Re: [PATCH 04/12] Use clock_settime to implement stime.

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 20/08/2019 10:21, Zack Weinberg wrote:
> Unconditionally, on all ports, use clock_settime to implement stime,
> not settimeofday or a direct syscall.
> 
> Note that the former stub implementation of stime would return -1 with
> errno set to EINVAL if passed a null pointer.  With this change, it
> instead unconditionally dereferences the pointer, so any hypothetical
> callers that passed NULL will now segfault.  I don’t think this will break
> any non-contrived programs.

I agree that using a null point does not make sense, so I would also recommend
to use __nonnull ((1)) on function prototype as well.

> 
> 	* time/stime.c (stime): No longer a stub implementation.
> 	Call __clock_settime.
> 
> 	* sysdeps/unix/stime.c: Delete file.
> 	* sysdeps/unix/sysv/linux/syscalls.list: Remove entry for stime.
> 
> 	* include/time.h: Add libc_hidden_proto for __clock_settime.
> 	* rt/clock_settime.c, sysdeps/unix/sysv/linux/clock_settime.c:
> 	Add libc_hidden_def for __clock_settime.

LGTM.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

> ---
>  include/time.h                          |  1 +
>  rt/clock_settime.c                      |  1 +
>  sysdeps/unix/stime.c                    | 39 -------------------------
>  sysdeps/unix/sysv/linux/clock_settime.c |  1 +
>  sysdeps/unix/sysv/linux/syscalls.list   |  1 -
>  time/stime.c                            | 15 +++-------
>  6 files changed, 7 insertions(+), 51 deletions(-)
>  delete mode 100644 sysdeps/unix/stime.c
> 
> diff --git a/include/time.h b/include/time.h
> index ac3163c2a5..c0421c7a28 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -22,6 +22,7 @@ extern __typeof (clock_getres) __clock_getres;
>  extern __typeof (clock_gettime) __clock_gettime;
>  libc_hidden_proto (__clock_gettime)
>  extern __typeof (clock_settime) __clock_settime;
> +libc_hidden_proto (__clock_settime)
>  extern __typeof (clock_nanosleep) __clock_nanosleep;
>  extern __typeof (clock_getcpuclockid) __clock_getcpuclockid;
>  

Ok.

> diff --git a/rt/clock_settime.c b/rt/clock_settime.c
> index 891925ab2c..9c4f4fbc10 100644
> --- a/rt/clock_settime.c
> +++ b/rt/clock_settime.c
> @@ -26,5 +26,6 @@ __clock_settime (clockid_t clock_id, const struct timespec *tp)
>    __set_errno (ENOSYS);
>    return -1;
>  }
> +libc_hidden_def (__clock_settime)
>  weak_alias (__clock_settime, clock_settime)
>  stub_warning (clock_settime)

Ok.

> diff --git a/sysdeps/unix/stime.c b/sysdeps/unix/stime.c
> deleted file mode 100644
> index b0809be400..0000000000
> --- a/sysdeps/unix/stime.c
> +++ /dev/null
> @@ -1,39 +0,0 @@
> -/* Copyright (C) 1992-2019 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 <errno.h>
> -#include <stddef.h>		/* For NULL.  */
> -#include <sys/time.h>
> -#include <time.h>
> -
> -/* Set the system clock to *WHEN.  */
> -
> -int
> -stime (const time_t *when)
> -{
> -  struct timeval tv;
> -
> -  if (when == NULL)
> -    {
> -      __set_errno (EINVAL);
> -      return -1;
> -    }
> -
> -  tv.tv_sec = *when;
> -  tv.tv_usec = 0;
> -  return __settimeofday (&tv, (struct timezone *) 0);
> -}

Ok.

> diff --git a/sysdeps/unix/sysv/linux/clock_settime.c b/sysdeps/unix/sysv/linux/clock_settime.c
> index d837e3019c..ef1512cc91 100644
> --- a/sysdeps/unix/sysv/linux/clock_settime.c
> +++ b/sysdeps/unix/sysv/linux/clock_settime.c
> @@ -34,4 +34,5 @@ __clock_settime (clockid_t clock_id, const struct timespec *tp)
>  
>    return INLINE_SYSCALL_CALL (clock_settime, clock_id, tp);
>  }
> +libc_hidden_def (__clock_settime)
>  weak_alias (__clock_settime, clock_settime)

Ok.

> diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
> index e374f97b5f..f6cb655e2c 100644
> --- a/sysdeps/unix/sysv/linux/syscalls.list
> +++ b/sysdeps/unix/sysv/linux/syscalls.list
> @@ -62,7 +62,6 @@ setfsgid	EXTRA	setfsgid	i:i	setfsgid
>  setfsuid	EXTRA	setfsuid	i:i	setfsuid
>  setpgid		-	setpgid		i:ii	__setpgid	setpgid
>  sigaltstack	-	sigaltstack	i:PP	__sigaltstack	sigaltstack
> -stime		-	stime		i:p	stime
>  sysinfo		EXTRA	sysinfo		i:p	__sysinfo	sysinfo
>  swapon		-	swapon		i:si	__swapon	swapon
>  swapoff		-	swapoff		i:s	__swapoff	swapoff

Ok.

> diff --git a/time/stime.c b/time/stime.c
> index de58c49562..b4d692ca32 100644
> --- a/time/stime.c
> +++ b/time/stime.c
> @@ -15,23 +15,16 @@
>     License along with the GNU C Library; if not, see
>     <http://www.gnu.org/licenses/>.  */
>  
> -#include <errno.h>
>  #include <time.h>
> -#include <stddef.h>
>  
>  /* Set the system clock to *WHEN.  */
>  
>  int
>  stime (const time_t *when)
>  {
> -  if (when == NULL)
> -    {
> -      __set_errno (EINVAL);
> -      return -1;
> -    }
> +  struct timespec ts;
> +  ts.tv_sec = *when;
> +  ts.tv_nsec = 0;
>  
> -  __set_errno (ENOSYS);
> -  return -1;
> +  return __clock_settime (CLOCK_REALTIME, &ts);
>  }
> -
> -stub_warning (stime)
> 

Ok.