Fix a test tool for OTS, ot-sanitise....

src/ots.cc

 // Copyright (c) 2009 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.
 
 #include "ots.h"
 
 #include <sys/types.h>
 
 #include <algorithm>
 #include <cstdlib>
@@ skipping 340 matching lines @@
 
     output->ResetChecksum();
     if (table_parsers[i].tag == Tag("head")) {
       head_table_offset = out.offset;
     }
     if (!table_parsers[i].serialise(output, header)) {
       return OTS_FAILURE();
     }
 
     const size_t end_offset = output->Tell();
+    if (end_offset <= out.offset) {
+      // paranoid check. |end_offset| is supposed to be greater than the offset,
+      // as long as the Tell() interface is implemented correctly.
+      return OTS_FAILURE();
+    }
     out.length = end_offset - out.offset;
 
     // align tables to four bytes
     if (!output->Pad((4 - (end_offset & 3)) % 4)) {
       return OTS_FAILURE();
     }
     out.chksum = output->chksum();
     out_tables.push_back(out);
   }
 
@@ skipping 76 matching lines @@
     va_start(va, format);
     std::vfprintf(stderr, format, va);
     va_end(va);
     std::fprintf(stderr, "\n");
     std::fflush(stderr);
   }
 }
 #endif
 
 }  // namespace ots