infrun.c

早期freebsd实现

  normal_stop ();
}

/* Record the pc and sp of the program the last time it stopped.
   These are just used internally by wait_for_inferior, but need
   to be preserved over calls to it and cleared when the inferior
   is started.  */
static CORE_ADDR prev_pc;
static CORE_ADDR prev_sp;
static CORE_ADDR prev_func_start;
static char *prev_func_name;

void
init_wait_for_inferior_keep_brkpts()
{
  /* These are meaningless until the first time through wait_for_inferior.  */
  prev_pc = 0;
  prev_sp = 0;
  prev_func_start = 0;
  prev_func_name = NULL;
  trap_expected_after_continue = 0;
  stop_signal = 0;            /* Don't confuse first call to proceed(). */
}

/* Initialize static vars when a new inferior begins.  */

void
init_wait_for_inferior ()
{
  init_wait_for_inferior_keep_brkpts();
  breakpoints_inserted = 0;
  mark_breakpoints_out ();
}

void
remote_go()
{
  clear_proceed_status();
  stop_soon_quietly = 1;
  trap_expected = 0;
  wait_for_inferior();
  normal_stop();
}


/* Wait for control to return from inferior to debugger.
   If inferior gets a signal, we may decide to start it up again
   instead of returning.  That is why there is a loop in this function.
   When this function actually returns it means the inferior
   should be left stopped and GDB should read more commands.  */

void
wait_for_inferior ()
{
  WAITTYPE w;
  int another_trap;
  int random_signal;
  CORE_ADDR stop_sp;
  CORE_ADDR stop_func_start;
  char *stop_func_name;
  CORE_ADDR prologue_pc, tmp;
  int stop_step_resume_break;
  struct symtab_and_line sal;
  int remove_breakpoints_on_following_step = 0;
  int current_line;
  int handling_longjmp = 0;	/* FIXME */

  sal = find_pc_line(prev_pc, 0);
  current_line = sal.line;

  while (1)
    {
      /* Clean up saved state that will become invalid.  */
      pc_changed = 0;
      flush_cached_frames ();
      registers_changed ();

      target_wait (&w);

#ifdef SIGTRAP_STOP_AFTER_LOAD

      /* Somebody called load(2), and it gave us a "trap signal after load".
         Ignore it gracefully. */

      SIGTRAP_STOP_AFTER_LOAD (w);
#endif

      /* See if the process still exists; clean up if it doesn't.  */
      if (WIFEXITED (w))
	{
	  target_terminal_ours ();	/* Must do this before mourn anyway */
	  if (WEXITSTATUS (w))
	    printf_filtered ("\nProgram exited with code 0%o.\n", 
		     (unsigned int)WEXITSTATUS (w));
	  else
	    if (!batch_mode())
	      printf_filtered ("\nProgram exited normally.\n");
	  fflush (stdout);
	  target_mourn_inferior ();
#ifdef NO_SINGLE_STEP
	  one_stepped = 0;
#endif
	  stop_print_frame = 0;
	  break;
	}
      else if (!WIFSTOPPED (w))
	{
	  stop_print_frame = 0;
	  stop_signal = WTERMSIG (w);
	  target_terminal_ours ();	/* Must do this before mourn anyway */
	  target_kill ();		/* kill mourns as well */
#ifdef PRINT_RANDOM_SIGNAL
	  printf_filtered ("\nProgram terminated: ");
	  PRINT_RANDOM_SIGNAL (stop_signal);
#else
	  printf_filtered ("\nProgram terminated with signal %d, %s\n",
			   stop_signal, safe_strsignal (stop_signal));
#endif
	  printf_filtered ("The inferior process no longer exists.\n");
	  fflush (stdout);
#ifdef NO_SINGLE_STEP
	  one_stepped = 0;
#endif
	  break;
	}
      
#ifdef NO_SINGLE_STEP
      if (one_stepped)
	single_step (0);	/* This actually cleans up the ss */
#endif /* NO_SINGLE_STEP */
      
      stop_pc = read_pc ();
      set_current_frame ( create_new_frame (read_register (FP_REGNUM),
					    read_pc ()));
      
      stop_frame_address = FRAME_FP (get_current_frame ());
      stop_sp = read_register (SP_REGNUM);
      stop_func_start = 0;
      stop_func_name = 0;
      /* Don't care about return value; stop_func_start and stop_func_name
	 will both be 0 if it doesn't work.  */
      find_pc_partial_function (stop_pc, &stop_func_name, &stop_func_start);
      stop_func_start += FUNCTION_START_OFFSET;
      another_trap = 0;
      bpstat_clear (&stop_bpstat);
      stop_step = 0;
      stop_stack_dummy = 0;
      stop_print_frame = 1;
      stop_step_resume_break = 0;
      random_signal = 0;
      stopped_by_random_signal = 0;
      breakpoints_failed = 0;
      
      /* Look at the cause of the stop, and decide what to do.
	 The alternatives are:
	 1) break; to really stop and return to the debugger,
	 2) drop through to start up again
	 (set another_trap to 1 to single step once)
	 3) set random_signal to 1, and the decision between 1 and 2
	 will be made according to the signal handling tables.  */
      
      stop_signal = WSTOPSIG (w);
      
      /* First, distinguish signals caused by the debugger from signals
	 that have to do with the program's own actions.
	 Note that breakpoint insns may cause SIGTRAP or SIGILL
	 or SIGEMT, depending on the operating system version.
	 Here we detect when a SIGILL or SIGEMT is really a breakpoint
	 and change it to SIGTRAP.  */
      
      if (stop_signal == SIGTRAP
	  || (breakpoints_inserted &&
	      (stop_signal == SIGILL
#ifdef SIGEMT
	       || stop_signal == SIGEMT
#endif
            ))
	  || stop_soon_quietly)
	{
	  if (stop_signal == SIGTRAP && stop_after_trap)
	    {
	      stop_print_frame = 0;
	      break;
	    }
	  if (stop_soon_quietly)
	    break;

	  /* Don't even think about breakpoints
	     if just proceeded over a breakpoint.

	     However, if we are trying to proceed over a breakpoint
	     and end up in sigtramp, then step_resume_break_address
	     will be set and we should check whether we've hit the
	     step breakpoint.  */
	  if (stop_signal == SIGTRAP && trap_expected
	      && step_resume_break_address == 0)
	    bpstat_clear (&stop_bpstat);
	  else
	    {
	      /* See if there is a breakpoint at the current PC.  */
#if DECR_PC_AFTER_BREAK
	      /* Notice the case of stepping through a jump
		 that lands just after a breakpoint.
		 Don't confuse that with hitting the breakpoint.
		 What we check for is that 1) stepping is going on
		 and 2) the pc before the last insn does not match
		 the address of the breakpoint before the current pc.  */
	      if (prev_pc == stop_pc - DECR_PC_AFTER_BREAK
		  || !step_range_end
		  || step_resume_break_address
		  || handling_longjmp /* FIXME */)
#endif /* DECR_PC_AFTER_BREAK not zero */
		{
		  /* See if we stopped at the special breakpoint for
		     stepping over a subroutine call.  If both are zero,
		     this wasn't the reason for the stop.  */
		  if (step_resume_break_address
		      && stop_pc - DECR_PC_AFTER_BREAK
		         == step_resume_break_address)
		    {
		      stop_step_resume_break = 1;
		      if (DECR_PC_AFTER_BREAK)
			{
			  stop_pc -= DECR_PC_AFTER_BREAK;
			  write_register (PC_REGNUM, stop_pc);
			  pc_changed = 0;
			}
		    }
		  else
		    {
		      stop_bpstat =
			bpstat_stop_status (&stop_pc, stop_frame_address);
		      /* Following in case break condition called a
			 function.  */
		      stop_print_frame = 1;
		    }
		}
	    }
	  
	  if (stop_signal == SIGTRAP)
	    random_signal
	      = !(bpstat_explains_signal (stop_bpstat)
		  || trap_expected
		  || stop_step_resume_break
		  || PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address)
		  || (step_range_end && !step_resume_break_address));
	  else
	    {
	      random_signal
		= !(bpstat_explains_signal (stop_bpstat)
		    || stop_step_resume_break
		    /* End of a stack dummy.  Some systems (e.g. Sony
		       news) give another signal besides SIGTRAP,
		       so check here as well as above.  */
		    || PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address)
		    );
	      if (!random_signal)
		stop_signal = SIGTRAP;
	    }
	}
      else
	random_signal = 1;
      
      /* For the program's own signals, act according to
	 the signal handling tables.  */
      
      if (random_signal)
	{
	  /* Signal not for debugging purposes.  */
	  int printed = 0;
	  
	  stopped_by_random_signal = 1;
	  
	  if (stop_signal >= NSIG
	      || signal_print[stop_signal])
	    {
	      printed = 1;
	      target_terminal_ours_for_output ();
#ifdef PRINT_RANDOM_SIGNAL
	      PRINT_RANDOM_SIGNAL (stop_signal);
#else
	      printf_filtered ("\nProgram received signal %d, %s\n",
			       stop_signal, safe_strsignal (stop_signal));
#endif /* PRINT_RANDOM_SIGNAL */
	      fflush (stdout);
	    }
	  if (stop_signal >= NSIG
	      || signal_stop[stop_signal])
	    break;
	  /* If not going to stop, give terminal back
	     if we took it away.  */
	  else if (printed)
	    target_terminal_inferior ();

	  /* Note that virtually all the code below does `if !random_signal'.
	     Perhaps this code should end with a goto or continue.  At least
	     one (now fixed) bug was caused by this -- a !random_signal was
	     missing in one of the tests below.  */
	}

      /* Handle cases caused by hitting a breakpoint.  */

      if (!random_signal)
	if (bpstat_explains_signal (stop_bpstat))
	  {
	    CORE_ADDR jmp_buf_pc;

	    switch (stop_bpstat->breakpoint_at->type) /* FIXME */
	      {
		/* If we hit the breakpoint at longjmp, disable it for the
		   duration of this command.  Then, install a temporary
		   breakpoint at the target of the jmp_buf. */
	      case bp_longjmp:
		disable_longjmp_breakpoint();
		remove_breakpoints ();
		breakpoints_inserted = 0;
		if (!GET_LONGJMP_TARGET(&jmp_buf_pc)) goto keep_going;

		/* Need to blow away step-resume breakpoint, as it
		   interferes with us */
		remove_step_breakpoint ();
		step_resume_break_address = 0;
		stop_step_resume_break = 0;

#if 0				/* FIXME - Need to implement nested temporary breakpoints */
		if (step_over_calls > 0)
		  set_longjmp_resume_breakpoint(jmp_buf_pc,
						get_current_frame());
		else
#endif				/* 0 */
		  set_longjmp_resume_breakpoint(jmp_buf_pc, NULL);
		handling_longjmp = 1; /* FIXME */
		goto keep_going;

	      case bp_longjmp_resume:
		remove_breakpoints ();
		breakpoints_inserted = 0;
#if 0				/* FIXME - Need to implement nested temporary breakpoints */
		if (step_over_calls
		    && (stop_frame_address
			INNER_THAN step_frame_address))
		  {
		    another_trap = 1;
		    goto keep_going;
		  }
#endif				/* 0 */
		disable_longjmp_breakpoint();
		handling_longjmp = 0; /* FIXME */
		break;

	      default:
		fprintf(stderr, "Unknown breakpoint type %d\n",
			stop_bpstat->breakpoint_at->type);
	      case bp_watchpoint:
	      case bp_breakpoint:
	      case bp_until:
	      case bp_finish:
		/* Does a breakpoint want us to stop?  */
		if (bpstat_stop (stop_bpstat))
		  {
		    stop_print_frame = bpstat_should_print (stop_bpstat);
		    goto stop_stepping;
		  }
		/* Otherwise, must remove breakpoints and single-step
		   to get us past the one we hit.  */
		else
		  {
		    remove_breakpoints ();
		    remove_step_breakpoint ();
		    breakpoints_inserted = 0;
		    another_trap = 1;
		  }
		break;
	      }
	  }
	else if (stop_step_resume_break)
	  {
	    /* But if we have hit the step-resumption breakpoint,
	       remove it.  It has done its job getting us here.
	       The sp test is to make sure that we don't get hung
	       up in recursive calls in functions without frame
	       pointers.  If the stack pointer isn't outside of
	       where the breakpoint was set (within a routine to be
	       stepped over), we're in the middle of a recursive
	       call. Not true for reg window machines (sparc)
	       because the must change frames to call things and
	       the stack pointer doesn't have to change if it
	       the bp was set in a routine without a frame (pc can
	       be stored in some other window).
	       
	       The removal of the sp test is to allow calls to
	       alloca.  Nasty things were happening.  Oh, well,
	       gdb can only handle one level deep of lack of
	       frame pointer. */

	    /*
	      Disable test for step_frame_address match so that we always stop even if the
	      frames don't match.  Reason: if we hit the step_resume_breakpoint, there is
	      no way to temporarily disable it so that we can step past it.  If we leave
	      the breakpoint in, then we loop forever repeatedly hitting, but never
	      getting past the breakpoint.  This change keeps nexting over recursive
	      function calls from hanging gdb.
	      */
#if 0
	    if (* step_frame_address == 0
		|| (step_frame_address == stop_frame_address))
#endif
	      {
		remove_step_breakpoint ();
		step_resume_break_address = 0;

		/* If were waiting for a trap, hitting the step_resume_break
		   doesn't count as getting it.  */
		if (trap_expected)
		  another_trap = 1;
	      }
	  }

      /* We come here if we hit a breakpoint but should not
	 stop for it.  Possibly we also were stepping
	 and should stop for that.  So fall through and
	 test for stepping.  But, if not stepping,
	 do not stop.  */

      /* If this is the breakpoint at the end of a stack dummy,
	 just stop silently.  */
      if (!random_signal 
	 && PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address))
	  {
	    stop_print_frame = 0;
	    stop_stack_dummy = 1;
#ifdef HP_OS_BUG
	    trap_expected_after_continue = 1;