glibc/sysdeps/unix/sysv/linux/clone3.h
Adhemerval Zanella Netto 2053c11331 linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn
The clone3 flag resets all signal handlers of the child not set to
SIG_IGN to SIG_DFL.  It allows to skip most of the sigaction calls
to setup child signal handling, where previously a posix_spawn
had to issue 2 times NSIG sigaction calls (one to obtain the current
disposition and another to set either SIG_DFL or SIG_IGN).

With POSIX_SPAWN_SETSIGDEF the child will setup the signal for the case
where the disposition is SIG_IGN.

The code must handle the fallback where clone3 is not available. This is
done by splitting __clone_internal_fallback from __clone_internal.

Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2023-02-01 08:42:11 -03:00

67 lines
2.4 KiB
C

/* The clone3 kernel interface definitions.
Copyright (C) 2021-2023 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/>. */
#ifndef _CLONE3_H
#define _CLONE3_H 1
#include <features.h>
#include <stddef.h>
#include <bits/types.h>
/* Flags for the clone3 syscall. */
#define CLONE_CLEAR_SIGHAND 0x100000000ULL /* Clear any signal handler and
reset to SIG_DFL. */
#define CLONE_INTO_CGROUP 0x200000000ULL /* Clone into a specific cgroup given
the right permissions. */
/* The unsigned 64-bit and 8-byte aligned integer type. */
typedef __U64_TYPE __aligned_uint64_t __attribute__ ((__aligned__ (8)));
/* This struct should only be used in an argument to the clone3 system
call (along with its size argument). It may be extended with new
fields in the future. */
struct clone_args
{
/* Flags bit mask. */
__aligned_uint64_t flags;
/* Where to store PID file descriptor (pid_t *). */
__aligned_uint64_t pidfd;
/* Where to store child TID, in child's memory (pid_t *). */
__aligned_uint64_t child_tid;
/* Where to store child TID, in parent's memory (int *). */
__aligned_uint64_t parent_tid;
/* Signal to deliver to parent on child termination */
__aligned_uint64_t exit_signal;
/* The lowest address of stack. */
__aligned_uint64_t stack;
/* Size of stack. */
__aligned_uint64_t stack_size;
/* Location of new TLS. */
__aligned_uint64_t tls;
/* Pointer to a pid_t array (since Linux 5.5). */
__aligned_uint64_t set_tid;
/* Number of elements in set_tid (since Linux 5.5). */
__aligned_uint64_t set_tid_size;
/* File descriptor for target cgroup of child (since Linux 5.7). */
__aligned_uint64_t cgroup;
};
#endif /* clone3.h */