stdlib/abort.c

   1 /* Copyright (C) 1991-2015 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
  25 /* Try to get a machine dependent instruction which will make the
  26    program crash.  This is used in case everything else fails.  */
  27 #include <abort-instr.h>
  28 #ifndef ABORT_INSTRUCTION
  29 /* No such instruction is available.  */
  30 # define ABORT_INSTRUCTION
  31 #endif
  32
  33 #include <libio/libioP.h>
  34 #define fflush(s) _IO_flush_all_lockp (0)
  35
  36 /* Exported variable to locate abort message in core files etc.  */
  37 struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
  38 libc_hidden_def (__abort_msg)
  39
  40 /* We must avoid to run in circles.  Therefore we remember how far we
  41    already got.  */
  42 static int stage;
  43
  44 /* We should be prepared for multiple threads trying to run abort.  */
  45 __libc_lock_define_initialized_recursive (static, lock);
  46
  47
  48 /* Cause an abnormal program termination with core-dump.  */
  49 void
  50 abort (void)
  51 {
  52   struct sigaction act;
  53   sigset_t sigs;
  54
  55   /* First acquire the lock.  */
  56   __libc_lock_lock_recursive (lock);
  57
  58   /* Now it's for sure we are alone.  But recursive calls are possible.  */
  59
  60   /* Unlock SIGABRT.  */
  61   if (stage == 0)
  62     {
  63       ++stage;
  64       if (__sigemptyset (&sigs) == 0 &&
  65           __sigaddset (&sigs, SIGABRT) == 0)
  66         __sigprocmask (SIG_UNBLOCK, &sigs, (sigset_t *) NULL);
  67     }
  68
  69   /* Flush all streams.  We cannot close them now because the user
  70      might have registered a handler for SIGABRT.  */
  71   if (stage == 1)
  72     {
  73       ++stage;
  74       fflush (NULL);
  75     }
  76
  77   /* Send signal which possibly calls a user handler.  */
  78   if (stage == 2)
  79     {
  80       /* This stage is special: we must allow repeated calls of
  81          `abort' when a user defined handler for SIGABRT is installed.
  82          This is risky since the `raise' implementation might also
  83          fail but I don't see another possibility.  */
  84       int save_stage = stage;
  85
  86       stage = 0;
  87       __libc_lock_unlock_recursive (lock);
  88
  89       raise (SIGABRT);
  90
  91       __libc_lock_lock_recursive (lock);
  92       stage = save_stage + 1;
  93     }
  94
  95   /* There was a handler installed.  Now remove it.  */
  96   if (stage == 3)
  97     {
  98       ++stage;
  99       memset (&act, '\0', sizeof (struct sigaction));
 100       act.sa_handler = SIG_DFL;
 101       __sigfillset (&act.sa_mask);
 102       act.sa_flags = 0;
 103       __sigaction (SIGABRT, &act, NULL);
 104     }
 105
 106   /* Now close the streams which also flushes the output the user
 107      defined handler might has produced.  */
 108   if (stage == 4)
 109     {
 110       ++stage;
 111       __fcloseall ();
 112     }
 113
 114   /* Try again.  */
 115   if (stage == 5)
 116     {
 117       ++stage;
 118       raise (SIGABRT);
 119     }
 120
 121   /* Now try to abort using the system specific command.  */
 122   if (stage == 6)
 123     {
 124       ++stage;
 125       ABORT_INSTRUCTION;
 126     }
 127
 128   /* If we can't signal ourselves and the abort instruction failed, exit.  */
 129   if (stage == 7)
 130     {
 131       ++stage;
 132       _exit (127);
 133     }
 134
 135   /* If even this fails try to use the provided instruction to crash
 136      or otherwise make sure we never return.  */
 137   while (1)
 138     /* Try for ever and ever.  */
 139     ABORT_INSTRUCTION;
 140 }
 141 libc_hidden_def (abort)