Fix null crash in CheckTrailer.

We are making checks in the incorrect order.  Also adds two test
cases, one for the this crash, and another for the original issue
that motivated the patch.

Original Patch by Bo at https://codereview.chromium.org/866003003/

BUG=450871
R=bo_xu@foxitsoftware.com

Review URL: https://codereview.chromium.org/872563002

1 files changed, 23 insertions, 0 deletions

diff --git a/fpdfsdk/src/fpdf_dataavail_unittest.cpp b/fpdfsdk/src/fpdf_dataavail_unittest.cpp
new file mode 100644
index 0000000000..6081fa52ac
--- /dev/null
+++ b/fpdfsdk/src/fpdf_dataavail_unittest.cpp
@@ -0,0 +1,23 @@
+// Copyright 2015 PDFium 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 "../../testing/embedder_test.h"
+#include "../../fpdfsdk/include/fpdfview.h"
+#include "../../fpdfsdk/include/fpdfdoc.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class FPDFDataAvailEmbeddertest : public EmbedderTest {
+};
+
+TEST_F(FPDFDataAvailEmbeddertest, TrailerUnterminated) {
+  // Document must open without crashing but is too malformed to be available.
+  EXPECT_TRUE(OpenDocument("testing/resources/trailer_unterminated.pdf"));
+  EXPECT_FALSE(FPDFAvail_IsDocAvail(avail_, &hints_));
+}
+
+TEST_F(FPDFDataAvailEmbeddertest, TrailerAsHexstring) {
+  // Document must open without crashing but is too malformed to be available.
+  EXPECT_TRUE(OpenDocument("testing/resources/trailer_as_hexstring.pdf"));
+  EXPECT_FALSE(FPDFAvail_IsDocAvail(avail_, &hints_));
+}