Base idle timeout on player->curup again, not current time

Idle timeout used to expire max_idle minutes after the last
player->curup update.  When we got rid of the idle thread in commit
08b94556 (v4.3.20), this got changed to "wait no more than max_idle
minutes for input".  Time spent computing and time spent blocked on
output no longer counts.  In particular, a connection can block
indefinitely on output since then.  Let's fix that.

Start with basing the input timeout on player->curup again.  The
missing output timeout will be added shortly.

Aside: since status() updates player->curup, the idle timer gets reset
when the update aborts a command.  Left for another day.

include/empio.h

@@ -44,6 +44,7 @@
 extern struct iop *io_open(int, int, int);
 extern void io_init(void);
 extern void io_close(struct iop *, struct timeval *);
+extern void io_timeout(struct timeval *, time_t);
 extern int io_input(struct iop *, struct timeval *);
 extern int io_inputwaiting(struct iop *);
 extern int io_outputwaiting(struct iop *);

src/lib/empthread/io.c

@@ -124,6 +124,24 @@ io_close(struct iop *iop, struct timeval *timeout)
     free(iop);
 }
 
+void
+io_timeout(struct timeval *timeout, time_t deadline)
+{
+    struct timeval now;
+
+    gettimeofday(&now, NULL);
+    if (now.tv_sec >= deadline) {
+	/* deadline reached already */
+	timeout->tv_sec = 0;
+	timeout->tv_usec = 0;
+    } else {
+	/* deadline in future */
+	timeout->tv_sec = deadline - now.tv_sec - 1;
+	timeout->tv_usec = 999999 - now.tv_usec;
+	/* yes, this is 1usec early; sue me */
+    }
+}
+
 /*
  * Read input from IOP and enqueue it.
  * If TIMEOUT is non-null, wait at most that long for input to arrive.

src/lib/player/accept.c

@@ -100,8 +100,7 @@ player_delete(struct player *lp)
 
     if (lp->iop) {
 	/* it's a real player */
-	timeout.tv_sec = minutes(max_idle);
-	timeout.tv_usec = 0;
+	io_timeout(&timeout, player->curup + minutes(max_idle));
 	io_close(lp->iop, &timeout);
 	lp->iop = NULL;
     }

src/lib/player/login.c

@@ -90,8 +90,7 @@ player_login(void *ud)
     for (;;) {
 	io_output(player->iop, 1);
 	if (io_gets(player->iop, buf, sizeof(buf)) < 0) {
-	    timeout.tv_sec = minutes(max_idle);
-	    timeout.tv_usec = 0;
+	    io_timeout(&timeout, player->curup + minutes(max_idle));
 	    res = io_input(player->iop, &timeout);
 	    if (res <= 0) {
 		if (res == 0 && !io_eof(player->iop))

src/lib/player/recvclient.c

@@ -92,8 +92,7 @@ recvclient(char *cmd, int size)
 	if (player->aborted)
 	    break;
 
-	timeout.tv_sec = minutes(max_idle);
-	timeout.tv_usec = 0;
+	io_timeout(&timeout, player->curup + minutes(max_idle));
 	res = io_input(player->iop, &timeout);
 	if (res > 0)
 	    ;