Use safe arithmentic in CFX_BinaryBuf::ExpandBuf.

Always call ExpandBuf(), and if it returns, we know the
subsequent calculations won't overflow.

Also use std::unique_ptr, and fix unintentional copies thus
detected by its suppressed copy ctor in fsdk_baseform.cpp

Also Remove unused CFX_BinaryBuf::TakeOver(), AppendFill(), CopyData().

Also remove operator= in favor of using <<, for similarity
with std::ostream and friends.

Also move ByteStringC methods to CFX_ByteTextBuf sub-class.

Also re-order members, may pack tighter on 64-bits.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1710403002 .

8 files changed, 145 insertions, 188 deletions

diff --git a/core/include/fxcrt/fx_basic.h b/core/include/fxcrt/fx_basic.h
index 7f47122dea..4402856996 100644
--- a/core/include/fxcrt/fx_basic.h
+++ b/core/include/fxcrt/fx_basic.h
@@ -8,6 +8,7 @@
 #define CORE_INCLUDE_FXCRT_FX_BASIC_H_
 
 #include <algorithm>
+#include <memory>
 
 #include "core/include/fxcrt/fx_memory.h"
 #include "core/include/fxcrt/fx_stream.h"
@@ -29,109 +30,90 @@
 template <typename T, size_t N>
 char(&ArraySizeHelper(T(&array)[N]))[N];
 
+// Used with std::unique_ptr to FX_Free raw memory.
+struct FxFreeDeleter {
+  inline void operator()(void* ptr) const { FX_Free(ptr); }
+};
+
+// Used with std::unique_ptr to Release() objects that can't be deleted.
+template <class T>
+struct ReleaseDeleter {
+  inline void operator()(T* ptr) const { ptr->Release(); }
+};
+
 class CFX_BinaryBuf {
  public:
   CFX_BinaryBuf();
-  CFX_BinaryBuf(FX_STRSIZE size);
+  explicit CFX_BinaryBuf(FX_STRSIZE size);
 
-  ~CFX_BinaryBuf();
+  uint8_t* GetBuffer() const { return m_pBuffer.get(); }
+  FX_STRSIZE GetSize() const { return m_DataSize; }
 
   void Clear();
-
   void EstimateSize(FX_STRSIZE size, FX_STRSIZE alloc_step = 0);
-
   void AppendBlock(const void* pBuf, FX_STRSIZE size);
-
-  void AppendFill(uint8_t byte, FX_STRSIZE count);
-
   void AppendString(const CFX_ByteStringC& str) {
     AppendBlock(str.GetPtr(), str.GetLength());
   }
 
-  inline void AppendByte(uint8_t byte) {
-    if (m_AllocSize <= m_DataSize) {
-      ExpandBuf(1);
-    }
-    m_pBuffer[m_DataSize++] = byte;
+  void AppendByte(uint8_t byte) {
+    ExpandBuf(1);
+    m_pBuffer.get()[m_DataSize++] = byte;
   }
 
   void InsertBlock(FX_STRSIZE pos, const void* pBuf, FX_STRSIZE size);
-
-  void AttachData(void* pBuf, FX_STRSIZE size);
-
-  void CopyData(const void* pBuf, FX_STRSIZE size);
-
-  void TakeOver(CFX_BinaryBuf& other);
-
   void Delete(int start_index, int count);
 
-  uint8_t* GetBuffer() const { return m_pBuffer; }
+  // Takes ownership of |pBuf|.
+  void AttachData(uint8_t* pBuf, FX_STRSIZE size);
 
-  FX_STRSIZE GetSize() const { return m_DataSize; }
-
-  CFX_ByteStringC GetByteString() const;
-
-  void DetachBuffer();
+  // Releases ownership of |m_pBuffer| and returns it.
+  uint8_t* DetachBuffer();
 
  protected:
-  FX_STRSIZE m_AllocStep;
-
-  uint8_t* m_pBuffer;
-
-  FX_STRSIZE m_DataSize;
+  void ExpandBuf(FX_STRSIZE size);
 
+  FX_STRSIZE m_AllocStep;
   FX_STRSIZE m_AllocSize;
-
-  void ExpandBuf(FX_STRSIZE size);
+  FX_STRSIZE m_DataSize;
+  std::unique_ptr<uint8_t, FxFreeDeleter> m_pBuffer;
 };
+
 class CFX_ByteTextBuf : public CFX_BinaryBuf {
  public:
-  void operator=(const CFX_ByteStringC& str);
-
   void AppendChar(int ch) { AppendByte((uint8_t)ch); }
+  FX_STRSIZE GetLength() const { return m_DataSize; }
+  CFX_ByteStringC GetByteString() const;
 
   CFX_ByteTextBuf& operator<<(int i);
-
   CFX_ByteTextBuf& operator<<(FX_DWORD i);
-
   CFX_ByteTextBuf& operator<<(double f);
-
   CFX_ByteTextBuf& operator<<(const CFX_ByteStringC& lpsz);
-
   CFX_ByteTextBuf& operator<<(const CFX_ByteTextBuf& buf);
-
-  FX_STRSIZE GetLength() const { return m_DataSize; }
 };
+
 class CFX_WideTextBuf : public CFX_BinaryBuf {
  public:
-  void operator=(const FX_WCHAR* lpsz);
-
-  void operator=(const CFX_WideStringC& str);
-
   void AppendChar(FX_WCHAR wch);
-
-  CFX_WideTextBuf& operator<<(int i);
-
-  CFX_WideTextBuf& operator<<(double f);
-
-  CFX_WideTextBuf& operator<<(const FX_WCHAR* lpsz);
-
-  CFX_WideTextBuf& operator<<(const CFX_WideStringC& str);
-  CFX_WideTextBuf& operator<<(const CFX_WideString& str);
-
-  CFX_WideTextBuf& operator<<(const CFX_WideTextBuf& buf);
-
   FX_STRSIZE GetLength() const { return m_DataSize / sizeof(FX_WCHAR); }
-
-  FX_WCHAR* GetBuffer() const { return (FX_WCHAR*)m_pBuffer; }
+  FX_WCHAR* GetBuffer() const {
+    return reinterpret_cast<FX_WCHAR*>(m_pBuffer.get());
+  }
+  CFX_WideStringC GetWideString() const;
 
   void Delete(int start_index, int count) {
     CFX_BinaryBuf::Delete(start_index * sizeof(FX_WCHAR),
                           count * sizeof(FX_WCHAR));
   }
 
-  CFX_WideStringC GetWideString() const;
+  CFX_WideTextBuf& operator<<(int i);
+  CFX_WideTextBuf& operator<<(double f);
+  CFX_WideTextBuf& operator<<(const FX_WCHAR* lpsz);
+  CFX_WideTextBuf& operator<<(const CFX_WideStringC& str);
+  CFX_WideTextBuf& operator<<(const CFX_WideString& str);
+  CFX_WideTextBuf& operator<<(const CFX_WideTextBuf& buf);
 };
+
 #ifdef PDF_ENABLE_XFA
 class CFX_ArchiveSaver {
  public:
@@ -1031,16 +1013,6 @@ class CFX_AutoRestorer {
   const T m_OldValue;
 };
 
-struct FxFreeDeleter {
-  inline void operator()(void* ptr) const { FX_Free(ptr); }
-};
-
-// Used with std::unique_ptr to Release() objects that can't be deleted.
-template <class T>
-struct ReleaseDeleter {
-  inline void operator()(T* ptr) const { ptr->Release(); }
-};
-
 #define FX_DATALIST_LENGTH 1024
 template <size_t unit>
 class CFX_SortListArray {
diff --git a/core/include/fxcrt/fx_safe_types.h b/core/include/fxcrt/fx_safe_types.h
index aec1ca7e96..6ae3ee1054 100644
--- a/core/include/fxcrt/fx_safe_types.h
+++ b/core/include/fxcrt/fx_safe_types.h
@@ -15,5 +15,6 @@ typedef pdfium::base::CheckedNumeric<FX_DWORD> FX_SAFE_DWORD;
 typedef pdfium::base::CheckedNumeric<int32_t> FX_SAFE_INT32;
 typedef pdfium::base::CheckedNumeric<size_t> FX_SAFE_SIZE_T;
 typedef pdfium::base::CheckedNumeric<FX_FILESIZE> FX_SAFE_FILESIZE;
+typedef pdfium::base::CheckedNumeric<FX_STRSIZE> FX_SAFE_STRSIZE;
 
 #endif  // CORE_INCLUDE_FXCRT_FX_SAFE_TYPES_H_
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 735cd2b38a..d52ef4fd34 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -1873,7 +1873,7 @@ CFX_ByteString CPDF_SyntaxParser::ReadHexString() {
   if (!GetNextChar(ch))
     return CFX_ByteString();
 
-  CFX_BinaryBuf buf;
+  CFX_ByteTextBuf buf;
   bool bFirst = true;
   uint8_t code = 0;
   while (1) {
@@ -1886,7 +1886,7 @@ CFX_ByteString CPDF_SyntaxParser::ReadHexString() {
         code = val * 16;
       } else {
         code += val;
-        buf.AppendByte((uint8_t)code);
+        buf.AppendByte(code);
       }
       bFirst = !bFirst;
     }
@@ -1895,7 +1895,7 @@ CFX_ByteString CPDF_SyntaxParser::ReadHexString() {
       break;
   }
   if (!bFirst)
-    buf.AppendByte((uint8_t)code);
+    buf.AppendByte(code);
 
   return buf.GetByteString();
 }
diff --git a/core/src/fxcodec/codec/fx_codec_fax.cpp b/core/src/fxcodec/codec/fx_codec_fax.cpp
index cacbc71456..36b92f06ff 100644
--- a/core/src/fxcodec/codec/fx_codec_fax.cpp
+++ b/core/src/fxcodec/codec/fx_codec_fax.cpp
@@ -799,9 +799,8 @@ void CCodec_FaxEncoder::Encode(uint8_t*& dest_buf, FX_DWORD& dest_size) {
   if (dest_bitpos) {
     m_DestBuf.AppendByte(last_byte);
   }
-  dest_buf = m_DestBuf.GetBuffer();
   dest_size = m_DestBuf.GetSize();
-  m_DestBuf.DetachBuffer();
+  dest_buf = m_DestBuf.DetachBuffer();
 }
 FX_BOOL CCodec_FaxModule::Encode(const uint8_t* src_buf,
                                  int width,
diff --git a/core/src/fxcrt/fx_basic_buffer.cpp b/core/src/fxcrt/fx_basic_buffer.cpp
index 4ef86bbf41..0551ef04de 100644
--- a/core/src/fxcrt/fx_basic_buffer.cpp
+++ b/core/src/fxcrt/fx_basic_buffer.cpp
@@ -5,208 +5,186 @@
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <algorithm>
+#include <limits>
 
 #include "core/include/fxcrt/fx_basic.h"
+#include "core/include/fxcrt/fx_safe_types.h"
 
-FX_STRSIZE FX_ftoa(FX_FLOAT f, FX_CHAR* buf);
 CFX_BinaryBuf::CFX_BinaryBuf()
-    : m_AllocStep(0), m_pBuffer(NULL), m_DataSize(0), m_AllocSize(0) {}
+    : m_AllocStep(0), m_AllocSize(0), m_DataSize(0) {}
+
 CFX_BinaryBuf::CFX_BinaryBuf(FX_STRSIZE size)
-    : m_AllocStep(0), m_DataSize(size), m_AllocSize(size) {
-  m_pBuffer = FX_Alloc(uint8_t, size);
-}
-CFX_BinaryBuf::~CFX_BinaryBuf() {
-  FX_Free(m_pBuffer);
+    : m_AllocStep(0), m_AllocSize(size), m_DataSize(size) {
+  m_pBuffer.reset(FX_Alloc(uint8_t, size));
 }
+
 void CFX_BinaryBuf::Delete(int start_index, int count) {
-  if (!m_pBuffer || start_index < 0 || start_index + count > m_DataSize) {
+  if (!m_pBuffer || start_index < 0 || count < 0 || count > m_DataSize ||
+      start_index > m_DataSize - count) {
     return;
   }
-  FXSYS_memmove(m_pBuffer + start_index, m_pBuffer + start_index + count,
+  FXSYS_memmove(m_pBuffer.get() + start_index,
+                m_pBuffer.get() + start_index + count,
                 m_DataSize - start_index - count);
   m_DataSize -= count;
 }
+
 void CFX_BinaryBuf::Clear() {
   m_DataSize = 0;
 }
-void CFX_BinaryBuf::DetachBuffer() {
+
+uint8_t* CFX_BinaryBuf::DetachBuffer() {
   m_DataSize = 0;
-  m_pBuffer = NULL;
   m_AllocSize = 0;
+  return m_pBuffer.release();
 }
-void CFX_BinaryBuf::AttachData(void* buffer, FX_STRSIZE size) {
-  FX_Free(m_pBuffer);
+
+void CFX_BinaryBuf::AttachData(uint8_t* buffer, FX_STRSIZE size) {
+  m_pBuffer.reset(buffer);
   m_DataSize = size;
-  m_pBuffer = (uint8_t*)buffer;
   m_AllocSize = size;
 }
-void CFX_BinaryBuf::TakeOver(CFX_BinaryBuf& other) {
-  AttachData(other.GetBuffer(), other.GetSize());
-  other.DetachBuffer();
-}
+
 void CFX_BinaryBuf::EstimateSize(FX_STRSIZE size, FX_STRSIZE step) {
   m_AllocStep = step;
-  if (m_AllocSize >= size) {
-    return;
-  }
-  ExpandBuf(size - m_DataSize);
+  if (m_AllocSize < size)
+    ExpandBuf(size - m_DataSize);
 }
+
 void CFX_BinaryBuf::ExpandBuf(FX_STRSIZE add_size) {
-  FX_STRSIZE new_size = add_size + m_DataSize;
-  if (m_AllocSize >= new_size) {
+  FX_SAFE_STRSIZE new_size = m_DataSize;
+  new_size += add_size;
+  if (m_AllocSize >= new_size.ValueOrDie())
     return;
-  }
-  int alloc_step;
-  if (m_AllocStep == 0) {
-    alloc_step = m_AllocSize / 4;
-    if (alloc_step < 128) {
-      alloc_step = 128;
-    }
-  } else {
-    alloc_step = m_AllocStep;
-  }
-  new_size = (new_size + alloc_step - 1) / alloc_step * alloc_step;
-  uint8_t* pNewBuffer = m_pBuffer;
-  if (pNewBuffer) {
-    pNewBuffer = FX_Realloc(uint8_t, m_pBuffer, new_size);
-  } else {
-    pNewBuffer = FX_Alloc(uint8_t, new_size);
-  }
-  m_pBuffer = pNewBuffer;
-  m_AllocSize = new_size;
-}
-void CFX_BinaryBuf::CopyData(const void* pStr, FX_STRSIZE size) {
-  if (size == 0) {
-    m_DataSize = 0;
-    return;
-  }
-  if (m_AllocSize < size) {
-    ExpandBuf(size - m_DataSize);
-  }
-  if (!m_pBuffer) {
-    return;
-  }
-  FXSYS_memcpy(m_pBuffer, pStr, size);
-  m_DataSize = size;
+
+  int alloc_step = std::min(128, m_AllocStep ? m_AllocStep : m_AllocSize / 4);
+  new_size += alloc_step - 1;  // Quantize, don't combine these lines.
+  new_size /= alloc_step;
+  new_size *= alloc_step;
+  m_AllocSize = new_size.ValueOrDie();
+  m_pBuffer.reset(m_pBuffer
+                      ? FX_Realloc(uint8_t, m_pBuffer.release(), m_AllocSize)
+                      : FX_Alloc(uint8_t, m_AllocSize));
 }
+
 void CFX_BinaryBuf::AppendBlock(const void* pBuf, FX_STRSIZE size) {
+  if (size <= 0)
+    return;
+
   ExpandBuf(size);
-  if (pBuf && m_pBuffer) {
-    FXSYS_memcpy(m_pBuffer + m_DataSize, pBuf, size);
+  if (pBuf) {
+    FXSYS_memcpy(m_pBuffer.get() + m_DataSize, pBuf, size);
+  } else {
+    FXSYS_memset(m_pBuffer.get() + m_DataSize, 0, size);
   }
   m_DataSize += size;
 }
+
 void CFX_BinaryBuf::InsertBlock(FX_STRSIZE pos,
                                 const void* pBuf,
                                 FX_STRSIZE size) {
-  ExpandBuf(size);
-  if (!m_pBuffer) {
+  if (size <= 0)
     return;
-  }
-  FXSYS_memmove(m_pBuffer + pos + size, m_pBuffer + pos, m_DataSize - pos);
+
+  ExpandBuf(size);
+  FXSYS_memmove(m_pBuffer.get() + pos + size, m_pBuffer.get() + pos,
+                m_DataSize - pos);
   if (pBuf) {
-    FXSYS_memcpy(m_pBuffer + pos, pBuf, size);
+    FXSYS_memcpy(m_pBuffer.get() + pos, pBuf, size);
+  } else {
+    FXSYS_memset(m_pBuffer.get() + pos, 0, size);
   }
   m_DataSize += size;
 }
-void CFX_BinaryBuf::AppendFill(uint8_t byte, FX_STRSIZE count) {
-  ExpandBuf(count);
-  if (!m_pBuffer) {
-    return;
-  }
-  FXSYS_memset(m_pBuffer + m_DataSize, byte, count);
-  m_DataSize += count;
-}
-CFX_ByteStringC CFX_BinaryBuf::GetByteString() const {
-  return CFX_ByteStringC(m_pBuffer, m_DataSize);
+
+CFX_ByteStringC CFX_ByteTextBuf::GetByteString() const {
+  return CFX_ByteStringC(m_pBuffer.get(), m_DataSize);
 }
+
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(const CFX_ByteStringC& lpsz) {
   AppendBlock(lpsz.GetPtr(), lpsz.GetLength());
   return *this;
 }
+
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(int i) {
   char buf[32];
   FXSYS_itoa(i, buf, 10);
   AppendBlock(buf, FXSYS_strlen(buf));
   return *this;
 }
+
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(FX_DWORD i) {
   char buf[32];
   FXSYS_itoa(i, buf, 10);
   AppendBlock(buf, FXSYS_strlen(buf));
   return *this;
 }
+
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(double f) {
   char buf[32];
   FX_STRSIZE len = FX_ftoa((FX_FLOAT)f, buf);
   AppendBlock(buf, len);
   return *this;
 }
+
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(const CFX_ByteTextBuf& buf) {
-  AppendBlock(buf.m_pBuffer, buf.m_DataSize);
+  AppendBlock(buf.m_pBuffer.get(), buf.m_DataSize);
   return *this;
 }
-void CFX_ByteTextBuf::operator=(const CFX_ByteStringC& str) {
-  CopyData(str.GetPtr(), str.GetLength());
-}
+
 void CFX_WideTextBuf::AppendChar(FX_WCHAR ch) {
-  if (m_AllocSize < m_DataSize + (FX_STRSIZE)sizeof(FX_WCHAR)) {
-    ExpandBuf(sizeof(FX_WCHAR));
-  }
-  ASSERT(m_pBuffer);
-  *(FX_WCHAR*)(m_pBuffer + m_DataSize) = ch;
+  ExpandBuf(sizeof(FX_WCHAR));
+  *(FX_WCHAR*)(m_pBuffer.get() + m_DataSize) = ch;
   m_DataSize += sizeof(FX_WCHAR);
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideStringC& str) {
   AppendBlock(str.GetPtr(), str.GetLength() * sizeof(FX_WCHAR));
   return *this;
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideString& str) {
   AppendBlock(str.c_str(), str.GetLength() * sizeof(FX_WCHAR));
   return *this;
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(int i) {
   char buf[32];
   FXSYS_itoa(i, buf, 10);
   FX_STRSIZE len = FXSYS_strlen(buf);
-  if (m_AllocSize < m_DataSize + (FX_STRSIZE)(len * sizeof(FX_WCHAR))) {
-    ExpandBuf(len * sizeof(FX_WCHAR));
-  }
-  ASSERT(m_pBuffer);
-  FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer + m_DataSize);
+  ExpandBuf(len * sizeof(FX_WCHAR));
+  FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer.get() + m_DataSize);
   for (FX_STRSIZE j = 0; j < len; j++) {
     *str++ = buf[j];
   }
   m_DataSize += len * sizeof(FX_WCHAR);
   return *this;
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(double f) {
   char buf[32];
   FX_STRSIZE len = FX_ftoa((FX_FLOAT)f, buf);
-  if (m_AllocSize < m_DataSize + (FX_STRSIZE)(len * sizeof(FX_WCHAR))) {
-    ExpandBuf(len * sizeof(FX_WCHAR));
-  }
-  ASSERT(m_pBuffer);
-  FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer + m_DataSize);
+  ExpandBuf(len * sizeof(FX_WCHAR));
+  FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer.get() + m_DataSize);
   for (FX_STRSIZE i = 0; i < len; i++) {
     *str++ = buf[i];
   }
   m_DataSize += len * sizeof(FX_WCHAR);
   return *this;
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const FX_WCHAR* lpsz) {
   AppendBlock(lpsz, FXSYS_wcslen(lpsz) * sizeof(FX_WCHAR));
   return *this;
 }
+
 CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideTextBuf& buf) {
-  AppendBlock(buf.m_pBuffer, buf.m_DataSize);
+  AppendBlock(buf.m_pBuffer.get(), buf.m_DataSize);
   return *this;
 }
-void CFX_WideTextBuf::operator=(const CFX_WideStringC& str) {
-  CopyData(str.GetPtr(), str.GetLength() * sizeof(FX_WCHAR));
-}
+
 CFX_WideStringC CFX_WideTextBuf::GetWideString() const {
-  return CFX_WideStringC((const FX_WCHAR*)m_pBuffer,
+  return CFX_WideStringC((const FX_WCHAR*)m_pBuffer.get(),
                          m_DataSize / sizeof(FX_WCHAR));
 }
 
diff --git a/fpdfsdk/src/fsdk_baseform.cpp b/fpdfsdk/src/fsdk_baseform.cpp
index 00ab6c2ef0..f05545a672 100644
--- a/fpdfsdk/src/fsdk_baseform.cpp
+++ b/fpdfsdk/src/fsdk_baseform.cpp
@@ -2461,7 +2461,6 @@ FX_BOOL CPDFSDK_InterForm::FDFToURLEncodedData(uint8_t*& pBuf,
       return FALSE;
 
     CFX_ByteTextBuf fdfEncodedData;
-
     for (FX_DWORD i = 0; i < pFields->GetCount(); i++) {
       CPDF_Dictionary* pField = pFields->GetDictAt(i);
       if (!pField)
@@ -2473,14 +2472,13 @@ FX_BOOL CPDFSDK_InterForm::FDFToURLEncodedData(uint8_t*& pBuf,
       CFX_WideString csWValue = PDF_DecodeText(csBValue);
       CFX_ByteString csValue_b = CFX_ByteString::FromUnicode(csWValue);
 
-      fdfEncodedData = fdfEncodedData << name_b.GetBuffer(name_b.GetLength());
+      fdfEncodedData << name_b.GetBuffer(name_b.GetLength());
       name_b.ReleaseBuffer();
-      fdfEncodedData = fdfEncodedData << "=";
-      fdfEncodedData = fdfEncodedData
-                       << csValue_b.GetBuffer(csValue_b.GetLength());
+      fdfEncodedData << "=";
+      fdfEncodedData << csValue_b.GetBuffer(csValue_b.GetLength());
       csValue_b.ReleaseBuffer();
       if (i != pFields->GetCount() - 1)
-        fdfEncodedData = fdfEncodedData << "&";
+        fdfEncodedData << "&";
     }
 
     nBufSize = fdfEncodedData.GetLength();
diff --git a/xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp b/xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp
index 529474f5eb..77cf79bd7b 100644
--- a/xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp
+++ b/xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp
@@ -3760,8 +3760,9 @@ void CXFA_FM2JSContext::DecodeURL(const CFX_ByteStringC& szURLString,
     ++i;
   }
   wsResultBuf.AppendChar(0);
-  szResultString =
-      FX_UTF8Encode(wsResultBuf.GetBuffer(), wsResultBuf.GetLength());
+  szResultString.Clear();
+  szResultString << FX_UTF8Encode(wsResultBuf.GetBuffer(),
+                                  wsResultBuf.GetLength());
 }
 void CXFA_FM2JSContext::DecodeHTML(const CFX_ByteStringC& szHTMLString,
                                    CFX_ByteTextBuf& szResultString) {
@@ -3833,8 +3834,9 @@ void CXFA_FM2JSContext::DecodeHTML(const CFX_ByteStringC& szHTMLString,
     ++i;
   }
   wsResultBuf.AppendChar(0);
-  szResultString =
-      FX_UTF8Encode(wsResultBuf.GetBuffer(), wsResultBuf.GetLength());
+  szResultString.Clear();
+  szResultString << FX_UTF8Encode(wsResultBuf.GetBuffer(),
+                                  wsResultBuf.GetLength());
 }
 void CXFA_FM2JSContext::DecodeXML(const CFX_ByteStringC& szXMLString,
                                   CFX_ByteTextBuf& szResultString) {
@@ -3930,7 +3932,8 @@ void CXFA_FM2JSContext::DecodeXML(const CFX_ByteStringC& szXMLString,
     iCode = 0;
   }
   wsXMLBuf.AppendChar(0);
-  szResultString = FX_UTF8Encode(wsXMLBuf.GetBuffer(), wsXMLBuf.GetLength());
+  szResultString.Clear();
+  szResultString << FX_UTF8Encode(wsXMLBuf.GetBuffer(), wsXMLBuf.GetLength());
 }
 void CXFA_FM2JSContext::Encode(FXJSE_HOBJECT hThis,
                                const CFX_ByteStringC& szFuncName,
@@ -4083,7 +4086,9 @@ void CXFA_FM2JSContext::EncodeURL(const CFX_ByteStringC& szURLString,
     }
   }
   wsResultBuf.AppendChar(0);
-  szResultBuf = FX_UTF8Encode(wsResultBuf.GetBuffer(), wsResultBuf.GetLength());
+  szResultBuf.Clear();
+  szResultBuf << FX_UTF8Encode(wsResultBuf.GetBuffer(),
+                               wsResultBuf.GetLength());
 }
 void CXFA_FM2JSContext::EncodeHTML(const CFX_ByteStringC& szHTMLString,
                                    CFX_ByteTextBuf& szResultBuf) {
@@ -4135,7 +4140,9 @@ void CXFA_FM2JSContext::EncodeHTML(const CFX_ByteStringC& szHTMLString,
     ++i;
   }
   wsResultBuf.AppendChar(0);
-  szResultBuf = FX_UTF8Encode(wsResultBuf.GetBuffer(), wsResultBuf.GetLength());
+  szResultBuf.Clear();
+  szResultBuf << FX_UTF8Encode(wsResultBuf.GetBuffer(),
+                               wsResultBuf.GetLength());
 }
 void CXFA_FM2JSContext::EncodeXML(const CFX_ByteStringC& szXMLString,
                                   CFX_ByteTextBuf& szResultBuf) {
@@ -4215,7 +4222,9 @@ void CXFA_FM2JSContext::EncodeXML(const CFX_ByteStringC& szXMLString,
     }
   }
   wsResultBuf.AppendChar(0);
-  szResultBuf = FX_UTF8Encode(wsResultBuf.GetBuffer(), wsResultBuf.GetLength());
+  szResultBuf.Clear();
+  szResultBuf << FX_UTF8Encode(wsResultBuf.GetBuffer(),
+                               wsResultBuf.GetLength());
 }
 FX_BOOL CXFA_FM2JSContext::HTMLSTR2Code(const CFX_WideStringC& pData,
                                         uint32_t& iCode) {
diff --git a/xfa/src/fxfa/src/fm2js/xfa_simpleexpression.cpp b/xfa/src/fxfa/src/fm2js/xfa_simpleexpression.cpp
index c67681f6ba..7048c38d5a 100644
--- a/xfa/src/fxfa/src/fm2js/xfa_simpleexpression.cpp
+++ b/xfa/src/fxfa/src/fm2js/xfa_simpleexpression.cpp
@@ -447,8 +447,8 @@ CXFA_FMCallExpression::~CXFA_FMCallExpression() {
   }
 }
 FX_BOOL CXFA_FMCallExpression::IsBuildInFunc(CFX_WideTextBuf& funcName) {
-  int32_t iLength = funcName.GetLength();
-  uint32_t uHash = FX_HashCode_String_GetW(funcName.GetBuffer(), iLength, TRUE);
+  uint32_t uHash =
+      FX_HashCode_String_GetW(funcName.GetBuffer(), funcName.GetLength(), TRUE);
   XFA_FMBuildInFunc buildinfunction;
   int32_t iStart = 0,
           iEnd = (sizeof(buildInFuncs) / sizeof(buildInFuncs[0])) - 1;