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/* The internal wrapper of clone and clone3.
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 <sysdep.h>
#include <stddef.h>
#include <errno.h>
#include <sched.h>
#include <clone_internal.h>
#include <libc-pointer-arith.h> /* For cast_to_pointer. */
#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
#define sizeof_field(TYPE, MEMBER) sizeof ((((TYPE *)0)->MEMBER))
#define offsetofend(TYPE, MEMBER) \
(offsetof (TYPE, MEMBER) + sizeof_field (TYPE, MEMBER))
_Static_assert (__alignof (struct clone_args) == 8,
"__alignof (struct clone_args) != 8");
_Static_assert (offsetofend (struct clone_args, tls) == CLONE_ARGS_SIZE_VER0,
"offsetofend (struct clone_args, tls) != CLONE_ARGS_SIZE_VER0");
_Static_assert (offsetofend (struct clone_args, set_tid_size) == CLONE_ARGS_SIZE_VER1,
"offsetofend (struct clone_args, set_tid_size) != CLONE_ARGS_SIZE_VER1");
_Static_assert (offsetofend (struct clone_args, cgroup) == CLONE_ARGS_SIZE_VER2,
"offsetofend (struct clone_args, cgroup) != CLONE_ARGS_SIZE_VER2");
_Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER2,
"sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER2");
int
__clone_internal_fallback (struct clone_args *cl_args,
int (*func) (void *arg), void *arg)
{
/* Map clone3 arguments to clone arguments. NB: No need to check
invalid clone3 specific bits in flags nor exit_signal since this
is an internal function. */
int flags = cl_args->flags | cl_args->exit_signal;
void *stack = cast_to_pointer (cl_args->stack);
int ret;
#ifdef __ia64__
ret = __clone2 (func, stack, cl_args->stack_size,
flags, arg,
cast_to_pointer (cl_args->parent_tid),
cast_to_pointer (cl_args->tls),
cast_to_pointer (cl_args->child_tid));
#else
# if !_STACK_GROWS_DOWN && !_STACK_GROWS_UP
# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
# endif
# if _STACK_GROWS_DOWN
stack += cl_args->stack_size;
# endif
ret = __clone (func, stack, flags, arg,
cast_to_pointer (cl_args->parent_tid),
cast_to_pointer (cl_args->tls),
cast_to_pointer (cl_args->child_tid));
#endif
return ret;
}
int
__clone3_internal (struct clone_args *cl_args, int (*func) (void *args),
void *arg)
{
#ifdef HAVE_CLONE3_WRAPPER
# if __ASSUME_CLONE3
return __clone3 (cl_args, sizeof (*cl_args), func, arg);
# else
static int clone3_supported = 1;
if (atomic_load_relaxed (&clone3_supported) == 1)
{
int ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
if (ret != -1 || errno != ENOSYS)
return ret;
atomic_store_relaxed (&clone3_supported, 0);
}
# endif
#endif
__set_errno (ENOSYS);
return -1;
}
int
__clone_internal (struct clone_args *cl_args,
int (*func) (void *arg), void *arg)
{
#ifdef HAVE_CLONE3_WRAPPER
int saved_errno = errno;
int ret = __clone3_internal (cl_args, func, arg);
if (ret != -1 || errno != ENOSYS)
return ret;
/* NB: Restore errno since errno may be checked against non-zero
return value. */
__set_errno (saved_errno);
#endif
return __clone_internal_fallback (cl_args, func, arg);
}
libc_hidden_def (__clone_internal)
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