Fix MSVC warnings about possible value truncation.

src/cff_type2_charstring.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A parser for the Type 2 Charstring Format.
 // http://www.adobe.com/devnet/font/pdfs/5177.Type2.pdf
 
 #include "cff_type2_charstring.h"
 
 #include <climits>
@@ skipping 712 matching lines @@
 
 namespace ots {
 
 bool ValidateType2CharStringIndex(
     const CFFIndex& char_strings_index,
     const CFFIndex& global_subrs_index,
     const std::map<uint16_t, uint8_t> &fd_select,
     const std::vector<CFFIndex *> &local_subrs_per_font,
     const CFFIndex *local_subrs,
     Buffer* cff_table) {
-  if (char_strings_index.offsets.size() == 0) {
+  const uint16_t num_offsets =
+      static_cast<uint16_t>(char_strings_index.offsets.size());
+  if (num_offsets != char_strings_index.offsets.size() || num_offsets == 0) {
     return OTS_FAILURE();  // no charstring.
   }
 
   // For each glyph, validate the corresponding charstring.
-  for (unsigned i = 1; i < char_strings_index.offsets.size(); ++i) {
+  for (uint16_t i = 1; i < num_offsets; ++i) {
     // Prepare a Buffer object, |char_string|, which contains the charstring
     // for the |i|-th glyph.
     const size_t length =
       char_strings_index.offsets[i] - char_strings_index.offsets[i - 1];
     if (length > kMaxCharStringLength) {
       return OTS_FAILURE();
     }
     const size_t offset = char_strings_index.offsets[i - 1];
     cff_table->set_offset(offset);
     if (!cff_table->Skip(length)) {
       return OTS_FAILURE();
     }
     Buffer char_string(cff_table->buffer() + offset, length);
 
     // Get a local subrs for the glyph.
-    const unsigned glyph_index = i - 1;  // index in the map is 0-origin.
+    const uint16_t glyph_index = i - 1;  // index in the map is 0-origin.
     const CFFIndex *local_subrs_to_use = NULL;
     if (!SelectLocalSubr(fd_select,
                          local_subrs_per_font,
                          local_subrs,
                          glyph_index,
                          &local_subrs_to_use)) {
       return OTS_FAILURE();
     }
     // If |local_subrs_to_use| is still NULL, use an empty one.
     CFFIndex default_empty_subrs;
@@ skipping 13 matching lines @@
       return OTS_FAILURE();
     }
     if (!found_endchar) {
       return OTS_FAILURE();
     }
   }
   return true;
 }
 
 }  // namespace ots