2 files changed, 64 insertions, 34 deletions

diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index 1b908eac55..96829b3b03 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -556,45 +556,75 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
     return data.hasFlags(what);
 }
 
+// Note: if \a shouldMkdirFirst is false, we assume the caller did try to mkdir
+// before calling this function.
+static bool createDirectoryWithParents(const QByteArray &nativeName, bool shouldMkdirFirst = true)
+{
+    // helper function to check if a given path is a directory, since mkdir can
+    // fail if the dir already exists (it may have been created by another
+    // thread or another process)
+    const auto isDir = [](const QByteArray &nativeName) {
+        QT_STATBUF st;
+        return QT_STAT(nativeName.constData(), &st) == 0 && (st.st_mode & S_IFMT) == S_IFDIR;
+    };
+
+    if (shouldMkdirFirst && QT_MKDIR(nativeName, 0777) == 0)
+        return true;
+    if (errno == EEXIST)
+        return isDir(nativeName);
+    if (errno != ENOENT)
+        return false;
+
+    // mkdir failed because the parent dir doesn't exist, so try to create it
+    int slash = nativeName.lastIndexOf('/');
+    if (slash < 1)
+        return false;
+
+    QByteArray parentNativeName = nativeName.left(slash);
+    if (!createDirectoryWithParents(parentNativeName))
+        return false;
+
+    // try again
+    if (QT_MKDIR(nativeName, 0777) == 0)
+        return true;
+    return errno == EEXIST && isDir(nativeName);
+}
+
 //static
 bool QFileSystemEngine::createDirectory(const QFileSystemEntry &entry, bool createParents)
 {
     QString dirName = entry.filePath();
-    if (createParents) {
-        dirName = QDir::cleanPath(dirName);
-        for (int oldslash = -1, slash=0; slash != -1; oldslash = slash) {
-            slash = dirName.indexOf(QDir::separator(), oldslash+1);
-            if (slash == -1) {
-                if (oldslash == dirName.length())
-                    break;
-                slash = dirName.length();
-            }
-            if (slash) {
-                const QByteArray chunk = QFile::encodeName(dirName.left(slash));
-                if (QT_MKDIR(chunk.constData(), 0777) != 0) {
-                    if (errno == EEXIST
-#if defined(Q_OS_QNX)
-                        // On QNX the QNet (VFS paths of other hosts mounted under a directory
-                        // such as /net) mountpoint returns ENOENT, despite existing. stat()
-                        // on the QNet mountpoint returns successfully and reports S_IFDIR.
-                        || errno == ENOENT
-#endif
-                    ) {
-                        QT_STATBUF st;
-                        if (QT_STAT(chunk.constData(), &st) == 0 && (st.st_mode & S_IFMT) == S_IFDIR)
-                            continue;
-                    }
-                    return false;
-                }
-            }
-        }
+
+    // Darwin doesn't support trailing /'s, so remove for everyone
+    while (dirName.size() > 1 && dirName.endsWith(QLatin1Char('/')))
+        dirName.chop(1);
+
+    // try to mkdir this directory
+    QByteArray nativeName = QFile::encodeName(dirName);
+    if (QT_MKDIR(nativeName, 0777) == 0)
         return true;
+    if (!createParents)
+        return false;
+
+    // we need the cleaned path in order to create the parents
+    // and we save errno just in case encodeName needs to load codecs
+    int savedErrno = errno;
+    bool pathChanged;
+    {
+        QString cleanName = QDir::cleanPath(dirName);
+
+        // Check if the cleaned name is the same or not. If we were given a
+        // path with resolvable "../" sections, cleanPath will remove them, but
+        // this may change the target dir if one of those segments was a
+        // symlink. This operation depends on cleanPath's optimization of
+        // returning the original string if it didn't modify anything.
+        pathChanged = !dirName.isSharedWith(cleanName);
+        if (pathChanged)
+            nativeName = QFile::encodeName(cleanName);
     }
-#if defined(Q_OS_DARWIN)  // Mac X doesn't support trailing /'s
-    if (dirName.endsWith(QLatin1Char('/')))
-        dirName.chop(1);
-#endif
-    return (QT_MKDIR(QFile::encodeName(dirName).constData(), 0777) == 0);
+
+    errno = savedErrno;
+    return createDirectoryWithParents(nativeName, pathChanged);
 }
 
 //static
diff --git a/tests/auto/corelib/io/qdir/tst_qdir.cpp b/tests/auto/corelib/io/qdir/tst_qdir.cpp
index b86c6e4dfa..c3774997e9 100644
--- a/tests/auto/corelib/io/qdir/tst_qdir.cpp
+++ b/tests/auto/corelib/io/qdir/tst_qdir.cpp
@@ -350,7 +350,7 @@ void tst_QDir::mkdir_data()
          << QDir::currentPath() + "/testdir/two/three";
     QTest::newRow("data0") << dirs.at(0) << true;
     QTest::newRow("data1") << dirs.at(1) << false;
-    QTest::newRow("data2") << dirs.at(2) << false;
+    QTest::newRow("data2") << dirs.at(2) << false; // note: requires data1 to have been run!
 
     // Ensure that none of these directories already exist
     QDir dir;