ych@maps.cs.cmu.edu (Yuan Hsieh) (12/02/89)
A questions on Sunview programming concerning use of window_read_event().
I have the following event handler for a canvas window:
canvas_handle_event(canvas,event,arg)
{
...
switch(event_acton(event)) {
...
case 'Z': z_proc(canvas); break;
...
}
...
}
When event 'Z' occurs, z_proc() is called and is defined as follows:
[z_proc() is suppose to wait for a 'down' event to occur.]
z_proc(canvas)
{
...
while(1) {
if ((winderr = window_read_event(canvas,event)) == 0) {
if (event_is_down(event)) break;
} else if (winderr == -1) {
printf("errno:%d\n",errno);
}
}
...
}
Problem:
if 'Z' event is the first thing I do, z_proc() executes with no fault.
But if there are any other event before 'Z', window_read_event() returns
-1 with errno of 14 which is, (according to man 2 intro):
14 EFAULT Bad address
The system encountered a hardware fault in attempting
to access the arguments of a system call.
I am pretty sure all other parts of my program does not affect this at
all. Anyone know what this means? Am I missing something?
Please reply to ych@maps.cs.cmu.edu.. Thanks.