Fix issue with H5_now_usec() with 32 bit systems (#1416)

* Implement H5ESget_requests() to retrieve request pointers and
corresponding connector IDs from an event set.  Add tests for this
function.

* Add "order" parameter to H5ESget_requests, to allow the user to specify
the order in which requests are returned.

* Fix bugs with H5ESinsert_request()

* Change H5ESget_requests() API to have separate input and output
parameters for the allocated array length(s) (in) and the number of events in
the event set (out).

* Fix issue with H5_now_usec() with 32 bit systems.  Also improve event
set test.

* Committing clang-format changes

* Add comments to H5_now_usec() explaining rationale for uint64_t casts.

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/src/H5timer.c b/src/H5timer.c
index b2cc5f0..b5dba97 100644
--- a/src/H5timer.c
+++ b/src/H5timer.c
@@ -193,17 +193,26 @@ H5_now_usec(void)
         struct timespec ts;
 
         HDclock_gettime(CLOCK_MONOTONIC, &ts);
-        now = (uint64_t)(ts.tv_sec * (1000 * 1000)) + (uint64_t)(ts.tv_nsec / 1000);
+
+        /* Cast all values in this expression to uint64_t to ensure that all intermediate
+         * calculations are done in 64 bit, to prevent overflow */
+        now = ((uint64_t)ts.tv_sec * ((uint64_t)1000 * (uint64_t)1000)) +
+              ((uint64_t)ts.tv_nsec / (uint64_t)1000);
     }
 #elif defined(H5_HAVE_GETTIMEOFDAY)
     {
         struct timeval now_tv;
 
         HDgettimeofday(&now_tv, NULL);
-        now = (uint64_t)(now_tv.tv_sec * (1000 * 1000)) + (uint64_t)now_tv.tv_usec;
+
+        /* Cast all values in this expression to uint64_t to ensure that all intermediate
+         * calculations are done in 64 bit, to prevent overflow */
+        now = ((uint64_t)now_tv.tv_sec * ((uint64_t)1000 * (uint64_t)1000)) + (uint64_t)now_tv.tv_usec;
     }
 #else  /* H5_HAVE_GETTIMEOFDAY */
-    now       = (uint64_t)(HDtime(NULL) * (1000 * 1000));
+    /* Cast all values in this expression to uint64_t to ensure that all intermediate calculations
+     * are done in 64 bit, to prevent overflow */
+    now       = ((uint64_t)HDtime(NULL) * ((uint64_t)1000 * (uint64_t)1000));
 #endif /* H5_HAVE_GETTIMEOFDAY */
 
     return (now);