Split CFDE_CSSTextBuf in two.

For the external buffer use case, use a CFDE_CSSExtTextBuf instead. With
the split, both text buffer implementations are simpler now. As a
result, it becomes obvious where it never fails. Adjust callers
accordingly.

Change-Id: I7b53d36593172487b8c939e6a55af2437ea4ee5a
Reviewed-on: https://pdfium-review.googlesource.com/6932
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

10 files changed, 99 insertions, 123 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 5b64e0408e..34b032fd89 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1451,6 +1451,8 @@ if (pdf_enable_xfa) {
       "xfa/fde/css/cfde_cssdeclaration.h",
       "xfa/fde/css/cfde_cssenumvalue.cpp",
       "xfa/fde/css/cfde_cssenumvalue.h",
+      "xfa/fde/css/cfde_cssexttextbuf.cpp",
+      "xfa/fde/css/cfde_cssexttextbuf.h",
       "xfa/fde/css/cfde_cssnumbervalue.cpp",
       "xfa/fde/css/cfde_cssnumbervalue.h",
       "xfa/fde/css/cfde_csspropertyholder.cpp",
diff --git a/testing/libfuzzer/pdf_css_fuzzer.cc b/testing/libfuzzer/pdf_css_fuzzer.cc
index 43ce686c22..d3b2e6a996 100644
--- a/testing/libfuzzer/pdf_css_fuzzer.cc
+++ b/testing/libfuzzer/pdf_css_fuzzer.cc
@@ -18,9 +18,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (input.GetLength() == 0)
     return 0;
 
-  CFDE_CSSSyntaxParser parser;
-  parser.Init(input.c_str(), input.GetLength());
-
+  CFDE_CSSSyntaxParser parser(input.c_str(), input.GetLength());
   FDE_CSSSyntaxStatus status;
   do {
     status = parser.DoSyntaxParse();
diff --git a/xfa/fde/css/cfde_cssexttextbuf.cpp b/xfa/fde/css/cfde_cssexttextbuf.cpp
new file mode 100644
index 0000000000..86f6776c48
--- /dev/null
+++ b/xfa/fde/css/cfde_cssexttextbuf.cpp
@@ -0,0 +1,17 @@
+// Copyright 2017 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.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "xfa/fde/css/cfde_cssexttextbuf.h"
+
+CFDE_CSSExtTextBuf::CFDE_CSSExtTextBuf()
+    : m_pExtBuffer(nullptr), m_iDatLen(0), m_iDatPos(0) {}
+
+CFDE_CSSExtTextBuf::~CFDE_CSSExtTextBuf() {}
+
+void CFDE_CSSExtTextBuf::AttachBuffer(const wchar_t* pBuffer, int32_t iBufLen) {
+  m_pExtBuffer = pBuffer;
+  m_iDatLen = iBufLen;
+}
diff --git a/xfa/fde/css/cfde_cssexttextbuf.h b/xfa/fde/css/cfde_cssexttextbuf.h
new file mode 100644
index 0000000000..0760182f25
--- /dev/null
+++ b/xfa/fde/css/cfde_cssexttextbuf.h
@@ -0,0 +1,34 @@
+// Copyright 2017 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.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#ifndef XFA_FDE_CSS_CFDE_CSSEXTTEXTBUF_H_
+#define XFA_FDE_CSS_CFDE_CSSEXTTEXTBUF_H_
+
+#include "core/fxcrt/fx_system.h"
+
+class CFDE_CSSExtTextBuf {
+ public:
+  CFDE_CSSExtTextBuf();
+  ~CFDE_CSSExtTextBuf();
+
+  void AttachBuffer(const wchar_t* pBuffer, int32_t iBufLen);
+
+  bool IsEOF() const { return m_iDatPos >= m_iDatLen; }
+
+  wchar_t GetChar() const { return m_pExtBuffer[m_iDatPos]; }
+  wchar_t GetNextChar() const {
+    return (m_iDatPos + 1 >= m_iDatLen) ? 0 : m_pExtBuffer[m_iDatPos + 1];
+  }
+
+  void MoveNext() { m_iDatPos++; }
+
+ protected:
+  const wchar_t* m_pExtBuffer;
+  int32_t m_iDatLen;
+  int32_t m_iDatPos;
+};
+
+#endif  // XFA_FDE_CSS_CFDE_CSSEXTTEXTBUF_H_
diff --git a/xfa/fde/css/cfde_cssstyleselector.cpp b/xfa/fde/css/cfde_cssstyleselector.cpp
index 461192e976..2fe306faec 100644
--- a/xfa/fde/css/cfde_cssstyleselector.cpp
+++ b/xfa/fde/css/cfde_cssstyleselector.cpp
@@ -142,10 +142,8 @@ void CFDE_CSSStyleSelector::AppendInlineStyle(CFDE_CSSDeclaration* pDecl,
                                               const CFX_WideString& style) {
   ASSERT(pDecl && !style.IsEmpty());
 
-  auto pSyntax = pdfium::MakeUnique<CFDE_CSSSyntaxParser>();
-  if (!pSyntax->Init(style.c_str(), style.GetLength(), 32, true))
-    return;
-
+  auto pSyntax = pdfium::MakeUnique<CFDE_CSSSyntaxParser>(
+      style.c_str(), style.GetLength(), 32, true);
   int32_t iLen2 = 0;
   const FDE_CSSPropertyTable* table = nullptr;
   CFX_WideString wsName;
diff --git a/xfa/fde/css/cfde_cssstylesheet.cpp b/xfa/fde/css/cfde_cssstylesheet.cpp
index c16e25156c..369279853e 100644
--- a/xfa/fde/css/cfde_cssstylesheet.cpp
+++ b/xfa/fde/css/cfde_cssstylesheet.cpp
@@ -35,12 +35,10 @@ CFDE_CSSStyleRule* CFDE_CSSStyleSheet::GetRule(int32_t index) const {
 }
 
 bool CFDE_CSSStyleSheet::LoadBuffer(const wchar_t* pBuffer, int32_t iBufSize) {
-  ASSERT(pBuffer && iBufSize > 0);
-
-  auto pSyntax = pdfium::MakeUnique<CFDE_CSSSyntaxParser>();
-  if (!pSyntax->Init(pBuffer, iBufSize))
-    return false;
+  ASSERT(pBuffer);
+  ASSERT(iBufSize > 0);
 
+  auto pSyntax = pdfium::MakeUnique<CFDE_CSSSyntaxParser>(pBuffer, iBufSize);
   Reset();
   FDE_CSSSyntaxStatus eStatus;
   do {
diff --git a/xfa/fde/css/cfde_csssyntaxparser.cpp b/xfa/fde/css/cfde_csssyntaxparser.cpp
index b896eb79b8..51d99f1992 100644
--- a/xfa/fde/css/cfde_csssyntaxparser.cpp
+++ b/xfa/fde/css/cfde_csssyntaxparser.cpp
@@ -22,39 +22,26 @@ bool IsSelectorStart(wchar_t wch) {
 
 }  // namespace
 
-CFDE_CSSSyntaxParser::CFDE_CSSSyntaxParser()
+CFDE_CSSSyntaxParser::CFDE_CSSSyntaxParser(const wchar_t* pBuffer,
+                                           int32_t iBufferSize)
+    : CFDE_CSSSyntaxParser(pBuffer, iBufferSize, 32, false) {}
+
+CFDE_CSSSyntaxParser::CFDE_CSSSyntaxParser(const wchar_t* pBuffer,
+                                           int32_t iBufferSize,
+                                           int32_t iTextDatSize,
+                                           bool bOnlyDeclaration)
     : m_iTextDataLen(0),
       m_dwCheck(0xFFFFFFFF),
-      m_eMode(FDE_CSSSyntaxMode::RuleSet),
-      m_eStatus(FDE_CSSSyntaxStatus::None) {}
-
-CFDE_CSSSyntaxParser::~CFDE_CSSSyntaxParser() {
-  m_TextData.Reset();
-  m_TextPlane.Reset();
-}
-
-bool CFDE_CSSSyntaxParser::Init(const wchar_t* pBuffer,
-                                int32_t iBufferSize,
-                                int32_t iTextDatSize,
-                                bool bOnlyDeclaration) {
+      m_eStatus(FDE_CSSSyntaxStatus::None) {
   ASSERT(pBuffer && iBufferSize > 0 && iTextDatSize > 0);
-  Reset(bOnlyDeclaration);
-  if (!m_TextData.EstimateSize(iTextDatSize))
-    return false;
-  m_TextPlane.AttachBuffer(pBuffer, iBufferSize);
-  return true;
-}
-
-void CFDE_CSSSyntaxParser::Reset(bool bOnlyDeclaration) {
-  m_TextPlane.Reset();
-  m_TextData.Reset();
-  m_iTextDataLen = 0;
-  m_dwCheck = 0xFFFFFFFF;
-  m_eStatus = FDE_CSSSyntaxStatus::None;
   m_eMode = bOnlyDeclaration ? FDE_CSSSyntaxMode::PropertyName
                              : FDE_CSSSyntaxMode::RuleSet;
+  m_TextData.InitWithSize(iTextDatSize);
+  m_TextPlane.AttachBuffer(pBuffer, iBufferSize);
 }
 
+CFDE_CSSSyntaxParser::~CFDE_CSSSyntaxParser() {}
+
 FDE_CSSSyntaxStatus CFDE_CSSSyntaxParser::DoSyntaxParse() {
   while (m_eStatus >= FDE_CSSSyntaxStatus::None) {
     if (m_TextPlane.IsEOF()) {
@@ -171,7 +158,7 @@ FDE_CSSSyntaxStatus CFDE_CSSSyntaxParser::DoSyntaxParse() {
           break;
         case FDE_CSSSyntaxMode::Comment:
           if (wch == '/' && m_TextData.GetLength() > 0 &&
-              m_TextData.GetAt(m_TextData.GetLength() - 1) == '*') {
+              m_TextData.GetBuffer()[m_TextData.GetLength() - 1] == '*') {
             RestoreMode();
           } else {
             m_TextData.AppendChar(wch);
diff --git a/xfa/fde/css/cfde_csssyntaxparser.h b/xfa/fde/css/cfde_csssyntaxparser.h
index a5e79d50e5..c17d84aef1 100644
--- a/xfa/fde/css/cfde_csssyntaxparser.h
+++ b/xfa/fde/css/cfde_csssyntaxparser.h
@@ -9,6 +9,8 @@
 
 #include <stack>
 
+#include "core/fxcrt/fx_string.h"
+#include "xfa/fde/css/cfde_cssexttextbuf.h"
 #include "xfa/fde/css/cfde_csstextbuf.h"
 
 #define FDE_CSSSYNTAXCHECK_AllowCharset 1
@@ -37,18 +39,17 @@ enum class FDE_CSSSyntaxStatus : uint8_t {
 
 class CFDE_CSSSyntaxParser {
  public:
-  CFDE_CSSSyntaxParser();
+  CFDE_CSSSyntaxParser(const wchar_t* pBuffer, int32_t iBufferSize);
+  CFDE_CSSSyntaxParser(const wchar_t* pBuffer,
+                       int32_t iBufferSize,
+                       int32_t iTextDatSize,
+                       bool bOnlyDeclaration);
   ~CFDE_CSSSyntaxParser();
 
-  bool Init(const wchar_t* pBuffer,
-            int32_t iBufferSize,
-            int32_t iTextDatSize = 32,
-            bool bOnlyDeclaration = false);
   FDE_CSSSyntaxStatus DoSyntaxParse();
   CFX_WideStringC GetCurrentString() const;
 
  protected:
-  void Reset(bool bOnlyDeclaration);
   void SwitchMode(FDE_CSSSyntaxMode eMode);
   int32_t SwitchToComment();
 
@@ -63,7 +64,7 @@ class CFDE_CSSSyntaxParser {
   void DisableImport() { m_dwCheck = 0; }
 
   CFDE_CSSTextBuf m_TextData;
-  CFDE_CSSTextBuf m_TextPlane;
+  CFDE_CSSExtTextBuf m_TextPlane;
   int32_t m_iTextDataLen;
   uint32_t m_dwCheck;
   FDE_CSSSyntaxMode m_eMode;
diff --git a/xfa/fde/css/cfde_csstextbuf.cpp b/xfa/fde/css/cfde_csstextbuf.cpp
index 8ccdca9fed..0d8ba2d6ce 100644
--- a/xfa/fde/css/cfde_csstextbuf.cpp
+++ b/xfa/fde/css/cfde_csstextbuf.cpp
@@ -6,69 +6,39 @@
 
 #include "xfa/fde/css/cfde_csstextbuf.h"
 
-#include "third_party/base/stl_util.h"
+#include "core/fxcrt/fx_memory.h"
 
 CFDE_CSSTextBuf::CFDE_CSSTextBuf()
-    : m_bExtBuf(false),
-      m_pExtBuffer(nullptr),
-      m_pBuffer(nullptr),
-      m_iBufLen(0),
-      m_iDatLen(0),
-      m_iDatPos(0) {}
+    : m_pBuffer(nullptr), m_iBufLen(0), m_iDatLen(0) {}
 
 CFDE_CSSTextBuf::~CFDE_CSSTextBuf() {
-  Reset();
+  FX_Free(m_pBuffer);
+  m_pBuffer = nullptr;
+  m_iDatLen = m_iBufLen;
 }
 
-void CFDE_CSSTextBuf::AttachBuffer(const wchar_t* pBuffer, int32_t iBufLen) {
-  Reset();
-  m_pExtBuffer = pBuffer;
-  m_iDatLen = m_iBufLen = iBufLen;
-  m_bExtBuf = true;
+void CFDE_CSSTextBuf::InitWithSize(int32_t iAllocSize) {
+  ExpandBuf(iAllocSize);
 }
 
-bool CFDE_CSSTextBuf::EstimateSize(int32_t iAllocSize) {
-  ASSERT(iAllocSize > 0);
-  Clear();
-  m_bExtBuf = false;
-  return ExpandBuf(iAllocSize);
-}
-
-bool CFDE_CSSTextBuf::AppendChar(wchar_t wch) {
-  if (m_iDatLen >= m_iBufLen && !ExpandBuf(m_iBufLen * 2))
-    return false;
+void CFDE_CSSTextBuf::AppendChar(wchar_t wch) {
+  if (m_iDatLen >= m_iBufLen)
+    ExpandBuf(m_iBufLen * 2);
 
-  ASSERT(!m_bExtBuf);
   m_pBuffer[m_iDatLen++] = wch;
-  return true;
-}
-
-void CFDE_CSSTextBuf::Reset() {
-  if (!m_bExtBuf) {
-    FX_Free(m_pBuffer);
-    m_pBuffer = nullptr;
-  }
-  m_iDatPos = m_iDatLen = m_iBufLen;
 }
 
 int32_t CFDE_CSSTextBuf::TrimEnd() {
-  ASSERT(!m_bExtBuf);
   while (m_iDatLen > 0 && m_pBuffer[m_iDatLen - 1] <= ' ')
     --m_iDatLen;
   AppendChar(0);
   return --m_iDatLen;
 }
 
-const wchar_t* CFDE_CSSTextBuf::GetBuffer() const {
-  return m_bExtBuf ? m_pExtBuffer : m_pBuffer;
-}
-
-bool CFDE_CSSTextBuf::ExpandBuf(int32_t iDesiredSize) {
-  if (m_bExtBuf)
-    return false;
-
+void CFDE_CSSTextBuf::ExpandBuf(int32_t iDesiredSize) {
+  ASSERT(iDesiredSize > 0);
   if (m_pBuffer && m_iBufLen == iDesiredSize)
-    return true;
+    return;
 
   if (m_pBuffer)
     m_pBuffer = FX_Realloc(wchar_t, m_pBuffer, iDesiredSize);
@@ -76,14 +46,4 @@ bool CFDE_CSSTextBuf::ExpandBuf(int32_t iDesiredSize) {
     m_pBuffer = FX_Alloc(wchar_t, iDesiredSize);
 
   m_iBufLen = iDesiredSize;
-  return true;
-}
-
-void CFDE_CSSTextBuf::Subtract(int32_t iStart, int32_t iLength) {
-  ASSERT(iStart >= 0 && iLength >= 0);
-  ASSERT(!m_bExtBuf);
-
-  iLength = pdfium::clamp(iLength, 0, m_iDatLen - iStart);
-  memmove(m_pBuffer, m_pBuffer + iStart, iLength * sizeof(wchar_t));
-  m_iDatLen = iLength;
 }
diff --git a/xfa/fde/css/cfde_csstextbuf.h b/xfa/fde/css/cfde_csstextbuf.h
index be6800fe3a..b2c17c95f8 100644
--- a/xfa/fde/css/cfde_csstextbuf.h
+++ b/xfa/fde/css/cfde_csstextbuf.h
@@ -7,9 +7,6 @@
 #ifndef XFA_FDE_CSS_CFDE_CSSTEXTBUF_H_
 #define XFA_FDE_CSS_CFDE_CSSTEXTBUF_H_
 
-#include "core/fxcrt/cfx_retain_ptr.h"
-#include "core/fxcrt/cfx_seekablestreamproxy.h"
-#include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/fx_system.h"
 
 class CFDE_CSSTextBuf {
@@ -17,38 +14,22 @@ class CFDE_CSSTextBuf {
   CFDE_CSSTextBuf();
   ~CFDE_CSSTextBuf();
 
-  void AttachBuffer(const wchar_t* pBuffer, int32_t iBufLen);
-  bool EstimateSize(int32_t iAllocSize);
-  bool AppendChar(wchar_t wch);
+  void InitWithSize(int32_t iAllocSize);
+  void AppendChar(wchar_t wch);
 
-  void Clear() { m_iDatPos = m_iDatLen = 0; }
-  void Reset();
+  void Clear() { m_iDatLen = 0; }
 
   int32_t TrimEnd();
 
-  void Subtract(int32_t iStart, int32_t iLength);
-  bool IsEOF() const { return m_iDatPos >= m_iDatLen; }
-
-  wchar_t GetAt(int32_t index) const { return GetBuffer()[index]; }
-  wchar_t GetChar() const { return GetBuffer()[m_iDatPos]; }
-  wchar_t GetNextChar() const {
-    return (m_iDatPos + 1 >= m_iDatLen) ? 0 : GetBuffer()[m_iDatPos + 1];
-  }
-
-  void MoveNext() { m_iDatPos++; }
-
   int32_t GetLength() const { return m_iDatLen; }
-  const wchar_t* GetBuffer() const;
+  const wchar_t* GetBuffer() const { return m_pBuffer; }
 
  protected:
-  bool ExpandBuf(int32_t iDesiredSize);
+  void ExpandBuf(int32_t iDesiredSize);
 
-  bool m_bExtBuf;
-  const wchar_t* m_pExtBuffer;
   wchar_t* m_pBuffer;
   int32_t m_iBufLen;
   int32_t m_iDatLen;
-  int32_t m_iDatPos;
 };
 
 #endif  // XFA_FDE_CSS_CFDE_CSSTEXTBUF_H_