Allow Linux dumper to work on PTRACE-hardened kernels

A=Chris Coulson <chris.coulson@canonical.com>
R=nealsid at http://breakpad.appspot.com/166001/show

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@673 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/client/linux/handler/exception_handler.h

@@ -184,6 +184,8 @@ class ExceptionHandler {
   void UninstallHandlers();
   void PreresolveSymbols();
   bool GenerateDump(CrashContext *context);
+  void SendContinueSignalToChild();
+  void WaitForContinueSignal();
 
   void UpdateNextID();
   static void SignalHandler(int sig, siginfo_t* info, void* uc);
@@ -223,6 +225,13 @@ class ExceptionHandler {
 
   // A vector of the old signal handlers.
   std::vector<std::pair<int, struct sigaction *> > old_handlers_;
+
+  // We need to explicitly enable ptrace of parent processes on some
+  // kernels, but we need to know the PID of the cloned process before we
+  // can do this. We create a pipe which we can use to block the
+  // cloned process after creating it, until we have explicitly enabled 
+  // ptrace. This is used to store the file descriptors for the pipe
+  int fdes[2];
 };
 
 }  // namespace google_breakpad