glibc/nptl/pthread_kill.c

/* Send a signal to a specific pthread.  Stub version.
   Copyright (C) 2014-2021 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
   <https://www.gnu.org/licenses/>.  */

#include <unistd.h>
#include <pthreadP.h>
#include <shlib-compat.h>

int
__pthread_kill_internal (pthread_t threadid, int signo)
{
  pid_t tid;
  struct pthread *pd = (struct pthread *) threadid;

  if (pd == THREAD_SELF)
    /* It is a special case to handle raise() implementation after a vfork
       call (which does not update the PD tid field).  */
    tid = INLINE_SYSCALL_CALL (gettid);
  else
    /* Force load of pd->tid into local variable or register.  Otherwise
       if a thread exits between ESRCH test and tgkill, we might return
       EINVAL, because pd->tid would be cleared by the kernel.  */
    tid = atomic_forced_read (pd->tid);

  int val;
  if (__glibc_likely (tid > 0))
    {
      pid_t pid = __getpid ();

      val = INTERNAL_SYSCALL_CALL (tgkill, pid, tid, signo);
      val = (INTERNAL_SYSCALL_ERROR_P (val)
	    ? INTERNAL_SYSCALL_ERRNO (val) : 0);
    }
  else
    /* The kernel reports that the thread has exited.  POSIX specifies
       the ESRCH error only for the case when the lifetime of a thread
       ID has ended, but calling pthread_kill on such a thread ID is
       undefined in glibc.  Therefore, do not treat kernel thread exit
       as an error.  */
    val = 0;

  return val;
}

int
__pthread_kill (pthread_t threadid, int signo)
{
  /* Disallow sending the signal we use for cancellation, timers,
     for the setxid implementation.  */
  if (__is_internal_signal (signo))
    return EINVAL;

  return __pthread_kill_internal (threadid, signo);
}
/* Some architectures (for instance arm) might pull raise through libgcc, so
   avoid the symbol version if it ends up being used on ld.so.  */
#if !IS_IN(rtld)
libc_hidden_def (__pthread_kill)
versioned_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_34);

# if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_0);
# endif
#endif