Fix a sentinel length value used in CFX_CMapByteStringToPtr::SetAt

core/src/fxcrt/fx_basic_maps.cpp

 // Copyright 2014 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/include/fxcrt/fx_basic.h"
 #include "plex.h"
 
+namespace {
+
+const uint8_t kFreeLength = 0xfe;
+const uint8_t kHasAllocatedBufferLength = 0xff;
+
+}  // namespace
+
 CFX_MapPtrToPtr::CFX_MapPtrToPtr(int nBlockSize)
     : m_pHashTable(NULL),
       m_nHashTableSize(17),
       m_nCount(0),
       m_pFreeList(NULL),
       m_pBlocks(NULL),
       m_nBlockSize(nBlockSize) {
   ASSERT(m_nBlockSize > 0);
 }
 void CFX_MapPtrToPtr::RemoveAll() {
@@ skipping 138 matching lines @@
   }
 }
 struct _CompactString {
   uint8_t m_CompactLen;
   uint8_t m_LenHigh;
   uint8_t m_LenLow;
   uint8_t m_Unused;
   uint8_t* m_pBuffer;
 };
 static void _CompactStringRelease(_CompactString* pCompact) {
-  if (pCompact->m_CompactLen == 0xff) {
+  if (pCompact->m_CompactLen == kHasAllocatedBufferLength) {
     FX_Free(pCompact->m_pBuffer);
   }
 }
 static FX_BOOL _CompactStringSame(_CompactString* pCompact,
                                   const uint8_t* pStr,
                                   int len) {
   if (len < sizeof(_CompactString)) {
     if (pCompact->m_CompactLen != len) {
       return FALSE;
     }
     return FXSYS_memcmp(&pCompact->m_LenHigh, pStr, len) == 0;
   }
-  if (pCompact->m_CompactLen != 0xff ||
+  if (pCompact->m_CompactLen != kHasAllocatedBufferLength ||
       pCompact->m_LenHigh * 256 + pCompact->m_LenLow != len) {
     return FALSE;
   }
   return FXSYS_memcmp(pCompact->m_pBuffer, pStr, len) == 0;
 }
 static void _CompactStringStore(_CompactString* pCompact,
                                 const uint8_t* pStr,
                                 int len) {
   if (len < (int)sizeof(_CompactString)) {
     pCompact->m_CompactLen = (uint8_t)len;
     FXSYS_memcpy(&pCompact->m_LenHigh, pStr, len);
     return;
   }
-  pCompact->m_CompactLen = 0xff;
+  pCompact->m_CompactLen = kHasAllocatedBufferLength;
   pCompact->m_LenHigh = len / 256;
   pCompact->m_LenLow = len % 256;
   pCompact->m_pBuffer = FX_Alloc(uint8_t, len);
   FXSYS_memcpy(pCompact->m_pBuffer, pStr, len);
 }
 static CFX_ByteStringC _CompactStringGet(_CompactString* pCompact) {
-  if (pCompact->m_CompactLen == 0xff) {
+  if (pCompact->m_CompactLen == kHasAllocatedBufferLength) {
     return CFX_ByteStringC(pCompact->m_pBuffer,
                            pCompact->m_LenHigh * 256 + pCompact->m_LenLow);
   }
-  if (pCompact->m_CompactLen == 0xfe) {
+  if (pCompact->m_CompactLen == kFreeLength) {
     return CFX_ByteStringC();
   }
   return CFX_ByteStringC(&pCompact->m_LenHigh, pCompact->m_CompactLen);
 }
 #define CMAP_ALLOC_STEP 8
 #define CMAP_INDEX_SIZE 8
 CFX_CMapByteStringToPtr::CFX_CMapByteStringToPtr()
     : m_Buffer(sizeof(_CompactString) + sizeof(void*),
                CMAP_ALLOC_STEP,
                CMAP_INDEX_SIZE) {}
 CFX_CMapByteStringToPtr::~CFX_CMapByteStringToPtr() {
   RemoveAll();
 }
 void CFX_CMapByteStringToPtr::RemoveAll() {
   int size = m_Buffer.GetSize();
   for (int i = 0; i < size; i++) {
     _CompactStringRelease((_CompactString*)m_Buffer.GetAt(i));
   }
   m_Buffer.RemoveAll();
 }
 FX_POSITION CFX_CMapByteStringToPtr::GetStartPosition() const {
   int size = m_Buffer.GetSize();
   for (int i = 0; i < size; i++) {
     _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(i);
-    if (pKey->m_CompactLen != 0xfe) {
+    if (pKey->m_CompactLen != kFreeLength) {
       return (FX_POSITION)(uintptr_t)(i + 1);
     }
   }
   return NULL;
 }
 void CFX_CMapByteStringToPtr::GetNextAssoc(FX_POSITION& rNextPosition,
                                            CFX_ByteString& rKey,
                                            void*& rValue) const {
   if (!rNextPosition) {
     return;
   }
   int index = (int)(uintptr_t)rNextPosition - 1;
   _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(index);
   rKey = _CompactStringGet(pKey);
   rValue = *(void**)(pKey + 1);
   index++;
   int size = m_Buffer.GetSize();
   while (index < size) {
     pKey = (_CompactString*)m_Buffer.GetAt(index);
-    if (pKey->m_CompactLen != 0xfe) {
+    if (pKey->m_CompactLen != kFreeLength) {
       rNextPosition = (FX_POSITION)(uintptr_t)(index + 1);
       return;
     }
     index++;
   }
   rNextPosition = NULL;
 }
 void* CFX_CMapByteStringToPtr::GetNextValue(FX_POSITION& rNextPosition) const {
   if (!rNextPosition) {
     return NULL;
   }
   int index = (int)(uintptr_t)rNextPosition - 1;
   _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(index);
   void* rValue = *(void**)(pKey + 1);
   index++;
   int size = m_Buffer.GetSize();
   while (index < size) {
     pKey = (_CompactString*)m_Buffer.GetAt(index);
-    if (pKey->m_CompactLen != 0xfe) {
+    if (pKey->m_CompactLen != kFreeLength) {
       rNextPosition = (FX_POSITION)(uintptr_t)(index + 1);
       return rValue;
     }
     index++;
   }
   rNextPosition = NULL;
   return rValue;
 }
 FX_BOOL _CMapLookupCallback(void* param, void* pData) {
   return !_CompactStringSame((_CompactString*)pData,
@@ skipping 16 matching lines @@
   for (int index = 0; index < size; index++) {
     _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(index);
     if (!_CompactStringSame(pKey, key.GetPtr(), key_len)) {
       continue;
     }
     *(void**)(pKey + 1) = value;
     return;
   }
   for (int index = 0; index < size; index++) {
     _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(index);
-    if (pKey->m_CompactLen) {
+    if (pKey->m_CompactLen != kFreeLength) {
       continue;
     }
     _CompactStringStore(pKey, key.GetPtr(), key_len);
     *(void**)(pKey + 1) = value;
     return;
   }
   _CompactString* pKey = (_CompactString*)m_Buffer.Add();
   _CompactStringStore(pKey, key.GetPtr(), key_len);
   *(void**)(pKey + 1) = value;
 }
 void CFX_CMapByteStringToPtr::AddValue(const CFX_ByteStringC& key,
                                        void* value) {
   ASSERT(value);
   _CompactString* pKey = (_CompactString*)m_Buffer.Add();
   _CompactStringStore(pKey, key.GetPtr(), key.GetLength());
   *(void**)(pKey + 1) = value;
 }
 void CFX_CMapByteStringToPtr::RemoveKey(const CFX_ByteStringC& key) {
   int key_len = key.GetLength();
   int size = m_Buffer.GetSize();
   for (int index = 0; index < size; index++) {
     _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(index);
     if (!_CompactStringSame(pKey, key.GetPtr(), key_len)) {
       continue;
     }
     _CompactStringRelease(pKey);
-    pKey->m_CompactLen = 0xfe;
+    pKey->m_CompactLen = kFreeLength;
     return;
   }
 }
 int CFX_CMapByteStringToPtr::GetCount() const {
   int count = 0;
   int size = m_Buffer.GetSize();
   for (int i = 0; i < size; i++) {
     _CompactString* pKey = (_CompactString*)m_Buffer.GetAt(i);
-    if (pKey->m_CompactLen != 0xfe) {
+    if (pKey->m_CompactLen != kFreeLength) {
       count++;
     }
   }
   return count;
 }