X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fxnanosleep.c;h=1c7de6241ca47baf8fd53e1c4e10f1cab03cc4cd;hb=b7285ef59198ab3a562df0c91c6b1c781620e45e;hp=ebbd7ee89a1f1d9bf79800f59a01fc028ef20030;hpb=3ac9552429c5a500717e1d3d129c32f7d0ea37a3;p=gnulib.git

diff --git a/lib/xnanosleep.c b/lib/xnanosleep.c
index ebbd7ee89..1c7de6241 100644
--- a/lib/xnanosleep.c
+++ b/lib/xnanosleep.c
@@ -3,10 +3,10 @@
    Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Free Software
    Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   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.
+   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
@@ -14,8 +14,7 @@
    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.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* Mostly written (for sleep.c) by Paul Eggert.
    Factored out (creating this file) by Jim Meyering.  */
@@ -50,36 +49,49 @@ xnanosleep (double seconds)
 {
   enum { BILLION = 1000000000 };
 
-  bool overflow = false;
-  double ns;
+  /* For overflow checking, use naive comparison if possible, widening
+     to long double if double is not wide enough.  Otherwise, use <=,
+     not <, to avoid problems when TIME_T_MAX is less than SECONDS but
+     compares equal to SECONDS after loss of precision when coercing
+     from time_t to long double.  This mishandles near-maximal values
+     in some rare (perhaps theoretical) cases but that is better than
+     undefined behavior.  */
+  bool overflow = ((time_t) ((double) TIME_T_MAX / 2) == TIME_T_MAX / 2
+		   ? TIME_T_MAX < seconds
+		   : (time_t) ((long double) TIME_T_MAX / 2) == TIME_T_MAX / 2
+		   ? TIME_T_MAX < (long double) seconds
+		   : TIME_T_MAX <= (long double) seconds);
+
   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)
+  /* Separate whole seconds from nanoseconds.  */
+  if (! overflow)
     {
-      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;
+      time_t floor_seconds = seconds;
+      double ns = BILLION * (seconds - floor_seconds);
+      ts_sleep.tv_sec = floor_seconds;
+
+      /* 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 = ns;
+      ts_sleep.tv_nsec += (ts_sleep.tv_nsec < ns);
+
+      /* Normalize the interval length.  nanosleep requires this.  */
+      if (BILLION <= ts_sleep.tv_nsec)
+	{
+	  if (ts_sleep.tv_sec == TIME_T_MAX)
+	    overflow = true;
+	  else
+	    {
+	      ts_sleep.tv_sec++;
+	      ts_sleep.tv_nsec -= BILLION;
+	    }
+	}
     }
 
   for (;;)