Fixup ASSERT in Bidi handling; Add bidi fuzzer.

This CL converts several asserts in the FX_Bidi code to continue instead
of asserting in the face of unexpected input.

A BIDI fuzzer has been added as well.

Bug: chromium:839695
Change-Id: If61f822bde7442c008d50be58f7cecffb6e5d658
Reviewed-on: https://pdfium-review.googlesource.com/32191
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/xfa/fgas/layout/cfx_txtbreak_unittest.cpp b/xfa/fgas/layout/cfx_txtbreak_unittest.cpp
new file mode 100644
index 0000000000..8cac2fa036
--- /dev/null
+++ b/xfa/fgas/layout/cfx_txtbreak_unittest.cpp
@@ -0,0 +1,47 @@
+// Copyright 2018 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 "xfa/fgas/layout/cfx_txtbreak.h"
+
+#include <utility>
+
+#include "core/fxcrt/fx_bidi.h"
+#include "core/fxge/cfx_font.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/test_support.h"
+#include "third_party/base/ptr_util.h"
+#include "xfa/fgas/font/cfgas_fontmgr.h"
+#include "xfa/fgas/font/cfgas_gefont.h"
+
+class CFX_TxtBreakTest : public testing::Test {
+ public:
+  void SetUp() override {
+    font_ =
+        CFGAS_GEFont::LoadFont(L"Arial Black", 0, 0, GetGlobalFontManager());
+    ASSERT(font_.Get());
+  }
+
+  std::unique_ptr<CFX_TxtBreak> CreateBreak() {
+    auto b = pdfium::MakeUnique<CFX_TxtBreak>();
+    b->SetFont(font_);
+    return b;
+  }
+
+ private:
+  RetainPtr<CFGAS_GEFont> font_;
+};
+
+TEST_F(CFX_TxtBreakTest, BidiLine) {
+  auto txt_break = CreateBreak();
+  txt_break->SetLineBreakTolerance(1);
+  txt_break->SetFontSize(12);
+
+  WideString input = WideString::FromUTF8(ByteStringView("\xa\x0\xa\xa", 4));
+  for (auto& ch : input)
+    txt_break->AppendChar(ch);
+
+  auto chars = txt_break->GetCurrentLineForTesting()->m_LineChars;
+  FX_BidiLine(&chars, chars.size());
+  EXPECT_EQ(3u, chars.size());
+}