Revert "Converting CFX_ByteTextBuf to ostringstream in SAX."

This reverts commit 7ca47d55c9cbbec7e0a0b0beffffe348ae655086.

Reason for revert: Caused pdfium:821

Original change's description:
> Converting CFX_ByteTextBuf to ostringstream in SAX.
>
> Bug: pdfium:731
> Change-Id: Ic492e8900c4a69082ff9c2384006a4e6bfa3313e
> Reviewed-on: https://pdfium-review.googlesource.com/6592
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Reviewed-by: dsinclair <dsinclair@chromium.org>
> Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

TBR=thestig@chromium.org,dsinclair@chromium.org,hnakashima@chromium.org

Bug: pdfium:731
Change-Id: Ic7390c3f53d67d6eecf7f669e329702daa16f339
Reviewed-on: https://pdfium-review.googlesource.com/8230
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

4 files changed, 20 insertions, 31 deletions

diff --git a/BUILD.gn b/BUILD.gn
index e02882085b..1853d78e5c 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -887,7 +887,6 @@ static_library("fxcrt") {
       "core/fxcrt/fx_arabic.h",
       "core/fxcrt/ifx_chariter.h",
       "core/fxcrt/ifx_locale.h",
-      "core/fxcrt/xml/cfx_saxcontext.cpp",
       "core/fxcrt/xml/cfx_saxcontext.h",
       "core/fxcrt/xml/cfx_saxreader.cpp",
       "core/fxcrt/xml/cfx_saxreader.h",
diff --git a/core/fxcrt/xml/cfx_saxcontext.cpp b/core/fxcrt/xml/cfx_saxcontext.cpp
deleted file mode 100644
index 4e2f0c58c9..0000000000
--- a/core/fxcrt/xml/cfx_saxcontext.cpp
+++ /dev/null
@@ -1,9 +0,0 @@
-// 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.
-
-#include "core/fxcrt/xml/cfx_saxcontext.h"
-
-CFX_SAXContext::CFX_SAXContext() : m_eNode(CFX_SAXItem::Type::Unknown) {}
-
-CFX_SAXContext::~CFX_SAXContext() {}
diff --git a/core/fxcrt/xml/cfx_saxcontext.h b/core/fxcrt/xml/cfx_saxcontext.h
index fcc889f7a3..7afebed98d 100644
--- a/core/fxcrt/xml/cfx_saxcontext.h
+++ b/core/fxcrt/xml/cfx_saxcontext.h
@@ -7,18 +7,15 @@
 #ifndef CORE_FXCRT_XML_CFX_SAXCONTEXT_H_
 #define CORE_FXCRT_XML_CFX_SAXCONTEXT_H_
 
-#include <sstream>
-
 #include "core/fxcrt/fx_basic.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/xml/cfx_saxreader.h"
 
 class CFX_SAXContext {
  public:
-  CFX_SAXContext();
-  ~CFX_SAXContext();
+  CFX_SAXContext() : m_eNode(CFX_SAXItem::Type::Unknown) {}
 
-  std::ostringstream m_TextBuf;
+  CFX_ByteTextBuf m_TextBuf;
   CFX_ByteString m_bsTagName;
   CFX_SAXItem::Type m_eNode;
 };
diff --git a/core/fxcrt/xml/cfx_saxreaderhandler.cpp b/core/fxcrt/xml/cfx_saxreaderhandler.cpp
index f1e0c7ad94..e7b6cd186c 100644
--- a/core/fxcrt/xml/cfx_saxreaderhandler.cpp
+++ b/core/fxcrt/xml/cfx_saxreaderhandler.cpp
@@ -26,11 +26,12 @@ CFX_SAXContext* CFX_SAXReaderHandler::OnTagEnter(
   }
 
   m_SAXContext.m_eNode = eType;
-  m_SAXContext.m_TextBuf << "<";
+  CFX_ByteTextBuf& textBuf = m_SAXContext.m_TextBuf;
+  textBuf << "<";
   if (eType == CFX_SAXItem::Type::Instruction)
-    m_SAXContext.m_TextBuf << "?";
+    textBuf << "?";
 
-  m_SAXContext.m_TextBuf << bsTagName;
+  textBuf << bsTagName;
   m_SAXContext.m_bsTagName = bsTagName;
   return &m_SAXContext;
 }
@@ -40,7 +41,7 @@ void CFX_SAXReaderHandler::OnTagAttribute(CFX_SAXContext* pTag,
                                           const CFX_ByteStringC& bsValue) {
   if (!pTag)
     return;
-  pTag->m_TextBuf << " " << bsAttri.c_str() << "=\"" << bsValue.c_str() << "\"";
+  pTag->m_TextBuf << " " << bsAttri << "=\"" << bsValue << "\"";
 }
 
 void CFX_SAXReaderHandler::OnTagBreak(CFX_SAXContext* pTag) {
@@ -58,22 +59,24 @@ void CFX_SAXReaderHandler::OnTagData(CFX_SAXContext* pTag,
   if (!pTag)
     return;
 
+  CFX_ByteTextBuf& textBuf = pTag->m_TextBuf;
   if (eType == CFX_SAXItem::Type::CharData)
-    pTag->m_TextBuf << "<![CDATA[";
+    textBuf << "<![CDATA[";
 
-  pTag->m_TextBuf << bsData.c_str();
+  textBuf << bsData;
   if (eType == CFX_SAXItem::Type::CharData)
-    pTag->m_TextBuf << "]]>";
+    textBuf << "]]>";
 }
 
 void CFX_SAXReaderHandler::OnTagClose(CFX_SAXContext* pTag, uint32_t dwEndPos) {
   if (!pTag)
     return;
 
+  CFX_ByteTextBuf& textBuf = pTag->m_TextBuf;
   if (pTag->m_eNode == CFX_SAXItem::Type::Instruction)
-    pTag->m_TextBuf << "?>";
+    textBuf << "?>";
   else if (pTag->m_eNode == CFX_SAXItem::Type::Tag)
-    pTag->m_TextBuf << "></" << pTag->m_bsTagName.AsStringC().c_str() << ">";
+    textBuf << "></" << pTag->m_bsTagName.AsStringC() << ">";
 
   UpdateChecksum(false);
 }
@@ -84,7 +87,7 @@ void CFX_SAXReaderHandler::OnTagEnd(CFX_SAXContext* pTag,
   if (!pTag)
     return;
 
-  pTag->m_TextBuf << "</" << bsTagName.c_str() << ">";
+  pTag->m_TextBuf << "</" << bsTagName << ">";
   UpdateChecksum(false);
 }
 
@@ -96,20 +99,19 @@ void CFX_SAXReaderHandler::OnTargetData(CFX_SAXContext* pTag,
     return;
 
   if (eType == CFX_SAXItem::Type::Comment) {
-    m_SAXContext.m_TextBuf << "<!--" << bsData.c_str() << "-->";
+    m_SAXContext.m_TextBuf << "<!--" << bsData << "-->";
     UpdateChecksum(false);
   } else {
-    pTag->m_TextBuf << " " << bsData.c_str();
+    pTag->m_TextBuf << " " << bsData;
   }
 }
 
 void CFX_SAXReaderHandler::UpdateChecksum(bool bCheckSpace) {
-  int32_t iLength = m_SAXContext.m_TextBuf.tellp();
+  int32_t iLength = m_SAXContext.m_TextBuf.GetLength();
   if (iLength < 1)
     return;
 
-  const uint8_t* pBuffer =
-      reinterpret_cast<const uint8_t*>(m_SAXContext.m_TextBuf.str().c_str());
+  uint8_t* pBuffer = m_SAXContext.m_TextBuf.GetBuffer();
   bool bUpdata = true;
   if (bCheckSpace) {
     bUpdata = false;
@@ -122,5 +124,5 @@ void CFX_SAXReaderHandler::UpdateChecksum(bool bCheckSpace) {
   if (bUpdata)
     m_pContext->Update(CFX_ByteStringC(pBuffer, iLength));
 
-  m_SAXContext.m_TextBuf.str("");
+  m_SAXContext.m_TextBuf.Clear();
 }