[v2,06/10] Use clock_gettime to implement ftime; withdraw 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 made a compatibility symbol.  The public
header file that declared it, its result structure, and nothing else,
is removed.

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.

	* time/tst-ftime.c
	* time/sys/timeb.h
	* sysdeps/unix/bsd/ftime.c
	* sysdeps/unix/sysv/linux/ftime.c: Delete file.
	* time/tst-ftime_l.c: Rename to tst-strftime_l.c.

	* time/ftime.c (ftime): Make a compatibility-only symbol.
	Replace implementation with the code formerly in
	sysdeps/unix/bsd/ftime.c, then change that code to use
	__clock_gettime instead of __gettimeofday and to truncate
	rather than rounding.  Always set the timezone and dstflag
	fields of the timebuf argument to zero.

	* time/Makefile (headers): Remove sys/timeb.h.
	(tests): Remove tst-ftime, change tst-ftime_l to
	tst-strftime_l.

	* conform/Makefile: XFAIL all tests related to sys/timeb.h.
---
 conform/Makefile                         |  9 ++++
 sysdeps/unix/bsd/ftime.c                 | 40 ----------------
 sysdeps/unix/sysv/linux/ftime.c          |  3 --
 time/Makefile                            |  8 ++--
 time/ftime.c                             | 40 +++++++++-------
 time/sys/timeb.h                         | 43 ------------------
 time/tst-ftime.c                         | 58 ------------------------
 time/{tst-ftime_l.c => tst-strftime_l.c} |  0
 8 files changed, 36 insertions(+), 165 deletions(-)
 delete mode 100644 sysdeps/unix/bsd/ftime.c
 delete mode 100644 sysdeps/unix/sysv/linux/ftime.c
 delete mode 100644 time/sys/timeb.h
 delete mode 100644 time/tst-ftime.c
 rename time/{tst-ftime_l.c => tst-strftime_l.c} (100%)
  

On 28/08/2019 12:32, Zack Weinberg wrote:
> 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 made a compatibility symbol.  The public
> header file that declared it, its result structure, and nothing else,
> is removed.
> 
> 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.

Sound reasonable.

> 
> 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.

Ok.

> 
> 	* time/tst-ftime.c
> 	* time/sys/timeb.h
> 	* sysdeps/unix/bsd/ftime.c
> 	* sysdeps/unix/sysv/linux/ftime.c: Delete file.
> 	* time/tst-ftime_l.c: Rename to tst-strftime_l.c.
> 
> 	* time/ftime.c (ftime): Make a compatibility-only symbol.
> 	Replace implementation with the code formerly in
> 	sysdeps/unix/bsd/ftime.c, then change that code to use
> 	__clock_gettime instead of __gettimeofday and to truncate
> 	rather than rounding.  Always set the timezone and dstflag
> 	fields of the timebuf argument to zero.
> 
> 	* time/Makefile (headers): Remove sys/timeb.h.
> 	(tests): Remove tst-ftime, change tst-ftime_l to
> 	tst-strftime_l.
> 
> 	* conform/Makefile: XFAIL all tests related to sys/timeb.h.
> ---
>  conform/Makefile                         |  9 ++++
>  sysdeps/unix/bsd/ftime.c                 | 40 ----------------
>  sysdeps/unix/sysv/linux/ftime.c          |  3 --
>  time/Makefile                            |  8 ++--
>  time/ftime.c                             | 40 +++++++++-------
>  time/sys/timeb.h                         | 43 ------------------
>  time/tst-ftime.c                         | 58 ------------------------
>  time/{tst-ftime_l.c => tst-strftime_l.c} |  0
>  8 files changed, 36 insertions(+), 165 deletions(-)
>  delete mode 100644 sysdeps/unix/bsd/ftime.c
>  delete mode 100644 sysdeps/unix/sysv/linux/ftime.c
>  delete mode 100644 time/sys/timeb.h
>  delete mode 100644 time/tst-ftime.c
>  rename time/{tst-ftime_l.c => tst-strftime_l.c} (100%)
> 
> diff --git a/conform/Makefile b/conform/Makefile
> index 59d569c4c5..8671c695e8 100644
> --- a/conform/Makefile
> +++ b/conform/Makefile
> @@ -241,3 +241,12 @@ test-xfail-XPG42/ndbm.h/linknamespace = yes
>  test-xfail-UNIX98/ndbm.h/linknamespace = yes
>  test-xfail-XOPEN2K/ndbm.h/linknamespace = yes
>  test-xfail-XOPEN2K8/ndbm.h/linknamespace = yes
> +
> +# Header no longer provided by glibc (obsoleted in newer POSIX
> +# standards).
> +test-xfail-UNIX98/sys/timeb.h/conform = yes
> +test-xfail-UNIX98/sys/timeb.h/linknamespace = yes
> +test-xfail-XOPEN2K/sys/timeb.h/conform = yes
> +test-xfail-XOPEN2K/sys/timeb.h/linknamespace = yes
> +test-xfail-XPG42/sys/timeb.h/conform = yes
> +test-xfail-XPG42/sys/timeb.h/linknamespace = yes

I think we will need to keep this header, at least one release, and mark is
as deprecated (maybe with a pragma warning) because some projects include
without configure checks (libsanitizer for instance).

> diff --git a/sysdeps/unix/bsd/ftime.c b/sysdeps/unix/bsd/ftime.c
> deleted file mode 100644
> index 3a1c6e9b01..0000000000
> --- 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;
> -}

Ok.

> diff --git a/sysdeps/unix/sysv/linux/ftime.c b/sysdeps/unix/sysv/linux/ftime.c
> deleted file mode 100644
> index 5a5949f608..0000000000
> --- 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/Makefile b/time/Makefile
> index 791db1c8e3..93c7cc28d4 100644
> --- a/time/Makefile
> +++ b/time/Makefile
> @@ -22,7 +22,7 @@ subdir	:= time
>  
>  include ../Makeconfig
>  
> -headers := time.h sys/time.h sys/timeb.h bits/time.h			\
> +headers := time.h sys/time.h bits/time.h				\
>  	   bits/types/clockid_t.h bits/types/clock_t.h			\
>  	   bits/types/struct_itimerspec.h				\
>  	   bits/types/struct_timespec.h bits/types/struct_timeval.h	\

As before.

> @@ -43,9 +43,9 @@ routines := offtime asctime clock ctime ctime_r difftime \
>  aux :=	    era alt_digit lc-time-cleanup
>  
>  tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
> -	   tst-getdate tst-mktime tst-mktime2 tst-ftime_l tst-strftime \
> +	   tst-getdate tst-mktime tst-mktime2 tst-strftime tst-strftime_l \
>  	   tst-mktime3 tst-strptime2 bug-asctime bug-asctime_r bug-mktime1 \
> -	   tst-strptime3 bug-getdate1 tst-strptime-whitespace tst-ftime \
> +	   tst-strptime3 bug-getdate1 tst-strptime-whitespace \
>  	   tst-tzname tst-y2039 bug-mktime4 tst-strftime2 tst-strftime3 \
>  	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1
>  
> @@ -59,7 +59,7 @@ LOCALES := de_DE.ISO-8859-1 en_US.ISO-8859-1 ja_JP.EUC-JP fr_FR.UTF-8 \
>  	   nan_TW.UTF-8 lzh_TW.UTF-8
>  include ../gen-locales.mk
>  
> -$(objpfx)tst-ftime_l.out: $(gen-locales)
> +$(objpfx)tst-strftime_l.out: $(gen-locales)
>  $(objpfx)tst-strptime.out: $(gen-locales)
>  endif
>  
> diff --git a/time/ftime.c b/time/ftime.c
> index 6c2a256048..0db6b70adf 100644
> --- a/time/ftime.c
> +++ b/time/ftime.c
> @@ -15,27 +15,33 @@
>     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 <shlib-compat.h>
>  
> -int
> -ftime (struct timeb *timebuf)
> -{
> -  int save = errno;
> -  struct tm tp;
> +#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_31)
>  
> -  __set_errno (0);
> -  if (time (&timebuf->time) == (time_t) -1 && errno != 0)
> -    return -1;
> -  timebuf->millitm = 0;
> +#include <time.h>
>  
> -  if (__localtime_r (&timebuf->time, &tp) == NULL)
> -    return -1;
> +struct timeb
> +{
> +  time_t time;			/* Seconds since epoch, as from `time'.  */
> +  unsigned short int millitm;	/* Additional milliseconds.  */
> +  short int timezone;		/* Minutes west of GMT.  */
> +  short int dstflag;		/* Nonzero if Daylight Savings Time used.  */
> +};
>  
> -  timebuf->timezone = tp.tm_gmtoff / 60;
> -  timebuf->dstflag = tp.tm_isdst;
> +int
> +attribute_compat_text_section
> +__ftime (struct timeb *timebuf)
> +{
> +  struct timespec ts;
> +  __clock_gettime (CLOCK_REALTIME, &ts);
>  
> -  __set_errno (save);
> +  timebuf->time = ts.tv_sec;
> +  timebuf->millitm = ts.tv_nsec / 1000000;
> +  timebuf->timezone = 0;
> +  timebuf->dstflag = 0;
>    return 0;
>  }
> +compat_symbol (libc, __ftime, ftime, GLIBC_2_0);
> +
> +#endif

Ok.

> diff --git a/time/sys/timeb.h b/time/sys/timeb.h
> deleted file mode 100644
> index 6333e8074d..0000000000
> --- a/time/sys/timeb.h
> +++ /dev/null
> @@ -1,43 +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/>.  */
> -
> -#ifndef _SYS_TIMEB_H
> -#define _SYS_TIMEB_H	1
> -
> -#include <features.h>
> -
> -#include <bits/types/time_t.h>
> -
> -__BEGIN_DECLS
> -
> -/* Structure returned by the `ftime' function.  */
> -
> -struct timeb
> -  {
> -    time_t time;		/* Seconds since epoch, as from `time'.  */
> -    unsigned short int millitm;	/* Additional milliseconds.  */
> -    short int timezone;		/* Minutes west of GMT.  */
> -    short int dstflag;		/* Nonzero if Daylight Savings Time used.  */
> -  };
> -
> -/* Fill in TIMEBUF with information about the current time.  */
> -
> -extern int ftime (struct timeb *__timebuf);
> -
> -__END_DECLS
> -
> -#endif	/* sys/timeb.h */
> diff --git a/time/tst-ftime.c b/time/tst-ftime.c
> deleted file mode 100644
> index 65b753dec8..0000000000
> --- a/time/tst-ftime.c
> +++ /dev/null
> @@ -1,58 +0,0 @@
> -/* Verify that ftime is sane.
> -   Copyright (C) 2014-2019 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 <stdio.h>
> -
> -static int
> -do_test (void)
> -{
> -  struct timeb prev, curr = {.time = 0, .millitm = 0};
> -  int sec = 0;
> -
> -  while (sec != 3)
> -    {
> -      prev = curr;
> -
> -      if (ftime (&curr))
> -        {
> -          printf ("ftime returned an error\n");
> -          return 1;
> -        }
> -
> -      if (curr.time < prev.time)
> -        {
> -          printf ("ftime's time flowed backwards\n");
> -          return 1;
> -        }
> -
> -      if (curr.time == prev.time
> -          && curr.millitm < prev.millitm)
> -        {
> -          printf ("ftime's millitm flowed backwards\n");
> -          return 1;
> -        }
> -
> -      if (curr.time > prev.time)
> -        sec ++;
> -    }
> -  return 0;
> -}
> -
> -#define TEST_FUNCTION do_test ()
> -#include "../test-skeleton.c"

We can make it a internal test using TEST_COMPAT instead.

> diff --git a/time/tst-ftime_l.c b/time/tst-strftime_l.c
> similarity index 100%
> rename from time/tst-ftime_l.c
> rename to time/tst-strftime_l.c
>