Add QFileInfo::isAlias() to reflect whether the file is a macOS alias

Change-Id: I772066d0d8e69893f7c4aee1cd2305d46d5834c4
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qfileinfo.cpp

@@ -1118,8 +1118,8 @@ bool QFileInfo::isSymLink() const
     opens the \l{symLinkTarget()}{link's target}.
 
     In contrast to isSymLink(), false will be returned for shortcuts
-    (\c *.lnk files) on Windows and aliases on \macos.
-    Use QFileInfo::isShortcut() on Windows instead.
+    (\c *.lnk files) on Windows and aliases on \macos. Use QFileInfo::isShortcut()
+    and QFileInfo::isAlias() instead.
 
     \note If the symlink points to a non existing file, exists() returns
     false.
@@ -1162,6 +1162,29 @@ bool QFileInfo::isShortcut() const
             [d]() { return d->getFileFlags(QAbstractFileEngine::LinkType); });
 }
 
+/*!
+    Returns \c true if this object points to an alias;
+    otherwise returns \c false.
+
+    \since 6.4
+
+    Aliases only exist on \macos. They are treated as regular files, so
+    opening an alias will open the file itself. In order to open the file
+    or directory an alias references use symLinkTarget().
+
+    \note Even if an alias points to a non existing file,
+    isAlias() returns true.
+
+    \sa isFile(), isDir(), isSymLink(), symLinkTarget()
+*/
+bool QFileInfo::isAlias() const
+{
+    Q_D(const QFileInfo);
+    return d->checkAttribute<bool>(
+            QFileSystemMetaData::LegacyLinkType,
+            [d]() { return d->metaData.isAlias(); },
+            [d]() { return d->getFileFlags(QAbstractFileEngine::LinkType); });
+}
 
 /*!
     \since 5.15

src/corelib/io/qfileinfo.h

@@ -156,6 +156,7 @@ public:
     bool isSymLink() const;
     bool isSymbolicLink() const;
     bool isShortcut() const;
+    bool isAlias() const;
     bool isJunction() const;
     bool isRoot() const;
     bool isBundle() const;

tests/auto/corelib/io/qfileinfo/CMakeLists.txt

@@ -45,3 +45,7 @@ qt_internal_extend_target(tst_qfileinfo CONDITION WIN32
         advapi32
         netapi32
 )
+
+if (APPLE)
+    target_compile_options(tst_qfileinfo PRIVATE -x objective-c++)
+endif()

tests/auto/corelib/io/qfileinfo/tst_qfileinfo.cpp

@@ -62,6 +62,10 @@
 #include <private/qfileinfo_p.h>
 #include "../../../../shared/filesystem.h"
 
+#if defined(Q_OS_MACOS)
+#include <Foundation/Foundation.h>
+#endif
+
 #if defined(Q_OS_VXWORKS)
 #define Q_NO_SYMLINKS
 #endif
@@ -218,6 +222,9 @@ private slots:
     void isShortcut_data();
     void isShortcut();
 
+    void isAlias_data();
+    void isAlias();
+
     void link_data();
     void link();
 
@@ -1345,6 +1352,57 @@ void tst_QFileInfo::isShortcut()
     QCOMPARE(fi.isShortcut(), isShortcut);
 }
 
+void tst_QFileInfo::isAlias_data()
+{
+    QFile::remove("symlink");
+    QFile::remove("file-alias");
+    QFile::remove("directory-alias");
+
+    QTest::addColumn<QString>("path");
+    QTest::addColumn<bool>("isAlias");
+
+    QFile regularFile(m_sourceFile);
+    QTest::newRow("regular-file") << regularFile.fileName() << false;
+    QTest::newRow("directory") << QDir::currentPath() << false;
+
+#if defined(Q_OS_MACOS)
+    auto createAlias = [](const QString &target, const QString &alias) {
+        NSURL *targetUrl = [NSURL fileURLWithPath:target.toNSString()];
+        NSURL *aliasUrl = [NSURL fileURLWithPath:alias.toNSString()];
+        NSData *bookmarkData = [targetUrl bookmarkDataWithOptions:NSURLBookmarkCreationSuitableForBookmarkFile
+            includingResourceValuesForKeys:nil relativeToURL:nil error:nullptr];
+        Q_ASSERT(bookmarkData);
+
+        bool success = [NSURL writeBookmarkData:bookmarkData toURL:aliasUrl
+            options:NSURLBookmarkCreationSuitableForBookmarkFile error:nullptr];
+        Q_ASSERT(success);
+    };
+
+    regularFile.link("symlink");
+    QTest::newRow("symlink") << "symlink" << false;
+
+    createAlias(regularFile.fileName(), QDir::current().filePath("file-alias"));
+    QTest::newRow("file-alias") << "file-alias" << true;
+
+    createAlias(QDir::currentPath(), QDir::current().filePath("directory-alias"));
+    QTest::newRow("directory-alias") << "directory-alias" << true;
+
+    regularFile.copy("non-existing-file");
+    createAlias("non-existing-file", QDir::current().filePath("non-existing-file-alias"));
+    QDir::current().remove("non-existing-file");
+    QTest::newRow("non-existing-file-alias") << "non-existing-file-alias" << true;
+#endif
+}
+
+void tst_QFileInfo::isAlias()
+{
+    QFETCH(QString, path);
+    QFETCH(bool, isAlias);
+
+    QFileInfo fi(path);
+    QCOMPARE(fi.isAlias(), isAlias);
+}
+
 void tst_QFileInfo::isSymbolicLink_data()
 {
     QTest::addColumn<QString>("path");