Fix an out-of-boundary issue for wide string

core/src/fxcrt/fx_basic_wstring.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 "../../include/fxcrt/fx_basic.h"
 #include "../../../third_party/numerics/safe_math.h"
 
 static CFX_StringDataW* FX_AllocStringW(int nLen)
@@ skipping 380 matching lines @@
     return m_pData->m_String;
 }
 CFX_WideString CFX_WideString::FromLocal(const char* str, FX_STRSIZE len)
 {
     CFX_WideString result;
     result.ConvertFrom(CFX_ByteString(str, len));
     return result;
 }
 CFX_WideString CFX_WideString::FromUTF8(const char* str, FX_STRSIZE len)
 {
-    if (!str) {
+    if (!str || 0 == len) {
         return CFX_WideString();
     }
-    if (len < 0) {
-        len = 0;
-        while (str[len]) {
-            len ++;
-        }
-    }
+
     CFX_UTF8Decoder decoder;
     for (FX_STRSIZE i = 0; i < len; i ++) {
         decoder.Input(str[i]);
     }
     return decoder.GetResult();
 }
 CFX_WideString CFX_WideString::FromUTF16LE(const unsigned short* wstr, FX_STRSIZE wlen)
 {
-    if (!wstr || !wlen) {
+    if (!wstr || 0 == wlen) {
         return CFX_WideString();
     }
-    if (wlen < 0) {
-        wlen = 0;
-        while (wstr[wlen]) {
-            wlen ++;
-        }
-    }
+
     CFX_WideString result;
     FX_WCHAR* buf = result.GetBuffer(wlen);
     for (int i = 0; i < wlen; i ++) {
         buf[i] = wstr[i];
     }
     result.ReleaseBuffer(wlen);
     return result;
 }
+FX_STRSIZE CFX_WideString::WStringLength(const unsigned short* str)
+{
+    FX_STRSIZE len = 0;
+    if (str)
+        while (str[len]) len++;
+    return len;
+}
+
+
+
 void CFX_WideString::AllocCopy(CFX_WideString& dest, FX_STRSIZE nCopyLen, FX_STRSIZE nCopyIndex) const
 {
     // |FX_STRSIZE| is currently typedef'd as in |int|. TODO(palmer): It
     // should be a |size_t|, or at least unsigned.
     if (nCopyLen == 0 || nCopyLen < 0) {
         return;
     }
     base::CheckedNumeric<FX_STRSIZE> iSize = static_cast<FX_STRSIZE>(sizeof(FX_WCHAR));
     iSize *= nCopyLen;
     ASSERT(dest.m_pData == NULL);
@@ skipping 675 matching lines @@
             return (CFX_CharMap*)&g_DefaultJISMapper;
         case 936:
             return (CFX_CharMap*)&g_DefaultGBKMapper;
         case 949:
             return (CFX_CharMap*)&g_DefaultUHCMapper;
         case 950:
             return (CFX_CharMap*)&g_DefaultBig5Mapper;
     }
     return NULL;
 }