crash-reporter: Add diagnostics to help diagnose failures in the wild

crash_collector.cc

 // Copyright (c) 2010 The Chromium OS 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 "crash-reporter/crash_collector.h"
 
 #include <dirent.h>
 #include <fcntl.h>  // For file creation modes.
 #include <pwd.h>  // For struct passwd.
 #include <sys/types.h>  // for mode_t.
@@ skipping 92 matching lines @@
   }
   argv[arguments.size()] = NULL;
 
   int pid = fork();
   if (pid < 0) {
     logger_->LogError("Fork failed: %d", errno);
     return -1;
   }
 
   if (pid == 0) {
-    int output_handle = HANDLE_EINTR(creat(output_file, 0600));
+    int output_handle = HANDLE_EINTR(
+        open(output_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0666));
     if (output_handle < 0) {
       logger_->LogError("Could not create %s: %d", output_file, errno);
       // Avoid exit() to avoid atexit handlers from parent.
       _exit(127);
     }
     dup2(output_handle, 1);
     dup2(output_handle, 2);
     execv(argv[0], &argv[0]);
     logger_->LogError("Exec failed: %d", errno);
     _exit(127);
@@ skipping 278 matching lines @@
                                        version.c_str(),
                                        payload_path.c_str(),
                                        payload_size);
   // We must use WriteNewFile instead of file_util::WriteFile as we
   // do not want to write with root access to a symlink that an attacker
   // might have created.
   if (WriteNewFile(meta_path, meta_data.c_str(), meta_data.size()) < 0) {
     logger_->LogError("Unable to write %s", meta_path.value().c_str());
   }
 }