On Wed, Nov 05, 2014 at 08:45:07PM +0100, Theo Buehler wrote:
> Pausing a tetris game currently causes a segfault due to a a null
> pointer dereference.
>
> Fix this by checking that s is non-NULL before accessing its members.
>
> A number of comments and an error message still refer to select()
> instead of poll(). Correct this as well.
>
>
> Index: input.c
> ===================================================================
> RCS file: /cvs/src/games/tetris/input.c,v
> retrieving revision 1.13
> diff -u -p -r1.13 input.c
> --- input.c 3 Nov 2014 22:14:54 -0000 1.13
> +++ input.c 5 Nov 2014 19:39:30 -0000
> @@ -64,12 +64,12 @@
> }
>
> /*
> - * Do a `read wait': select for reading from stdin, with timeout *tvp.
> + * Do a `read wait': poll for reading from stdin, with timeout *tvp.
> * On return, modify *tvp to reflect the amount of time spent waiting.
> * It will be positive only if input appeared before the time ran out;
> * otherwise it will be zero or perhaps negative.
> *
> - * If tvp is nil, wait forever, but return if select is interrupted.
> + * If tvp is nil, wait forever, but return if poll is interrupted.
> *
> * Return 0 => no input, 1 => can read() from stdin
> */
> @@ -90,14 +90,15 @@ rwait(struct timeval *tvp)
> again:
> pfd[0].fd = STDIN_FILENO;
> pfd[0].events = POLLIN;
> - switch (poll(pfd, 1, s->tv_sec * 1000 + s->tv_usec / 1000)) {
> + switch (poll(pfd, 1, s ? s->tv_sec * 1000 + s->tv_usec / 1000 :
I propose getting rid of the s pointer all together as such:
Index: input.c
===================================================================
RCS file: /cvs/obsd/src/games/tetris/input.c,v
retrieving revision 1.13
diff -u -p -u -p -r1.13 input.c
--- input.c 3 Nov 2014 22:14:54 -0000 1.13
+++ input.c 5 Nov 2014 22:40:47 -0000
@@ -64,19 +64,20 @@
}
/*
- * Do a `read wait': select for reading from stdin, with timeout *tvp.
+ * Do a `read wait': poll for reading from stdin, with timeout *tvp.
* On return, modify *tvp to reflect the amount of time spent waiting.
* It will be positive only if input appeared before the time ran out;
* otherwise it will be zero or perhaps negative.
*
- * If tvp is nil, wait forever, but return if select is interrupted.
+ * If tvp is nil, wait forever, but return if poll is interrupted.
*
* Return 0 => no input, 1 => can read() from stdin
*/
int
rwait(struct timeval *tvp)
{
- struct timeval starttv, endtv, *s;
+ int timo = INFTIM;
+ struct timeval starttv, endtv;
struct pollfd pfd[1];
#define NILTZ ((struct timezone *)0)
@@ -84,20 +85,19 @@ rwait(struct timeval *tvp)
if (tvp) {
(void) gettimeofday(&starttv, NILTZ);
endtv = *tvp;
- s = &endtv;
- } else
- s = NULL;
+ timo = endtv.tv_sec * 1000 + endtv.tv_usec / 1000;
+ }
again:
pfd[0].fd = STDIN_FILENO;
pfd[0].events = POLLIN;
- switch (poll(pfd, 1, s->tv_sec * 1000 + s->tv_usec / 1000)) {
+ switch (poll(pfd, 1, timo)) {
case -1:
if (tvp == 0)
return (-1);
if (errno == EINTR)
goto again;
- stop("select failed, help");
+ stop("poll failed, help");
/* NOTREACHED */
case 0: /* timed out */
@@ -115,7 +115,7 @@ again:
}
/*
- * `sleep' for the current turn time (using select).
+ * `sleep' for the current turn time (using poll).
* Eat any input that might be available.
*/
void
--patrick
> + INFTIM)) {
>
> case -1:
> if (tvp == 0)
> return (-1);
> if (errno == EINTR)
> goto again;
> - stop("select failed, help");
> + stop("poll failed, help");
> /* NOTREACHED */
>
> case 0: /* timed out */
> @@ -115,7 +116,7 @@ again:
> }
>
> /*
> - * `sleep' for the current turn time (using select).
> + * `sleep' for the current turn time (using poll).
> * Eat any input that might be available.
> */
> void
>
