PDF: Always call FPDFAvail_IsDocAvail() when loading.

pdf/pdfium/pdfium_engine.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "pdf/pdfium/pdfium_engine.h"
 
 #include <math.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 280 matching lines @@
   EnumFonts,
   MapFont,
   0,
   GetFontData,
   0,
   0,
   DeleteFont
 };
 #endif  // defined(OS_LINUX)
 
-PDFiumEngine* g_engine_for_unsupported;
+PDFiumEngine* g_engine_for_unsupported = nullptr;
 
 void Unsupported_Handler(UNSUPPORT_INFO*, int type) {
   if (!g_engine_for_unsupported) {
     NOTREACHED();
     return;
   }
 
   g_engine_for_unsupported->UnsupportedFeature(type);
 }
 
@@ skipping 2072 matching lines @@
   }
 
   CalculateVisiblePages();
   if (document_size_ != old_document_size)
     client_->DocumentSizeUpdated(document_size_);
 }
 
 void PDFiumEngine::LoadDocument() {
   // Check if the document is ready for loading. If it isn't just bail for now,
   // we will call LoadDocument() again later.
-  if (!doc_ && !doc_loader_.IsDocumentComplete() &&
-      !FPDFAvail_IsDocAvail(fpdf_availability_, &download_hints_)) {

[Wei Li, 2016/05/24 00:21:27]

Should these conditions be ORed instead?

[Lei Zhang, 2016/05/25 17:16:36]

No, we have to continue past this point to turn |doc_| non-NULL. If it's ORed,
then this if statement always evals to false. Basically it's "we are looking for
a reason to try to load the document" so only return early if no such reason
exists.

+  if (!doc_ && !doc_loader_.IsDocumentComplete())
     return;
-  }
+
+ // Always call FPDFAvail_IsDocAvail() so PDFium initializes internal data
+ // structures.
+  if (!FPDFAvail_IsDocAvail(fpdf_availability_, &download_hints_))
+    return;
 
   // If we're in the middle of getting a password, just return. We will retry
   // loading the document after we get the password anyway.
   if (getting_password_)
     return;
 
   ScopedUnsupportedFeature scoped_unsupported_feature(this);
   bool needs_password = false;
   if (TryLoadingDoc(false, std::string(), &needs_password)) {
     ContinueLoadingDocument(false, std::string());
@@ skipping 1469 matching lines @@
   FPDF_DOCUMENT doc =
       FPDF_LoadMemDocument(pdf_buffer, pdf_buffer_size, nullptr);
   if (!doc)
     return false;
   bool success = FPDF_GetPageSizeByIndex(doc, page_number, width, height) != 0;
   FPDF_CloseDocument(doc);
   return success;
 }
 
 }  // namespace chrome_pdf