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Re: RFC: fix bug with std::terminate handler


Pedro> A `gdb_assert (type != bp_breakpoint)' in
Pedro> set_momentary_breakpoint would be a Nice To Have.

I didn't do this, as I'm not familiar enough with the process record
code.

Pedro> There's also the option of making the breakpoint at
Pedro> std::terminate be a real internal breakpoint, enabled/disabled
Pedro> on need, a-la-E.g., enable_overlay_breakpoints or
Pedro> set_longjmp_breakpoint.

I took this route.

Pedro> Also see a couple of PRs I just opened related to this.
Pedro> <http://sourceware.org/bugzilla/show_bug.cgi?id=11328>
Pedro>  <http://sourceware.org/bugzilla/show_bug.cgi?id=11327>

This patch fixes these problems as well.  Thanks for pointing them out.

There are a couple of things in this patch that may be unusual.

First, I changed the type of stop_stack_dummy to be an enum.  Then I use
this to record whether we hit a stack dummy or a std::terminate
breakpoint.  This seemed pretty direct and ok to me, but if you want
something else, just say what and I will implement it.  I think the
names of the enumerators are not super.

Second, create_std_terminate_master_breakpoint had to use
lookup_minimal_symbol and not lookup_minimal_symbol_text, because we
pass in the demangled name.  I could change that and use _ZSt9terminatev,
but that seemed to be a bit too chummy with the C++ ABI.

Built and regtested on x86-64 (compile farm).  I also ran my valgrind
test case by hand.

Tom

2010-03-16  Tom Tromey  <tromey@redhat.com>

	PR gdb/11327, PR gdb/11328:
	* infrun.c (handle_inferior_event): Change initialization of
	stop_stack_dummy.
	(handle_inferior_event): Change assignment to stop_stack_dummy.
	(normal_stop): Update use of stop_stack_dummy.
	(struct inferior_status) <stop_stack_dummy>: Change type.
	* inferior.h (stop_stack_dummy): Update.
	* infcmd.c (stop_stack_dummy): Change type.
	* infcall.c (cleanup_delete_std_terminate_breakpoint): New
	function.
	(call_function_by_hand): Call set_std_terminate_breakpoint.
	Rewrite std::terminate handling.
	* breakpoint.h (enum bptype) <bp_std_terminate,
	bp_std_terminate_master>: New.
	(enum stop_stack_kind): New.
	(struct bpstat_what) <call_dummy>: Change type.
	(set_std_terminate_breakpoint, delete_std_terminate_breakpoint):
	Declare.
	* breakpoint.c (create_std_terminate_master_breakpoint): New
	function.
	(update_breakpoints_after_exec): Handle bp_std_terminate_master.
	Call create_std_terminate_master_breakpoint.
	(breakpoint_init_inferior): Handle bp_std_terminate.
	(print_it_typical): Handle new breakpoint kinds.
	(bpstat_stop_status): Handle bp_std_terminate_master.
	(bpstat_what): Correctly set call_dummy field.  Handle
	bp_std_terminate_master and bp_std_terminate.
	(print_one_breakpoint_location): Update.
	(allocate_bp_location): Update.
	(set_std_terminate_breakpoint): New function.
	(delete_std_terminate_breakpoint): Likewise.
	(create_thread_event_breakpoint): Update.
	(delete_command): Update.
	(breakpoint_re_set_one): Update.
	(breakpoint_re_set): Call create_std_terminate_master_breakpoint.

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 628f2f7..df6775f 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -1951,6 +1951,41 @@ create_longjmp_master_breakpoint (char *func_name)
   do_cleanups (old_chain);
 }
 
+/* Create a master std::terminate breakpoint.  The actual function
+   looked for is named FUNC_NAME.  */
+static void
+create_std_terminate_master_breakpoint (const char *func_name)
+{
+  struct program_space *pspace;
+  struct objfile *objfile;
+  struct cleanup *old_chain;
+
+  old_chain = save_current_program_space ();
+
+  ALL_PSPACES (pspace)
+    ALL_OBJFILES (objfile)
+    {
+      struct breakpoint *b;
+      struct minimal_symbol *m;
+
+      set_current_program_space (pspace);
+
+      m = lookup_minimal_symbol (func_name, NULL, objfile);
+      if (m == NULL || (MSYMBOL_TYPE (m) != mst_text
+			&& MSYMBOL_TYPE (m) != mst_file_text))
+        continue;
+
+      b = create_internal_breakpoint (get_objfile_arch (objfile),
+				      SYMBOL_VALUE_ADDRESS (m),
+                                      bp_std_terminate_master);
+      b->addr_string = xstrdup (func_name);
+      b->enable_state = bp_disabled;
+    }
+  update_global_location_list (1);
+
+  do_cleanups (old_chain);
+}
+
 void
 update_breakpoints_after_exec (void)
 {
@@ -1992,7 +2027,7 @@ update_breakpoints_after_exec (void)
     /* Thread event breakpoints must be set anew after an exec(),
        as must overlay event and longjmp master breakpoints.  */
     if (b->type == bp_thread_event || b->type == bp_overlay_event
-	|| b->type == bp_longjmp_master)
+	|| b->type == bp_longjmp_master || b->type == bp_std_terminate_master)
       {
 	delete_breakpoint (b);
 	continue;
@@ -2068,6 +2103,7 @@ update_breakpoints_after_exec (void)
   create_longjmp_master_breakpoint ("_longjmp");
   create_longjmp_master_breakpoint ("siglongjmp");
   create_longjmp_master_breakpoint ("_siglongjmp");
+  create_std_terminate_master_breakpoint ("std::terminate()");
 }
 
 int
@@ -2295,6 +2331,7 @@ breakpoint_init_inferior (enum inf_context context)
     switch (b->type)
       {
       case bp_call_dummy:
+      case bp_std_terminate:
 
 	/* If the call dummy breakpoint is at the entry point it will
 	   cause problems when the inferior is rerun, so we better get
@@ -2993,6 +3030,12 @@ print_it_typical (bpstat bs)
       result = PRINT_NOTHING;
       break;
 
+    case bp_std_terminate_master:
+      /* These should never be enabled.  */
+      printf_filtered (_("std::terminate Master Breakpoint: gdb should not stop!\n"));
+      result = PRINT_NOTHING;
+      break;
+
     case bp_watchpoint:
     case bp_hardware_watchpoint:
       annotate_watchpoint (b->number);
@@ -3083,6 +3126,7 @@ print_it_typical (bpstat bs)
     case bp_step_resume:
     case bp_watchpoint_scope:
     case bp_call_dummy:
+    case bp_std_terminate:
     case bp_tracepoint:
     case bp_fast_tracepoint:
     case bp_jit_event:
@@ -3825,7 +3869,8 @@ bpstat_stop_status (struct address_space *aspace,
 	    continue;
 
 	  if (b->type == bp_thread_event || b->type == bp_overlay_event
-	      || b->type == bp_longjmp_master)
+	      || b->type == bp_longjmp_master
+	      || b->type == bp_std_terminate_master)
 	    /* We do not stop for these.  */
 	    bs->stop = 0;
 	  else
@@ -4033,7 +4078,7 @@ bpstat_what (bpstat bs)
   enum bpstat_what_main_action current_action = BPSTAT_WHAT_KEEP_CHECKING;
   struct bpstat_what retval;
 
-  retval.call_dummy = 0;
+  retval.call_dummy = STOP_NONE;
   for (; bs != NULL; bs = bs->next)
     {
       enum class bs_class = no_effect;
@@ -4106,6 +4151,7 @@ bpstat_what (bpstat bs)
 	case bp_thread_event:
 	case bp_overlay_event:
 	case bp_longjmp_master:
+	case bp_std_terminate_master:
 	  bs_class = bp_nostop;
 	  break;
 	case bp_catchpoint:
@@ -4125,7 +4171,13 @@ bpstat_what (bpstat bs)
 	  /* Make sure the action is stop (silent or noisy),
 	     so infrun.c pops the dummy frame.  */
 	  bs_class = bp_silent;
-	  retval.call_dummy = 1;
+	  retval.call_dummy = STOP_STACK_DUMMY;
+	  break;
+	case bp_std_terminate:
+	  /* Make sure the action is stop (silent or noisy),
+	     so infrun.c pops the dummy frame.  */
+	  bs_class = bp_silent;
+	  retval.call_dummy = STOP_STD_TERMINATE;
 	  break;
 	case bp_tracepoint:
 	case bp_fast_tracepoint:
@@ -4253,10 +4305,12 @@ print_one_breakpoint_location (struct breakpoint *b,
     {bp_step_resume, "step resume"},
     {bp_watchpoint_scope, "watchpoint scope"},
     {bp_call_dummy, "call dummy"},
+    {bp_std_terminate, "std::terminate"},
     {bp_shlib_event, "shlib events"},
     {bp_thread_event, "thread events"},
     {bp_overlay_event, "overlay events"},
     {bp_longjmp_master, "longjmp master"},
+    {bp_std_terminate_master, "std::terminate master"},
     {bp_catchpoint, "catchpoint"},
     {bp_tracepoint, "tracepoint"},
     {bp_fast_tracepoint, "fast tracepoint"},
@@ -4384,10 +4438,12 @@ print_one_breakpoint_location (struct breakpoint *b,
       case bp_step_resume:
       case bp_watchpoint_scope:
       case bp_call_dummy:
+      case bp_std_terminate:
       case bp_shlib_event:
       case bp_thread_event:
       case bp_overlay_event:
       case bp_longjmp_master:
+      case bp_std_terminate_master:
       case bp_tracepoint:
       case bp_fast_tracepoint:
       case bp_jit_event:
@@ -5043,11 +5099,13 @@ allocate_bp_location (struct breakpoint *bpt)
     case bp_step_resume:
     case bp_watchpoint_scope:
     case bp_call_dummy:
+    case bp_std_terminate:
     case bp_shlib_event:
     case bp_thread_event:
     case bp_overlay_event:
     case bp_jit_event:
     case bp_longjmp_master:
+    case bp_std_terminate_master:
       loc->loc_type = bp_loc_software_breakpoint;
       break;
     case bp_hardware_breakpoint:
@@ -5300,6 +5358,33 @@ disable_overlay_breakpoints (void)
     }
 }
 
+/* Set an active std::terminate breakpoint for each std::terminate
+   master breakpoint.  */
+void
+set_std_terminate_breakpoint (void)
+{
+  struct breakpoint *b, *temp;
+
+  ALL_BREAKPOINTS_SAFE (b, temp)
+    if (b->pspace == current_program_space
+	&& b->type == bp_std_terminate_master)
+      {
+	struct breakpoint *clone = clone_momentary_breakpoint (b);
+	clone->type = bp_std_terminate;
+      }
+}
+
+/* Delete all the std::terminate breakpoints.  */
+void
+delete_std_terminate_breakpoint (void)
+{
+  struct breakpoint *b, *temp;
+
+  ALL_BREAKPOINTS_SAFE (b, temp)
+    if (b->type == bp_std_terminate)
+      delete_breakpoint (b);
+}
+
 struct breakpoint *
 create_thread_event_breakpoint (struct gdbarch *gdbarch, CORE_ADDR address)
 {
@@ -6342,12 +6427,14 @@ mention (struct breakpoint *b)
       case bp_longjmp_resume:
       case bp_step_resume:
       case bp_call_dummy:
+      case bp_std_terminate:
       case bp_watchpoint_scope:
       case bp_shlib_event:
       case bp_thread_event:
       case bp_overlay_event:
       case bp_jit_event:
       case bp_longjmp_master:
+      case bp_std_terminate_master:
 	break;
       }
 
@@ -9026,11 +9113,13 @@ delete_command (char *arg, int from_tty)
       ALL_BREAKPOINTS (b)
       {
 	if (b->type != bp_call_dummy
+	    && b->type != bp_std_terminate
 	    && b->type != bp_shlib_event
 	    && b->type != bp_jit_event
 	    && b->type != bp_thread_event
 	    && b->type != bp_overlay_event
 	    && b->type != bp_longjmp_master
+	    && b->type != bp_std_terminate_master
 	    && b->number >= 0)
 	  {
 	    breaks_to_delete = 1;
@@ -9045,11 +9134,13 @@ delete_command (char *arg, int from_tty)
 	  ALL_BREAKPOINTS_SAFE (b, temp)
 	  {
 	    if (b->type != bp_call_dummy
+		&& b->type != bp_std_terminate
 		&& b->type != bp_shlib_event
 		&& b->type != bp_thread_event
 		&& b->type != bp_jit_event
 		&& b->type != bp_overlay_event
 		&& b->type != bp_longjmp_master
+		&& b->type != bp_std_terminate_master
 		&& b->number >= 0)
 	      delete_breakpoint (b);
 	  }
@@ -9360,6 +9451,7 @@ breakpoint_re_set_one (void *bint)
 	 reset later by breakpoint_re_set.  */
     case bp_overlay_event:
     case bp_longjmp_master:
+    case bp_std_terminate_master:
       delete_breakpoint (b);
       break;
 
@@ -9379,6 +9471,7 @@ breakpoint_re_set_one (void *bint)
     case bp_finish:
     case bp_watchpoint_scope:
     case bp_call_dummy:
+    case bp_std_terminate:
     case bp_step_resume:
     case bp_longjmp:
     case bp_longjmp_resume:
@@ -9424,6 +9517,7 @@ breakpoint_re_set (void)
   create_longjmp_master_breakpoint ("_longjmp");
   create_longjmp_master_breakpoint ("siglongjmp");
   create_longjmp_master_breakpoint ("_siglongjmp");
+  create_std_terminate_master_breakpoint ("std::terminate()");
 }
 
 /* Reset the thread number of this breakpoint:
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 73e2223..3c1db4b 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -83,6 +83,10 @@ enum bptype
        of scope (with hardware support for watchpoints)).  */
     bp_call_dummy,
 
+    /* A breakpoint set on std::terminate, that is used to catch
+       otherwise uncaught exceptions thrown during an inferior call.  */
+    bp_std_terminate,
+
     /* Some dynamic linkers (HP, maybe Solaris) can arrange for special
        code in the inferior to run when significant events occur in the
        dynamic linker (for example a library is loaded or unloaded).
@@ -118,6 +122,9 @@ enum bptype
 
     bp_longjmp_master,
 
+    /* Master copies of std::terminate breakpoints.  */
+    bp_std_terminate_master,
+
     bp_catchpoint,
 
     bp_tracepoint,
@@ -601,6 +608,20 @@ enum bpstat_what_main_action
     BPSTAT_WHAT_LAST
   };
 
+/* An enum indicating the kind of "stack dummy" stop.  This is a bit
+   of a misnomer because only one kind of truly a stack dummy.  */
+enum stop_stack_kind
+  {
+    /* We didn't stop at a stack dummy breakpoint.  */
+    STOP_NONE = 0,
+
+    /* Stopped at a stack dummy.  */
+    STOP_STACK_DUMMY,
+
+    /* Stopped at std::terminate.  */
+    STOP_STD_TERMINATE
+  };
+
 struct bpstat_what
   {
     enum bpstat_what_main_action main_action;
@@ -609,7 +630,7 @@ struct bpstat_what
        of BPSTAT_WHAT_STOP_SILENT or BPSTAT_WHAT_STOP_NOISY (the concept of
        continuing from a call dummy without popping the frame is not a
        useful one).  */
-    int call_dummy;
+    enum stop_stack_kind call_dummy;
   };
 
 /* The possible return values for print_bpstat, print_it_normal,
@@ -851,6 +872,9 @@ extern void delete_longjmp_breakpoint (int thread);
 extern void enable_overlay_breakpoints (void);
 extern void disable_overlay_breakpoints (void);
 
+extern void set_std_terminate_breakpoint (void);
+extern void delete_std_terminate_breakpoint (void);
+
 /* These functions respectively disable or reenable all currently
    enabled watchpoints.  When disabled, the watchpoints are marked
    call_disabled.  When reenabled, they are marked enabled.
diff --git a/gdb/infcall.c b/gdb/infcall.c
index 2d8bd2c..537e0b6 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -402,6 +402,13 @@ run_inferior_call (struct thread_info *call_thread, CORE_ADDR real_pc)
   return e;
 }
 
+/* A cleanup function that calls delete_std_terminate_breakpoint.  */
+static void
+cleanup_delete_std_terminate_breakpoint (void *ignore)
+{
+  delete_std_terminate_breakpoint ();
+}
+
 /* All this stuff with a dummy frame may seem unnecessarily complicated
    (why not just save registers in GDB?).  The purpose of pushing a dummy
    frame which looks just like a real frame is so that if you call a
@@ -439,9 +446,7 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
   struct cleanup *args_cleanup;
   struct frame_info *frame;
   struct gdbarch *gdbarch;
-  struct breakpoint *terminate_bp = NULL;
-  struct minimal_symbol *tm;
-  struct cleanup *terminate_bp_cleanup = NULL;
+  struct cleanup *terminate_bp_cleanup;
   ptid_t call_thread_ptid;
   struct gdb_exception e;
   const char *name;
@@ -753,13 +758,7 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
      call.  Place a momentary breakpoint in the std::terminate function
      and if triggered in the call, rewind.  */
   if (unwind_on_terminating_exception_p)
-     {
-       struct minimal_symbol *tm = lookup_minimal_symbol  ("std::terminate()",
-							   NULL, NULL);
-       if (tm != NULL)
-	   terminate_bp = set_momentary_breakpoint_at_pc
-	     (gdbarch, SYMBOL_VALUE_ADDRESS (tm),  bp_breakpoint);
-     }
+    set_std_terminate_breakpoint ();
 
   /* Everything's ready, push all the info needed to restore the
      caller (and identify the dummy-frame) onto the dummy-frame
@@ -772,8 +771,8 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
   discard_cleanups (inf_status_cleanup);
 
   /* Register a clean-up for unwind_on_terminating_exception_breakpoint.  */
-  if (terminate_bp)
-    terminate_bp_cleanup = make_cleanup_delete_breakpoint (terminate_bp);
+  terminate_bp_cleanup = make_cleanup (cleanup_delete_std_terminate_breakpoint,
+				       NULL);
 
   /* - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP -
      If you're looking to implement asynchronous dummy-frames, then
@@ -874,7 +873,7 @@ When the function is done executing, GDB will silently stop."),
 	       name);
     }
 
-  if (stopped_by_random_signal || !stop_stack_dummy)
+  if (stopped_by_random_signal || stop_stack_dummy != STOP_STACK_DUMMY)
     {
       const char *name = get_function_name (funaddr,
 					    name_buf, sizeof (name_buf));
@@ -928,30 +927,17 @@ When the function is done executing, GDB will silently stop."),
 	    }
 	}
 
-      if (!stop_stack_dummy)
+      if (stop_stack_dummy == STOP_STD_TERMINATE)
 	{
+	  /* We must get back to the frame we were before the dummy
+	     call.  */
+	  dummy_frame_pop (dummy_id);
 
-	  /* Check if unwind on terminating exception behaviour is on.  */
-	  if (unwind_on_terminating_exception_p)
-	    {
-	      /* Check that the breakpoint is our special std::terminate
-		 breakpoint.  If it is, we do not want to kill the inferior
-		 in an inferior function call. Rewind, and warn the
-		 user.  */
-
-	      if (terminate_bp != NULL
-		  && (inferior_thread ()->stop_bpstat->breakpoint_at->address
-		      == terminate_bp->loc->address))
-		{
-		  /* We must get back to the frame we were before the
-		     dummy call.  */
-		  dummy_frame_pop (dummy_id);
-
-		  /* We also need to restore inferior status to that before the
-		     dummy call.  */
-		  restore_inferior_status (inf_status);
-
-		  error (_("\
+	  /* We also need to restore inferior status to that before
+	     the dummy call.  */
+	  restore_inferior_status (inf_status);
+
+	  error (_("\
 The program being debugged entered a std::terminate call, most likely\n\
 caused by an unhandled C++ exception.  GDB blocked this call in order\n\
 to prevent the program from being terminated, and has restored the\n\
@@ -959,9 +945,11 @@ context to its original state before the call.\n\
 To change this behaviour use \"set unwind-on-terminating-exception off\".\n\
 Evaluation of the expression containing the function (%s)\n\
 will be abandoned."),
-			 name);
-		}
-	    }
+		 name);
+	}
+      else if (stop_stack_dummy == STOP_NONE)
+	{
+
 	  /* We hit a breakpoint inside the FUNCTION.
 	     Keep the dummy frame, the user may want to examine its state.
 	     Discard inferior status, we're not at the same point
@@ -988,10 +976,7 @@ When the function is done executing, GDB will silently stop."),
       internal_error (__FILE__, __LINE__, _("... should not be here"));
     }
 
-  /* If we get here and the std::terminate() breakpoint has been set,
-     it has to be cleaned manually.  */
-  if (terminate_bp)
-    do_cleanups (terminate_bp_cleanup);
+  do_cleanups (terminate_bp_cleanup);
 
   /* If we get here the called FUNCTION ran to completion,
      and the dummy frame has already been popped.  */
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 29cf427..12382bc 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -156,7 +156,7 @@ int breakpoint_proceeded;
 
 /* Nonzero if stopped due to completion of a stack dummy routine.  */
 
-int stop_stack_dummy;
+enum stop_stack_kind stop_stack_dummy;
 
 /* Nonzero if stopped due to a random (unexpected) signal in inferior
    process.  */
diff --git a/gdb/inferior.h b/gdb/inferior.h
index dc87a9e..17b2c6f 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -297,7 +297,7 @@ extern CORE_ADDR stop_pc;
 
 /* Nonzero if stopped due to completion of a stack dummy routine.  */
 
-extern int stop_stack_dummy;
+extern enum stop_stack_kind stop_stack_dummy;
 
 /* Nonzero if program stopped due to a random (unexpected) signal in
    inferior process.  */
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 83cfe3c..f5369cd 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2904,7 +2904,7 @@ handle_inferior_event (struct execution_control_state *ecs)
   target_last_waitstatus = ecs->ws;
 
   /* Always clear state belonging to the previous time we stopped.  */
-  stop_stack_dummy = 0;
+  stop_stack_dummy = STOP_NONE;
 
   /* If it's a new process, add it to the thread database */
 
@@ -3970,7 +3970,7 @@ process_event_stop_test:
 
     if (what.call_dummy)
       {
-	stop_stack_dummy = 1;
+	stop_stack_dummy = what.call_dummy;
       }
 
     switch (what.main_action)
@@ -5460,7 +5460,7 @@ Further execution is probably impossible.\n"));
       stop_registers = regcache_dup (get_current_regcache ());
     }
 
-  if (stop_stack_dummy)
+  if (stop_stack_dummy == STOP_STACK_DUMMY)
     {
       /* Pop the empty frame that contains the stack dummy.
 	 This also restores inferior state prior to the call
@@ -6038,7 +6038,7 @@ struct inferior_status
 {
   bpstat stop_bpstat;
   int stop_step;
-  int stop_stack_dummy;
+  enum stop_stack_kind stop_stack_dummy;
   int stopped_by_random_signal;
   int stepping_over_breakpoint;
   CORE_ADDR step_range_start;


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