1 files changed, 76 insertions, 0 deletions
diff --git a/lib/xnanosleep.c b/lib/xnanosleep.c
new file mode 100644
index 0000000..8619c6d
--- /dev/null
+++ b/lib/xnanosleep.c
@@ -0,0 +1,76 @@
+/* xnanosleep.c -- a more convenient interface to nanosleep
+
+   Copyright (C) 2002-2007, 2009-2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Mostly written (for sleep.c) by Paul Eggert.
+   Factored out (creating this file) by Jim Meyering.  */
+
+#include <config.h>
+
+#include "xnanosleep.h"
+
+#include <intprops.h>
+#include <timespec.h>
+
+#include <errno.h>
+#include <time.h>
+#include <unistd.h>
+
+/* Sleep until the time (call it WAKE_UP_TIME) specified as
+   SECONDS seconds after the time this function is called.
+   SECONDS must be non-negative.  If SECONDS is so large that
+   it is not representable as a 'struct timespec', then use
+   the maximum value for that interval.  Return -1 on failure
+   (setting errno), 0 on success.  */
+
+int
+xnanosleep (double seconds)
+{
+#if HAVE_PAUSE
+  if (1.0 + TYPE_MAXIMUM (time_t) <= seconds)
+    {
+      do
+        pause ();
+      while (errno == EINTR);
+
+      /* pause failed (!); fall back on repeated nanosleep calls.  */
+    }
+#endif
+
+  struct timespec ts_sleep = dtotimespec (seconds);
+
+  for (;;)
+    {
+      /* Linux-2.6.8.1's nanosleep returns -1, but doesn't set errno
+         when resumed after being suspended.  Earlier versions would
+         set errno to EINTR.  nanosleep from linux-2.6.10, as well as
+         implementations by (all?) other vendors, doesn't return -1
+         in that case;  either it continues sleeping (if time remains)
+         or it returns zero (if the wake-up time has passed).
+
+         Gnulib's replacement nanosleep sometimes does not update
+         TS_SLEEP, and it is possible some kernels have a similar bug.
+         However, this merely causes xnanosleep to sleep longer than
+         necessary, which is not a correctness bug.  */
+      errno = 0;
+      if (nanosleep (&ts_sleep, &ts_sleep) == 0)
+        break;
+      if (errno != EINTR && errno != 0)
+        return -1;
+    }
+
+  return 0;
+}