[PATCH xf86-input-synaptics] Update touch state when device is off too

[Peter Hutterer]

On Tue, Feb 21, 2012 at 09:42:16PM +0100, Chase Douglas wrote:
> If the device is turned off, usually by syndaemon to disable the
> touchpad while the typing, the touch state will not be updated with the
> latest hardware state changes. If a touch begins while the device is
> off and ends while the device is on, then the touch count will be
> decremented without any previous increment. A similar effect will occur
> if the device is on when the touch begins, but off when the touch ends.
> 
> If the touch count goes negative, the index into the touch slot mask
> array will be out of bounds. This can corrupt memory and cause random
> crashes.
> 
> Signed-off-by: Chase Douglas <chase.douglas at canonical.com>

   dfc3a8e..0a2fd56  master -> master

thanks.

Cheers,
  Peter

> ---
>  src/synaptics.c |   74 ++++++++++++++++++++++++++++++------------------------
>  1 files changed, 41 insertions(+), 33 deletions(-)
> 
> diff --git a/src/synaptics.c b/src/synaptics.c
> index 65b48ee..4784157 100644
> --- a/src/synaptics.c
> +++ b/src/synaptics.c
> @@ -2596,6 +2596,42 @@ repeat_scrollbuttons(const InputInfoPtr pInfo,
>      return delay;
>  }
>  
> +/* Update the open slots and number of active touches */
> +static void
> +UpdateTouchState(InputInfoPtr pInfo, struct SynapticsHwState *hw)
> +{
> +#ifdef HAVE_MULTITOUCH
> +    SynapticsPrivate *priv = (SynapticsPrivate *)pInfo->private;
> +    int i;
> +
> +    for (i = 0; i < hw->num_mt_mask; i++)
> +    {
> +        if (hw->slot_state[i] == SLOTSTATE_OPEN)
> +        {
> +            priv->open_slots[priv->num_active_touches] = i;
> +            priv->num_active_touches++;
> +        } else if (hw->slot_state[i] == SLOTSTATE_CLOSE)
> +        {
> +            Bool found = FALSE;
> +            int j;
> +
> +            for (j = 0; j < priv->num_active_touches - 1; j++)
> +            {
> +                if (priv->open_slots[j] == i)
> +                    found = TRUE;
> +
> +                if (found)
> +                    priv->open_slots[j] = priv->open_slots[j + 1];
> +            }
> +
> +            priv->num_active_touches--;
> +        }
> +    }
> +
> +    SynapticsResetTouchHwState(hw);
> +#endif
> +}
> +
>  static void
>  HandleTouches(InputInfoPtr pInfo, struct SynapticsHwState *hw)
>  {
> @@ -2675,40 +2711,9 @@ HandleTouches(InputInfoPtr pInfo, struct SynapticsHwState *hw)
>              xf86PostTouchEvent(pInfo->dev, slot, XI_TouchEnd, 0,
>                                 hw->mt_mask[slot]);
>      }
> -            
> -out:
> -    /* Update the open slots and number of active touches */
> -    for (i = 0; i < hw->num_mt_mask; i++)
> -    {
> -        if (hw->slot_state[i] == SLOTSTATE_OPEN)
> -        {
> -            priv->open_slots[priv->num_active_touches] = i;
> -            priv->num_active_touches++;
> -        } else if (hw->slot_state[i] == SLOTSTATE_CLOSE)
> -        {
> -            Bool found = FALSE;
> -            int j;
>  
> -            for (j = 0; j < priv->num_active_touches - 1; j++)
> -            {
> -                if (priv->open_slots[j] == i)
> -                    found = TRUE;
> -
> -                if (found)
> -                    priv->open_slots[j] = priv->open_slots[j + 1];
> -            }
> -
> -            priv->num_active_touches--;
> -        }
> -    }
> -
> -    /* We calculated the value twice, might as well double check our math */
> -    if (priv->num_active_touches != new_active_touches)
> -        xf86IDrvMsg(pInfo, X_WARNING,
> -                    "calculated wrong number of active touches (%d vs %d)\n",
> -                    priv->num_active_touches, new_active_touches);
> -
> -    SynapticsResetTouchHwState(hw);
> +out:
> +    UpdateTouchState(pInfo, hw);
>  #endif
>  }
>  
> @@ -2741,7 +2746,10 @@ HandleState(InputInfoPtr pInfo, struct SynapticsHwState *hw, CARD32 now,
>  
>      /* If touchpad is switched off, we skip the whole thing and return delay */
>      if (para->touchpad_off == 1)
> +    {
> +	UpdateTouchState(pInfo, hw);
>  	return delay;
> +    }
>  
>      /* apply hysteresis before doing anything serious. This cancels
>       * out a lot of noise which might surface in strange phenomena
> -- 
> 1.7.9
>