[widget] Require user interaction when picking files or folders v2

Now with extra sauce to make it work cross-platform and cross-versions and
for HTML input elements only.

2 files changed, 23 insertions, 4 deletions

diff --git a/widget/windows/nsFilePicker.cpp b/widget/windows/nsFilePicker.cpp
index 78656165d9..59ae152ec6 100644
--- a/widget/windows/nsFilePicker.cpp
+++ b/widget/windows/nsFilePicker.cpp
@@ -29,6 +29,7 @@
 #include "GeckoProfiler.h"
 
 using mozilla::IsWin8OrLater;
+using mozilla::IsWin10OrLater;
 using mozilla::MakeUnique;
 using mozilla::mscom::EnsureMTA;
 using mozilla::UniquePtr;
@@ -193,11 +194,13 @@ nsFilePicker::~nsFilePicker()
 
 NS_IMPL_ISUPPORTS(nsFilePicker, nsIFilePicker)
 
-NS_IMETHODIMP nsFilePicker::Init(mozIDOMWindowProxy *aParent, const nsAString& aTitle, int16_t aMode)
+NS_IMETHODIMP nsFilePicker::Init(mozIDOMWindowProxy *aParent, const nsAString& aTitle, int16_t aMode,
+                                 bool aRequireInteraction)
 {
   nsCOMPtr<nsPIDOMWindowOuter> window = do_QueryInterface(aParent);
   nsIDocShell* docShell = window ? window->GetDocShell() : nullptr;  
   mLoadContext = do_QueryInterface(docShell);
+  mRequireInteraction = aRequireInteraction;
   
   return nsBaseFilePicker::Init(aParent, aTitle, aMode);
 }
@@ -360,7 +363,14 @@ nsFilePicker::ShowFolderPicker(const nsString& aInitialDir)
   dialog->Advise(this, &mFDECookie);
 
   // options
-  FILEOPENDIALOGOPTIONS fos = FOS_PICKFOLDERS | FOS_OKBUTTONNEEDSINTERACTION;
+  FILEOPENDIALOGOPTIONS fos = FOS_PICKFOLDERS;
+  // Require interaction if the folder picker is triggered by an element that
+  // is potentially unsafe to use the default value in.
+  // Win 10+ only, because this dialog flag is broken in earlier versions.
+  if (IsWin10OrLater() && mRequireInteraction) {
+    fos |= FOS_OKBUTTONNEEDSINTERACTION;
+  }
+
   dialog->SetOptions(fos);
  
   // initial strings
@@ -459,7 +469,14 @@ nsFilePicker::ShowFilePicker(const nsString& aInitialDir)
 
   FILEOPENDIALOGOPTIONS fos = 0;
   fos |= FOS_SHAREAWARE | FOS_OVERWRITEPROMPT |
-         FOS_FORCEFILESYSTEM | FOS_OKBUTTONNEEDSINTERACTION;
+         FOS_FORCEFILESYSTEM;
+  
+  // Require interaction if the file picker is triggered by an element that
+  // is potentially unsafe to use the default value in.
+  // Win 10+ only, because this dialog flag is broken in earlier versions.
+  if (IsWin10OrLater() && mRequireInteraction) {
+    fos |= FOS_OKBUTTONNEEDSINTERACTION;
+  }
 
   // Handle add to recent docs settings
   if (IsPrivacyModeEnabled() || !mAddToRecentDocs) {
diff --git a/widget/windows/nsFilePicker.h b/widget/windows/nsFilePicker.h
index 740f07a7d8..7a3fbbe073 100644
--- a/widget/windows/nsFilePicker.h
+++ b/widget/windows/nsFilePicker.h
@@ -49,7 +49,8 @@ class nsFilePicker :
 public:
   nsFilePicker();
 
-  NS_IMETHOD Init(mozIDOMWindowProxy *aParent, const nsAString& aTitle, int16_t aMode);
+  NS_IMETHOD Init(mozIDOMWindowProxy *aParent, const nsAString& aTitle, int16_t aMode,
+                  bool aRequireInteraction = false);
 
   NS_DECL_ISUPPORTS
 
@@ -101,6 +102,7 @@ protected:
   nsString               mUnicodeFile;
   static char16_t      *mLastUsedUnicodeDirectory;
   HWND                   mDlgWnd;
+  bool                   mRequireInteraction;
 
   class ComDlgFilterSpec
   {