[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.

7 files changed, 33 insertions, 9 deletions

diff --git a/widget/nsBaseFilePicker.cpp b/widget/nsBaseFilePicker.cpp
index d65ffb651a..1bcd78b462 100644
--- a/widget/nsBaseFilePicker.cpp
+++ b/widget/nsBaseFilePicker.cpp
@@ -166,7 +166,8 @@ nsBaseFilePicker::~nsBaseFilePicker()
 
 NS_IMETHODIMP nsBaseFilePicker::Init(mozIDOMWindowProxy* aParent,
                                      const nsAString& aTitle,
-                                     int16_t aMode)
+                                     int16_t aMode,
+                                     bool aRequireInteraction)
 {
   NS_PRECONDITION(aParent, "Null parent passed to filepicker, no file "
                   "picker for you!");
diff --git a/widget/nsBaseFilePicker.h b/widget/nsBaseFilePicker.h
index 56ca5acc8d..c0a197e263 100644
--- a/widget/nsBaseFilePicker.h
+++ b/widget/nsBaseFilePicker.h
@@ -25,7 +25,8 @@ public:
 
   NS_IMETHOD Init(mozIDOMWindowProxy* aParent,
                   const nsAString& aTitle,
-                  int16_t aMode);
+                  int16_t aMode,
+                  bool aRequireInteraction = false);
 
   NS_IMETHOD Open(nsIFilePickerShownCallback *aCallback);
   NS_IMETHOD AppendFilters(int32_t filterMask);
diff --git a/widget/nsFilePickerProxy.cpp b/widget/nsFilePickerProxy.cpp
index 8828c416e9..077168c455 100644
--- a/widget/nsFilePickerProxy.cpp
+++ b/widget/nsFilePickerProxy.cpp
@@ -27,7 +27,7 @@ nsFilePickerProxy::~nsFilePickerProxy()
 
 NS_IMETHODIMP
 nsFilePickerProxy::Init(mozIDOMWindowProxy* aParent, const nsAString& aTitle,
-                        int16_t aMode)
+                        int16_t aMode, bool aRequireInteraction)
 {
   TabChild* tabChild = TabChild::GetFrom(aParent);
   if (!tabChild) {
diff --git a/widget/nsFilePickerProxy.h b/widget/nsFilePickerProxy.h
index fbffb93dee..62d343d72f 100644
--- a/widget/nsFilePickerProxy.h
+++ b/widget/nsFilePickerProxy.h
@@ -34,7 +34,7 @@ public:
     NS_DECL_ISUPPORTS
 
     // nsIFilePicker (less what's in nsBaseFilePicker)
-    NS_IMETHOD Init(mozIDOMWindowProxy* aParent, const nsAString& aTitle, int16_t aMode) override;
+    NS_IMETHOD Init(mozIDOMWindowProxy* aParent, const nsAString& aTitle, int16_t aMode, bool aRequireInteraction = false) override;
     NS_IMETHOD AppendFilter(const nsAString& aTitle, const nsAString& aFilter) override;
     NS_IMETHOD GetDefaultString(nsAString& aDefaultString) override;
     NS_IMETHOD SetDefaultString(const nsAString& aDefaultString) override;
diff --git a/widget/nsIFilePicker.idl b/widget/nsIFilePicker.idl
index 62efe93ecf..8de69c56e9 100644
--- a/widget/nsIFilePicker.idl
+++ b/widget/nsIFilePicker.idl
@@ -66,9 +66,12 @@ interface nsIFilePicker : nsISupports
   *                      on this parent. parent must be non-null.
   * @param      title    The title for the file widget
   * @param      mode     load, save, or get folder
+  * @param      requireinteraction (optional)
+  *                      require interaction before confirmation is possible
   *
   */
-  void init(in mozIDOMWindowProxy parent, in AString title, in short mode);
+  void init(in mozIDOMWindowProxy parent, in AString title, in short mode,
+            [optional] in boolean requireinteraction);
 
  /**
   * Append to the  filter list with things from the predefined list
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
   {