Use a more robust test for absolute paths in QDir

Its filePath() and absoluteFilePath() don't trust its own
isAbsolute(), due to some infelicities on MS-Win; and kludged round a
consequent problem with resource paths; but other virtual file systems
weren't catered for.  Replace the convoluted test there with a static
bool function (so that future kludges in this area shall only need to
edit one place; and can document why they're needed) and use a more
robust test that handles all virtual file systems (by asking
QFileInfo) but falls back to QFileSystemEntry to work round the known
infelicities on MS-Win.  Add regression test for asset library paths
issue on iOS.  Ammends 27f1f84c1c.

Moved a couple of local variables to after the early return, since it
doesn't need them, in the process.

Task-number: QTBUG-70237
Change-Id: Ib3954826df40ccf816beebe5c3751497e3bf6433
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

src/corelib/io/qdir.cpp

@@ -748,6 +748,21 @@ static int drivePrefixLength(const QString &path)
 }
 #endif // Q_OS_WIN
 
+static bool treatAsAbsolute(const QString &path)
+{
+    // ### Qt 6: be consistent about absolute paths
+
+    // QFileInfo will use the right FS-engine for virtual file-systems
+    // (e.g. resource paths).  Unfortunately, for real file-systems, it relies
+    // on QFileSystemEntry's isRelative(), which is flawed on MS-Win, ignoring
+    // its (correct) isAbsolute().  So only use that isAbsolute() unless there's
+    // a colon in the path.
+    // FIXME: relies on virtual file-systems having colons in their prefixes.
+    // The case of an MS-absolute C:/... path happens to work either way.
+    return (path.contains(QLatin1Char(':')) && QFileInfo(path).isAbsolute())
+        || QFileSystemEntry(path).isAbsolute();
+}
+
 /*!
     Returns the path name of a file in the directory. Does \e not
     check if the file actually exists in the directory; but see
@@ -759,13 +774,10 @@ static int drivePrefixLength(const QString &path)
 */
 QString QDir::filePath(const QString &fileName) const
 {
-    const QDirPrivate* d = d_ptr.constData();
+    if (treatAsAbsolute(fileName))
-    // Mistrust our own isAbsolutePath() for real files; Q_OS_WIN needs a drive.
-    if (fileName.startsWith(QLatin1Char(':')) // i.e. resource path
-        ? isAbsolutePath(fileName) : QFileSystemEntry(fileName).isAbsolute()) {
         return fileName;
-    }
 
+    const QDirPrivate* d = d_ptr.constData();
     QString ret = d->dirEntry.filePath();
     if (fileName.isEmpty())
         return ret;
@@ -793,13 +805,10 @@ QString QDir::filePath(const QString &fileName) const
 */
 QString QDir::absoluteFilePath(const QString &fileName) const
 {
-    const QDirPrivate* d = d_ptr.constData();
+    if (treatAsAbsolute(fileName))
-    // Mistrust our own isAbsolutePath() for real files; Q_OS_WIN needs a drive.
-    if (fileName.startsWith(QLatin1Char(':')) // i.e. resource path
-        ? isAbsolutePath(fileName) : QFileSystemEntry(fileName).isAbsolute()) {
         return fileName;
-    }
 
+    const QDirPrivate* d = d_ptr.constData();
     d->resolveAbsoluteEntry();
     const QString absoluteDirPath = d->absoluteDirEntry.filePath();
     if (fileName.isEmpty())

tests/auto/corelib/io/qdir/Info.plist

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDisplayName</key>
+	<string>${PRODUCT_NAME}</string>
+	<key>CFBundleExecutable</key>
+	<string>${EXECUTABLE_NAME}</string>
+	<key>CFBundleGetInfoString</key>
+	<string>Created by Qt/QMake</string>
+	<key>CFBundleIconFile</key>
+	<string>${ASSETCATALOG_COMPILER_APPICON_NAME}</string>
+	<key>CFBundleIdentifier</key>
+	<string>${PRODUCT_BUNDLE_IDENTIFIER}</string>
+	<key>CFBundleName</key>
+	<string>${PRODUCT_NAME}</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>${QMAKE_SHORT_VERSION}</string>
+	<key>CFBundleSignature</key>
+	<string>${QMAKE_PKGINFO_TYPEINFO}</string>
+	<key>CFBundleVersion</key>
+	<string>${QMAKE_FULL_VERSION}</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>MinimumOSVersion</key>
+	<string>${IPHONEOS_DEPLOYMENT_TARGET}</string>
+	<key>UILaunchStoryboardName</key>
+	<string>LaunchScreen</string>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+        <key>NSPhotoLibraryUsageDescription</key>
+        <string>Enables use of assets file engine</string>
+</dict>
+</plist>

tests/auto/corelib/io/qdir/qdir.pro

@@ -3,6 +3,7 @@ TARGET = tst_qdir
 QT = core core-private testlib
 SOURCES = tst_qdir.cpp
 RESOURCES += qdir.qrc
+ios: QMAKE_INFO_PLIST = Info.plist
 
 TESTDATA += testdir testData searchdir resources entrylist types tst_qdir.cpp
 

tests/auto/corelib/io/qdir/tst_qdir.cpp

@@ -1523,6 +1523,11 @@ void tst_QDir::filePath_data()
     QTest::newRow("rel-rel") << "relative" << "path" << "relative/path";
     QTest::newRow("empty-empty") << "" << "" << ".";
     QTest::newRow("resource") << ":/prefix" << "foo.bar" << ":/prefix/foo.bar";
+#ifdef Q_OS_IOS
+    QTest::newRow("assets-rel") << "assets-library:/" << "foo/bar.baz" << "assets-library:/foo/bar.baz";
+    QTest::newRow("assets-abs") << "assets-library:/" << "/foo/bar.baz" << "/foo/bar.baz";
+    QTest::newRow("abs-assets") << "/some/path" << "assets-library:/foo/bar.baz" << "assets-library:/foo/bar.baz";
+#endif
 #ifdef Q_OS_WIN
     QTest::newRow("abs-LTUNC") << "Q:/path" << "\\/leaning\\tooth/pick" << "\\/leaning\\tooth/pick";
     QTest::newRow("LTUNC-slash") << "\\/leaning\\tooth/pick" << "/path" << "//leaning/tooth/path";