glibc/sysdeps/nptl/_Fork.c

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/* _Fork implementation. Linux version.
Copyright (C) 2021-2022 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 <arch-fork.h>
#include <pthreadP.h>
/* Pointer to the fork generation counter in the thread library. */
extern unsigned long int *__fork_generation_pointer attribute_hidden;
pid_t
_Fork (void)
{
pid_t pid = arch_fork (&THREAD_SELF->tid);
if (pid == 0)
{
struct pthread *self = THREAD_SELF;
/* Initialize the robust mutex list setting in the kernel which has
been reset during the fork. We do not check for errors because if
it fails here, it must have failed at process startup as well and
nobody could have used robust mutexes.
Before we do that, we have to clear the list of robust mutexes
because we do not inherit ownership of mutexes from the parent.
We do not have to set self->robust_head.futex_offset since we do
inherit the correct value from the parent. We do not need to clear
the pending operation because it must have been zero when fork was
called. */
#if __PTHREAD_MUTEX_HAVE_PREV
self->robust_prev = &self->robust_head;
#endif
self->robust_head.list = &self->robust_head;
INTERNAL_SYSCALL_CALL (set_robust_list, &self->robust_head,
sizeof (struct robust_list_head));
}
return pid;
}
libc_hidden_def (_Fork)