Properly redeliver (or don't) signals to the previous handlers.

If none of the installed ExceptionHandlers handle a signal (their
FilterCallbacks or HandlerCallbacks all return false), then the signal
should be delivered to the signal handlers that were previously
installed.

This requires that old_handlers_ become a static vector so that we can
restore the handlers in the static HandleSignal.

Currently it is also restoring signals in ~ExceptionHandler (if there
are no others). This should not be required since our documentation
states that a process can only have one ExceptionHandler for which
install_handlers is true (and so we get the correct behavior if we
simply leave our handlers installed forever), but even the tests
themselves violate that.

Patch by Chris Hopman <cjhopman@chromium.org>

Review URL: https://breakpad.appspot.com/440002/


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1025 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 5 insertions, 9 deletions

diff --git a/src/client/linux/handler/exception_handler.h b/src/client/linux/handler/exception_handler.h
index f9e7ce3b..cde5ee8a 100644
--- a/src/client/linux/handler/exception_handler.h
+++ b/src/client/linux/handler/exception_handler.h
@@ -46,8 +46,6 @@
 #include "google_breakpad/common/minidump_format.h"
 #include "processor/scoped_ptr.h"
 
-struct sigaction;
-
 namespace google_breakpad {
 
 // ExceptionHandler
@@ -194,8 +192,11 @@ class ExceptionHandler {
   // Force signal handling for the specified signal.
   bool SimulateSignalDelivery(int sig);
  private:
-  bool InstallHandlers();
-  void UninstallHandlers();
+  // Save the old signal handlers and install new ones.
+  static bool InstallHandlersLocked();
+  // Restore the old signal handlers.
+  static void RestoreHandlersLocked();
+
   void PreresolveSymbols();
   bool GenerateDump(CrashContext *context);
   void SendContinueSignalToChild();
@@ -221,13 +222,8 @@ class ExceptionHandler {
   // multiple ExceptionHandler instances in a process. Each will have itself
   // registered in this stack.
   static std::vector<ExceptionHandler*> *handler_stack_;
-  // The index of the handler that should handle the next exception.
-  static unsigned handler_stack_index_;
   static pthread_mutex_t handler_stack_mutex_;
 
-  // 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