Use unsigned type for iteration to avoid int overflow.

core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.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/fpdfapi/fpdf_parser.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fxcodec/fx_codec.h"
 #include <limits.h>
 #define _STREAM_MAX_SIZE_               20 * 1024 * 1024
 FX_DWORD _A85Decode(const FX_BYTE* src_buf, FX_DWORD src_size, FX_LPBYTE& dest_buf, FX_DWORD& dest_size)
 {
     dest_size = 0;
@@ skipping 380 matching lines @@
     0x00dc, 0x00dd, 0x00de, 0x00df, 0x00e0, 0x00e1, 0x00e2, 0x00e3, 0x00e4, 0x00e5,
     0x00e6, 0x00e7, 0x00e8, 0x00e9, 0x00ea, 0x00eb, 0x00ec, 0x00ed, 0x00ee, 0x00ef,
     0x00f0, 0x00f1, 0x00f2, 0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7, 0x00f8, 0x00f9,
     0x00fa, 0x00fb, 0x00fc, 0x00fd, 0x00fe, 0x00ff
 };
 CFX_WideString PDF_DecodeText(FX_LPCBYTE src_data, FX_DWORD src_len, CFX_CharMap* pCharMap)
 {
     CFX_WideString result;
     if (src_len >= 2 && ((src_data[0] == 0xfe && src_data[1] == 0xff) || (src_data[0] == 0xff && src_data[1] == 0xfe))) {
         FX_BOOL bBE = src_data[0] == 0xfe;
-        int max_chars = (src_len - 2) / 2;
+        FX_DWORD max_chars = (src_len - 2) / 2;
         if (!max_chars) {
             return result;
         }
         if (src_data[0] == 0xff) {
             bBE = !src_data[2];
         }
         FX_LPWSTR dest_buf = result.GetBuffer(max_chars);
         FX_LPCBYTE uni_str = src_data + 2;
         int dest_pos = 0;
-        for (int i = 0; i < max_chars * 2; i += 2) {
+        for (FX_DWORD i = 0; i < max_chars * 2; i += 2) {
             FX_WORD unicode = bBE ? (uni_str[i] << 8 | uni_str[i + 1]) : (uni_str[i + 1] << 8 | uni_str[i]);
             if (unicode == 0x1b) {
                 i += 2;
                 while (i < max_chars * 2) {
                     FX_WORD unicode = bBE ? (uni_str[i] << 8 | uni_str[i + 1]) : (uni_str[i + 1] << 8 | uni_str[i]);
                     i += 2;
                     if (unicode == 0x1b) {
                         break;
                     }
                 }
@@ skipping 99 matching lines @@
     }
 }
 FX_DWORD FlateDecode(const FX_BYTE* src_buf, FX_DWORD src_size, FX_LPBYTE& dest_buf, FX_DWORD& dest_size)
 {
     CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
     if (pEncoders) {
         return pEncoders->GetFlateModule()->FlateOrLZWDecode(FALSE, src_buf, src_size, FALSE, 0, 0, 0, 0, 0, dest_buf, dest_size);
     }
     return 0;
 }