Use clock_settime to implement settimeofday.

Unconditionally, on all ports, use clock_settime to implement
settimeofday.  Remove sysdeps/unix/clock_settime.c, which implemented
clock_settime by calling settimeofday; new OS ports must henceforth
provide a real implementation of clock_settime.

Hurd had a real implementation of settimeofday but not of
clock_settime; this patch converts it into an implementation of
clock_settime.  It only supports CLOCK_REALTIME and microsecond
resolution; Hurd/Mach does not appear to have any support for
finer-resolution clocks.

The vestigial "set time zone" feature of settimeofday complicates the
generic settimeofday implementation a little.  The only remaining uses
of this feature that aren't just bugs, are using it to inform the
Linux kernel of the offset between the hardware clock and UTC, on
systems where the hardware clock doesn't run in UTC (usually because
of dual-booting with Windows).  There currently isn't any other way to
do this.  However, the callers that do this call settimeofday with
_only_ the timezone argument non-NULL.  Therefore, glibc's new
behavior is: callers of settimeofday must supply one and only one of
the two arguments.  If both arguments are non-NULL, or both arguments
are NULL, the call fails and sets errno to EINVAL.

When only the timeval argument is supplied, settimeofday calls
__clock_settime(CLOCK_REALTIME), same as stime.

When only the timezone argument is supplied, settimeofday calls a new
internal function called __settimezone.  On Linux, only, this function
will pass the timezone structure to the settimeofday system call.  On
all other operating systems, and on Linux architectures that don't
define __NR_settimeofday, __settimezone is a stub that always sets
errno to ENOSYS and returns -1.

The settimeoday syscall is enabled on Linux by the flag
COMPAT_32BIT_TIME, which is an option to either 32-bits ABIs or COMPAT
builds (defined usually by 64-bit kernels that want to support 32-bit
 ABIs, such as x86).  The idea to future 64-bit time_t only ABIs
is to not provide settimeofday syscall.

The same semantics are implemented for Linux/Alpha's GLIBC_2.0 compat
symbol for settimeofday.

There are no longer any internal callers of __settimeofday, so the
internal prototype is removed.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
This commit is contained in:
Zack Weinberg 2019-08-28 08:25:49 -04:00 committed by Adhemerval Zanella
parent 12cbde1dae
commit c3f9aef063
12 changed files with 150 additions and 69 deletions

24
NEWS
View File

@ -34,6 +34,30 @@ Deprecated and removed features, and other changes affecting compatibility:
binaries and it has been removed from <time.h> header. This function
has been deprecated in favor of clock_settime.
* The settimeofday function can still be used to set a system-wide time
zone when the operating system supports it. This is because the Linux
kernel reused the API, on some architectures, to describe a system-wide
time-zone-like offset between the software clock maintained by the kernel,
and the "RTC" clock that keeps time when the system is shut down.
However, to reduce the odds of this offset being set by accident,
settimeofday can no longer be used to set the time and the offset
simultaneously. If both of its two arguments are non-null, the call
will fail (setting errno to EINVAL).
Callers attempting to set this offset should also be prepared for the call
to fail and set errno to ENOSYS; this already happens on the Hurd and on
some Linux architectures. The Linux kernel maintainers are discussing a
more principled replacement for the reused API. After a replacement
becomes available, we will change settimeofday to fail with ENOSYS on all
platforms when its 'tzp' argument is not a null pointer.
Note that settimeofday itself is obsolescent according to POSIX.
Programs that set the system time should use clock_settime and/or
the adjtime family of functions instead. We may also cease to make
settimeofday available to newly linked binaries after there is a
replacement for Linux's time-zone-like offset API.
Changes to build and runtime requirements:
[Add changes to build and runtime requirements here]

View File

@ -24,8 +24,7 @@ extern int __gettimeofday (struct timeval *__tv,
struct timezone *__tz);
libc_hidden_proto (__gettimeofday)
libc_hidden_proto (gettimeofday)
extern int __settimeofday (const struct timeval *__tv,
const struct timezone *__tz)
extern int __settimezone (const struct timezone *__tz)
attribute_hidden;
extern int __adjtime (const struct timeval *__delta,
struct timeval *__olddelta);

View File

@ -1,4 +1,4 @@
/* Copyright (C) 1999-2019 Free Software Foundation, Inc.
/* Copyright (C) 1991-2019 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
@ -17,38 +17,32 @@
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include <hurd.h>
#include <hurd/port.h>
#include <shlib-compat.h>
/* Set CLOCK to value TP. */
/* Set the current time of day.
This call is restricted to the super-user. */
int
__clock_settime (clockid_t clock_id, const struct timespec *tp)
__clock_settime (clockid_t clock_id, const struct timespec *ts)
{
int retval = -1;
error_t err;
mach_port_t hostpriv;
time_value_t tv;
/* Make sure the time cvalue is OK. */
if (! valid_nanoseconds (tp->tv_nsec))
{
__set_errno (EINVAL);
return -1;
}
if (clock_id != CLOCK_REALTIME
|| ! valid_nanoseconds (ts->tv_nsec))
return __hurd_fail (EINVAL);
switch (clock_id)
{
case CLOCK_REALTIME:
{
struct timeval tv;
TIMESPEC_TO_TIMEVAL (&tv, tp);
retval = __settimeofday (&tv, NULL);
}
break;
err = __get_privileged_ports (&hostpriv, NULL);
if (err)
return __hurd_fail (EPERM);
default:
__set_errno (EINVAL);
break;
}
TIMESPEC_TO_TIME_VALUE (&tv, ts);
err = __host_set_time (hostpriv, tv);
__mach_port_deallocate (__mach_task_self (), hostpriv);
return retval;
return __hurd_fail (err);
}
libc_hidden_def (__clock_settime)

View File

@ -76,7 +76,6 @@ setreuid - setreuid i:ii __setreuid setreuid
setrlimit - setrlimit i:ip __setrlimit setrlimit
setsid - setsid i: __setsid setsid
setsockopt - setsockopt i:iiibn setsockopt __setsockopt
settimeofday - settimeofday i:PP __settimeofday settimeofday
setuid - setuid i:i __setuid setuid
shutdown - shutdown i:ii shutdown
sigaction - sigaction i:ipp __sigaction sigaction

View File

@ -32,8 +32,18 @@ attribute_compat_text_section
__settimeofday_tv32 (const struct timeval32 *tv32,
const struct timezone *tz)
{
struct timeval tv = valid_timeval_to_timeval64 (*tv32);
return __settimeofday (&tv, tz);
if (__glibc_unlikely (tz != 0))
{
if (tv32 != 0)
{
__set_errno (EINVAL);
return -1;
}
return __settimezone (tz);
}
struct timespec ts = valid_timeval32_to_timespec (*tv32);
return __clock_settime (CLOCK_REALTIME, &ts);
}
compat_symbol (libc, __settimeofday_tv32, settimeofday, GLIBC_2_0);

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@ -0,0 +1,22 @@
/* settimeofday -- Set the current time of day. Linux/Alpha/tv64 version.
Copyright (C) 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/>. */
/* We can use the generic implementation, but we have to override its
default symbol version. */
#define VERSION_settimeofday GLIBC_2.1
#include <time/settimeofday.c>

View File

@ -24,7 +24,6 @@ pciconfig_iobase EXTRA pciconfig_iobase 3 __pciconfig_iobase pciconfig_iobase
# timeval64 entry points (see osf_*.c for GLIBC_2.0 timeval32 equivalents)
gettimeofday - gettimeofday i:pP __GI___gettimeofday gettimeofday@@GLIBC_2.1 __gettimeofday@@GLIBC_2.1
settimeofday - settimeofday i:PP __settimeofday settimeofday@@GLIBC_2.1
getitimer - getitimer i:ip __getitimer getitimer@@GLIBC_2.1
setitimer - setitimer i:ipP __setitimer setitimer@@GLIBC_2.1
utimes - utimes i:sp __utimes utimes@@GLIBC_2.1

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@ -83,6 +83,12 @@ valid_timeval64_to_timeval (const struct timeval tv64)
return (struct timeval32) { tv64.tv_sec, tv64.tv_usec };
}
static inline struct timespec
valid_timeval32_to_timespec (const struct timeval32 tv)
{
return (struct timespec) { tv.tv_sec, tv.tv_usec * 1000 };
}
static inline void
rusage64_to_rusage32 (struct rusage32 *restrict r32,
const struct rusage *restrict r64)

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@ -0,0 +1,36 @@
/* Obsolete set system time. Linux version.
Copyright (C) 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 <sys/time.h>
#include <sysdep.h>
/* Set the system-wide timezone.
This call is restricted to the super-user.
This operation is considered obsolete, kernel support may not be
available on all architectures. */
int
__settimezone (const struct timezone *tz)
{
#ifdef __NR_settimeofday
return INLINE_SYSCALL_CALL (settimeofday, NULL, tz);
#else
__set_errno (ENOSYS);
return -1;
#endif
}

View File

@ -31,13 +31,13 @@ headers := time.h sys/time.h sys/timeb.h bits/time.h \
routines := offtime asctime clock ctime ctime_r difftime \
gmtime localtime mktime time \
gettimeofday settimeofday adjtime tzset \
tzfile getitimer setitimer \
gettimeofday settimeofday settimezone \
adjtime tzset tzfile getitimer setitimer \
stime dysize timegm ftime \
getdate strptime strptime_l \
strftime wcsftime strftime_l wcsftime_l \
timespec_get \
clock_getcpuclockid clock_getres \
timespec_get \
clock_getcpuclockid clock_getres \
clock_gettime clock_settime clock_nanosleep
aux := era alt_digit lc-time-cleanup

View File

@ -16,6 +16,7 @@
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <time.h>
#include <sys/time.h>
/* Set the current time of day and timezone information.
@ -23,9 +24,24 @@
int
__settimeofday (const struct timeval *tv, const struct timezone *tz)
{
__set_errno (ENOSYS);
return -1;
}
stub_warning (settimeofday)
if (__glibc_unlikely (tz != 0))
{
if (tv != 0)
{
__set_errno (EINVAL);
return -1;
}
return __settimezone (tz);
}
weak_alias (__settimeofday, settimeofday)
struct timespec ts;
TIMEVAL_TO_TIMESPEC (tv, &ts);
return __clock_settime (CLOCK_REALTIME, &ts);
}
#ifdef VERSION_settimeofday
weak_alias (__settimeofday, __settimeofday_w);
default_symbol_version (__settimeofday_w, settimeofday, VERSION_settimeofday);
#else
weak_alias (__settimeofday, settimeofday);
#endif

View File

@ -1,4 +1,4 @@
/* Copyright (C) 1991-2019 Free Software Foundation, Inc.
/* Copyright (C) 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
@ -17,36 +17,12 @@
#include <errno.h>
#include <sys/time.h>
#include <hurd.h>
#include <hurd/port.h>
/* Set the current time of day and timezone information.
/* Set the system-wide timezone.
This call is restricted to the super-user. */
int
__settimeofday (const struct timeval *tv, const struct timezone *tz)
__settimezone (const struct timezone *tz)
{
error_t err;
mach_port_t hostpriv;
if (tz != NULL)
{
errno = ENOSYS;
return -1;
}
err = __get_privileged_ports (&hostpriv, NULL);
if (err)
return __hurd_fail (EPERM);
/* `time_value_t' and `struct timeval' are in fact identical with the
names changed. */
err = __host_set_time (hostpriv, *(time_value_t *) tv);
__mach_port_deallocate (__mach_task_self (), hostpriv);
if (err)
return __hurd_fail (err);
return 0;
__set_errno (ENOSYS);
return -1;
}
weak_alias (__settimeofday, settimeofday)