stdlib/abort.c

   1 /* Copyright (C) 1991-2017 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <libc-lock.h>
  19 #include <signal.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <sigsetops.h>
  25
  26 /* Try to get a machine dependent instruction which will make the
  27    program crash.  This is used in case everything else fails.  */
  28 #include <abort-instr.h>
  29 #ifndef ABORT_INSTRUCTION
  30 /* No such instruction is available.  */
  31 # define ABORT_INSTRUCTION
  32 #endif
  33
  34 /* Exported variable to locate abort message in core files etc.  */
  35 struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
  36 libc_hidden_def (__abort_msg)
  37
  38 /* We must avoid to run in circles.  Therefore we remember how far we
  39    already got.  */
  40 static int stage;
  41
  42 /* We should be prepared for multiple threads trying to run abort.  */
  43 __libc_lock_define_initialized_recursive (static, lock);
  44
  45
  46 /* Cause an abnormal program termination with core-dump.  */
  47 void
  48 abort (void)
  49 {
  50   struct sigaction act;
  51   sigset_t sigs;
  52
  53   /* First acquire the lock.  */
  54   __libc_lock_lock_recursive (lock);
  55
  56   /* Now it's for sure we are alone.  But recursive calls are possible.  */
  57
  58   /* Unblock SIGABRT.  */
  59   if (stage == 0)
  60     {
  61       ++stage;
  62       __sigemptyset (&sigs);
  63       __sigaddset (&sigs, SIGABRT);
  64       __sigprocmask (SIG_UNBLOCK, &sigs, 0);
  65     }
  66
  67   /* Send signal which possibly calls a user handler.  */
  68   if (stage == 1)
  69     {
  70       /* This stage is special: we must allow repeated calls of
  71          `abort' when a user defined handler for SIGABRT is installed.
  72          This is risky since the `raise' implementation might also
  73          fail but I don't see another possibility.  */
  74       int save_stage = stage;
  75
  76       stage = 0;
  77       __libc_lock_unlock_recursive (lock);
  78
  79       raise (SIGABRT);
  80
  81       __libc_lock_lock_recursive (lock);
  82       stage = save_stage + 1;
  83     }
  84
  85   /* There was a handler installed.  Now remove it.  */
  86   if (stage == 2)
  87     {
  88       ++stage;
  89       memset (&act, '\0', sizeof (struct sigaction));
  90       act.sa_handler = SIG_DFL;
  91       __sigfillset (&act.sa_mask);
  92       act.sa_flags = 0;
  93       __sigaction (SIGABRT, &act, NULL);
  94     }
  95
  96   /* Try again.  */
  97   if (stage == 3)
  98     {
  99       ++stage;
 100       raise (SIGABRT);
 101     }
 102
 103   /* Now try to abort using the system specific command.  */
 104   if (stage == 4)
 105     {
 106       ++stage;
 107       ABORT_INSTRUCTION;
 108     }
 109
 110   /* If we can't signal ourselves and the abort instruction failed, exit.  */
 111   if (stage == 5)
 112     {
 113       ++stage;
 114       _exit (127);
 115     }
 116
 117   /* If even this fails try to use the provided instruction to crash
 118      or otherwise make sure we never return.  */
 119   while (1)
 120     /* Try for ever and ever.  */
 121     ABORT_INSTRUCTION;
 122 }
 123 libc_hidden_def (abort)