Use bytestringC rather than raw ptr/len pairs in syntax parser

core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp

 // Copyright 2016 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 "core/fpdfapi/fpdf_parser/cpdf_syntax_parser.h"
 
 #include <vector>
 
 #include "core/fpdfapi/fpdf_parser/cpdf_boolean.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_crypto_handler.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_null.h"
 #include "core/fpdfapi/fpdf_parser/fpdf_parser_utility.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_array.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_dictionary.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_name.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_number.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_reference.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_stream.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_string.h"
 #include "core/fpdfapi/fpdf_parser/include/fpdf_parser_decode.h"
 #include "core/fpdfapi/include/cpdf_modulemgr.h"
 #include "core/fxcrt/include/fx_ext.h"
 #include "third_party/base/numerics/safe_math.h"
 
 namespace {
 
 struct SearchTagRecord {
-  const char* m_pTag;
-  uint32_t m_Len;
+  CFX_ByteStringC m_bsTag;
   uint32_t m_Offset;
 };
 
 }  // namespace
 
 // static
 int CPDF_SyntaxParser::s_CurrentRecursionDepth = 0;
 
 CPDF_SyntaxParser::CPDF_SyntaxParser()
     : m_MetadataObjnum(0),
@@ skipping 864 matching lines @@
 
 int32_t CPDF_SyntaxParser::SearchMultiWord(const CFX_ByteStringC& tags,
                                            FX_BOOL bWholeWord,
                                            FX_FILESIZE limit) {
   int32_t ntags = 1;
   for (int i = 0; i < tags.GetLength(); ++i) {
     if (tags[i] == 0)
       ++ntags;
   }
 
+  // Ensure that the input byte string happens to be nul-terminated. This
+  // need not be the case, but the loop below uses this guarantee to put
+  // the last pattern into the vector.
+  ASSERT(tags[tags.GetLength()] == 0);
   std::vector<SearchTagRecord> patterns(ntags);
   uint32_t start = 0;
   uint32_t itag = 0;
   uint32_t max_len = 0;
   for (int i = 0; i <= tags.GetLength(); ++i) {
     if (tags[i] == 0) {
       uint32_t len = i - start;
       max_len = std::max(len, max_len);
-      patterns[itag].m_pTag = tags.c_str() + start;
-      patterns[itag].m_Len = len;
+      patterns[itag].m_bsTag = tags.Mid(start, len);
       patterns[itag].m_Offset = 0;
       start = i + 1;
       ++itag;
     }
   }
 
   const FX_FILESIZE pos_limit = m_Pos + limit;
   for (FX_FILESIZE pos = m_Pos; !limit || pos < pos_limit; ++pos) {
     uint8_t byte;
     if (!GetCharAt(pos, byte))
       break;
 
     for (int i = 0; i < ntags; ++i) {
       SearchTagRecord& pat = patterns[i];
-      if (pat.m_pTag[pat.m_Offset] != byte) {
-        pat.m_Offset = (pat.m_pTag[0] == byte) ? 1 : 0;
+      if (pat.m_bsTag[pat.m_Offset] != byte) {
+        pat.m_Offset = (pat.m_bsTag[0] == byte) ? 1 : 0;
         continue;
       }
 
       ++pat.m_Offset;
-      if (pat.m_Offset != pat.m_Len)
+      if (pat.m_Offset != pat.m_bsTag.GetLength())
         continue;
 
-      if (!bWholeWord ||
-          IsWholeWord(pos - pat.m_Len, limit,
-                      CFX_ByteStringC(pat.m_pTag, pat.m_Len), FALSE)) {
+      if (!bWholeWord || IsWholeWord(pos - pat.m_bsTag.GetLength(), limit,
+                                     pat.m_bsTag, FALSE)) {
         return i;
       }
 
-      pat.m_Offset = (pat.m_pTag[0] == byte) ? 1 : 0;
+      pat.m_Offset = (pat.m_bsTag[0] == byte) ? 1 : 0;
     }
   }
   return -1;
 }
 
 FX_FILESIZE CPDF_SyntaxParser::FindTag(const CFX_ByteStringC& tag,
                                        FX_FILESIZE limit) {
   int32_t taglen = tag.GetLength();
   int32_t match = 0;
   limit += m_Pos;
@@ skipping 15 matching lines @@
     if (limit && m_Pos == limit)
       return -1;
   }
   return -1;
 }
 
 void CPDF_SyntaxParser::SetEncrypt(
     std::unique_ptr<CPDF_CryptoHandler> pCryptoHandler) {
   m_pCryptoHandler = std::move(pCryptoHandler);
 }