PDF: Interpret printing permission bits correctly.

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 4b279462043f0ec0d381973849d26b5f089a255a..3189c546a1177573c9eb4d1a41c37e4c16ed1ac5 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -592,6 +592,7 @@ PDFiumEngine::PDFiumEngine(PDFEngine::Client* client)
       last_page_to_search_(-1),
       last_character_index_to_search_(-1),
       permissions_(0),
+      permissions_handler_revision_(-1),
       fpdf_availability_(NULL),
       next_timer_id_(0),
       last_page_mouse_down_(-1),
@@ -2324,16 +2325,30 @@ bool PDFiumEngine::IsSelecting() {
 }
 
 bool PDFiumEngine::HasPermission(DocumentPermission permission) const {

[raymes, 2015/06/09 00:32:59]

Is it worth checking that this is not -1?

[Lei Zhang, 2015/06/09 00:39:41]

I'm interpreting -1 as unknown and treating it as "we are not respecting any
permission bits", so it fits with the < 2 comparison.

+  // PDF 1.7 spec, section 3.5.2 says: "If the revision number is 2 or greater,
+  // the operations to which user access can be controlled are as follows: ..."
+  //
+  // Thus for revision numbers less than 2, permissions are ignored and this
+  // always returns true.
+  if (permissions_handler_revision_ < 2)
+    return true;
+
+  // Handle high quality printing permission separately for security handler
+  // revision 3+.
+  if (permission == PERMISSION_PRINT_HIGH_QUALITY &&
+      permissions_handler_revision_ >= 3) {
+    return (permissions_ & kPDFPermissionPrintLowQualityMask) != 0 &&
+           (permissions_ & kPDFPermissionPrintHighQualityMask) != 0;
+  }
+
   switch (permission) {
     case PERMISSION_COPY:
       return (permissions_ & kPDFPermissionCopyMask) != 0;
     case PERMISSION_COPY_ACCESSIBLE:
       return (permissions_ & kPDFPermissionCopyAccessibleMask) != 0;
     case PERMISSION_PRINT_LOW_QUALITY:
-      return (permissions_ & kPDFPermissionPrintLowQualityMask) != 0;
     case PERMISSION_PRINT_HIGH_QUALITY:

[raymes, 2015/06/09 00:32:59]

So I guess that if the revision is <3 then you only need the low quality bit in
order to print at high quality? Is that true? It might be worth making a note of
that here and also above in the revision >=3 branch

[Lei Zhang, 2015/06/09 00:39:41]

Sure.

-      return (permissions_ & kPDFPermissionPrintLowQualityMask) != 0 &&
-             (permissions_ & kPDFPermissionPrintHighQualityMask) != 0;
+      return (permissions_ & kPDFPermissionPrintLowQualityMask) != 0;
     default:
       return true;
   }
@@ -2622,6 +2637,7 @@ void PDFiumEngine::ContinueLoadingDocument(
     client_->DocumentHasUnsupportedFeature("Bookmarks");
 
   permissions_ = FPDF_GetDocPermissions(doc_);
+  permissions_handler_revision_ = FPDF_GetSecurityHandlerRevision(doc_);
 
   if (!form_) {
     // Only returns 0 when data isn't available.  If form data is downloaded, or