/* 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 <stdio.h> #include <errno.h> #include <atomic.h> #include <bits/uClibc_mutex.h> __UCLIBC_MUTEX_EXTERN(__atexit_lock) attribute_hidden; 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); int old_atexit(aefuncp func) #endif { /* * glibc casts aefuncp to cxaefuncp. * This seems dodgy, but I guess calling 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; __UCLIBC_MUTEX_LOCK(__atexit_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) { __set_errno(ENOMEM); goto DONE; } __exit_function_table = efp; __exit_slots += 20; } #else if (__exit_count >= __UCLIBC_MAX_ATEXIT) { __set_errno(ENOMEM); efp = NULL; goto DONE; } #endif __exit_cleanup = __exit_handler; /* enable cleanup */ efp = &__exit_function_table[__exit_count++]; efp->type = ef_in_use; DONE: __UCLIBC_MUTEX_UNLOCK(__atexit_lock); 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 */ free(__exit_function_table); #endif } #endif #ifdef L_exit /* Defeat compiler optimization which assumes function addresses are never NULL */ static __always_inline int not_null_ptr(const void *p) { const void *q; __asm__ ("" : "=r" (q) /* output */ : "0" (p) /* input */ ); return q != 0; } extern void weak_function _stdio_term(void) attribute_hidden; attribute_hidden void (*__exit_cleanup)(int) = 0; __UCLIBC_MUTEX_INIT(__atexit_lock, PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP); extern void __uClibc_fini(void) attribute_hidden; /* * Normal program termination */ void exit(int rv) { /* Perform exit-specific cleanup (atexit and on_exit) */ __UCLIBC_MUTEX_LOCK(__atexit_lock); if (not_null_ptr(__exit_cleanup)) { __exit_cleanup(rv); } __UCLIBC_MUTEX_UNLOCK(__atexit_lock); __uClibc_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 (not_null_ptr(_stdio_term)) _stdio_term(); _exit(rv); } libc_hidden_def(exit) #endif