Misc changes to cert_verify_tool for errors

net/tools/cert_verify_tool/cert_verify_tool_util.cc

 // Copyright 2016 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 "net/tools/cert_verify_tool/cert_verify_tool_util.h"
 
 #include <iostream>
 
 #include "base/files/file_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 42 matching lines @@
   std::string file_data;
   if (!base::ReadFileToString(file_path, &file_data)) {
     std::cerr << "ERROR: ReadFileToString " << file_path.value() << ": "
               << strerror(errno) << "\n";
     return false;
   }
   ExtractCertificatesFromData(file_data, file_path, certs);
   return true;
 }
 
-void ReadChainFromFile(const base::FilePath& file_path,
+bool ReadChainFromFile(const base::FilePath& file_path,
                        CertInput* target,
                        std::vector<CertInput>* intermediates) {
   std::vector<CertInput> tmp_certs;
   if (!ReadCertificatesFromFile(file_path, &tmp_certs))
-    return;
+    return false;
+
+  if (tmp_certs.empty())
+    return true;
 
   *target = tmp_certs.front();
 
   intermediates->insert(intermediates->end(), ++tmp_certs.begin(),
                         tmp_certs.end());
+  return true;
 }
 
 bool WriteToFile(const base::FilePath& file_path, const std::string& data) {
   if (base::WriteFile(file_path, data.data(), data.size()) < 0) {
     std::cerr << "ERROR: WriteFile " << file_path.value() << ": "
               << strerror(errno) << "\n";
     return false;
   }
   return true;
 }
 
 void PrintCertError(const std::string& error, const CertInput& cert) {
   std::cerr << error << " " << cert.source_file_path.value();
   if (!cert.source_details.empty())
     std::cerr << " (" << cert.source_details << ")";
   std::cerr << "\n";
 }