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