Make sure the clock never runs backwards.

* process.c, rootdir.c: When converting timeval structures
  into seconds or jiffies, make sure that floating point rounding errors
  don't make the clock the result jump backwards on second boundaries.

2 files changed, 6 insertions, 6 deletions

diff --git a/process.c b/process.c
index 1f9d5781..68e7bc1d 100644
--- a/process.c
+++ b/process.c
@@ -58,8 +58,8 @@ static const char *state_string (struct proc_stat *ps)
 
 static long long int timeval_jiffies (time_value_t tv)
 {
-  double secs = tv.seconds + tv.microseconds / 1000000.;
-  return secs * opt_clk_tck;
+  double secs = tv.seconds * 1000000. + tv.microseconds;
+  return secs * opt_clk_tck / 1000000.;
 }
 
 /* Actual content generators */
diff --git a/rootdir.c b/rootdir.c
index 728008e5..c6ddd87c 100644
--- a/rootdir.c
+++ b/rootdir.c
@@ -140,8 +140,8 @@ rootdir_gc_uptime (void *hook, char **contents, ssize_t *contents_len)
     return err;
 
   timersub (&time, &boottime, &time);
-  up_secs = time.tv_sec + time.tv_usec / 1000000.;
-  idle_secs = idletime.tv_sec + idletime.tv_usec / 1000000.;
+  up_secs = (time.tv_sec * 1000000. + time.tv_usec) / 1000000.;
+  idle_secs = (idletime.tv_sec * 1000000. + idletime.tv_usec) / 1000000.;
 
   /* The second field is the total idle time. As far as I know we don't
      keep track of it.  However, procps uses it to compute "USER_HZ", and
@@ -178,8 +178,8 @@ rootdir_gc_stat (void *hook, char **contents, ssize_t *contents_len)
     return EIO;
 
   timersub (&time, &boottime, &time);
-  up_ticks = opt_clk_tck * (time.tv_sec + time.tv_usec / 1000000.);
-  idle_ticks = opt_clk_tck * (idletime.tv_sec + idletime.tv_usec / 1000000.);
+  up_ticks = opt_clk_tck * (time.tv_sec * 1000000. + time.tv_usec) / 1000000.;
+  idle_ticks = opt_clk_tck * (idletime.tv_sec * 1000000. + idletime.tv_usec) / 1000000.;
 
   *contents_len = asprintf (contents,
       "cpu  %lu 0 0 %lu 0 0 0 0 0\n"