Consolidate and deprecate 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,
and then the function is deprecated.

For some reason, the implementation of ftime in terms of gettimeofday
was rounding rather than truncating microseconds to milliseconds.  In
all the other places where we use a higher-resolution time function to
implement a lower-resolution one, we truncate.  ftime is changed to
match, just for tidiness' sake.

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.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, and powerpc-linux-gnu.

Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Lukasz Majewski <lukma@denx.de>

NEWS

@@ -58,6 +58,9 @@ Deprecated and removed features, and other changes affecting compatibility:
   settimeofday available to newly linked binaries after there is a
   replacement for Linux's time-zone-like offset API.
 
+* The obsolete functions ftime has been deprecated and will be removed from
+  a future version of glibc.  Application should use clock_gettime instead.
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]

sysdeps/unix/bsd/ftime.c

@@ -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
-   <https://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;
-}

sysdeps/unix/sysv/linux/ftime.c

@@ -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>

time/ftime.c

@@ -1,4 +1,5 @@
-/* Copyright (C) 1994-2019 Free Software Foundation, Inc.
+/* Deprecated return date and time.
+   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
@@ -15,27 +16,18 @@
    License along with the GNU C Library; if not, see
    <https://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 timespec ts;
-  struct tm tp;
+  __clock_gettime (CLOCK_REALTIME, &ts);
 
-  __set_errno (0);
+  timebuf->time = ts.tv_sec;
-  if (time (&timebuf->time) == (time_t) -1 && errno != 0)
+  timebuf->millitm = ts.tv_nsec / 1000000;
-    return -1;
+  timebuf->timezone = 0;
-  timebuf->millitm = 0;
+  timebuf->dstflag = 0;
-
-  if (__localtime_r (&timebuf->time, &tp) == NULL)
-    return -1;
-
-  timebuf->timezone = tp.tm_gmtoff / 60;
-  timebuf->dstflag = tp.tm_isdst;
-
-  __set_errno (save);
   return 0;
 }

time/sys/timeb.h

@@ -36,7 +36,8 @@ struct timeb
 
 /* Fill in TIMEBUF with information about the current time.  */
 
-extern int ftime (struct timeb *__timebuf);
+extern int ftime (struct timeb *__timebuf)
+  __nonnull ((1)) __attribute_deprecated__;
 
 __END_DECLS
 

time/tst-ftime.c

@@ -18,6 +18,7 @@
 
 #include <sys/timeb.h>
 #include <stdio.h>
+#include <libc-diag.h>
 
 static int
 do_test (void)
@@ -29,12 +30,18 @@ do_test (void)
     {
       prev = curr;
 
+      /* ftime was deprecated on 2.31.  */
+      DIAG_PUSH_NEEDS_COMMENT;
+      DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdeprecated-declarations");
+
       if (ftime (&curr))
         {
           printf ("ftime returned an error\n");
           return 1;
         }
 
+      DIAG_POP_NEEDS_COMMENT;
+
       if (curr.time < prev.time)
         {
           printf ("ftime's time flowed backwards\n");