Re: [Bug-gnulib] Re: GNULib Module gettime Breaks CVS Build On Windows

[Paul Eggert]

Derek Robert Price <address@hidden> writes:

> Are you aware of any function available on Windows that _does_ yield a
> high resolution time?  Preferrably one based on some standard, such as
> C89, C99, or POSIX?

I'd rather not spend time worrying about Microsoft-Windows-specific
time functions, but it does seem reasonable to remove the assumption
that gettimeofday always works, as that assumption is also false on
ancient Unix hosts.  coreutils/src/ls.c already does this (in a
slightly different context) so this sounds quite safe.  Similarly for
settimeofday.

So I installed this patch into gnulib.  It also fixes a dependency bug
(gettime and settime depend on gl_TIMESPEC being called).

2004-05-13  Paul Eggert  <address@hidden>

        * lib/gettime.c (gettime): Fall back on `time' if `gettimeofday'
        doesn't work.
        * lib/settime.c: Include <unistd.h>, for stime (on Solaris 8, anyway).
        (ENOSYS): Define if not defined.
        (settime): Fall back on stime if it exists and settimeofday fails.
        But don't bother with fallbacks if a method fails with errno == EPERM.
        * m4/gettime.m4 (gl_GETTIME): Require gl_TIMESPEC.
        Check for gettimeofday.
        * m4/settime.m4 (gl_SETTIME): Require gl_TIMESPEC.
        Check for settimeofday, stime.

Index: lib/gettime.c
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/gettime.c,v
retrieving revision 1.2
diff -p -u -r1.2 gettime.c
--- lib/gettime.c       1 Mar 2002 23:54:52 -0000       1.2
+++ lib/gettime.c       13 May 2004 21:54:44 -0000
@@ -1,5 +1,5 @@
 /* gettime -- get the system clock
-   Copyright (C) 2002 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2004 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
@@ -33,14 +33,27 @@ gettime (struct timespec *ts)
     return 0;
 #endif
 
+#if HAVE_GETTIMEOFDAY
   {
     struct timeval tv;
-    int r = gettimeofday (&tv, 0);
-    if (r == 0)
+    if (gettimeofday (&tv, 0) == 0)
       {
        ts->tv_sec = tv.tv_sec;
        ts->tv_nsec = tv.tv_usec * 1000;
+       return 0;
       }
-    return r;
   }
+#endif
+
+  {
+    time_t t = time (0);
+    if (t != (time_t) -1)
+      {
+       ts->tv_sec = t;
+       ts->tv_nsec = 0;
+       return 0;
+      }
+  }
+
+  return -1;
 }
Index: lib/settime.c
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/settime.c,v
retrieving revision 1.1
diff -p -u -r1.1 settime.c
--- lib/settime.c       1 Mar 2002 23:20:20 -0000       1.1
+++ lib/settime.c       13 May 2004 21:54:44 -0000
@@ -1,5 +1,5 @@
 /* settime -- set the system clock
-   Copyright (C) 2002 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2004 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
@@ -23,21 +23,52 @@
 
 #include "timespec.h"
 
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#include <errno.h>
+
+/* Some systems don't have ENOSYS.  */
+#ifndef ENOSYS
+# ifdef ENOTSUP
+#  define ENOSYS ENOTSUP
+# else
+/* Some systems don't have ENOTSUP either.  */
+#  define ENOSYS EINVAL
+# endif
+#endif
+
 /* Set the system time.  */
 
 int
 settime (struct timespec const *ts)
 {
 #if defined CLOCK_REALTIME && HAVE_CLOCK_SETTIME
-  if (clock_settime (CLOCK_REALTIME, ts) == 0)
-    return 0;
+  {
+    int r = clock_settime (CLOCK_REALTIME, ts);
+    if (r == 0 || errno == EPERM)
+      return r;
+  }
 #endif
 
+#if HAVE_SETTIMEOFDAY
   {
     struct timeval tv;
+    int r;
 
     tv.tv_sec = ts->tv_sec;
     tv.tv_usec = ts->tv_nsec / 1000;
-    return settimeofday (&tv, 0);
+    r = settimeofday (&tv, 0);
+    if (r == 0 || errno == EPERM)
+      return r;
   }
+#endif
+
+#if HAVE_STIME
+  return stime (&ts->tv_sec);
+#endif
+
+  errno = ENOSYS;
+  return -1;
 }
Index: m4/gettime.m4
===================================================================
RCS file: /cvsroot/gnulib/gnulib/m4/gettime.m4,v
retrieving revision 1.1
diff -p -u -r1.1 gettime.m4
--- m4/gettime.m4       31 Dec 2002 13:42:07 -0000      1.1
+++ m4/gettime.m4       13 May 2004 21:54:45 -0000
@@ -1,5 +1,5 @@
-# gettime.m4 serial 1
-dnl Copyright (C) 2002 Free Software Foundation, Inc.
+# gettime.m4 serial 2
+dnl Copyright (C) 2002, 2004 Free Software Foundation, Inc.
 dnl This file is free software, distributed under the terms of the GNU
 dnl General Public License.  As a special exception to the GNU General
 dnl Public License, this file may be distributed as part of a program
@@ -9,6 +9,7 @@ dnl the same distribution terms as the r
 AC_DEFUN([gl_GETTIME],
 [
   dnl Prerequisites of lib/gettime.c.
-  # Need clock_gettime.
   AC_REQUIRE([gl_CLOCK_TIME])
+  AC_REQUIRE([gl_TIMESPEC])
+  AC_CHECK_FUNCS_ONCE(gettimeofday)
 ])
Index: m4/settime.m4
===================================================================
RCS file: /cvsroot/gnulib/gnulib/m4/settime.m4,v
retrieving revision 1.1
diff -p -u -r1.1 settime.m4
--- m4/settime.m4       31 Dec 2002 13:42:07 -0000      1.1
+++ m4/settime.m4       13 May 2004 21:54:45 -0000
@@ -1,5 +1,5 @@
-# settime.m4 serial 1
-dnl Copyright (C) 2002 Free Software Foundation, Inc.
+# settime.m4 serial 2
+dnl Copyright (C) 2002, 2004 Free Software Foundation, Inc.
 dnl This file is free software, distributed under the terms of the GNU
 dnl General Public License.  As a special exception to the GNU General
 dnl Public License, this file may be distributed as part of a program
@@ -9,6 +9,7 @@ dnl the same distribution terms as the r
 AC_DEFUN([gl_SETTIME],
 [
   dnl Prerequisites of lib/settime.c.
-  # Need clock_settime.
   AC_REQUIRE([gl_CLOCK_TIME])
+  AC_REQUIRE([gl_TIMESPEC])
+  AC_CHECK_FUNCS_ONCE(settimeofday stime)
 ])