[glibc/zack/y2038-preliminaries] Use clock_gettime to implement ftime.

[Zack Weinberg <zack@sourceware.org>]

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a98d0813fb5de58a9a99dca8495f87b3e6ea86bd

commit a98d0813fb5de58a9a99dca8495f87b3e6ea86bd
Author: Zack Weinberg <zackw@panix.com>
Date:   Fri Aug 16 20:56:02 2019 -0400

    Use clock_gettime to implement ftime.
    
    ftime is an obsolete variation on gettimeofday, offering only
    millisecond time resolution; it was probably a system call in ooold
    versions of BSD Unix.  For historic reasons, we had three
    implementations of it.  These are all consolidated into time/ftime.c.
    
    Like gettimeofday, ftime tries to report the time zone, and using that
    information is always a bug.  This patch dummies out the reported
    timezone information; the ‘timezone’ and ‘dstflag’ fields of the
    returned ‘struct timeb’ will always be zero.
    
    (There is an argument for turning this function into a compat symbol,
    and not installing sys/timeb.h anymore.  Thoughts?)
    
    	* time/ftime.c (ftime): Replace implementation with the code
    	formerly in sysdeps/unix/bsd/ftime.c, then change that code to use
    	__clock_gettime instead of __gettimeofday.  Always set the
    	timezone and dstflag fields of the ‘timebuf’ argument to zero.
    
    	* sysdeps/unix/bsd/ftime.c
    	* sysdeps/unix/sysv/linux/ftime.c: Delete file.

Diff:
---
 sysdeps/unix/bsd/ftime.c        | 40 ----------------------------------------
 sysdeps/unix/sysv/linux/ftime.c |  3 ---
 time/ftime.c                    | 26 ++++++++++++--------------
 3 files changed, 12 insertions(+), 57 deletions(-)

diff --git a/sysdeps/unix/bsd/ftime.c b/sysdeps/unix/bsd/ftime.c
deleted file mode 100644
index 3a1c6e9..0000000
--- a/sysdeps/unix/bsd/ftime.c
+++ /dev/null
@@ -1,40 +0,0 @@
-/* Copyright (C) 1994-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   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
-   <http://www.gnu.org/licenses/>.  */
-
-#include <sys/timeb.h>
-#include <sys/time.h>
-
-int
-ftime (struct timeb *timebuf)
-{
-  struct timeval tv;
-  struct timezone tz;
-
-  if (__gettimeofday (&tv, &tz) < 0)
-    return -1;
-
-  timebuf->time = tv.tv_sec;
-  timebuf->millitm = (tv.tv_usec + 500) / 1000;
-  if (timebuf->millitm == 1000)
-    {
-      ++timebuf->time;
-      timebuf->millitm = 0;
-    }
-  timebuf->timezone = tz.tz_minuteswest;
-  timebuf->dstflag = tz.tz_dsttime;
-  return 0;
-}
diff --git a/sysdeps/unix/sysv/linux/ftime.c b/sysdeps/unix/sysv/linux/ftime.c
deleted file mode 100644
index 5a5949f..0000000
--- a/sysdeps/unix/sysv/linux/ftime.c
+++ /dev/null
@@ -1,3 +0,0 @@
-/* Linux defines the ftime system call but doesn't actually implement
-   it.  Use the BSD implementation.  */
-#include <sysdeps/unix/bsd/ftime.c>
diff --git a/time/ftime.c b/time/ftime.c
index 6c2a256..de8d043 100644
--- a/time/ftime.c
+++ b/time/ftime.c
@@ -15,27 +15,25 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <time.h>
 #include <sys/timeb.h>
+#include <time.h>
 
 int
 ftime (struct timeb *timebuf)
 {
-  int save = errno;
-  struct tm tp;
+  struct timespec ts;
 
-  __set_errno (0);
-  if (time (&timebuf->time) == (time_t) -1 && errno != 0)
+  if (__clock_gettime (CLOCK_REALTIME, &ts) < 0)
     return -1;
-  timebuf->millitm = 0;
-
-  if (__localtime_r (&timebuf->time, &tp) == NULL)
-    return -1;
-
-  timebuf->timezone = tp.tm_gmtoff / 60;
-  timebuf->dstflag = tp.tm_isdst;
 
-  __set_errno (save);
+  timebuf->time = ts.tv_sec;
+  timebuf->millitm = (ts.tv_nsec + 500000) / 1000000;
+  if (timebuf->millitm == 1000)
+    {
+      ++timebuf->time;
+      timebuf->millitm = 0;
+    }
+  timebuf->timezone = 0;
+  timebuf->dstflag = 0;
   return 0;
 }