists(), openResult);
         QCOMPARE(file3.exists(), openResult);