Linux: Use _exit() instead of exit() in the child after fork() in failure conditions.

base/process_util_linux.cc

 // Copyright (c) 2008 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 "base/process_util.h"
 
 #include <ctype.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <sys/types.h>
@@ skipping 95 matching lines @@
          it != environ.end(); ++it) {
       if (it->first) {
         if (it->second) {
           setenv(it->first, it->second, 1);
         } else {
           unsetenv(it->first);
         }
       }
     }
 
+    // Obscure fork() rule: in the child, if you don't end up doing exec*(),
+    // you call _exit() instead of exit(). This is because _exit() does not
+    // call any previously-registered (in the parent) exit handlers, which
+    // might do things like block waiting for threads that don't even exist
+    // in the child.
     if (!ShuffleFileDescriptors(fd_shuffle))
-      exit(127);
+      _exit(127);
 
     // If we are using the SUID sandbox, it sets a magic environment variable
     // ("SBX_D"), so we remove that variable from the environment here on the
     // off chance that it's already set.
     unsetenv("SBX_D");
 
     CloseSuperfluousFds(fd_shuffle);
 
     scoped_array<char*> argv_cstr(new char*[argv.size() + 1]);
     for (size_t i = 0; i < argv.size(); i++)
       argv_cstr[i] = const_cast<char*>(argv[i].c_str());
     argv_cstr[argv.size()] = NULL;
     execvp(argv_cstr[0], argv_cstr.get());
     LOG(ERROR) << "LaunchApp: exec failed!, argv_cstr[0] " << argv_cstr[0]
         << ", errno " << errno;
-    exit(127);
+    _exit(127);
   } else {
     // Parent process
     if (wait)
       HANDLE_EINTR(waitpid(pid, 0, 0));
 
     if (process_handle)
       *process_handle = pid;
   }
 
   return true;
@@ skipping 262 matching lines @@
           (*io_counters).WriteTransferCount = StringToInt64(tokenizer.token());
         }
         state = KEY_NAME;
         break;
     }
   }
   return true;
 }
 
 }  // namespace base