mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-05 03:01:05 +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.
98 lines
2.9 KiB
C
98 lines
2.9 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 <pthread.h>
|
|
#include <setjmp.h>
|
|
#include <signal.h>
|
|
#include <sys/types.h>
|
|
|
|
|
|
/* Nonzero if the system calls are not available. */
|
|
extern int __no_posix_timers attribute_hidden;
|
|
|
|
/* Callback to start helper thread. */
|
|
extern void __start_helper_thread (void) attribute_hidden;
|
|
|
|
/* Control variable for helper thread creation. */
|
|
extern pthread_once_t __helper_once attribute_hidden;
|
|
|
|
/* TID of the helper thread. */
|
|
extern pid_t __helper_tid attribute_hidden;
|
|
|
|
/* List of active SIGEV_THREAD timers. */
|
|
extern struct timer *__active_timer_sigev_thread attribute_hidden;
|
|
/* Lock for the __active_timer_sigev_thread. */
|
|
extern pthread_mutex_t __active_timer_sigev_thread_lock attribute_hidden;
|
|
|
|
|
|
/* Type of timers in the kernel. */
|
|
typedef int kernel_timer_t;
|
|
|
|
/* Internal representation of SIGEV_THREAD timer. */
|
|
struct timer
|
|
{
|
|
kernel_timer_t ktimerid;
|
|
|
|
void (*thrfunc) (sigval_t);
|
|
sigval_t sival;
|
|
pthread_attr_t attr;
|
|
|
|
/* Next element in list of active SIGEV_THREAD timers. */
|
|
struct timer *next;
|
|
};
|
|
|
|
|
|
/* 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 the MSB bit of the returned
|
|
'timer_t' to indicate the timer handles a SIGEV_THREAD. */
|
|
|
|
static inline timer_t
|
|
kernel_timer_to_timerid (kernel_timer_t ktimerid)
|
|
{
|
|
return (timer_t) ((intptr_t) ktimerid);
|
|
}
|
|
|
|
static inline timer_t
|
|
timer_to_timerid (struct timer *ptr)
|
|
{
|
|
return (timer_t) (INTPTR_MIN | (uintptr_t) ptr >> 1);
|
|
}
|
|
|
|
static inline bool
|
|
timer_is_sigev_thread (timer_t timerid)
|
|
{
|
|
return (intptr_t) timerid < 0;
|
|
}
|
|
|
|
static inline struct timer *
|
|
timerid_to_timer (timer_t timerid)
|
|
{
|
|
return (struct timer *)((uintptr_t) timerid << 1);
|
|
}
|
|
|
|
static inline kernel_timer_t
|
|
timerid_to_kernel_timer (timer_t timerid)
|
|
{
|
|
if (timer_is_sigev_thread (timerid))
|
|
return timerid_to_timer (timerid)->ktimerid;
|
|
else
|
|
return (kernel_timer_t) ((uintptr_t) timerid);
|
|
}
|