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/* Copyright (C) 2002-2021 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 <libc-lock.h>
#include <stdbool.h>
#include <register-atfork.h>
#define DYNARRAY_ELEMENT struct fork_handler
#define DYNARRAY_STRUCT fork_handler_list
#define DYNARRAY_PREFIX fork_handler_list_
#define DYNARRAY_INITIAL_SIZE 48
#include <malloc/dynarray-skeleton.c>
static struct fork_handler_list fork_handlers;
static bool fork_handler_init = false;
static int atfork_lock = LLL_LOCK_INITIALIZER;
int
__register_atfork (void (*prepare) (void), void (*parent) (void),
void (*child) (void), void *dso_handle)
{
lll_lock (atfork_lock, LLL_PRIVATE);
if (!fork_handler_init)
{
fork_handler_list_init (&fork_handlers);
fork_handler_init = true;
}
struct fork_handler *newp = fork_handler_list_emplace (&fork_handlers);
if (newp != NULL)
{
newp->prepare_handler = prepare;
newp->parent_handler = parent;
newp->child_handler = child;
newp->dso_handle = dso_handle;
}
/* Release the lock. */
lll_unlock (atfork_lock, LLL_PRIVATE);
return newp == NULL ? ENOMEM : 0;
}
libc_hidden_def (__register_atfork)
static struct fork_handler *
fork_handler_list_find (struct fork_handler_list *fork_handlers,
void *dso_handle)
{
for (size_t i = 0; i < fork_handler_list_size (fork_handlers); i++)
{
struct fork_handler *elem = fork_handler_list_at (fork_handlers, i);
if (elem->dso_handle == dso_handle)
return elem;
}
return NULL;
}
void
__unregister_atfork (void *dso_handle)
{
lll_lock (atfork_lock, LLL_PRIVATE);
struct fork_handler *first = fork_handler_list_find (&fork_handlers,
dso_handle);
/* Removing is done by shifting the elements in the way the elements
that are not to be removed appear in the beginning in dynarray.
This avoid the quadradic run-time if a naive strategy to remove and
shift one element at time. */
if (first != NULL)
{
struct fork_handler *new_end = first;
first++;
for (; first != fork_handler_list_end (&fork_handlers); ++first)
{
if (first->dso_handle != dso_handle)
{
*new_end = *first;
++new_end;
}
}
ptrdiff_t removed = first - new_end;
for (size_t i = 0; i < removed; i++)
fork_handler_list_remove_last (&fork_handlers);
}
lll_unlock (atfork_lock, LLL_PRIVATE);
}
void
__run_fork_handlers (enum __run_fork_handler_type who, _Bool do_locking)
{
struct fork_handler *runp;
if (who == atfork_run_prepare)
{
if (do_locking)
lll_lock (atfork_lock, LLL_PRIVATE);
size_t sl = fork_handler_list_size (&fork_handlers);
for (size_t i = sl; i > 0; i--)
{
runp = fork_handler_list_at (&fork_handlers, i - 1);
if (runp->prepare_handler != NULL)
runp->prepare_handler ();
}
}
else
{
size_t sl = fork_handler_list_size (&fork_handlers);
for (size_t i = 0; i < sl; i++)
{
runp = fork_handler_list_at (&fork_handlers, i);
if (who == atfork_run_child && runp->child_handler)
runp->child_handler ();
else if (who == atfork_run_parent && runp->parent_handler)
runp->parent_handler ();
}
if (do_locking)
lll_unlock (atfork_lock, LLL_PRIVATE);
}
}
libc_freeres_fn (free_mem)
{
lll_lock (atfork_lock, LLL_PRIVATE);
fork_handler_list_free (&fork_handlers);
lll_unlock (atfork_lock, LLL_PRIVATE);
}
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