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113 lines
3.8 KiB
C
113 lines
3.8 KiB
C
/* The internal wrapper of clone and clone3.
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Copyright (C) 2021-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <stddef.h>
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#include <errno.h>
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#include <sched.h>
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#include <clone_internal.h>
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#include <libc-pointer-arith.h> /* For cast_to_pointer. */
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#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
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#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
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#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
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#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
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#define sizeof_field(TYPE, MEMBER) sizeof ((((TYPE *)0)->MEMBER))
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#define offsetofend(TYPE, MEMBER) \
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(offsetof (TYPE, MEMBER) + sizeof_field (TYPE, MEMBER))
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_Static_assert (__alignof (struct clone_args) == 8,
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"__alignof (struct clone_args) != 8");
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_Static_assert (offsetofend (struct clone_args, tls) == CLONE_ARGS_SIZE_VER0,
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"offsetofend (struct clone_args, tls) != CLONE_ARGS_SIZE_VER0");
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_Static_assert (offsetofend (struct clone_args, set_tid_size) == CLONE_ARGS_SIZE_VER1,
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"offsetofend (struct clone_args, set_tid_size) != CLONE_ARGS_SIZE_VER1");
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_Static_assert (offsetofend (struct clone_args, cgroup) == CLONE_ARGS_SIZE_VER2,
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"offsetofend (struct clone_args, cgroup) != CLONE_ARGS_SIZE_VER2");
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_Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER2,
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"sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER2");
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int
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__clone_internal_fallback (struct clone_args *cl_args,
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int (*func) (void *arg), void *arg)
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{
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/* Map clone3 arguments to clone arguments. NB: No need to check
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invalid clone3 specific bits in flags nor exit_signal since this
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is an internal function. */
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int flags = cl_args->flags | cl_args->exit_signal;
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void *stack = cast_to_pointer (cl_args->stack);
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int ret;
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#if !_STACK_GROWS_DOWN && !_STACK_GROWS_UP
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# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
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#endif
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#if _STACK_GROWS_DOWN
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stack += cl_args->stack_size;
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#endif
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ret = __clone (func, stack, flags, arg,
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cast_to_pointer (cl_args->parent_tid),
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cast_to_pointer (cl_args->tls),
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cast_to_pointer (cl_args->child_tid));
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return ret;
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}
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int
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__clone3_internal (struct clone_args *cl_args, int (*func) (void *args),
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void *arg)
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{
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#ifdef HAVE_CLONE3_WRAPPER
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# if __ASSUME_CLONE3
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return __clone3 (cl_args, sizeof (*cl_args), func, arg);
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# else
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static int clone3_supported = 1;
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if (atomic_load_relaxed (&clone3_supported) == 1)
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{
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int ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
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if (ret != -1 || errno != ENOSYS)
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return ret;
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atomic_store_relaxed (&clone3_supported, 0);
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}
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# endif
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#endif
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__set_errno (ENOSYS);
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return -1;
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}
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int
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__clone_internal (struct clone_args *cl_args,
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int (*func) (void *arg), void *arg)
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{
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#ifdef HAVE_CLONE3_WRAPPER
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int saved_errno = errno;
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int ret = __clone3_internal (cl_args, func, arg);
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if (ret != -1 || errno != ENOSYS)
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return ret;
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/* NB: Restore errno since errno may be checked against non-zero
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return value. */
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__set_errno (saved_errno);
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#endif
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return __clone_internal_fallback (cl_args, func, arg);
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}
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libc_hidden_def (__clone_internal)
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