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>

4 files changed, 66 insertions, 3 deletions

diff --git a/xfa/fgas/layout/cfx_break.h b/xfa/fgas/layout/cfx_break.h
index 7356cff3ba..cc985b7c59 100644
--- a/xfa/fgas/layout/cfx_break.h
+++ b/xfa/fgas/layout/cfx_break.h
@@ -57,6 +57,7 @@ class CFX_Break {
   void ClearBreakPieces();
 
   CFX_Char* GetLastChar(int32_t index, bool bOmitChar, bool bRichText) const;
+  const CFX_BreakLine* GetCurrentLineForTesting() const { return m_pCurLine; }
 
  protected:
   explicit CFX_Break(uint32_t dwLayoutStyles);
diff --git a/xfa/fgas/layout/cfx_rtfbreak.h b/xfa/fgas/layout/cfx_rtfbreak.h
index 3f302ca7a8..c2320fab7f 100644
--- a/xfa/fgas/layout/cfx_rtfbreak.h
+++ b/xfa/fgas/layout/cfx_rtfbreak.h
@@ -63,8 +63,6 @@ class CFX_RTFBreak : public CFX_Break {
 
   CFX_BreakType AppendChar(wchar_t wch);
 
-  CFX_BreakLine* GetCurrentLineForTesting() const { return m_pCurLine; }
-
  private:
   void AppendChar_Combination(CFX_Char* pCurChar);
   void AppendChar_Tab(CFX_Char* pCurChar);
diff --git a/xfa/fgas/layout/cfx_rtfbreak_unittest.cpp b/xfa/fgas/layout/cfx_rtfbreak_unittest.cpp
index 5f24631315..6a0cd3f187 100644
--- a/xfa/fgas/layout/cfx_rtfbreak_unittest.cpp
+++ b/xfa/fgas/layout/cfx_rtfbreak_unittest.cpp
@@ -7,7 +7,10 @@
 #include "xfa/fgas/layout/cfx_rtfbreak.h"
 
 #include <memory>
+#include <utility>
 
+#include "core/fxcrt/fx_bidi.h"
+#include "core/fxge/cfx_font.h"
 #include "core/fxge/cfx_gemodule.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
@@ -20,7 +23,7 @@ class CFX_RTFBreakTest : public testing::Test {
   void SetUp() override {
     font_ =
         CFGAS_GEFont::LoadFont(L"Arial Black", 0, 0, GetGlobalFontManager());
-    ASSERT(font_.Get() != nullptr);
+    ASSERT(font_.Get());
   }
 
   std::unique_ptr<CFX_RTFBreak> CreateBreak(int32_t args) {
@@ -72,3 +75,17 @@ TEST_F(CFX_RTFBreakTest, ControlCharacters) {
   ASSERT_EQ(1, b->CountBreakPieces());
   EXPECT_EQ(L"\v", b->GetBreakPieceUnstable(0)->GetString());
 }
+
+TEST_F(CFX_RTFBreakTest, BidiLine) {
+  auto rtf_break = CreateBreak(FX_LAYOUTSTYLE_ExpandTab);
+  rtf_break->SetLineBreakTolerance(1);
+  rtf_break->SetFontSize(12);
+
+  WideString input = WideString::FromUTF8(ByteStringView("\xa\x0\xa\xa", 4));
+  for (auto& ch : input)
+    rtf_break->AppendChar(ch);
+
+  auto chars = rtf_break->GetCurrentLineForTesting()->m_LineChars;
+  FX_BidiLine(&chars, chars.size());
+  EXPECT_EQ(3u, chars.size());
+}
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());
+}