[04/12] Use clock_settime to implement stime.

Message ID 20190820132152.24100-5-zackw@panix.com
State New
Headers show
Series
  • Y2038 preparation: use clock_[gs]ettime to implement the other time-getting and -setting functions
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Commit Message

Zack Weinberg Aug. 20, 2019, 1:21 p.m.
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.

	* 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.
---
 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

-- 
2.23.0.rc1

Comments

Adhemerval Zanella Aug. 21, 2019, 3:10 p.m. | #1
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.
Zack Weinberg Aug. 22, 2019, 12:57 p.m. | #2
On 8/21/19 11:10 AM, Adhemerval Zanella wrote:
> 

> 

> 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.


Good point, but I'm not going to make this change because instead I'm
going to add a patch to the series that demotes stime to a compatibility
symbol, so its public prototype will be removed.

zw

Patch

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;
 
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)
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);
-}
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)
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
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)