stdlib/exit.c

   1 /* Copyright (C) 1991-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <unistd.h>
  21 #include <pointer_guard.h>
  22 #include <libc-lock.h>
  23 #include <libio/libioP.h>
  24 #include "exit.h"
  25
  26 /* Initialize the flag that indicates exit function processing
  27    is complete. See concurrency notes in stdlib/exit.h where
  28    __exit_funcs_lock is declared.  */
  29 bool __exit_funcs_done = false;
  30
  31 /* Call all functions registered with `atexit' and `on_exit',
  32    in the reverse of the order in which they were registered
  33    perform stdio cleanup, and terminate program execution with STATUS.  */
  34 void
  35 attribute_hidden
  36 __run_exit_handlers (int status, struct exit_function_list **listp,
  37                      bool run_list_atexit, bool run_dtors)
  38 {
  39   /* First, call the TLS destructors.  */
  40 #ifndef SHARED
  41   if (&__call_tls_dtors != NULL)
  42 #endif
  43     if (run_dtors)
  44       __call_tls_dtors ();
  45
  46   __libc_lock_lock (__exit_funcs_lock);
  47
  48   /* We do it this way to handle recursive calls to exit () made by
  49      the functions registered with `atexit' and `on_exit'. We call
  50      everyone on the list and use the status value in the last
  51      exit (). */
  52   while (true)
  53     {
  54       struct exit_function_list *cur = *listp;
  55
  56       if (cur == NULL)
  57         {
  58           /* Exit processing complete.  We will not allow any more
  59              atexit/on_exit registrations.  */
  60           __exit_funcs_done = true;
  61           break;
  62         }
  63
  64       while (cur->idx > 0)
  65         {
  66           struct exit_function *const f = &cur->fns[--cur->idx];
  67           const uint64_t new_exitfn_called = __new_exitfn_called;
  68
  69           switch (f->flavor)
  70             {
  71               void (*atfct) (void);
  72               void (*onfct) (int status, void *arg);
  73               void (*cxafct) (void *arg, int status);
  74               void *arg;
  75
  76             case ef_free:
  77             case ef_us:
  78               break;
  79             case ef_on:
  80               onfct = f->func.on.fn;
  81               arg = f->func.on.arg;
  82               PTR_DEMANGLE (onfct);
  83
  84               /* Unlock the list while we call a foreign function.  */
  85               __libc_lock_unlock (__exit_funcs_lock);
  86               onfct (status, arg);
  87               __libc_lock_lock (__exit_funcs_lock);
  88               break;
  89             case ef_at:
  90               atfct = f->func.at;
  91               PTR_DEMANGLE (atfct);
  92
  93               /* Unlock the list while we call a foreign function.  */
  94               __libc_lock_unlock (__exit_funcs_lock);
  95               atfct ();
  96               __libc_lock_lock (__exit_funcs_lock);
  97               break;
  98             case ef_cxa:
  99               /* To avoid dlclose/exit race calling cxafct twice (BZ 22180),
 100                  we must mark this function as ef_free.  */
 101               f->flavor = ef_free;
 102               cxafct = f->func.cxa.fn;
 103               arg = f->func.cxa.arg;
 104               PTR_DEMANGLE (cxafct);
 105
 106               /* Unlock the list while we call a foreign function.  */
 107               __libc_lock_unlock (__exit_funcs_lock);
 108               cxafct (arg, status);
 109               __libc_lock_lock (__exit_funcs_lock);
 110               break;
 111             }
 112
 113           if (__glibc_unlikely (new_exitfn_called != __new_exitfn_called))
 114             /* The last exit function, or another thread, has registered
 115                more exit functions.  Start the loop over.  */
 116             continue;
 117         }
 118
 119       *listp = cur->next;
 120       if (*listp != NULL)
 121         /* Don't free the last element in the chain, this is the statically
 122            allocate element.  */
 123         free (cur);
 124     }
 125
 126   __libc_lock_unlock (__exit_funcs_lock);
 127
 128   if (run_list_atexit)
 129     call_function_static_weak (_IO_cleanup);
 130
 131   _exit (status);
 132 }
 133
 134
 135 void
 136 exit (int status)
 137 {
 138   __run_exit_handlers (status, &__exit_funcs, true, true);
 139 }
 140 libc_hidden_def (exit)