151 lines
4.1 KiB
C
151 lines
4.1 KiB
C
/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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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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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fork.h>
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#include <atomic.h>
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#define DYNARRAY_ELEMENT struct fork_handler
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#define DYNARRAY_STRUCT fork_handler_list
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#define DYNARRAY_PREFIX fork_handler_list_
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#define DYNARRAY_INITIAL_SIZE 48
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#include <malloc/dynarray-skeleton.c>
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static struct fork_handler_list fork_handlers;
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static bool fork_handler_init = false;
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static int atfork_lock = LLL_LOCK_INITIALIZER;
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int
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__register_atfork (void (*prepare) (void), void (*parent) (void),
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void (*child) (void), void *dso_handle)
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{
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lll_lock (atfork_lock, LLL_PRIVATE);
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if (!fork_handler_init)
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{
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fork_handler_list_init (&fork_handlers);
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fork_handler_init = true;
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}
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struct fork_handler *newp = fork_handler_list_emplace (&fork_handlers);
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if (newp != NULL)
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{
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newp->prepare_handler = prepare;
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newp->parent_handler = parent;
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newp->child_handler = child;
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newp->dso_handle = dso_handle;
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}
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/* Release the lock. */
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lll_unlock (atfork_lock, LLL_PRIVATE);
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return newp == NULL ? ENOMEM : 0;
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}
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libc_hidden_def (__register_atfork)
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static struct fork_handler *
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fork_handler_list_find (struct fork_handler_list *fork_handlers,
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void *dso_handle)
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{
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for (size_t i = 0; i < fork_handler_list_size (fork_handlers); i++)
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{
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struct fork_handler *elem = fork_handler_list_at (fork_handlers, i);
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if (elem->dso_handle == dso_handle)
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return elem;
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}
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return NULL;
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}
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void
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__unregister_atfork (void *dso_handle)
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{
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lll_lock (atfork_lock, LLL_PRIVATE);
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struct fork_handler *first = fork_handler_list_find (&fork_handlers,
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dso_handle);
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/* Removing is done by shifting the elements in the way the elements
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that are not to be removed appear in the beginning in dynarray.
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This avoid the quadradic run-time if a naive strategy to remove and
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shift one element at time. */
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if (first != NULL)
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{
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struct fork_handler *new_end = first;
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first++;
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for (; first != fork_handler_list_end (&fork_handlers); ++first)
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{
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if (first->dso_handle != dso_handle)
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{
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*new_end = *first;
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++new_end;
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}
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}
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ptrdiff_t removed = first - new_end;
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for (size_t i = 0; i < removed; i++)
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fork_handler_list_remove_last (&fork_handlers);
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}
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lll_unlock (atfork_lock, LLL_PRIVATE);
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}
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void
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__run_fork_handlers (enum __run_fork_handler_type who, _Bool do_locking)
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{
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struct fork_handler *runp;
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if (who == atfork_run_prepare)
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{
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if (do_locking)
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lll_lock (atfork_lock, LLL_PRIVATE);
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size_t sl = fork_handler_list_size (&fork_handlers);
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for (size_t i = sl; i > 0; i--)
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{
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runp = fork_handler_list_at (&fork_handlers, i - 1);
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if (runp->prepare_handler != NULL)
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runp->prepare_handler ();
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}
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}
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else
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{
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size_t sl = fork_handler_list_size (&fork_handlers);
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for (size_t i = 0; i < sl; i++)
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{
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runp = fork_handler_list_at (&fork_handlers, i);
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if (who == atfork_run_child && runp->child_handler)
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runp->child_handler ();
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else if (who == atfork_run_parent && runp->parent_handler)
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runp->parent_handler ();
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}
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if (do_locking)
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lll_unlock (atfork_lock, LLL_PRIVATE);
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}
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}
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libc_freeres_fn (free_mem)
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{
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lll_lock (atfork_lock, LLL_PRIVATE);
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fork_handler_list_free (&fork_handlers);
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lll_unlock (atfork_lock, LLL_PRIVATE);
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}
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