1/* Copyright (C) 1991-2016 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. */
37struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
38libc_hidden_def (__abort_msg)
39
40/* We must avoid to run in circles. Therefore we remember how far we
41 already got. */
42static 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. */
49void
50abort (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}
141libc_hidden_def (abort)
142