sysdeps/nptl/futex-internal.c

   1 /* futex helper functions for glibc-internal use.
   2    Copyright (C) 2020-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sysdep.h>
  21 #include <time.h>
  22 #include <futex-internal.h>
  23 #include <kernel-features.h>
  24
  25 #ifndef __ASSUME_TIME64_SYSCALLS
  26 static int
  27 __futex_abstimed_wait_common32 (unsigned int* futex_word,
  28                                 unsigned int expected, int op,
  29                                 const struct __timespec64* abstime,
  30                                 int private, bool cancel)
  31 {
  32   struct timespec ts32, *pts32 = NULL;
  33   if (abstime != NULL)
  34     {
  35       if (! in_time_t_range (abstime->tv_sec))
  36         return -EOVERFLOW;
  37
  38       ts32 = valid_timespec64_to_timespec (*abstime);
  39       pts32 = &ts32;
  40     }
  41
  42   if (cancel)
  43     return INTERNAL_SYSCALL_CANCEL (futex, futex_word, op, expected,
  44                                     pts32, NULL /* Unused.  */,
  45                                     FUTEX_BITSET_MATCH_ANY);
  46   else
  47     return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
  48                                   pts32, NULL /* Unused.  */,
  49                                   FUTEX_BITSET_MATCH_ANY);
  50 }
  51 #endif /* ! __ASSUME_TIME64_SYSCALLS */
  52
  53 static int
  54 __futex_abstimed_wait_common64 (unsigned int* futex_word,
  55                                 unsigned int expected, clockid_t clockid,
  56                                 const struct __timespec64* abstime,
  57                                 int private, bool cancel)
  58 {
  59   unsigned int clockbit;
  60   int err;
  61
  62   /* Work around the fact that the kernel rejects negative timeout values
  63      despite them being valid.  */
  64   if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
  65     return ETIMEDOUT;
  66
  67   if (! lll_futex_supported_clockid (clockid))
  68     return EINVAL;
  69
  70   clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
  71   int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
  72
  73   if (cancel)
  74     err = INTERNAL_SYSCALL_CANCEL (futex_time64, futex_word, op, expected,
  75                                    abstime, NULL /* Unused.  */,
  76                                    FUTEX_BITSET_MATCH_ANY);
  77   else
  78     err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
  79                                  abstime, NULL /* Ununsed.  */,
  80                                  FUTEX_BITSET_MATCH_ANY);
  81 #ifndef __ASSUME_TIME64_SYSCALLS
  82   if (err == -ENOSYS)
  83     err = __futex_abstimed_wait_common32 (futex_word, expected, op, abstime,
  84                                           private, cancel);
  85 #endif
  86
  87   switch (err)
  88     {
  89     case 0:
  90     case -EAGAIN:
  91     case -EINTR:
  92     case -ETIMEDOUT:
  93     case -EINVAL:
  94     case -EOVERFLOW:  /* Passed absolute timeout uses 64 bit time_t type, but
  95                          underlying kernel does not support 64 bit time_t futex
  96                          syscalls.  */
  97       return -err;
  98
  99     case -EFAULT: /* Must have been caused by a glibc or application bug.  */
 100     case -ENOSYS: /* Must have been caused by a glibc bug.  */
 101     /* No other errors are documented at this time.  */
 102     default:
 103       futex_fatal_error ();
 104     }
 105 }
 106
 107 int
 108 __futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
 109                          clockid_t clockid,
 110                          const struct __timespec64* abstime, int private)
 111 {
 112   return __futex_abstimed_wait_common64 (futex_word, expected, clockid,
 113                                          abstime, private, false);
 114 }
 115 libpthread_hidden_def (__futex_abstimed_wait64)
 116
 117 int
 118 __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
 119                                     unsigned int expected, clockid_t clockid,
 120                                     const struct __timespec64* abstime,
 121                                     int private)
 122 {
 123   return __futex_abstimed_wait_common64 (futex_word, expected, clockid,
 124                                          abstime, private, true);
 125 }
 126 libpthread_hidden_def (__futex_abstimed_wait_cancelable64)