From d1ddbad053cf092e70c593a67fdd41494005eda7 Mon Sep 17 00:00:00 2001
From: Freddie Akeroyd <freddie.akeroyd@stfc.ac.uk>
Date: Tue, 18 May 2021 12:24:07 +0100
Subject: [PATCH] Fix issue with very large timeout passed to
 epicsEventWaitWithTimeout()

A very large timeout was getting converted to a 0 wait and causing
some unit tests to fail in strange and random ways. Not trapping
large timeouts was an oversight when converting to waitable timers
on WIN32
---
 src/libCom/osi/os/WIN32/osdEvent.c  | 14 ++++++++++++--
 src/libCom/osi/os/WIN32/osdThread.c | 14 ++++++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/libCom/osi/os/WIN32/osdEvent.c b/src/libCom/osi/os/WIN32/osdEvent.c
index fb67d6c79..e39608255 100644
--- a/src/libCom/osi/os/WIN32/osdEvent.c
+++ b/src/libCom/osi/os/WIN32/osdEvent.c
@@ -92,17 +92,27 @@ epicsShareFunc epicsEventStatus epicsEventWait ( epicsEventId pSem )
 epicsShareFunc epicsEventStatus epicsEventWaitWithTimeout (
     epicsEventId pSem, double timeOut )
 { 
-    static const unsigned nSec100PerSec = 10000000u;
+    /* waitable timers use 100 nanosecond intervals, like FILETIME */
+    static const unsigned ivalPerSec = 10000000u; /* number of 100ns intervals per second */
+    static const unsigned mSecPerSec = 1000u;     /* milliseconds per second */
     HANDLE handles[2];
     DWORD status;
     LARGE_INTEGER tmo;
     HANDLE timer;
+    LONGLONG nIvals;  /* number of intervals */
 
     if ( timeOut <= 0.0 ) {
         tmo.QuadPart = 0u;
     }
+    else if ( timeOut >= INFINITE / mSecPerSec  ) {
+        /* we need to apply a maximum wait time to stop an overflow. We choose (INFINITE - 1) milliseconds,
+           to be compatible with previous WaitForSingleObject() implementation */    
+        nIvals = (LONGLONG)(INFINITE - 1) * (ivalPerSec / mSecPerSec);
+        tmo.QuadPart = -nIvals;  /* negative value means a relative time offset for timer */
+    }
     else {
-        tmo.QuadPart = -((LONGLONG)(timeOut * nSec100PerSec + 0.5));
+        nIvals = (LONGLONG)(timeOut * ivalPerSec + 0.999999);
+        tmo.QuadPart = -nIvals;
     }
 
     if (tmo.QuadPart < 0) {
diff --git a/src/libCom/osi/os/WIN32/osdThread.c b/src/libCom/osi/os/WIN32/osdThread.c
index 0057ee953..092432e71 100644
--- a/src/libCom/osi/os/WIN32/osdThread.c
+++ b/src/libCom/osi/os/WIN32/osdThread.c
@@ -807,15 +807,25 @@ HANDLE osdThreadGetTimer()
  */
 epicsShareFunc void epicsShareAPI epicsThreadSleep ( double seconds )
 {
-    static const unsigned nSec100PerSec = 10000000u;
+    /* waitable timers use 100 nanosecond intervals, like FILETIME */
+    static const unsigned ivalPerSec = 10000000u; /* number of 100ns intervals per second */
+    static const unsigned mSecPerSec = 1000u;     /* milliseconds per second */
     LARGE_INTEGER tmo;
     HANDLE timer;
+    LONGLONG nIvals; /* number of intervals */
 
     if ( seconds <= 0.0 ) {
         tmo.QuadPart = 0u;
     }
+    else if ( seconds >= INFINITE / mSecPerSec  ) { 
+        /* we need to apply a maximum wait time to stop an overflow. We choose (INFINITE - 1) milliseconds,
+           to be compatible with previous WaitForSingleObject() implementation */    
+        nIvals = (LONGLONG)(INFINITE - 1) * (ivalPerSec / mSecPerSec);
+        tmo.QuadPart = -nIvals; /* negative value means a relative time offset for timer */
+    }
     else {
-        tmo.QuadPart = -((LONGLONG)(seconds * nSec100PerSec + 0.5));
+        nIvals = (LONGLONG)(seconds * ivalPerSec + 0.999999);
+        tmo.QuadPart = -nIvals;
     }
 
     if (tmo.QuadPart == 0) {