diff options
Diffstat (limited to 'nptl/register-atfork.c')
| -rw-r--r-- | nptl/register-atfork.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/nptl/register-atfork.c b/nptl/register-atfork.c new file mode 100644 index 0000000000..2cc49540b9 --- /dev/null +++ b/nptl/register-atfork.c @@ -0,0 +1,145 @@ +/* Copyright (C) 2002-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <stdlib.h> +#include <string.h> +#include <fork.h> +#include <atomic.h> + + +/* Lock to protect allocation and deallocation of fork handlers. */ +int __fork_lock = LLL_LOCK_INITIALIZER; + + +/* Number of pre-allocated handler entries. */ +#define NHANDLER 48 + +/* Memory pool for fork handler structures. */ +static struct fork_handler_pool +{ + struct fork_handler_pool *next; + struct fork_handler mem[NHANDLER]; +} fork_handler_pool; + + +static struct fork_handler * +fork_handler_alloc (void) +{ + struct fork_handler_pool *runp = &fork_handler_pool; + struct fork_handler *result = NULL; + unsigned int i; + + do + { + /* Search for an empty entry. */ + for (i = 0; i < NHANDLER; ++i) + if (runp->mem[i].refcntr == 0) + goto found; + } + while ((runp = runp->next) != NULL); + + /* We have to allocate a new entry. */ + runp = (struct fork_handler_pool *) calloc (1, sizeof (*runp)); + if (runp != NULL) + { + /* Enqueue the new memory pool into the list. */ + runp->next = fork_handler_pool.next; + fork_handler_pool.next = runp; + + /* We use the last entry on the page. This means when we start + searching from the front the next time we will find the first + entry unused. */ + i = NHANDLER - 1; + + found: + result = &runp->mem[i]; + result->refcntr = 1; + result->need_signal = 0; + } + + return result; +} + + +int +__register_atfork (prepare, parent, child, dso_handle) + void (*prepare) (void); + void (*parent) (void); + void (*child) (void); + void *dso_handle; +{ + /* Get the lock to not conflict with other allocations. */ + lll_lock (__fork_lock, LLL_PRIVATE); + + struct fork_handler *newp = fork_handler_alloc (); + + if (newp != NULL) + { + /* Initialize the new record. */ + newp->prepare_handler = prepare; + newp->parent_handler = parent; + newp->child_handler = child; + newp->dso_handle = dso_handle; + + __linkin_atfork (newp); + } + + /* Release the lock. */ + lll_unlock (__fork_lock, LLL_PRIVATE); + + return newp == NULL ? ENOMEM : 0; +} +libc_hidden_def (__register_atfork) + + +void +attribute_hidden +__linkin_atfork (struct fork_handler *newp) +{ + do + newp->next = __fork_handlers; + while (catomic_compare_and_exchange_bool_acq (&__fork_handlers, + newp, newp->next) != 0); +} + + +libc_freeres_fn (free_mem) +{ + /* Get the lock to not conflict with running forks. */ + lll_lock (__fork_lock, LLL_PRIVATE); + + /* No more fork handlers. */ + __fork_handlers = NULL; + + /* Free eventually allocated memory blocks for the object pool. */ + struct fork_handler_pool *runp = fork_handler_pool.next; + + memset (&fork_handler_pool, '\0', sizeof (fork_handler_pool)); + + /* Release the lock. */ + lll_unlock (__fork_lock, LLL_PRIVATE); + + /* We can free the memory after releasing the lock. */ + while (runp != NULL) + { + struct fork_handler_pool *oldp = runp; + runp = runp->next; + free (oldp); + } +} |