Handle an empty or invalid documentDir correctly

Not specifying the documentDir, but enabling the installer would
- unexpectedly - use $PWD as documentDir. The code does now
follow the documentation: if not set, no document directories
will be created on package installation.

Also, we now fail early if the documentDir and installationDir
are sub-directories of each other, as that would lead to mayhem
on PackageManager::cleanupBrokenInstallations().

Change-Id: Id8d89f82bf0d63c771f3d86a963c66681f43f195
Fixes: QTBUG-101881
Pick-to: 6.3 6.2 5.15
Reviewed-by: Bernd Weimer <bernd.weimer@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main-lib/main.cpp b/src/main-lib/main.cpp
index 323431aa..a0140294 100644
--- a/src/main-lib/main.cpp
+++ b/src/main-lib/main.cpp
@@ -491,6 +491,15 @@ void Main::setupInstaller(bool devMode, bool allowUnsigned, const QStringList &c
                                     "even automatically switching to C.UTF-8 or en_US.UTF-8 failed.";
     }
 
+    // make sure the installation and document dirs are valid
+    Q_ASSERT(!m_installationDir.isEmpty());
+    const auto instPath = QDir(m_installationDir).canonicalPath();
+    const auto docPath = m_documentDir.isEmpty() ? QString { }
+                                                 : QDir(m_documentDir).canonicalPath();
+
+    if (!docPath.isEmpty() && (instPath.startsWith(docPath) || docPath.startsWith(instPath)))
+        throw Exception("either installationDir or documentDir cannot be a sub-directory of the other");
+
     // we only output these deployment warnings, if we are on embedded, applicationUserIdSeparation
     // is enabled and either...
     if (isRunningOnEmbedded() && userIdSeparation && userIdSeparation(nullptr, nullptr, nullptr)) {