problem report #99

problem report #99

[Dan Nicolaescu]

CID: 99
Checker: UNINIT (help)
File: base/src/emacs/src/keyboard.c
Function: kbd_buffer_get_event
Description: Using uninitialized value "bar_window" in call to function "make_lispy_movement"

Event var_decl: Declared variable "bar_window" without initializer
Also see events: [uninit_use_in_call]

4259 	      Lisp_Object bar_window;
4260 	      enum scroll_bar_part part;
4261 	      Lisp_Object x, y;
4262 	      unsigned long time;
4263 	
4264 	      *kbp = current_kboard;
4265 	      /* Note that this uses F to determine which terminal to look at.
4266 		 If there is no valid info, it does not store anything
4267 		 so x remains nil.  */
4268 	      x = Qnil;
4269 	
4270 	      /* XXX Can f or mouse_position_hook be NULL here? */

At conditional (1): "f != 0" taking true path
At conditional (2): "((f)->terminal)->mouse_position_hook != 0" taking false path

4271 	      if (f && FRAME_TERMINAL (f)->mouse_position_hook)
4272 	        (*FRAME_TERMINAL (f)->mouse_position_hook) (&f, 0, &bar_window,
4273 	                                                    &part, &x, &y, &time);
4274 	
4275 	      obj = Qnil;
4276 	
4277 	      /* Decide if we should generate a switch-frame event.  Don't
4278 		 generate switch-frame events for motion outside of all Emacs
4279 		 frames.  */

At conditional (3): "x != Qnil" taking true path
At conditional (4): "f != 0" taking true path

4280 	      if (!NILP (x) && f)
4281 		{
4282 		  Lisp_Object frame;
4283 	
4284 		  frame = FRAME_FOCUS_FRAME (f);

At conditional (5): "frame == Qnil" taking true path

4285 		  if (NILP (frame))
4286 		    XSETFRAME (frame, f);
4287 	

At conditional (6): "frame != internal_last_event_frame" taking true path
At conditional (7): "frame != selected_frame" taking true path

4288 		  if (! EQ (frame, internal_last_event_frame)
4289 		      && !EQ (frame, selected_frame))
4290 		    obj = make_lispy_switch_frame (frame);
4291 		  internal_last_event_frame = frame;
4292 		}
4293 	
4294 	      /* If we didn't decide to make a switch-frame event, go ahead and
4295 		 return a mouse-motion event.  */

At conditional (8): "x != Qnil" taking true path
At conditional (9): "obj == Qnil" taking true path

4296 	      if (!NILP (x) && NILP (obj))

Event uninit_use_in_call: Using uninitialized value "bar_window" in call to function "make_lispy_movement" [model]
Also see events: [var_decl]

4297 		obj = make_lispy_movement (f, bar_window, part, x, y, time);
4298 	    }

Re: problem report #99

[Davis Herring]

> 4265 	      /* Note that this uses F to determine which terminal to look
> at.
> 4266 		 If there is no valid info, it does not store anything
> 4267 		 so x remains nil.  */
> 4268 	      x = Qnil;
> 4269
> 4270 	      /* XXX Can f or mouse_position_hook be NULL here? */

This comment says it all.  When this is skipped:

> At conditional (1): "f != 0" taking true path
> At conditional (2): "((f)->terminal)->mouse_position_hook != 0" taking
> false path
>
> 4271 	      if (f && FRAME_TERMINAL (f)->mouse_position_hook)
> 4272 	        (*FRAME_TERMINAL (f)->mouse_position_hook) (&f, 0,
> &bar_window,
> 4273 	                                                    &part, &x, &y,
> &time);

...then this can't happen:

> At conditional (8): "x != Qnil" taking true path
> At conditional (9): "obj == Qnil" taking true path
>
> 4296 	      if (!NILP (x) && NILP (obj))
>
> Event uninit_use_in_call: Using uninitialized value "bar_window" in call
> to function "make_lispy_movement" [model]
> Also see events: [var_decl]
>
> 4297 		obj = make_lispy_movement (f, bar_window, part, x, y, time);
> 4298 	    }

No bug.

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
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shipping.

Re: problem report #99

[Davis Herring]

My analysis for the "first #99" applies to all four of them, since they
analyze the same portion of code; perhaps that's why they got the same
number.  Anyway: #2: no bug, #3: no bug, and #4: no bug.

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
too sparse, it is because mass-energy conversion has occurred during
shipping.