Fix two CloneNonCycle issues

CloneNonCycle() tries to detect cyclic object references without copying
them. There are two issues:
-- for elements in an array or a dictionary, they should be able to
refer to the same object, which are not cyclic;
-- for cyclic referenced elements in an array or a dictionary, do not
clone the element at all. Having nullptr or <key, nullptr> as an element,
like we did before, might cause crash when the element being accessed.

BUG=chromium:701860

Change-Id: Id0304accde76ed06fa5ce640994c7628359600fb
Reviewed-on: https://pdfium-review.googlesource.com/3156
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 38 insertions, 2 deletions

diff --git a/fpdfsdk/fpdfppo_embeddertest.cpp b/fpdfsdk/fpdfppo_embeddertest.cpp
index 0972316534..db39700ca1 100644
--- a/fpdfsdk/fpdfppo_embeddertest.cpp
+++ b/fpdfsdk/fpdfppo_embeddertest.cpp
@@ -15,6 +15,12 @@ namespace {
 
 class FPDFPPOEmbeddertest : public EmbedderTest {};
 
+int FakeBlockWriter(FPDF_FILEWRITE* pThis,
+                    const void* pData,
+                    unsigned long size) {
+  return size;
+}
+
 }  // namespace
 
 TEST_F(FPDFPPOEmbeddertest, NoViewerPreferences) {
@@ -36,13 +42,13 @@ TEST_F(FPDFPPOEmbeddertest, ViewerPreferences) {
 }
 
 TEST_F(FPDFPPOEmbeddertest, ImportPages) {
-  EXPECT_TRUE(OpenDocument("viewer_ref.pdf"));
+  ASSERT_TRUE(OpenDocument("viewer_ref.pdf"));
 
   FPDF_PAGE page = LoadPage(0);
   EXPECT_TRUE(page);
 
   FPDF_DOCUMENT output_doc = FPDF_CreateNewDocument();
-  EXPECT_TRUE(output_doc);
+  ASSERT_TRUE(output_doc);
   EXPECT_TRUE(FPDF_CopyViewerPreferences(output_doc, document()));
   EXPECT_TRUE(FPDF_ImportPages(output_doc, document(), "1", 0));
   EXPECT_EQ(1, FPDF_GetPageCount(output_doc));
@@ -51,6 +57,36 @@ TEST_F(FPDFPPOEmbeddertest, ImportPages) {
   UnloadPage(page);
 }
 
+TEST_F(FPDFPPOEmbeddertest, BadRepeatViewerPref) {
+  ASSERT_TRUE(OpenDocument("repeat_viewer_ref.pdf"));
+
+  FPDF_DOCUMENT output_doc = FPDF_CreateNewDocument();
+  EXPECT_TRUE(output_doc);
+  EXPECT_TRUE(FPDF_CopyViewerPreferences(output_doc, document()));
+
+  FPDF_FILEWRITE writer;
+  writer.version = 1;
+  writer.WriteBlock = FakeBlockWriter;
+
+  EXPECT_TRUE(FPDF_SaveAsCopy(output_doc, &writer, 0));
+  FPDF_CloseDocument(output_doc);
+}
+
+TEST_F(FPDFPPOEmbeddertest, BadCircularViewerPref) {
+  ASSERT_TRUE(OpenDocument("circular_viewer_ref.pdf"));
+
+  FPDF_DOCUMENT output_doc = FPDF_CreateNewDocument();
+  EXPECT_TRUE(output_doc);
+  EXPECT_TRUE(FPDF_CopyViewerPreferences(output_doc, document()));
+
+  FPDF_FILEWRITE writer;
+  writer.version = 1;
+  writer.WriteBlock = FakeBlockWriter;
+
+  EXPECT_TRUE(FPDF_SaveAsCopy(output_doc, &writer, 0));
+  FPDF_CloseDocument(output_doc);
+}
+
 TEST_F(FPDFPPOEmbeddertest, BadRanges) {
   EXPECT_TRUE(OpenDocument("viewer_ref.pdf"));