1 files changed, 65 insertions, 0 deletions
diff --git a/support/timespec-add.c b/support/timespec-add.c
new file mode 100644
index 0000000000..8efb8a6eb6
--- /dev/null
+++ b/support/timespec-add.c
@@ -0,0 +1,65 @@
+/* Add two struct timespec values.
+   Copyright (C) 2011-2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library and is also part of gnulib.
+   Patches to this file should be submitted to both projects.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* Return the sum of two timespec values A and B.  On overflow, return
+   an extremal value.  This assumes 0 <= tv_nsec < TIMESPEC_HZ.  */
+
+#include <config.h>
+#include "timespec.h"
+
+#include "intprops.h"
+
+struct timespec
+timespec_add (struct timespec a, struct timespec b)
+{
+  time_t rs = a.tv_sec;
+  time_t bs = b.tv_sec;
+  int ns = a.tv_nsec + b.tv_nsec;
+  int nsd = ns - TIMESPEC_HZ;
+  int rns = ns;
+
+  if (0 <= nsd)
+    {
+      rns = nsd;
+      time_t bs1;
+      if (!INT_ADD_WRAPV (bs, 1, &bs1))
+        bs = bs1;
+      else if (rs < 0)
+        rs++;
+      else
+        goto high_overflow;
+    }
+
+  if (INT_ADD_WRAPV (rs, bs, &rs))
+    {
+      if (bs < 0)
+        {
+          rs = TYPE_MINIMUM (time_t);
+          rns = 0;
+        }
+      else
+        {
+        high_overflow:
+          rs = TYPE_MAXIMUM (time_t);
+          rns = TIMESPEC_HZ - 1;
+        }
+    }
+
+  return make_timespec (rs, rns);
+}