Do not load main cross refs for first page in linearized pdf.

fpdfsdk/fpdf_dataavail_embeddertest.cpp

Index: fpdfsdk/fpdf_dataavail_embeddertest.cpp
diff --git a/fpdfsdk/fpdf_dataavail_embeddertest.cpp b/fpdfsdk/fpdf_dataavail_embeddertest.cpp
index 47ba54bcdeb3891a76c9c29bbb9113b19308cc45..36627e8fdab73f717e32fe75da9cf86de2fe0634 100644
--- a/fpdfsdk/fpdf_dataavail_embeddertest.cpp
+++ b/fpdfsdk/fpdf_dataavail_embeddertest.cpp
@@ -45,13 +45,22 @@ class TestAsyncLoader : public FX_DOWNLOADHINTS, FX_FILEAVAIL {
     return requested_segments_;
   }
 
-  void ClearRequestedSegments() { requested_segments_.clear(); }
+  size_t max_requested_bound() const { return max_requested_bound_; }
+
+  void ClearRequestedSegments() {
+    requested_segments_.clear();
+    max_requested_bound_ = 0;
+  }
 
   bool is_new_data_available() const { return is_new_data_available_; }
   void set_is_new_data_available(bool is_new_data_available) {
     is_new_data_available_ = is_new_data_available;
   }
 
+  size_t max_already_available_bound() const {
+    return available_ranges_.empty() ? 0 : available_ranges_.rbegin()->second;
+  }
+
  private:
   void SetDataAvailable(size_t start, size_t size) {
     if (size == 0)
@@ -109,6 +118,7 @@ class TestAsyncLoader : public FX_DOWNLOADHINTS, FX_FILEAVAIL {
 
   void AddSegmentImpl(size_t offset, size_t size) {
     requested_segments_.push_back(std::make_pair(offset, size));
+    max_requested_bound_ = std::max(max_requested_bound_, offset + size);
   }
 
   bool IsDataAvailImpl(size_t offset, size_t size) {
@@ -143,6 +153,7 @@ class TestAsyncLoader : public FX_DOWNLOADHINTS, FX_FILEAVAIL {
   std::unique_ptr<char, pdfium::FreeDeleter> file_contents_;
   size_t file_length_;
   std::vector<std::pair<size_t, size_t>> requested_segments_;
+  size_t max_requested_bound_ = 0;
   bool is_new_data_available_ = true;
 
   using Range = std::pair<size_t, size_t>;
@@ -185,3 +196,42 @@ TEST_F(FPDFDataAvailEmbeddertest, LoadUsingHintTables) {
   EXPECT_TRUE(page);
   UnloadPage(page);
 }
+
+TEST_F(FPDFDataAvailEmbeddertest,
+       DoNotLoadMainCrossRefForFirstPageIfLinearized) {
+  TestAsyncLoader loader("feature_linearized_loading.pdf");
+  avail_ = FPDFAvail_Create(loader.file_avail(), loader.file_access());
+  ASSERT_EQ(PDF_DATA_AVAIL, FPDFAvail_IsDocAvail(avail_, loader.hints()));
+  document_ = FPDFAvail_GetDocument(avail_, nullptr);
+  ASSERT_TRUE(document_);
+  const int first_page_num = FPDFAvail_GetFirstPageNum(document_);

[Lei Zhang, 2016/11/09 08:51:12]

Might as well check the result since we have it?

[snake, 2016/11/09 12:41:49]

We always should have it. For this test is not matter, what value of this.

+
+  // The main cross ref table should not be processed.
+  // (It is always at file end)
+  EXPECT_GT(loader.file_access()->m_FileLen,
+            loader.max_already_available_bound());
+
+  // No new data available, to took the download request.

[Lei Zhang, 2016/11/09 08:51:12]

"to took the download request" doesn't parse.

[snake, 2016/11/09 12:41:49]

Done.

+  loader.set_is_new_data_available(false);
+  FPDFAvail_IsPageAvail(avail_, first_page_num, loader.hints());

[Lei Zhang, 2016/11/09 08:51:12]

Do you care about the return value?

[snake, 2016/11/09 12:41:49]

No. For first call this is not matter. (Currently the first page availability is
checked as part of document availability check, and on first call it is already
available, but this can be changed in future and not related to this test). But
on second call it is should be available always (in this test case).

+
+  // The main cross ref table should not be requested.
+  // (It is always at file end)
+  EXPECT_GT(loader.file_access()->m_FileLen, loader.max_requested_bound());
+
+  // Allow parse page.
+  loader.set_is_new_data_available(true);
+  ASSERT_EQ(PDF_DATA_AVAIL,
+            FPDFAvail_IsPageAvail(avail_, first_page_num, loader.hints()));
+
+  // The main cross ref table should not be processed.
+  // (It is always at file end)
+  EXPECT_GT(loader.file_access()->m_FileLen,
+            loader.max_already_available_bound());
+
+  // Prevent loading data, while page loading.
+  loader.set_is_new_data_available(false);
+  FPDF_PAGE page = LoadPage(first_page_num);
+  EXPECT_TRUE(page);
+  UnloadPage(page);
+}