nptl/pthread_sigqueue.c

   1 /* Copyright (C) 2009-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <signal.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22 #include <pthreadP.h>
  23 #include <tls.h>
  24 #include <sysdep.h>
  25 #include <shlib-compat.h>
  26
  27 int
  28 __pthread_sigqueue (pthread_t threadid, int signo, const union sigval value)
  29 {
  30 #ifdef __NR_rt_tgsigqueueinfo
  31   struct pthread *pd = (struct pthread *) threadid;
  32
  33   /* Force load of pd->tid into local variable or register.  Otherwise
  34      if a thread exits between ESRCH test and tgkill, we might return
  35      EINVAL, because pd->tid would be cleared by the kernel.  */
  36   pid_t tid = atomic_forced_read (pd->tid);
  37   if (__glibc_unlikely (tid <= 0))
  38     /* Not a valid thread handle.  */
  39     return ESRCH;
  40
  41   /* Disallow sending the signal we use for cancellation, timers,
  42      for the setxid implementation.  */
  43   if (signo == SIGCANCEL || signo == SIGTIMER || signo == SIGSETXID)
  44     return EINVAL;
  45
  46   pid_t pid = getpid ();
  47
  48   /* Set up the siginfo_t structure.  */
  49   siginfo_t info;
  50   memset (&info, '\0', sizeof (siginfo_t));
  51   info.si_signo = signo;
  52   info.si_code = SI_QUEUE;
  53   info.si_pid = pid;
  54   info.si_uid = __getuid ();
  55   info.si_value = value;
  56
  57   /* We have a special syscall to do the work.  */
  58   int val = INTERNAL_SYSCALL_CALL (rt_tgsigqueueinfo, pid, tid, signo,
  59                                    &info);
  60   return (INTERNAL_SYSCALL_ERROR_P (val)
  61           ? INTERNAL_SYSCALL_ERRNO (val) : 0);
  62 #else
  63   return ENOSYS;
  64 #endif
  65 }
  66 versioned_symbol (libc, __pthread_sigqueue, pthread_sigqueue, GLIBC_2_34);
  67
  68 #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_11, GLIBC_2_34)
  69 compat_symbol (libpthread, __pthread_sigqueue, pthread_sigqueue, GLIBC_2_11);
  70 #endif