This fixes a number of things that are warnings in the Mac compiler....

import/cross/tar_generator.cc

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 89 matching lines @@
   // File mode
   ::snprintf(p + kFileModeOffset, 8, "%07o", is_directory ? 0755 : 0644);
 
   // UserID
   ::snprintf(p + kUserIDOffset, 8, "%07o", 0765);
 
   // GroupID
   ::snprintf(p + kGroupIDOffset, 8, "%07o", 0204);
 
   // File size
-  ::snprintf(p + kFileSizeOffset, 12, "%011o", file_size);
+  ::snprintf(p + kFileSizeOffset, 12, "%011o",
+             static_cast<unsigned int>(file_size));
 
   // Modification time
   // TODO: write the correct current time here...
   ::snprintf(p + kModifyTimeOffset, 12, "%07o", 011131753141);
 
   // Initialize Header checksum so check sum can be computed
   // by ComputeCheckSum() which will fill in the value here
   ::memset(p + kHeaderCheckSumOffset, 32, 8);
 
   // We only support ordinary files and directories, which is fine
@@ skipping 20 matching lines @@
   }
 }
 
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 void TarGenerator::ComputeCheckSum(uint8 *header) {
   unsigned int checksum = 0;
   for (int i = 0; i < TAR_HEADER_SIZE; ++i) {
     checksum += header[i];
   }
   snprintf(reinterpret_cast<char*>(header + kHeaderCheckSumOffset),
-           8, "%06o\0\0", checksum);
+           8, "%06o%c%c", checksum, 0, 0);
 }
 
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 int TarGenerator::AddFileBytes(MemoryReadStream *stream, size_t n) {
   if (callback_client_) {
     FlushDataBuffer(false);  // flush any old data sitting around
 
     // we'll directly write as much of the data as we can, writing full blocks
     int nblocks = n / TAR_BLOCK_SIZE;
     size_t direct_bytes_to_write = nblocks * TAR_BLOCK_SIZE;
@@ skipping 28 matching lines @@
     data_buffer_stream_.Seek(0);
   }
 }
 
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 void TarGenerator::Finalize() {
   FlushDataBuffer(true);
 }
 
 }  // namespace o3d