Fix QDir::operator==(const QDir &) const

We can't rely on absolute paths when comparing directories for equality
as these don't take into account symbolic links and may also bypass ../
and ./ simplification.

Instead, canonical paths must be computed and can then be compared
according to the case sensitivity rules for the platform or file engine,
as is done in QFileInfo.

Task-number: QTBUG-20495
Reviewed-by: Prasanth Ullattil

3 files changed, 10 insertions, 3 deletions

diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index f9196e0..6e25d91 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -1633,9 +1633,9 @@ bool QDir::operator==(const QDir &dir) const
     if (d->filters == other->filters
        && d->sort == other->sort
        && d->nameFilters == other->nameFilters) {
-        d->resolveAbsoluteEntry();
-        other->resolveAbsoluteEntry();
-        return d->absoluteDirEntry.filePath().compare(other->absoluteDirEntry.filePath(), sensitive) == 0;
+
+        // Fallback to expensive canonical path computation
+        return canonicalPath().compare(dir.canonicalPath(), sensitive) == 0;
     }
     return false;
 }
diff --git a/src/corelib/io/qfileinfo.cpp b/src/corelib/io/qfileinfo.cpp
index ca42c87..6e25206 100644
--- a/src/corelib/io/qfileinfo.cpp
+++ b/src/corelib/io/qfileinfo.cpp
@@ -406,6 +406,7 @@ bool QFileInfo::operator==(const QFileInfo &fileinfo) const
     if (fileinfo.size() != size()) //if the size isn't the same...
         return false;
 
+   // Fallback to expensive canonical path computation
    return canonicalFilePath().compare(fileinfo.canonicalFilePath(), sensitive) == 0;
 }
 
diff --git a/tests/auto/qdir/tst_qdir.cpp b/tests/auto/qdir/tst_qdir.cpp
index 0a42a97..419eaae 100644
--- a/tests/auto/qdir/tst_qdir.cpp
+++ b/tests/auto/qdir/tst_qdir.cpp
@@ -444,9 +444,15 @@ void tst_QDir::QDir_default()
 void tst_QDir::compare()
 {
     // operator==
+
+    // Not using QCOMPARE to test result of QDir::operator==
+
     QDir dir;
     dir.makeAbsolute();
     QVERIFY(dir == QDir::currentPath());
+
+    QVERIFY(QDir() == QDir(QDir::currentPath()));
+    QVERIFY(QDir("../") == QDir(QDir::currentPath() + "/.."));
 }
 
 static QStringList filterLinks(const QStringList &list)