Set correct stream index when parsing is done in several steps.

When parsing happens in several steps (in pages with > 100 page
objects), the position is reset to 0 and the start pointer is
advanced. This breaks the calculation of which stream an object
belongs to.

Passing in the base pointer separately from the start offset allows
the correct position to be calculated and the correct stream to be
identified.

Change-Id: Ic0d5f59f437609158aa97b3c8a18dbd48cd3b0d4
Reviewed-on: https://pdfium-review.googlesource.com/42270
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

1 files changed, 74 insertions, 0 deletions

diff --git a/fpdfsdk/fpdf_edit_embeddertest.cpp b/fpdfsdk/fpdf_edit_embeddertest.cpp
index 47c8f8b394..3d10ba06d9 100644
--- a/fpdfsdk/fpdf_edit_embeddertest.cpp
+++ b/fpdfsdk/fpdf_edit_embeddertest.cpp
@@ -1450,6 +1450,80 @@ TEST_F(FPDFEditEmbeddertest, InsertPageObjectEditAndSave) {
   CloseSavedDocument();
 }
 
+TEST_F(FPDFEditEmbeddertest, InsertAndRemoveLargeFile) {
+  const int kOriginalObjectCount = 600;
+
+  // Load document with many objects.
+  EXPECT_TRUE(OpenDocument("many_rectangles.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+  const char kOriginalMD5[] = "b0170c575b65ecb93ebafada0ff0f038";
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 300, kOriginalMD5);
+  }
+
+  // Add a black rectangle.
+  ASSERT_EQ(kOriginalObjectCount, FPDFPage_CountObjects(page));
+  FPDF_PAGEOBJECT black_rect = FPDFPageObj_CreateNewRect(20, 100, 50, 50);
+  EXPECT_TRUE(FPDFPath_SetFillColor(black_rect, 0, 0, 0, 255));
+  EXPECT_TRUE(FPDFPath_SetDrawMode(black_rect, FPDF_FILLMODE_ALTERNATE, 0));
+  FPDFPage_InsertObject(page, black_rect);
+
+  // Verify the black rectangle was added.
+  ASSERT_EQ(kOriginalObjectCount + 1, FPDFPage_CountObjects(page));
+  const char kPlusRectangleMD5[] = "6b9396ab570754b32b04ca629e902f77";
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 300, kPlusRectangleMD5);
+  }
+
+  // Save the file.
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the rectangle added is still there.
+  OpenSavedDocument(nullptr);
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+  EXPECT_EQ(kOriginalObjectCount + 1, FPDFPage_CountObjects(saved_page));
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 300, kPlusRectangleMD5);
+  }
+
+  // Remove the added rectangle.
+  FPDF_PAGEOBJECT added_object =
+      FPDFPage_GetObject(saved_page, kOriginalObjectCount);
+  EXPECT_TRUE(FPDFPage_RemoveObject(saved_page, added_object));
+  FPDFPageObj_Destroy(added_object);
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 300, kOriginalMD5);
+  }
+  EXPECT_EQ(kOriginalObjectCount, FPDFPage_CountObjects(saved_page));
+
+  // Save the file again.
+  EXPECT_TRUE(FPDFPage_GenerateContent(saved_page));
+  EXPECT_TRUE(FPDF_SaveAsCopy(saved_document_, this, 0));
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+
+  // Re-open the file (again) and check the black rectangle was removed and the
+  // rest is intact.
+  OpenSavedDocument(nullptr);
+  saved_page = LoadSavedPage(0);
+  EXPECT_EQ(kOriginalObjectCount, FPDFPage_CountObjects(saved_page));
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 300, kOriginalMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
 TEST_F(FPDFEditEmbeddertest, AddAndRemovePaths) {
   // Start with a blank page.
   FPDF_PAGE page = FPDFPage_New(CreateNewDocument(), 0, 612, 792);