Avoid crashing on CPDF_ToUnicodeMap::Load by using ValueOrDefault()

core/fpdfapi/font/fpdf_font.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/fpdfapi/font/font_int.h"
 
 #include "core/fpdfapi/cpdf_modulemgr.h"
 #include "core/fpdfapi/page/cpdf_form.h"
@@ skipping 181 matching lines @@
     }
     return result;
   }
   return result;
 }
 
 CPDF_ToUnicodeMap::CPDF_ToUnicodeMap() : m_pBaseMap(nullptr) {}
 
 CPDF_ToUnicodeMap::~CPDF_ToUnicodeMap() {}
 
+uint32_t CPDF_ToUnicodeMap::GetUnicode() {
+  FX_SAFE_UINT32 uni = m_MultiCharBuf.GetLength();
+  uni = uni * 0x10000 + 0xffff;
+  return uni.ValueOrDefault(0);
+}
+
 void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
   CIDSet cid_set = CIDSET_UNKNOWN;
   CPDF_StreamAcc stream;
   stream.LoadAllData(pStream, FALSE);
   CPDF_SimpleParser parser(stream.GetData(), stream.GetSize());
   while (1) {
     CFX_ByteStringC word = parser.GetWord();
     if (word.IsEmpty()) {
       break;
     }
     if (word == "beginbfchar") {
       while (1) {
         word = parser.GetWord();
         if (word.IsEmpty() || word == "endbfchar") {
           break;
         }
         uint32_t srccode = StringToCode(word);
         word = parser.GetWord();
         CFX_WideString destcode = StringToWideString(word);
         int len = destcode.GetLength();
         if (len == 0) {
           continue;
         }
         if (len == 1) {
           m_Map[srccode] = destcode.GetAt(0);
         } else {
-          FX_SAFE_UINT32 uni = m_MultiCharBuf.GetLength();
-          uni *= 0x10000;
-          uni += 0xffff;
-          m_Map[srccode] = uni.ValueOrDie();
+          m_Map[srccode] = GetUnicode();
           m_MultiCharBuf.AppendChar(destcode.GetLength());
           m_MultiCharBuf << destcode;
         }
       }
     } else if (word == "beginbfrange") {
       while (1) {
         CFX_ByteString low, high;
         low = parser.GetWord();
         if (low.IsEmpty() || low == "endbfrange") {
           break;
@@ skipping 10 matching lines @@
           for (uint32_t code = lowcode; code <= highcode; code++) {
             CFX_ByteString dest(parser.GetWord());
             CFX_WideString destcode = StringToWideString(dest.AsStringC());
             int len = destcode.GetLength();
             if (len == 0) {
               continue;
             }
             if (len == 1) {
               m_Map[code] = destcode.GetAt(0);
             } else {
-              FX_SAFE_UINT32 uni = m_MultiCharBuf.GetLength();
-              uni *= 0x10000;
-              uni += 0xffff;
-              m_Map[code] = uni.ValueOrDie();
+              m_Map[code] = GetUnicode();
               m_MultiCharBuf.AppendChar(destcode.GetLength());
               m_MultiCharBuf << destcode;
             }
           }
           parser.GetWord();
         } else {
           CFX_WideString destcode = StringToWideString(start.AsStringC());
           int len = destcode.GetLength();
           uint32_t value = 0;
           if (len == 1) {
             value = StringToCode(start.AsStringC());
             for (uint32_t code = lowcode; code <= highcode; code++) {
               m_Map[code] = value++;
             }
           } else {
             for (uint32_t code = lowcode; code <= highcode; code++) {
               CFX_WideString retcode;
               if (code == lowcode) {
                 retcode = destcode;
               } else {
                 retcode = StringDataAdd(destcode);
               }
-              FX_SAFE_UINT32 uni = m_MultiCharBuf.GetLength();
-              uni *= 0x10000;
-              uni += 0xffff;
-              m_Map[code] = uni.ValueOrDie();
+              m_Map[code] = GetUnicode();
               m_MultiCharBuf.AppendChar(retcode.GetLength());
               m_MultiCharBuf << retcode;
               destcode = retcode;
             }
           }
         }
       }
     } else if (word == "/Adobe-Korea1-UCS2") {
       cid_set = CIDSET_KOREA1;
     } else if (word == "/Adobe-Japan1-UCS2") {
       cid_set = CIDSET_JAPAN1;
     } else if (word == "/Adobe-CNS1-UCS2") {
       cid_set = CIDSET_CNS1;
     } else if (word == "/Adobe-GB1-UCS2") {
       cid_set = CIDSET_GB1;
     }
   }
   if (cid_set) {
     m_pBaseMap = CPDF_ModuleMgr::Get()
                      ->GetPageModule()
                      ->GetFontGlobals()
                      ->m_CMapManager.GetCID2UnicodeMap(cid_set, FALSE);
   } else {
     m_pBaseMap = nullptr;
   }
 }