Added support for symlinks and junction points on Windows

Since ntfs symlinks (not .lnk files) can use
relative paths to targets, support for relative links
needed to be added.
Directory junctions can also be used to mount another
filesystem directly into an existing folder.
Such junctions in that case use the volume id of the
target volume for the link path. Therefor this commit
also includes an implementation for resolving volume ids.

To be independent of existing directories in test code
i added a function to create own junction points.

Reviewed-by: Joao
Task-number: QTBUG-9009, QTBUG-7036

3 files changed, 213 insertions, 2 deletions

diff --git a/tests/auto/qfileinfo/tst_qfileinfo.cpp b/tests/auto/qfileinfo/tst_qfileinfo.cpp
index 403c5f9..d482cbc 100644
--- a/tests/auto/qfileinfo/tst_qfileinfo.cpp
+++ b/tests/auto/qfileinfo/tst_qfileinfo.cpp
@@ -56,6 +56,7 @@
 #endif
 #ifdef Q_OS_WIN
 #include <qt_windows.h>
+#include <qlibrary.h>
 #endif
 #include <qplatformdefs.h>
 #include <qdebug.h>
@@ -65,6 +66,7 @@
 #endif
 #include "../network-settings.h"
 #include <private/qfileinfo_p.h>
+#include "../../shared/filesystem.h"
 
 #if defined(Q_OS_SYMBIAN)
 # define SRCDIR ""
@@ -161,6 +163,8 @@ private slots:
     void refresh();
 
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+    void ntfsJunctionPointsAndSymlinks_data();
+    void ntfsJunctionPointsAndSymlinks();
     void brokenShortcut();
 #endif
 
@@ -194,8 +198,15 @@ tst_QFileInfo::~tst_QFileInfo()
 #if defined(Q_OS_UNIX) && !defined(Q_OS_SYMBIAN)
     QDir().rmdir("./.hidden-directory");
 #endif
-#ifdef Q_OS_WIN
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
     QDir().rmdir("./hidden-directory");
+    QDir().rmdir("abs_symlink");
+    QDir().rmdir("rel_symlink");
+    QDir().rmdir("junction_pwd");
+    QDir().rmdir("junction_root");
+    QDir().rmdir("mountpoint");
+    QFile::remove("abs_symlink.cpp");
+    QFile::remove("rel_symlink.cpp");
 #endif
 }
 
@@ -1236,6 +1247,106 @@ void tst_QFileInfo::refresh()
 }
 
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+void tst_QFileInfo::ntfsJunctionPointsAndSymlinks_data()
+{
+    QTest::addColumn<QString>("path");
+    QTest::addColumn<bool>("isSymLink");
+    QTest::addColumn<QString>("linkTarget");
+    QTest::addColumn<QString>("canonicalFilePath");
+
+    QDir pwd;
+    pwd.mkdir("target");
+
+    QLibrary kernel32("kernel32");
+    typedef BOOLEAN (WINAPI *PtrCreateSymbolicLink)(LPCWSTR, LPCWSTR, DWORD);
+    PtrCreateSymbolicLink createSymbolicLinkW = 0;
+    createSymbolicLinkW = (PtrCreateSymbolicLink) kernel32.resolve("CreateSymbolicLinkW");
+    if (!createSymbolicLinkW)
+        QSKIP("symbolic links not supported by operating system",SkipSingle);
+
+    {
+        //Directory symlinks
+        QDir target("target");
+        QVERIFY(target.exists());
+
+        QString absTarget = QDir::toNativeSeparators(target.absolutePath());
+        QString absSymlink = QDir::toNativeSeparators(pwd.absolutePath()).append("\\abs_symlink");
+        QString relTarget = "target";
+        QString relSymlink = "rel_symlink";
+        QString fileInTarget(absTarget);
+        fileInTarget.append("\\file");
+        QString fileInSymlink(absSymlink);
+        fileInSymlink.append("\\file");
+        QFile file(fileInTarget);
+        file.open(QIODevice::ReadWrite);
+        file.close();
+
+        QVERIFY(pwd.exists("abs_symlink") || createSymbolicLinkW(absSymlink.utf16(),absTarget.utf16(),0x1));
+        QVERIFY(pwd.exists(relSymlink) || createSymbolicLinkW(relSymlink.utf16(),relTarget.utf16(),0x1));
+        QVERIFY(file.exists());
+
+        QTest::newRow("absolute dir symlink") << absSymlink << true << QDir::fromNativeSeparators(absTarget) << target.canonicalPath();
+        QTest::newRow("relative dir symlink") << relSymlink << true << QDir::fromNativeSeparators(relTarget) << target.canonicalPath();
+        QTest::newRow("file in symlink dir") << fileInSymlink << false << "" << target.canonicalPath().append("/file");
+    }
+    {
+        //File symlinks
+        QFileInfo target(SRCDIR "tst_qfileinfo.cpp");
+        QString absTarget = QDir::toNativeSeparators(target.absoluteFilePath());
+        QString absSymlink = QDir::toNativeSeparators(pwd.absolutePath()).append("\\abs_symlink.cpp");
+        QString relTarget = QDir::toNativeSeparators(pwd.relativeFilePath(target.absoluteFilePath()));
+        QString relSymlink = "rel_symlink.cpp";
+        QVERIFY(pwd.exists("abs_symlink.cpp") || createSymbolicLinkW(absSymlink.utf16(),absTarget.utf16(),0x0));
+        QVERIFY(pwd.exists(relSymlink) || createSymbolicLinkW(relSymlink.utf16(),relTarget.utf16(),0x0));
+
+        QTest::newRow("absolute file symlink") << absSymlink << true << QDir::fromNativeSeparators(absTarget) << target.canonicalFilePath();
+        QTest::newRow("relative file symlink") << relSymlink << true << QDir::fromNativeSeparators(relTarget) << target.canonicalFilePath();
+    }
+
+    //Junctions
+    QString target = "target";
+    QString junction = "junction_pwd";
+    FileSystem::createNtfsJunction(target, junction);
+    QFileInfo targetInfo(target);
+    QTest::newRow("junction_pwd") << junction << true << targetInfo.absoluteFilePath() << targetInfo.canonicalFilePath();
+
+    QFileInfo fileInJunction(targetInfo.absoluteFilePath().append("/file"));
+    QFile file(fileInJunction.absoluteFilePath());
+    file.open(QIODevice::ReadWrite);
+    file.close();
+    QVERIFY(file.exists());
+    QTest::newRow("file in junction") << fileInJunction.absoluteFilePath() << false << "" << fileInJunction.canonicalFilePath();
+
+    target = QDir::rootPath();
+    junction = "junction_root";
+    FileSystem::createNtfsJunction(target, junction);
+    targetInfo.setFile(target);
+    QTest::newRow("junction_root") << junction << true << targetInfo.absoluteFilePath() << targetInfo.canonicalFilePath();
+
+    //Mountpoint
+    wchar_t buffer[MAX_PATH];
+    QString rootPath = QDir::toNativeSeparators(QDir::rootPath());
+    QVERIFY(GetVolumeNameForVolumeMountPointW(rootPath.utf16(), buffer, MAX_PATH));
+    QString rootVolume = QString::fromWCharArray(buffer);
+    junction = "mountpoint";
+    rootVolume.replace("\\\\?\\","\\??\\");
+    FileSystem::createNtfsJunction(rootVolume, junction);
+    QTest::newRow("mountpoint") << junction << true <<  QDir::fromNativeSeparators(rootPath) << QDir::rootPath();
+}
+
+void tst_QFileInfo::ntfsJunctionPointsAndSymlinks()
+{
+    QFETCH(QString, path);
+    QFETCH(bool, isSymLink);
+    QFETCH(QString, linkTarget);
+    QFETCH(QString, canonicalFilePath);
+
+    QFileInfo fi(path);
+    QCOMPARE(fi.isSymLink(), isSymLink);
+    QCOMPARE(fi.symLinkTarget(), linkTarget);
+    QCOMPARE(fi.canonicalFilePath(), canonicalFilePath);
+}
+
 void tst_QFileInfo::brokenShortcut()
 {
     QString linkName("borkenlink.lnk");
diff --git a/tests/benchmarks/corelib/io/qfileinfo/main.cpp b/tests/benchmarks/corelib/io/qfileinfo/main.cpp
index 025787f..b272bda 100644
--- a/tests/benchmarks/corelib/io/qfileinfo/main.cpp
+++ b/tests/benchmarks/corelib/io/qfileinfo/main.cpp
@@ -43,15 +43,20 @@
 #include <QtTest/QtTest>
 #include <QtCore/QCoreApplication>
 #include <QtCore/QFileInfo>
+#include <QtCore/QFile>
 
 #include "private/qfsfileengine_p.h"
+#include "../../../../shared/filesystem.h"
 
 class qfileinfo : public QObject
 {
     Q_OBJECT
 private slots:
     void canonicalFileNamePerformance();
-
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+    void symLinkTargetPerformanceLNK();
+    void symLinkTargetPerformanceMounpoint();
+#endif
     void initTestCase();
     void cleanupTestCase();
 public:
@@ -78,6 +83,43 @@ void qfileinfo::canonicalFileNamePerformance()
     }
 }
 
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+void qfileinfo::symLinkTargetPerformanceLNK()
+{
+    QVERIFY(QFile::link("file","link.lnk"));
+    QFileInfo info("link.lnk");
+    info.setCaching(false);
+    QVERIFY(info.isSymLink());
+    QString linkTarget;
+    QBENCHMARK {
+        for(int i=0; i<100; i++)
+            linkTarget = info.readLink();
+    }
+    QVERIFY(QFile::remove("link.lnk"));
+}
+
+void qfileinfo::symLinkTargetPerformanceMounpoint()
+{
+    wchar_t buffer[MAX_PATH];
+    QString rootPath = QDir::toNativeSeparators(QDir::rootPath());
+    QVERIFY(GetVolumeNameForVolumeMountPointW(rootPath.utf16(), buffer, MAX_PATH));
+    QString rootVolume = QString::fromWCharArray(buffer);
+    QString mountpoint = "mountpoint";
+    rootVolume.replace("\\\\?\\","\\??\\");
+    FileSystem::createNtfsJunction(rootVolume, mountpoint);
+
+    QFileInfo info(mountpoint);
+    info.setCaching(false);
+    QVERIFY(info.isSymLink());
+    QString linkTarget;
+    QBENCHMARK {
+        for(int i=0; i<100; i++)
+            linkTarget = info.readLink();
+    }
+    QVERIFY(QDir().rmdir(mountpoint));
+}
+#endif
+
 QTEST_MAIN(qfileinfo)
 
 #include "main.moc"
diff --git a/tests/shared/filesystem.h b/tests/shared/filesystem.h
index 2d46c0d..cc1781e 100644
--- a/tests/shared/filesystem.h
+++ b/tests/shared/filesystem.h
@@ -48,6 +48,11 @@
 #include <QDir>
 #include <QFile>
 
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+# define IO_REPARSE_TAG_MOUNT_POINT       (0xA0000003L)
+# define REPARSE_MOUNTPOINT_HEADER_SIZE   8
+#endif
+
 struct FileSystem
 {
     ~FileSystem()
@@ -86,6 +91,59 @@ struct FileSystem
         }
         return false;
     }
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
+    static void createNtfsJunction(QString target, QString linkName)
+    {
+        typedef struct {
+            DWORD   ReparseTag;
+            DWORD   ReparseDataLength;
+            WORD    Reserved;
+            WORD    ReparseTargetLength;
+            WORD    ReparseTargetMaximumLength;
+            WORD    Reserved1;
+            WCHAR   ReparseTarget[1];
+        } REPARSE_MOUNTPOINT_DATA_BUFFER, *PREPARSE_MOUNTPOINT_DATA_BUFFER;
+
+        char    reparseBuffer[MAX_PATH*3];
+        HANDLE  hFile;
+        DWORD   returnedLength;
+        wchar_t fileSystem[MAX_PATH] = L"";
+        PREPARSE_MOUNTPOINT_DATA_BUFFER reparseInfo = (PREPARSE_MOUNTPOINT_DATA_BUFFER) reparseBuffer;
+
+        QFileInfo junctionInfo(linkName);
+        linkName = QDir::toNativeSeparators(junctionInfo.absoluteFilePath());
+
+        GetVolumeInformationW( linkName.left(3).utf16(), NULL, 0, NULL, NULL, NULL,
+                               fileSystem, sizeof(fileSystem)/sizeof(WCHAR));
+        if(QString().fromWCharArray(fileSystem) != "NTFS")
+            QSKIP("This seems not to be an NTFS volume. Junctions are not allowed.",SkipSingle);
+
+        if (!target.startsWith("\\??\\") && !target.startsWith("\\\\?\\")) {
+            QFileInfo targetInfo(target);
+            target = QDir::toNativeSeparators(targetInfo.absoluteFilePath());
+            target.prepend("\\??\\");
+            if(target.endsWith('\\') && target.at(target.length()-2) != ':')
+                target.chop(1);
+        }
+        QDir().mkdir(linkName);
+        hFile = CreateFileW( linkName.utf16(), GENERIC_WRITE, 0, NULL, OPEN_EXISTING,
+                             FILE_FLAG_OPEN_REPARSE_POINT|FILE_FLAG_BACKUP_SEMANTICS, NULL );
+        QVERIFY(hFile != INVALID_HANDLE_VALUE );
+
+        memset( reparseInfo, 0, sizeof( *reparseInfo ));
+        reparseInfo->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
+        reparseInfo->ReparseTargetLength = target.size() * sizeof(wchar_t);
+        reparseInfo->ReparseTargetMaximumLength = reparseInfo->ReparseTargetLength + sizeof(wchar_t);
+        target.toWCharArray(reparseInfo->ReparseTarget);
+        reparseInfo->ReparseDataLength = reparseInfo->ReparseTargetLength + 12;
+
+        bool ioc = DeviceIoControl(hFile, FSCTL_SET_REPARSE_POINT, reparseInfo,
+                                 reparseInfo->ReparseDataLength + REPARSE_MOUNTPOINT_HEADER_SIZE,
+                                 NULL, 0, &returnedLength, NULL);
+        CloseHandle( hFile );
+        QVERIFY(ioc);
+    }
+#endif
 
 private:
     QDir currentDir;