Fix comparison of absolute, unclean paths in QDir

QDir::operator== was creating a clean absolute path for comparison
purposes if the original path was relative.
However original absolute paths were trusted, even though they could
be unclean. Now they are checked for cleanliness first.

Task-Number: QTBUG-19995
Task-Number: QTBUG-20495
Change-Id: I047a1a40ae5151e4604085e4ac87f30a4e4979c4
Reviewed-on: http://codereview.qt.nokia.com/4099
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Prasanth Ullattil <prasanth.ullattil@nokia.com>

3 files changed, 33 insertions, 1 deletions

diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index c0c62e1..3271148 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -198,7 +198,7 @@ inline void QDirPrivate::resolveAbsoluteEntry() const
 
     QString absoluteName;
     if (fileEngine.isNull()) {
-        if (!dirEntry.isRelative()) {
+        if (!dirEntry.isRelative() && dirEntry.isClean()) {
             absoluteDirEntry = dirEntry;
             return;
         }
diff --git a/src/corelib/io/qfilesystementry.cpp b/src/corelib/io/qfilesystementry.cpp
index bb7cb4e..2f37542 100644
--- a/src/corelib/io/qfilesystementry.cpp
+++ b/src/corelib/io/qfilesystementry.cpp
@@ -380,4 +380,35 @@ void QFileSystemEntry::findFileNameSeparators() const
     }
 }
 
+bool QFileSystemEntry::isClean() const
+{
+    resolveFilePath();
+    int dots = 0;
+    bool dotok = true; // checking for ".." or "." starts to relative paths
+    bool slashok = true;
+    for (QString::const_iterator iter = m_filePath.constBegin(); iter != m_filePath.constEnd(); iter++) {
+        if (*iter == QLatin1Char('/')) {
+            if (dots == 1 || dots == 2)
+                return false; // path contains "./" or "../"
+            if (!slashok)
+                return false; // path contains "//"
+            dots = 0;
+            dotok = true;
+            slashok = false;
+        } else if (dotok) {
+            slashok = true;
+            if (*iter == QLatin1Char('.')) {
+                dots++;
+                if (dots > 2)
+                    dotok = false;
+            } else {
+                //path element contains a character other than '.', it's clean
+                dots = 0;
+                dotok = false;
+            }
+        }
+    }
+    return (dots != 1 && dots != 2); // clean if path doesn't end in . or ..
+}
+
 QT_END_NAMESPACE
diff --git a/src/corelib/io/qfilesystementry_p.h b/src/corelib/io/qfilesystementry_p.h
index 34b083a..8d524c0 100644
--- a/src/corelib/io/qfilesystementry_p.h
+++ b/src/corelib/io/qfilesystementry_p.h
@@ -91,6 +91,7 @@ public:
     QString completeSuffix() const;
     bool isAbsolute() const;
     bool isRelative() const;
+    bool isClean() const;
 
 #if defined(Q_OS_WIN) || defined(Q_OS_SYMBIAN)
     bool isDriveRoot() const;