Issue #1911 - Follow-up: Filter out illegal file extensions also.RC_20230317

We already did this for file names, just not extensions.

1 files changed, 5 insertions, 1 deletions

diff --git a/widget/windows/nsFilePicker.cpp b/widget/windows/nsFilePicker.cpp
index 3d733fcb7f..101eac6922 100644
--- a/widget/windows/nsFilePicker.cpp
+++ b/widget/windows/nsFilePicker.cpp
@@ -355,7 +355,11 @@ nsFilePicker::ShowFilePicker(const nsString& aInitialDir)
 
   // default extension to append to new files
   if (!mDefaultExtension.IsEmpty()) {
-    hr = dialog->SetDefaultExtension(mDefaultExtension.get());
+    // We don't want environment variables expanded in the extension either.
+    nsAutoString sanitizedExtension(mDefaultExtension);
+    sanitizedExtension.ReplaceChar('%', '_');
+
+    hr = dialog->SetDefaultExtension(sanitizedExtension.get());
     if (FAILED(hr)) {
       return false;
     }