Get rid of gotos in CPDF_SyntaxParser and FlateUncompress().

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1360103002 .

4 files changed, 322 insertions, 331 deletions

diff --git a/core/include/fpdfapi/fpdf_parser.h b/core/include/fpdfapi/fpdf_parser.h
index 6194247568..04c7d90f6f 100644
--- a/core/include/fpdfapi/fpdf_parser.h
+++ b/core/include/fpdfapi/fpdf_parser.h
@@ -453,10 +453,10 @@ class CPDF_Parser {
 
   FX_BOOL LoadAllCrossRefV5(FX_FILESIZE pos);
 
-  FX_BOOL LoadCrossRefV4(FX_FILESIZE pos,
-                         FX_FILESIZE streampos,
-                         FX_BOOL bSkip,
-                         FX_BOOL bFirst);
+  bool LoadCrossRefV4(FX_FILESIZE pos,
+                      FX_FILESIZE streampos,
+                      FX_BOOL bSkip,
+                      FX_BOOL bFirst);
 
   FX_BOOL LoadCrossRefV5(FX_FILESIZE pos, FX_FILESIZE& prev, FX_BOOL bMainXRef);
 
@@ -482,6 +482,8 @@ class CPDF_Parser {
 
   FX_BOOL IsLinearizedFile(IFX_FileRead* pFileAccess, FX_DWORD offset);
 
+  bool FindPosInOffsets(FX_FILESIZE pos) const;
+
   int m_FileVersion;
 
   CPDF_Dictionary* m_pTrailer;
diff --git a/core/include/fxcrt/fx_basic.h b/core/include/fxcrt/fx_basic.h
index 7412b8db3c..9ed5fbafcf 100644
--- a/core/include/fxcrt/fx_basic.h
+++ b/core/include/fxcrt/fx_basic.h
@@ -936,15 +936,13 @@ class IFX_Pause {
 template <typename T>
 class CFX_AutoRestorer {
  public:
-  explicit CFX_AutoRestorer(T* location) {
-    m_Location = location;
-    m_OldValue = *location;
-  }
+  explicit CFX_AutoRestorer(T* location)
+      : m_Location(location), m_OldValue(*location) {}
   ~CFX_AutoRestorer() { *m_Location = m_OldValue; }
 
  private:
-  T* m_Location;
-  T m_OldValue;
+  T* const m_Location;
+  const T m_OldValue;
 };
 
 struct FxFreeDeleter {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index cd923f3e22..984e08d882 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -8,12 +8,59 @@
 #include <utility>
 #include <vector>
 
+#include "../../../../third_party/base/nonstd_unique_ptr.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_parser.h"
 #include "../../../include/fxcrt/fx_safe_types.h"
 #include "../fpdf_page/pageint.h"
 
+namespace {
+
+int CompareFileSize(const void* p1, const void* p2) {
+  return *(FX_FILESIZE*)p1 - *(FX_FILESIZE*)p2;
+}
+
+int32_t GetHeaderOffset(IFX_FileRead* pFile) {
+  const FX_DWORD tag = FXDWORD_FROM_LSBFIRST(0x46445025);
+  const size_t kBufSize = 4;
+  uint8_t buf[kBufSize];
+  int32_t offset = 0;
+  while (offset <= 1024) {
+    if (!pFile->ReadBlock(buf, offset, kBufSize))
+      return -1;
+
+    if (*(FX_DWORD*)buf == tag)
+      return offset;
+
+    ++offset;
+  }
+  return -1;
+}
+
+int32_t GetDirectInteger(CPDF_Dictionary* pDict, const CFX_ByteStringC& key) {
+  CPDF_Object* pObj = pDict->GetElement(key);
+  if (pObj && (pObj->GetType() == PDFOBJ_NUMBER))
+    return ((CPDF_Number*)pObj)->GetInteger();
+  return 0;
+}
+
+bool CheckDirectType(CPDF_Dictionary* pDict,
+                     const CFX_ByteStringC& key,
+                     int32_t iType) {
+  CPDF_Object* pObj = pDict->GetElement(key);
+  return !pObj || pObj->GetType() == iType;
+}
+
+FX_DWORD GetVarInt(const uint8_t* p, int32_t n) {
+  FX_DWORD result = 0;
+  for (int32_t i = 0; i < n; ++i)
+    result = result * 256 + p[i];
+  return result;
+}
+
+}  // namespace
+
 FX_BOOL IsSignatureDict(const CPDF_Dictionary* pDict) {
   CPDF_Object* pType = pDict->GetElementValue(FX_BSTRC("Type"));
   if (!pType) {
@@ -27,16 +74,6 @@ FX_BOOL IsSignatureDict(const CPDF_Dictionary* pDict) {
   }
   return FALSE;
 }
-static int _CompareFileSize(const void* p1, const void* p2) {
-  FX_FILESIZE ret = (*(FX_FILESIZE*)p1) - (*(FX_FILESIZE*)p2);
-  if (ret > 0) {
-    return 1;
-  }
-  if (ret < 0) {
-    return -1;
-  }
-  return 0;
-}
 
 CPDF_Parser::CPDF_Parser() {
   m_pDocument = NULL;
@@ -99,24 +136,6 @@ void CPDF_Parser::CloseParser(FX_BOOL bReParse) {
     m_pLinearized = NULL;
   }
 }
-static int32_t GetHeaderOffset(IFX_FileRead* pFile) {
-  FX_DWORD tag = FXDWORD_FROM_LSBFIRST(0x46445025);
-  uint8_t buf[4];
-  int32_t offset = 0;
-  while (1) {
-    if (!pFile->ReadBlock(buf, offset, 4)) {
-      return -1;
-    }
-    if (*(FX_DWORD*)buf == tag) {
-      return offset;
-    }
-    offset++;
-    if (offset > 1024) {
-      return -1;
-    }
-  }
-  return -1;
-}
 CPDF_SecurityHandler* FPDF_CreateStandardSecurityHandler();
 CPDF_SecurityHandler* FPDF_CreatePubKeyHandler(void*);
 FX_DWORD CPDF_Parser::StartParse(IFX_FileRead* pFileAccess,
@@ -159,7 +178,7 @@ FX_DWORD CPDF_Parser::StartParse(IFX_FileRead* pFileAccess,
     FX_FILESIZE startxref_offset = m_Syntax.SavePos();
     void* pResult = FXSYS_bsearch(&startxref_offset, m_SortedOffset.GetData(),
                                   m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-                                  _CompareFileSize);
+                                  CompareFileSize);
     if (pResult == NULL) {
       m_SortedOffset.Add(startxref_offset);
     }
@@ -207,7 +226,7 @@ FX_DWORD CPDF_Parser::StartParse(IFX_FileRead* pFileAccess,
     }
   }
   FXSYS_qsort(m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-              sizeof(FX_FILESIZE), _CompareFileSize);
+              sizeof(FX_FILESIZE), CompareFileSize);
   FX_DWORD RootObjNum = GetRootObjNum();
   if (RootObjNum == 0) {
     ReleaseEncryptHandler();
@@ -313,26 +332,7 @@ FX_FILESIZE CPDF_Parser::GetObjectOffset(FX_DWORD objnum) {
   }
   return 0;
 }
-static int32_t GetDirectInteger(CPDF_Dictionary* pDict,
-                                const CFX_ByteStringC& key) {
-  CPDF_Object* pObj = pDict->GetElement(key);
-  if (pObj == NULL) {
-    return 0;
-  }
-  if (pObj->GetType() == PDFOBJ_NUMBER) {
-    return ((CPDF_Number*)pObj)->GetInteger();
-  }
-  return 0;
-}
-static FX_BOOL CheckDirectType(CPDF_Dictionary* pDict,
-                               const CFX_ByteStringC& key,
-                               int32_t iType) {
-  CPDF_Object* pObj = pDict->GetElement(key);
-  if (!pObj) {
-    return TRUE;
-  }
-  return pObj->GetType() == iType;
-}
+
 FX_BOOL CPDF_Parser::LoadAllCrossRefV4(FX_FILESIZE xrefpos) {
   if (!LoadCrossRefV4(xrefpos, 0, TRUE, FALSE)) {
     return FALSE;
@@ -424,7 +424,7 @@ FX_BOOL CPDF_Parser::LoadLinearizedCrossRefV4(FX_FILESIZE pos,
   m_Syntax.RestorePos(dwStartPos);
   void* pResult =
       FXSYS_bsearch(&pos, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-                    sizeof(FX_FILESIZE), _CompareFileSize);
+                    sizeof(FX_FILESIZE), CompareFileSize);
   if (pResult == NULL) {
     m_SortedOffset.Add(pos);
   }
@@ -471,7 +471,7 @@ FX_BOOL CPDF_Parser::LoadLinearizedCrossRefV4(FX_FILESIZE pos,
         if (m_CrossRef[objnum] < m_Syntax.m_FileLen) {
           void* pResult = FXSYS_bsearch(
               &m_CrossRef[objnum], m_SortedOffset.GetData(),
-              m_SortedOffset.GetSize(), sizeof(FX_FILESIZE), _CompareFileSize);
+              m_SortedOffset.GetSize(), sizeof(FX_FILESIZE), CompareFileSize);
           if (pResult == NULL) {
             m_SortedOffset.Add(m_CrossRef[objnum]);
           }
@@ -484,51 +484,48 @@ FX_BOOL CPDF_Parser::LoadLinearizedCrossRefV4(FX_FILESIZE pos,
   m_Syntax.RestorePos(SavedPos + count * recordsize);
   return TRUE;
 }
-FX_BOOL CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos,
-                                    FX_FILESIZE streampos,
-                                    FX_BOOL bSkip,
-                                    FX_BOOL bFirst) {
+
+bool CPDF_Parser::FindPosInOffsets(FX_FILESIZE pos) const {
+  return FXSYS_bsearch(&pos, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
+                       sizeof(FX_FILESIZE), CompareFileSize);
+}
+
+bool CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos,
+                                 FX_FILESIZE streampos,
+                                 FX_BOOL bSkip,
+                                 FX_BOOL bFirst) {
   m_Syntax.RestorePos(pos);
-  if (m_Syntax.GetKeyword() != FX_BSTRC("xref")) {
-    return FALSE;
-  }
-  void* pResult =
-      FXSYS_bsearch(&pos, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-                    sizeof(FX_FILESIZE), _CompareFileSize);
-  if (pResult == NULL) {
+  if (m_Syntax.GetKeyword() != FX_BSTRC("xref"))
+    return false;
+
+  if (!FindPosInOffsets(pos))
     m_SortedOffset.Add(pos);
-  }
-  if (streampos) {
-    void* pResult = FXSYS_bsearch(&streampos, m_SortedOffset.GetData(),
-                                  m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-                                  _CompareFileSize);
-    if (pResult == NULL) {
+
+  if (streampos && !FindPosInOffsets(streampos))
       m_SortedOffset.Add(streampos);
-    }
-  }
+
   while (1) {
     FX_FILESIZE SavedPos = m_Syntax.SavePos();
     FX_BOOL bIsNumber;
     CFX_ByteString word = m_Syntax.GetNextWord(bIsNumber);
-    if (word.IsEmpty()) {
-      return FALSE;
-    }
+    if (word.IsEmpty())
+      return false;
+
     if (!bIsNumber) {
       m_Syntax.RestorePos(SavedPos);
       break;
     }
     FX_DWORD start_objnum = FXSYS_atoi(word);
-    if (start_objnum >= (1 << 20)) {
-      return FALSE;
-    }
+    if (start_objnum >= (1 << 20))
+      return false;
+
     FX_DWORD count = m_Syntax.GetDirectNum();
     m_Syntax.ToNextWord();
     SavedPos = m_Syntax.SavePos();
     FX_BOOL bFirstItem = FALSE;
     int32_t recordsize = 20;
-    if (bFirst) {
+    if (bFirst)
       bFirstItem = TRUE;
-    }
     m_dwXrefStartObjNum = start_objnum;
     if (!bSkip) {
       char* pBuf = FX_Alloc(char, 1024 * recordsize + 1);
@@ -562,7 +559,7 @@ FX_BOOL CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos,
               for (int32_t c = 0; c < 10; c++) {
                 if (pEntry[c] < '0' || pEntry[c] > '9') {
                   FX_Free(pBuf);
-                  return FALSE;
+                  return false;
                 }
               }
             }
@@ -572,14 +569,9 @@ FX_BOOL CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos,
               m_bVersionUpdated = TRUE;
             }
             m_ObjVersion.SetAtGrow(objnum, version);
-            if (m_CrossRef[objnum] < m_Syntax.m_FileLen) {
-              void* pResult =
-                  FXSYS_bsearch(&m_CrossRef[objnum], m_SortedOffset.GetData(),
-                                m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-                                _CompareFileSize);
-              if (pResult == NULL) {
-                m_SortedOffset.Add(m_CrossRef[objnum]);
-              }
+            if (m_CrossRef[objnum] < m_Syntax.m_FileLen &&
+                !FindPosInOffsets(m_CrossRef[objnum])) {
+              m_SortedOffset.Add(m_CrossRef[objnum]);
             }
             m_V5Type.SetAtGrow(objnum, 1);
           }
@@ -592,12 +584,9 @@ FX_BOOL CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos,
     }
     m_Syntax.RestorePos(SavedPos + count * recordsize);
   }
-  if (streampos)
-    if (!LoadCrossRefV5(streampos, streampos, FALSE)) {
-      return FALSE;
-    }
-  return TRUE;
+  return !streampos || LoadCrossRefV5(streampos, streampos, FALSE);
 }
+
 FX_BOOL CPDF_Parser::LoadAllCrossRefV5(FX_FILESIZE xrefpos) {
   if (!LoadCrossRefV5(xrefpos, xrefpos, TRUE)) {
     return FALSE;
@@ -772,7 +761,7 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                 void* pResult =
                     FXSYS_bsearch(&obj_pos, m_SortedOffset.GetData(),
                                   m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-                                  _CompareFileSize);
+                                  CompareFileSize);
                 if (pResult == NULL) {
                   m_SortedOffset.Add(obj_pos);
                 }
@@ -990,20 +979,14 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
   FX_FILESIZE offset = last_trailer - m_Syntax.m_HeaderOffset;
   void* pResult =
       FXSYS_bsearch(&offset, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-                    sizeof(FX_FILESIZE), _CompareFileSize);
+                    sizeof(FX_FILESIZE), CompareFileSize);
   if (pResult == NULL) {
     m_SortedOffset.Add(offset);
   }
   FX_Free(buffer);
   return TRUE;
 }
-static FX_DWORD _GetVarInt(const uint8_t* p, int32_t n) {
-  FX_DWORD result = 0;
-  for (int32_t i = 0; i < n; i++) {
-    result = result * 256 + p[i];
-  }
-  return result;
-}
+
 FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
                                     FX_FILESIZE& prev,
                                     FX_BOOL bMainXRef) {
@@ -1110,15 +1093,15 @@ FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
       int32_t type = 1;
       const uint8_t* entrystart = segstart + j * totalWidth;
       if (WidthArray[0]) {
-        type = _GetVarInt(entrystart, WidthArray[0]);
+        type = GetVarInt(entrystart, WidthArray[0]);
       }
       if (m_V5Type[startnum + j] == 255) {
         FX_FILESIZE offset =
-            _GetVarInt(entrystart + WidthArray[0], WidthArray[1]);
+            GetVarInt(entrystart + WidthArray[0], WidthArray[1]);
         m_CrossRef[startnum + j] = offset;
         void* pResult = FXSYS_bsearch(&offset, m_SortedOffset.GetData(),
                                       m_SortedOffset.GetSize(),
-                                      sizeof(FX_FILESIZE), _CompareFileSize);
+                                      sizeof(FX_FILESIZE), CompareFileSize);
         if (pResult == NULL) {
           m_SortedOffset.Add(offset);
         }
@@ -1132,12 +1115,12 @@ FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
         m_CrossRef[startnum + j] = 0;
       } else {
         FX_FILESIZE offset =
-            _GetVarInt(entrystart + WidthArray[0], WidthArray[1]);
+            GetVarInt(entrystart + WidthArray[0], WidthArray[1]);
         m_CrossRef[startnum + j] = offset;
         if (type == 1) {
           void* pResult = FXSYS_bsearch(&offset, m_SortedOffset.GetData(),
                                         m_SortedOffset.GetSize(),
-                                        sizeof(FX_FILESIZE), _CompareFileSize);
+                                        sizeof(FX_FILESIZE), CompareFileSize);
           if (pResult == NULL) {
             m_SortedOffset.Add(offset);
           }
@@ -1199,7 +1182,7 @@ FX_BOOL CPDF_Parser::IsFormStream(FX_DWORD objnum, FX_BOOL& bForm) {
   FX_FILESIZE pos = m_CrossRef[objnum];
   void* pResult =
       FXSYS_bsearch(&pos, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-                    sizeof(FX_FILESIZE), _CompareFileSize);
+                    sizeof(FX_FILESIZE), CompareFileSize);
   if (pResult == NULL) {
     return TRUE;
   }
@@ -1282,7 +1265,7 @@ FX_FILESIZE CPDF_Parser::GetObjectSize(FX_DWORD objnum) {
     }
     void* pResult = FXSYS_bsearch(&offset, m_SortedOffset.GetData(),
                                   m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-                                  _CompareFileSize);
+                                  CompareFileSize);
     if (pResult == NULL) {
       return 0;
     }
@@ -1363,7 +1346,7 @@ void CPDF_Parser::GetIndirectBinary(FX_DWORD objnum,
     }
     void* pResult =
         FXSYS_bsearch(&pos, m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-                      sizeof(FX_FILESIZE), _CompareFileSize);
+                      sizeof(FX_FILESIZE), CompareFileSize);
     if (pResult == NULL) {
       m_Syntax.RestorePos(SavedPos);
       return;
@@ -1642,7 +1625,7 @@ FX_DWORD CPDF_Parser::StartAsynParse(IFX_FileRead* pFileAccess,
     }
   }
   FXSYS_qsort(m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-              sizeof(FX_FILESIZE), _CompareFileSize);
+              sizeof(FX_FILESIZE), CompareFileSize);
   FX_DWORD RootObjNum = GetRootObjNum();
   if (RootObjNum == 0) {
     ReleaseEncryptHandler();
@@ -1714,7 +1697,7 @@ FX_DWORD CPDF_Parser::LoadLinearizedMainXRefTable() {
     return PDFPARSE_ERROR_FORMAT;
   }
   FXSYS_qsort(m_SortedOffset.GetData(), m_SortedOffset.GetSize(),
-              sizeof(FX_FILESIZE), _CompareFileSize);
+              sizeof(FX_FILESIZE), CompareFileSize);
   m_Syntax.m_MetadataObjnum = dwSaveMetadataObjnum;
   return PDFPARSE_ERROR_SUCCESS;
 }
@@ -1735,13 +1718,13 @@ CPDF_SyntaxParser::CPDF_SyntaxParser() {
 CPDF_SyntaxParser::~CPDF_SyntaxParser() {
   FX_Free(m_pFileBuf);
 }
+
 FX_BOOL CPDF_SyntaxParser::GetCharAt(FX_FILESIZE pos, uint8_t& ch) {
-  FX_FILESIZE save_pos = m_Pos;
+  CFX_AutoRestorer<FX_FILESIZE> save_pos(&m_Pos);
   m_Pos = pos;
-  FX_BOOL ret = GetNextChar(ch);
-  m_Pos = save_pos;
-  return ret;
+  return GetNextChar(ch);
 }
+
 FX_BOOL CPDF_SyntaxParser::GetNextChar(uint8_t& ch) {
   FX_FILESIZE pos = m_Pos + m_HeaderOffset;
   if (pos >= m_FileLen) {
@@ -2690,76 +2673,67 @@ FX_BOOL CPDF_SyntaxParser::SearchWord(const CFX_ByteStringC& tag,
   }
   return FALSE;
 }
+
 struct _SearchTagRecord {
   const uint8_t* m_pTag;
   FX_DWORD m_Len;
   FX_DWORD m_Offset;
 };
+
 int32_t CPDF_SyntaxParser::SearchMultiWord(const CFX_ByteStringC& tags,
                                            FX_BOOL bWholeWord,
                                            FX_FILESIZE limit) {
-  int32_t ntags = 1, i;
-  for (i = 0; i < tags.GetLength(); i++)
+  int32_t ntags = 1;
+  for (int i = 0; i < tags.GetLength(); ++i) {
     if (tags[i] == 0) {
-      ntags++;
+      ++ntags;
     }
-  _SearchTagRecord* pPatterns = FX_Alloc(_SearchTagRecord, ntags);
-  FX_DWORD start = 0, itag = 0, max_len = 0;
-  for (i = 0; i <= tags.GetLength(); i++) {
+  }
+
+  std::vector<_SearchTagRecord> patterns(ntags);
+  FX_DWORD start = 0;
+  FX_DWORD itag = 0;
+  FX_DWORD max_len = 0;
+  for (int i = 0; i <= tags.GetLength(); ++i) {
     if (tags[i] == 0) {
       FX_DWORD len = i - start;
-      if (len > max_len) {
-        max_len = len;
-      }
-      pPatterns[itag].m_pTag = tags.GetPtr() + start;
-      pPatterns[itag].m_Len = len;
-      pPatterns[itag].m_Offset = 0;
+      max_len = std::max(len, max_len);
+      patterns[itag].m_pTag = tags.GetPtr() + start;
+      patterns[itag].m_Len = len;
+      patterns[itag].m_Offset = 0;
       start = i + 1;
-      itag++;
+      ++itag;
     }
   }
-  FX_FILESIZE pos = m_Pos;
-  uint8_t byte;
-  GetCharAt(pos++, byte);
-  int32_t found = -1;
-  while (1) {
-    for (i = 0; i < ntags; i++) {
-      if (pPatterns[i].m_pTag[pPatterns[i].m_Offset] == byte) {
-        pPatterns[i].m_Offset++;
-        if (pPatterns[i].m_Offset == pPatterns[i].m_Len) {
-          if (!bWholeWord ||
-              IsWholeWord(pos - pPatterns[i].m_Len, limit, pPatterns[i].m_pTag,
-                          pPatterns[i].m_Len, FALSE)) {
-            found = i;
-            goto end;
-          } else {
-            if (pPatterns[i].m_pTag[0] == byte) {
-              pPatterns[i].m_Offset = 1;
-            } else {
-              pPatterns[i].m_Offset = 0;
-            }
-          }
-        }
-      } else {
-        if (pPatterns[i].m_pTag[0] == byte) {
-          pPatterns[i].m_Offset = 1;
-        } else {
-          pPatterns[i].m_Offset = 0;
-        }
+
+  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;
+        continue;
       }
+
+      ++pat.m_Offset;
+      if (pat.m_Offset != pat.m_Len)
+        continue;
+
+      if (!bWholeWord ||
+          IsWholeWord(pos - pat.m_Len, limit, pat.m_pTag, pat.m_Len, FALSE)) {
+        return i;
+      }
+
+      pat.m_Offset = (pat.m_pTag[0] == byte) ? 1 : 0;
     }
-    if (limit && pos >= m_Pos + limit) {
-      goto end;
-    }
-    if (!GetCharAt(pos, byte)) {
-      goto end;
-    }
-    pos++;
   }
-end:
-  FX_Free(pPatterns);
-  return found;
+  return -1;
 }
+
 FX_FILESIZE CPDF_SyntaxParser::FindTag(const CFX_ByteStringC& tag,
                                        FX_FILESIZE limit) {
   int32_t taglen = tag.GetLength();
@@ -2804,20 +2778,19 @@ class CPDF_DataAvail final : public IPDF_DataAvail {
   CPDF_DataAvail(IFX_FileAvail* pFileAvail, IFX_FileRead* pFileRead);
   ~CPDF_DataAvail() override;
 
-  virtual FX_BOOL IsDocAvail(IFX_DownloadHints* pHints) override;
+  FX_BOOL IsDocAvail(IFX_DownloadHints* pHints) override;
 
-  virtual void SetDocument(CPDF_Document* pDoc) override;
+  void SetDocument(CPDF_Document* pDoc) override;
 
-  virtual FX_BOOL IsPageAvail(int iPage, IFX_DownloadHints* pHints) override;
+  FX_BOOL IsPageAvail(int iPage, IFX_DownloadHints* pHints) override;
 
-  virtual int32_t IsFormAvail(IFX_DownloadHints* pHints) override;
+  int32_t IsFormAvail(IFX_DownloadHints* pHints) override;
 
-  virtual int32_t IsLinearizedPDF() override;
+  int32_t IsLinearizedPDF() override;
 
-  virtual FX_BOOL IsLinearized() override { return m_bLinearized; }
+  FX_BOOL IsLinearized() override { return m_bLinearized; }
 
-  virtual void GetLinearizedMainXRefInfo(FX_FILESIZE* pPos,
-                                         FX_DWORD* pSize) override;
+  void GetLinearizedMainXRefInfo(FX_FILESIZE* pPos, FX_DWORD* pSize) override;
 
  protected:
   static const int kMaxDataAvailRecursionDepth = 64;
@@ -3097,7 +3070,7 @@ FX_DWORD CPDF_DataAvail::GetObjectSize(FX_DWORD objnum, FX_FILESIZE& offset) {
     }
     void* pResult = FXSYS_bsearch(&offset, pParser->m_SortedOffset.GetData(),
                                   pParser->m_SortedOffset.GetSize(),
-                                  sizeof(FX_FILESIZE), _CompareFileSize);
+                                  sizeof(FX_FILESIZE), CompareFileSize);
     if (pResult == NULL) {
       return 0;
     }
@@ -3349,7 +3322,7 @@ FX_BOOL CPDF_DataAvail::LoadAllXref(IFX_DownloadHints* pHints) {
   }
   FXSYS_qsort(m_parser.m_SortedOffset.GetData(),
               m_parser.m_SortedOffset.GetSize(), sizeof(FX_FILESIZE),
-              _CompareFileSize);
+              CompareFileSize);
   m_dwRootObjNum = m_parser.GetRootObjNum();
   m_dwInfoObjNum = m_parser.GetInfoObjNum();
   m_pCurrentParser = &m_parser;
diff --git a/core/src/fxcodec/codec/fx_codec_flate.cpp b/core/src/fxcodec/codec/fx_codec_flate.cpp
index 37aecf106d..519ff00522 100644
--- a/core/src/fxcodec/codec/fx_codec_flate.cpp
+++ b/core/src/fxcodec/codec/fx_codec_flate.cpp
@@ -75,6 +75,8 @@ void FPDFAPI_FlateEnd(void* context) {
 }
 }  // extern "C"
 
+namespace {
+
 class CLZWDecoder {
  public:
   int Decode(uint8_t* output,
@@ -222,7 +224,8 @@ int CLZWDecoder::Decode(uint8_t* dest_buf,
   src_size = (m_InPos + 7) / 8;
   return 0;
 }
-static uint8_t PaethPredictor(int a, int b, int c) {
+
+uint8_t PaethPredictor(int a, int b, int c) {
   int p = a + b - c;
   int pa = FXSYS_abs(p - a);
   int pb = FXSYS_abs(p - b);
@@ -235,12 +238,13 @@ static uint8_t PaethPredictor(int a, int b, int c) {
   }
   return (uint8_t)c;
 }
-static FX_BOOL PNG_PredictorEncode(uint8_t*& data_buf,
-                                   FX_DWORD& data_size,
-                                   int predictor,
-                                   int Colors,
-                                   int BitsPerComponent,
-                                   int Columns) {
+
+FX_BOOL PNG_PredictorEncode(uint8_t*& data_buf,
+                            FX_DWORD& data_size,
+                            int predictor,
+                            int Colors,
+                            int BitsPerComponent,
+                            int Columns) {
   const int BytesPerPixel = (Colors * BitsPerComponent + 7) / 8;
   const int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
   if (row_size <= 0)
@@ -324,12 +328,13 @@ static FX_BOOL PNG_PredictorEncode(uint8_t*& data_buf,
               (last_row_size > 0 ? (row_size - last_row_size) : 0);
   return TRUE;
 }
-static void PNG_PredictLine(uint8_t* pDestData,
-                            const uint8_t* pSrcData,
-                            const uint8_t* pLastLine,
-                            int bpc,
-                            int nColors,
-                            int nPixels) {
+
+void PNG_PredictLine(uint8_t* pDestData,
+                     const uint8_t* pSrcData,
+                     const uint8_t* pLastLine,
+                     int bpc,
+                     int nColors,
+                     int nPixels) {
   int row_size = (nPixels * bpc * nColors + 7) / 8;
   int BytesPerPixel = (bpc * nColors + 7) / 8;
   uint8_t tag = pSrcData[0];
@@ -390,11 +395,12 @@ static void PNG_PredictLine(uint8_t* pDestData,
     }
   }
 }
-static FX_BOOL PNG_Predictor(uint8_t*& data_buf,
-                             FX_DWORD& data_size,
-                             int Colors,
-                             int BitsPerComponent,
-                             int Columns) {
+
+FX_BOOL PNG_Predictor(uint8_t*& data_buf,
+                      FX_DWORD& data_size,
+                      int Colors,
+                      int BitsPerComponent,
+                      int Columns) {
   const int BytesPerPixel = (Colors * BitsPerComponent + 7) / 8;
   const int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
   if (row_size <= 0)
@@ -483,11 +489,12 @@ static FX_BOOL PNG_Predictor(uint8_t*& data_buf,
               (last_row_size > 0 ? (row_size + 1 - last_row_size) : 0);
   return TRUE;
 }
-static void TIFF_PredictorEncodeLine(uint8_t* dest_buf,
-                                     int row_size,
-                                     int BitsPerComponent,
-                                     int Colors,
-                                     int Columns) {
+
+void TIFF_PredictorEncodeLine(uint8_t* dest_buf,
+                              int row_size,
+                              int BitsPerComponent,
+                              int Colors,
+                              int Columns) {
   int BytesPerPixel = BitsPerComponent * Colors / 8;
   if (BitsPerComponent < 8) {
     uint8_t mask = 0x01;
@@ -528,11 +535,12 @@ static void TIFF_PredictorEncodeLine(uint8_t* dest_buf,
     }
   }
 }
-static FX_BOOL TIFF_PredictorEncode(uint8_t*& data_buf,
-                                    FX_DWORD& data_size,
-                                    int Colors,
-                                    int BitsPerComponent,
-                                    int Columns) {
+
+FX_BOOL TIFF_PredictorEncode(uint8_t*& data_buf,
+                             FX_DWORD& data_size,
+                             int Colors,
+                             int BitsPerComponent,
+                             int Columns) {
   int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
   if (row_size == 0)
     return FALSE;
@@ -548,11 +556,12 @@ static FX_BOOL TIFF_PredictorEncode(uint8_t*& data_buf,
   }
   return TRUE;
 }
-static void TIFF_PredictLine(uint8_t* dest_buf,
-                             int row_size,
-                             int BitsPerComponent,
-                             int Colors,
-                             int Columns) {
+
+void TIFF_PredictLine(uint8_t* dest_buf,
+                      int row_size,
+                      int BitsPerComponent,
+                      int Colors,
+                      int Columns) {
   if (BitsPerComponent == 1) {
     int row_bits = FX_MIN(BitsPerComponent * Colors * Columns, row_size * 8);
     int index_pre = 0;
@@ -586,11 +595,12 @@ static void TIFF_PredictLine(uint8_t* dest_buf,
     }
   }
 }
-static FX_BOOL TIFF_Predictor(uint8_t*& data_buf,
-                              FX_DWORD& data_size,
-                              int Colors,
-                              int BitsPerComponent,
-                              int Columns) {
+
+FX_BOOL TIFF_Predictor(uint8_t*& data_buf,
+                       FX_DWORD& data_size,
+                       int Colors,
+                       int BitsPerComponent,
+                       int Columns) {
   int row_size = (Colors * BitsPerComponent * Columns + 7) / 8;
   if (row_size == 0)
     return FALSE;
@@ -606,6 +616,120 @@ static FX_BOOL TIFF_Predictor(uint8_t*& data_buf,
   return TRUE;
 }
 
+void FlateUncompress(const uint8_t* src_buf,
+                     FX_DWORD src_size,
+                     FX_DWORD orig_size,
+                     uint8_t*& dest_buf,
+                     FX_DWORD& dest_size,
+                     FX_DWORD& offset) {
+  FX_DWORD guess_size = orig_size ? orig_size : src_size * 2;
+  const FX_DWORD kStepSize = 10240;
+  FX_DWORD alloc_step = orig_size ? kStepSize : std::min(src_size, kStepSize);
+  static const FX_DWORD kMaxInitialAllocSize = 10000000;
+  if (guess_size > kMaxInitialAllocSize) {
+    guess_size = kMaxInitialAllocSize;
+    alloc_step = kMaxInitialAllocSize;
+  }
+  FX_DWORD buf_size = guess_size;
+  FX_DWORD last_buf_size = buf_size;
+
+  dest_buf = nullptr;
+  dest_size = 0;
+  void* context = FPDFAPI_FlateInit(my_alloc_func, my_free_func);
+  if (!context)
+    return;
+
+  nonstd::unique_ptr<uint8_t, FxFreeDeleter> guess_buf(
+      FX_Alloc(uint8_t, guess_size + 1));
+  guess_buf.get()[guess_size] = '\0';
+
+  FPDFAPI_FlateInput(context, src_buf, src_size);
+
+  if (src_size < kStepSize) {
+    // This is the old implementation.
+    uint8_t* cur_buf = guess_buf.get();
+    while (1) {
+      int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
+      if (ret != Z_OK)
+        break;
+      int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
+      if (avail_buf_size != 0)
+        break;
+
+      FX_DWORD old_size = guess_size;
+      guess_size += alloc_step;
+      if (guess_size < old_size || guess_size + 1 < guess_size) {
+        FPDFAPI_FlateEnd(context);
+        return;
+      }
+
+      {
+        uint8_t* new_buf =
+            FX_Realloc(uint8_t, guess_buf.release(), guess_size + 1);
+        guess_buf.reset(new_buf);
+      }
+      guess_buf.get()[guess_size] = '\0';
+      cur_buf = guess_buf.get() + old_size;
+      buf_size = guess_size - old_size;
+    }
+    dest_size = FPDFAPI_FlateGetTotalOut(context);
+    offset = FPDFAPI_FlateGetTotalIn(context);
+    if (guess_size / 2 > dest_size) {
+      {
+        uint8_t* new_buf =
+            FX_Realloc(uint8_t, guess_buf.release(), dest_size + 1);
+        guess_buf.reset(new_buf);
+      }
+      guess_size = dest_size;
+      guess_buf.get()[guess_size] = '\0';
+    }
+    dest_buf = guess_buf.release();
+  } else {
+    CFX_ArrayTemplate<uint8_t*> result_tmp_bufs;
+    uint8_t* cur_buf = guess_buf.release();
+    while (1) {
+      int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
+      int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
+      if (ret != Z_OK) {
+        last_buf_size = buf_size - avail_buf_size;
+        result_tmp_bufs.Add(cur_buf);
+        break;
+      }
+      if (avail_buf_size != 0) {
+        last_buf_size = buf_size - avail_buf_size;
+        result_tmp_bufs.Add(cur_buf);
+        break;
+      }
+
+      result_tmp_bufs.Add(cur_buf);
+      cur_buf = FX_Alloc(uint8_t, buf_size + 1);
+      cur_buf[buf_size] = '\0';
+    }
+    dest_size = FPDFAPI_FlateGetTotalOut(context);
+    offset = FPDFAPI_FlateGetTotalIn(context);
+    if (result_tmp_bufs.GetSize() == 1) {
+      dest_buf = result_tmp_bufs[0];
+    } else {
+      uint8_t* result_buf = FX_Alloc(uint8_t, dest_size);
+      FX_DWORD result_pos = 0;
+      for (int32_t i = 0; i < result_tmp_bufs.GetSize(); i++) {
+        uint8_t* tmp_buf = result_tmp_bufs[i];
+        FX_DWORD tmp_buf_size = buf_size;
+        if (i == result_tmp_bufs.GetSize() - 1) {
+          tmp_buf_size = last_buf_size;
+        }
+        FXSYS_memcpy(result_buf + result_pos, tmp_buf, tmp_buf_size);
+        result_pos += tmp_buf_size;
+        FX_Free(result_tmp_bufs[i]);
+      }
+      dest_buf = result_buf;
+    }
+  }
+  FPDFAPI_FlateEnd(context);
+}
+
+}  // namespace
+
 class CCodec_FlateScanlineDecoder : public CCodec_ScanlineDecoder {
  public:
   CCodec_FlateScanlineDecoder();
@@ -761,113 +885,7 @@ uint8_t* CCodec_FlateScanlineDecoder::v_GetNextLine() {
 FX_DWORD CCodec_FlateScanlineDecoder::GetSrcOffset() {
   return FPDFAPI_FlateGetTotalIn(m_pFlate);
 }
-static void FlateUncompress(const uint8_t* src_buf,
-                            FX_DWORD src_size,
-                            FX_DWORD orig_size,
-                            uint8_t*& dest_buf,
-                            FX_DWORD& dest_size,
-                            FX_DWORD& offset) {
-  const FX_BOOL useOldImpl = src_size < 10240;
-  FX_DWORD guess_size = orig_size ? orig_size : src_size * 2;
-  FX_DWORD alloc_step =
-      orig_size ? 10240 : (src_size < 10240 ? 10240 : src_size);
-  static const FX_DWORD kMaxInitialAllocSize = 10000000;
-  if (guess_size > kMaxInitialAllocSize) {
-    guess_size = kMaxInitialAllocSize;
-    alloc_step = kMaxInitialAllocSize;
-  }
-  FX_DWORD buf_size = guess_size;
-  FX_DWORD last_buf_size = buf_size;
-  void* context = nullptr;
 
-  uint8_t* guess_buf = FX_Alloc(uint8_t, guess_size + 1);
-  uint8_t* cur_buf = guess_buf;
-  guess_buf[guess_size] = '\0';
-  context = FPDFAPI_FlateInit(my_alloc_func, my_free_func);
-  if (!context)
-    goto fail;
-  FPDFAPI_FlateInput(context, src_buf, src_size);
-  if (useOldImpl) {
-    while (1) {
-      int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
-      if (ret != Z_OK)
-        break;
-      int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
-      if (avail_buf_size != 0)
-        break;
-
-      // |avail_buf_size| == 0 case.
-      FX_DWORD old_size = guess_size;
-      guess_size += alloc_step;
-      if (guess_size < old_size || guess_size + 1 < guess_size)
-        goto fail;
-      guess_buf = FX_Realloc(uint8_t, guess_buf, guess_size + 1);
-      if (!guess_buf)
-        goto fail;
-      guess_buf[guess_size] = '\0';
-      cur_buf = guess_buf + old_size;
-      buf_size = guess_size - old_size;
-    }
-    dest_size = FPDFAPI_FlateGetTotalOut(context);
-    offset = FPDFAPI_FlateGetTotalIn(context);
-    if (guess_size / 2 > dest_size) {
-      guess_buf = FX_Realloc(uint8_t, guess_buf, dest_size + 1);
-      if (!guess_buf)
-        goto fail;
-      guess_size = dest_size;
-      guess_buf[guess_size] = '\0';
-    }
-    dest_buf = guess_buf;
-  } else {
-    CFX_ArrayTemplate<uint8_t*> result_tmp_bufs;
-    while (1) {
-      int32_t ret = FPDFAPI_FlateOutput(context, cur_buf, buf_size);
-      int32_t avail_buf_size = FPDFAPI_FlateGetAvailOut(context);
-      if (ret != Z_OK) {
-        last_buf_size = buf_size - avail_buf_size;
-        result_tmp_bufs.Add(cur_buf);
-        break;
-      }
-      if (avail_buf_size != 0) {
-        last_buf_size = buf_size - avail_buf_size;
-        result_tmp_bufs.Add(cur_buf);
-        break;
-      }
-
-      // |avail_buf_size| == 0 case.
-      result_tmp_bufs.Add(cur_buf);
-      cur_buf = FX_Alloc(uint8_t, buf_size + 1);
-      cur_buf[buf_size] = '\0';
-    }
-    dest_size = FPDFAPI_FlateGetTotalOut(context);
-    offset = FPDFAPI_FlateGetTotalIn(context);
-    if (result_tmp_bufs.GetSize() == 1) {
-      dest_buf = result_tmp_bufs[0];
-    } else {
-      uint8_t* result_buf = FX_Alloc(uint8_t, dest_size);
-      FX_DWORD result_pos = 0;
-      for (int32_t i = 0; i < result_tmp_bufs.GetSize(); i++) {
-        uint8_t* tmp_buf = result_tmp_bufs[i];
-        FX_DWORD tmp_buf_size = buf_size;
-        if (i == result_tmp_bufs.GetSize() - 1) {
-          tmp_buf_size = last_buf_size;
-        }
-        FXSYS_memcpy(result_buf + result_pos, tmp_buf, tmp_buf_size);
-        result_pos += tmp_buf_size;
-        FX_Free(result_tmp_bufs[i]);
-      }
-      dest_buf = result_buf;
-    }
-  }
-  FPDFAPI_FlateEnd(context);
-  return;
-
-fail:
-  FX_Free(guess_buf);
-  dest_buf = nullptr;
-  dest_size = 0;
-  return;
-}
 ICodec_ScanlineDecoder* CCodec_FlateModule::CreateDecoder(
     const uint8_t* src_buf,
     FX_DWORD src_size,