diff options
Diffstat (limited to 'libc/stdlib/_atexit.c')
| -rw-r--r-- | libc/stdlib/_atexit.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/libc/stdlib/_atexit.c b/libc/stdlib/_atexit.c new file mode 100644 index 000000000..959d08edb --- /dev/null +++ b/libc/stdlib/_atexit.c @@ -0,0 +1,356 @@ +/* Copyright (C) 1995,1996 Robert de Bath <rdebath@cix.compulink.co.uk> + * This file is part of the Linux-8086 C library and is distributed + * under the GNU Library General Public License. + */ + +/* + * Dec 2000 Manuel Novoa III + * + * Made atexit handling conform to standards... i.e. no args. + * Removed on_exit since it did not match gnu libc definition. + * Combined atexit and __do_exit into one object file. + * + * Feb 2001 Manuel Novoa III + * + * Reworked file after addition of __uClibc_main. + * Changed name of __do_exit to atexit_handler. + * Changed name of __cleanup to __uClibc_cleanup. + * Moved declaration of __uClibc_cleanup to __uClibc_main + * where it is initialized with (possibly weak alias) + * _stdio_term. + * + * Jul 2001 Steve Thayer + * + * Added an on_exit implementation (that now matches gnu libc definition.) + * Pulled atexit_handler out of the atexit object since it is now required by + * on_exit as well. Renamed it to __exit_handler. + * Fixed a problem where exit functions stop getting called if one of + * them calls exit(). + * As a side effect of these changes, abort() no longer calls the exit + * functions (it now matches the gnu libc definition). + * + * August 2002 Erik Andersen + * Added locking so atexit and friends can be thread safe + * + * August 2005 Stephen Warren + * Added __cxa_atexit and __cxa_finalize support + * + */ + +#include <features.h> +#include <unistd.h> +#include <stdlib.h> +#include <errno.h> +#include <atomic.h> + +libc_hidden_proto(exit) +libc_hidden_proto(_exit) + +#ifdef __UCLIBC_HAS_THREADS__ +# include <pthread.h> +extern pthread_mutex_t mylock; +libc_hidden_proto(mylock) +#endif +#define LOCK __pthread_mutex_lock(&mylock) +#define UNLOCK __pthread_mutex_unlock(&mylock) + + +typedef void (*aefuncp) (void); /* atexit function pointer */ +typedef void (*oefuncp) (int, void *); /* on_exit function pointer */ +typedef void (*cxaefuncp) (void *); /* __cxa_atexit function pointer */ +typedef enum { + ef_free, + ef_in_use, + ef_on_exit, + ef_cxa_atexit +} ef_type; /* exit function types */ + +/* this is in the L_exit object */ +extern void (*__exit_cleanup) (int) attribute_hidden; + +/* these are in the L___do_exit object */ +extern int __exit_slots attribute_hidden; +extern int __exit_count attribute_hidden; +extern void __exit_handler(int) attribute_hidden; +struct exit_function { + /* + * 'type' should be of type of the 'enum ef_type' above but since we + * need this element in an atomic operation we have to use 'long int'. + */ + long int type; /* enum ef_type */ + union { + struct { + oefuncp func; + void *arg; + } on_exit; + struct { + cxaefuncp func; + void *arg; + void* dso_handle; + } cxa_atexit; + } funcs; +}; +#ifdef __UCLIBC_DYNAMIC_ATEXIT__ +extern struct exit_function *__exit_function_table attribute_hidden; +#else +extern struct exit_function __exit_function_table[__UCLIBC_MAX_ATEXIT] attribute_hidden; +#endif +extern struct exit_function *__new_exitfn (void) attribute_hidden; + +/* this is in the L___cxa_atexit object */ +extern int __cxa_atexit (cxaefuncp, void *arg, void *dso_handle); + + +/* remove old_atexit after 0.9.29 */ +#if defined(L_atexit) || defined(L_old_atexit) +extern void *__dso_handle __attribute__ ((__weak__)); + +/* + * register a function to be called at normal program termination + * (the registered function takes no arguments) + */ +#ifdef L_atexit +int attribute_hidden atexit(aefuncp func) +#else +int old_atexit(aefuncp func) +#endif +{ + /* + * glibc casts aefuncp to cxaefuncp. + * This seems dodgy, but I guess callling a function with more + * parameters than it needs will work everywhere? + */ + return __cxa_atexit((cxaefuncp)func, NULL, + &__dso_handle == NULL ? NULL : __dso_handle); +} +#ifndef L_atexit +weak_alias(old_atexit,atexit) +#endif +#endif + +#ifdef L_on_exit +/* + * register a function to be called at normal program termination + * the registered function takes two arguments: + * status - the exit status that was passed to the exit() function + * arg - generic argument + */ +int on_exit(oefuncp func, void *arg) +{ + struct exit_function *efp; + + if (func == NULL) { + return 0; + } + + efp = __new_exitfn(); + if (efp == NULL) { + return -1; + } + + efp->funcs.on_exit.func = func; + efp->funcs.on_exit.arg = arg; + /* assign last for thread safety, since we're now unlocked */ + efp->type = ef_on_exit; + + return 0; +} +#endif + +#ifdef L___cxa_atexit +libc_hidden_proto(__cxa_atexit) +int __cxa_atexit (cxaefuncp func, void *arg, void *dso_handle) +{ + struct exit_function *efp; + + if (func == NULL) { + return 0; + } + + efp = __new_exitfn(); + if (efp == NULL) { + return -1; + } + + efp->funcs.cxa_atexit.func = func; + efp->funcs.cxa_atexit.arg = arg; + efp->funcs.cxa_atexit.dso_handle = dso_handle; + /* assign last for thread safety, since we're now unlocked */ + efp->type = ef_cxa_atexit; + + return 0; +} +libc_hidden_def(__cxa_atexit) +#endif + +#ifdef L___cxa_finalize +/* + * If D is non-NULL, call all functions registered with `__cxa_atexit' + * with the same dso handle. Otherwise, if D is NULL, call all of the + * registered handlers. + */ +void __cxa_finalize (void *dso_handle); +void __cxa_finalize (void *dso_handle) +{ + struct exit_function *efp; + int exit_count_snapshot = __exit_count; + + /* In reverse order */ + while (exit_count_snapshot) { + efp = &__exit_function_table[--exit_count_snapshot]; + + /* + * We check dso_handle match before we verify the type of the union entry. + * However, the atomic_exchange will validate that we were really "allowed" + * to read dso_handle... + */ + if ((dso_handle == NULL || dso_handle == efp->funcs.cxa_atexit.dso_handle) + /* We don't want to run this cleanup more than once. */ + && !atomic_compare_and_exchange_bool_acq(&efp->type, ef_free, ef_cxa_atexit) + ) { + /* glibc passes status (0) too, but that's not in the prototype */ + (*efp->funcs.cxa_atexit.func)(efp->funcs.cxa_atexit.arg); + } + } + +#if 0 /* haven't looked into this yet... */ + /* + * Remove the registered fork handlers. We do not have to + * unregister anything if the program is going to terminate anyway. + */ +#ifdef UNREGISTER_ATFORK + if (d != NULL) { + UNREGISTER_ATFORK (d); + } +#endif +#endif +} +#endif + +#ifdef L___exit_handler +int __exit_count = 0; /* Number of registered exit functions */ +#ifdef __UCLIBC_DYNAMIC_ATEXIT__ +struct exit_function *__exit_function_table = NULL; +int __exit_slots = 0; /* Size of __exit_function_table */ +#else +struct exit_function __exit_function_table[__UCLIBC_MAX_ATEXIT]; +#endif + +/* + * Find and return a new exit_function pointer, for atexit, + * onexit and __cxa_atexit to initialize + */ +struct exit_function attribute_hidden *__new_exitfn(void) +{ + struct exit_function *efp; + + LOCK; + +#ifdef __UCLIBC_DYNAMIC_ATEXIT__ + /* If we are out of function table slots, make some more */ + if (__exit_slots < __exit_count+1) { + efp=realloc(__exit_function_table, + (__exit_slots+20)*sizeof(struct exit_function)); + if (efp == NULL) { + UNLOCK; + __set_errno(ENOMEM); + return 0; + } + __exit_function_table = efp; + __exit_slots += 20; + } +#else + if (__exit_count >= __UCLIBC_MAX_ATEXIT) { + UNLOCK; + __set_errno(ENOMEM); + return 0; + } +#endif + + __exit_cleanup = __exit_handler; /* enable cleanup */ + efp = &__exit_function_table[__exit_count++]; + efp->type = ef_in_use; + + UNLOCK; + + return efp; +} + +/* + * Handle the work of executing the registered exit functions + * This is called while we are locked, so no additional locking + * is needed... + */ +void __exit_handler(int status) +{ + struct exit_function *efp; + + /* In reverse order */ + while ( __exit_count ) { + efp = &__exit_function_table[--__exit_count]; + switch (efp->type) { + case ef_on_exit: + if (efp->funcs.on_exit.func) { + (efp->funcs.on_exit.func) (status, efp->funcs.on_exit.arg); + } + break; + case ef_cxa_atexit: + if (efp->funcs.cxa_atexit.func) { + /* glibc passes status too, but that's not in the prototype */ + (efp->funcs.cxa_atexit.func) (efp->funcs.cxa_atexit.arg); + } + break; + } + } +#ifdef __UCLIBC_DYNAMIC_ATEXIT__ + /* Free up memory used by the __exit_function_table structure */ + if (__exit_function_table) + free(__exit_function_table); +#endif +} +#endif + +#ifdef L_exit +extern void weak_function _stdio_term(void) attribute_hidden; +attribute_hidden void (*__exit_cleanup) (int) = 0; +#ifdef __UCLIBC_HAS_THREADS__ +pthread_mutex_t mylock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; +libc_hidden_data_def(mylock) +#endif + +#ifdef __UCLIBC_CTOR_DTOR__ +extern void (*__app_fini)(void); +#endif + +extern void (*__rtld_fini)(void); + +/* + * Normal program termination + */ +void exit(int rv) +{ + /* Perform exit-specific cleanup (atexit and on_exit) */ + LOCK; + if (__exit_cleanup) { + __exit_cleanup(rv); + } + UNLOCK; + +#ifdef __UCLIBC_CTOR_DTOR__ + if (__app_fini != NULL) + (__app_fini)(); +#endif + if (__rtld_fini != NULL) + (__rtld_fini)(); + + /* If we are using stdio, try to shut it down. At the very least, + * this will attempt to commit all buffered writes. It may also + * unbuffer all writable files, or close them outright. + * Check the stdio routines for details. */ + if (_stdio_term) + _stdio_term(); + + _exit(rv); +} +libc_hidden_def(exit) +#endif |