sync: Avoid ridiculously long timeouts

On OpenBSD, passing a timeout longer than 100000000 seconds to select(2) will
make it fail with EINVAL.  As this is original 4.4BSD behaviour it is not
inconceivable that other systems suffer from the same problem.  And Linux,
though not suffering from any 4.4BSD heritage, briefly did something similar:

<https://lkml.org/lkml/2012/8/31/263>

So avoid calling AdjustWaitForDelay() instead of setting the timeout to
(effectively) ULONG_MAX milliseconds.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>

1 files changed, 2 insertions, 5 deletions

diff --git a/Xext/sync.c b/Xext/sync.c
index 97c9d5183..755ed94a1 100644
--- a/Xext/sync.c
+++ b/Xext/sync.c
@@ -2731,27 +2731,24 @@ IdleTimeBlockHandler(void *pCounter, struct timeval **wt, void *LastSelectMask)
          * If we've been idle more than it, and someone wants to know about
          * that level-triggered, schedule an immediate wakeup.
          */
-        unsigned long timeout = -1;
 
         if (XSyncValueLessThan(idle, *greater)) {
             XSyncValue value;
             Bool overflow;
 
             XSyncValueSubtract(&value, *greater, idle, &overflow);
-            timeout = min(timeout, XSyncValueLow32(value));
+            AdjustWaitForDelay(wt, XSyncValueLow32(value));
         }
         else {
             for (list = counter->sync.pTriglist; list;
                  list = list->next) {
                 trig = list->pTrigger;
                 if (trig->CheckTrigger(trig, old_idle)) {
-                    timeout = min(timeout, 0);
+                    AdjustWaitForDelay(wt, 0);
                     break;
                 }
             }
         }
-
-        AdjustWaitForDelay(wt, timeout);
     }
 
     counter->value = old_idle;  /* pop */