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The Linux nptl implementation is used as base for generic fork implementation to handle the internal locks and mutexes. The system specific bits are moved a new internal _Fork symbol. (This new implementation will be used to provide a async-signal-safe _Fork now that POSIX has clarified that fork might not be async-signal-safe [1]). For Hurd it means that the __nss_database_fork_prepare_parent and __nss_database_fork_subprocess will be run in a slight different order. [1] https://austingroupbugs.net/view.php?id=62
60 lines
2.2 KiB
C
60 lines
2.2 KiB
C
/* arch_fork definition for Linux fork implementation.
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Copyright (C) 2014-2021 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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#ifndef __ARCH_FORK_H
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#define __ARCH_FORK_H
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#include <sysdep.h>
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#include <sched.h>
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#include <signal.h>
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#include <unistd.h>
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/* Call the clone syscall with fork semantic. The CTID address is used
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to store the child thread ID at its locationm, to erase it in child memory
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when the child exits, and do a wakeup on the futex at that address.
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The architecture with non-default kernel abi semantic should correctlly
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override it with one of the supported calling convention (check generic
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kernel-features.h for the clone abi variants). */
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static inline pid_t
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arch_fork (void *ctid)
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{
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const int flags = CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD;
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long int ret;
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#ifdef __ASSUME_CLONE_BACKWARDS
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# ifdef INLINE_CLONE_SYSCALL
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ret = INLINE_CLONE_SYSCALL (flags, 0, NULL, 0, ctid);
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# else
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ret = INLINE_SYSCALL_CALL (clone, flags, 0, NULL, 0, ctid);
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# endif
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#elif defined(__ASSUME_CLONE_BACKWARDS2)
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ret = INLINE_SYSCALL_CALL (clone, 0, flags, NULL, ctid, 0);
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#elif defined(__ASSUME_CLONE_BACKWARDS3)
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ret = INLINE_SYSCALL_CALL (clone, flags, 0, 0, NULL, ctid, 0);
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#elif defined(__ASSUME_CLONE2)
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ret = INLINE_SYSCALL_CALL (clone2, flags, 0, 0, NULL, ctid, 0);
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#elif defined(__ASSUME_CLONE_DEFAULT)
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ret = INLINE_SYSCALL_CALL (clone, flags, 0, NULL, ctid, 0);
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#else
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# error "Undefined clone variant"
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#endif
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return ret;
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}
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#endif /* __ARCH_FORK_H */
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