1 files changed, 107 insertions, 0 deletions
diff --git a/lib/xnanosleep.c b/lib/xnanosleep.c
new file mode 100644
index 0000000..ebbd7ee
--- /dev/null
+++ b/lib/xnanosleep.c
@@ -0,0 +1,107 @@
+/* xnanosleep.c -- a more convenient interface to nanosleep
+
+   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Mostly written (for sleep.c) by Paul Eggert.
+   Factored out (creating this file) by Jim Meyering.  */
+
+#include <config.h>
+
+#include "xnanosleep.h"
+
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <assert.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <time.h>
+
+#include "intprops.h"
+
+#ifndef TIME_T_MAX
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
+#endif
+
+/* 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)
+{
+  enum { BILLION = 1000000000 };
+
+  bool overflow = false;
+  double ns;
+  struct timespec ts_sleep;
+
+  assert (0 <= seconds);
+
+  /* Separate whole seconds from nanoseconds.
+     Be careful to detect any overflow.  */
+  ts_sleep.tv_sec = seconds;
+  ns = BILLION * (seconds - ts_sleep.tv_sec);
+  overflow |= ! (ts_sleep.tv_sec <= seconds && 0 <= ns && ns <= BILLION);
+  ts_sleep.tv_nsec = ns;
+
+  /* Round up to the next whole number, if necessary, so that we
+     always sleep for at least the requested amount of time.  Assuming
+     the default rounding mode, we don't have to worry about the
+     rounding error when computing 'ns' above, since the error won't
+     cause 'ns' to drop below an integer boundary.  */
+  ts_sleep.tv_nsec += (ts_sleep.tv_nsec < ns);
+
+  /* Normalize the interval length.  nanosleep requires this.  */
+  if (BILLION <= ts_sleep.tv_nsec)
+    {
+      time_t t = ts_sleep.tv_sec + 1;
+
+      /* Detect integer overflow.  */
+      overflow |= (t < ts_sleep.tv_sec);
+
+      ts_sleep.tv_sec = t;
+      ts_sleep.tv_nsec -= BILLION;
+    }
+
+  for (;;)
+    {
+      if (overflow)
+	{
+	  ts_sleep.tv_sec = TIME_T_MAX;
+	  ts_sleep.tv_nsec = BILLION - 1;
+	}
+
+      /* 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).  */
+      errno = 0;
+      if (nanosleep (&ts_sleep, NULL) == 0)
+	break;
+      if (errno != EINTR && errno != 0)
+	return -1;
+    }
+
+  return 0;
+}