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
(cherry-picked from dcee6e1371d899eb79717b8e3f3eec08b765db82)

Change-Id: Ib5f2a6ee11311c55782ea5dd0e9c3b45f9231686
Reviewed-on: http://codereview.qt-project.org/5812
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

2 files changed, 4 insertions, 3 deletions

diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index 9faa9f17b3..0c7050095d 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -1599,9 +1599,9 @@ 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 c83c39195a..b560a81ac5 100644
--- a/src/corelib/io/qfileinfo.cpp
+++ b/src/corelib/io/qfileinfo.cpp
@@ -418,6 +418,7 @@ 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;
 }