mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-04 10:50:07 +00:00
7a887dd537
GCC 11 -Warray-bounds triggers invalid warnings when building
Linux timer_create.c:
../sysdeps/unix/sysv/linux/timer_create.c: In function '__timer_create_new':
../sysdeps/unix/sysv/linux/timer_create.c:83:17: warning: array subscript 'struct timer[0]' is partly outside array bounds of 'unsigned char[8]' [-Warray-bounds]
83 | newp->sigev_notify = (evp != NULL
| ^~
../sysdeps/unix/sysv/linux/timer_create.c:59:47: note: referencing an object of size 8 allocated by 'malloc'
59 | struct timer *newp = (struct timer *) malloc (offsetof (struct timer,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
60 | thrfunc));
| ~~~~~~~~~
The struct allocated for !SIGEV_THREAD timers only requires two 'int'
fields (sigev_notify and ktimerid) and the offsetof trick tries minimize
the memory usage by only allocation the required size. However,
although the resulting size is suffice for !SIGEV_THREAD time, accessing
the partially allocated object is error-prone and UB.
This patch fixes both issues by embedding the information whether
the timer if a SIGEV_THREAD in the returned 'timer_t'. For
!SIGEV_THREAD, the resulting 'timer_t' is the returned kernel timer
identifer (kernel_timer_t), while for SIGEV_THREAD it uses the fact
malloc returns at least _Alignof (max_align_t) pointers plus that
valid kernel_timer_t are always positive to set MSB bit of the returned
'timer_t' to indicate the timer handles a SIGEV_THREAD.
It allows to remove the memory allocation for !SIGEV_THREAD and also
remove the 'sigev_notify' field from 'struct timer'.
Checked on x86_64-linux-gnu and i686-linux-gnu.
45 lines
1.6 KiB
C
45 lines
1.6 KiB
C
/* Copyright (C) 2003-2020 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
|
|
|
|
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; see the file COPYING.LIB. If
|
|
not, see <https://www.gnu.org/licenses/>. */
|
|
|
|
#include <shlib-compat.h>
|
|
#include <sysdep.h>
|
|
#include "kernel-posix-timers.h"
|
|
#include "compat-timer.h"
|
|
|
|
int
|
|
__timer_settime_new (timer_t timerid, int flags, const struct itimerspec *value,
|
|
struct itimerspec *ovalue)
|
|
{
|
|
kernel_timer_t ktimerid = timerid_to_kernel_timer (timerid);
|
|
|
|
return INLINE_SYSCALL_CALL (timer_settime, ktimerid, flags, value, ovalue);
|
|
}
|
|
versioned_symbol (librt, __timer_settime_new, timer_settime, GLIBC_2_3_3);
|
|
|
|
|
|
#if SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_3_3)
|
|
int
|
|
__timer_settime_old (int timerid, int flags, const struct itimerspec *value,
|
|
struct itimerspec *ovalue)
|
|
{
|
|
return __timer_settime_new (__compat_timer_list[timerid], flags,
|
|
value, ovalue);
|
|
}
|
|
compat_symbol (librt, __timer_settime_old, timer_settime, GLIBC_2_2);
|
|
#endif
|