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#include <libio/libioP.h>
35#define fflush(s) _IO_flush_all_lockp (0)
36
37/* Exported variable to locate abort message in core files etc. */
38struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
39libc_hidden_def (__abort_msg)
40
41/* We must avoid to run in circles. Therefore we remember how far we
42 already got. */
43static int stage;
44
45/* We should be prepared for multiple threads trying to run abort. */
46__libc_lock_define_initialized_recursive (static, lock);
47
48
49/* Cause an abnormal program termination with core-dump. */
50void
51abort (void)
52{
53 struct sigaction act;
54 sigset_t sigs;
55
56 /* First acquire the lock. */
57 __libc_lock_lock_recursive (lock);
58
59 /* Now it's for sure we are alone. But recursive calls are possible. */
60
61 /* Unblock SIGABRT. */
62 if (stage == 0)
63 {
64 ++stage;
65 __sigemptyset (&sigs);
66 __sigaddset (&sigs, SIGABRT);
67 __sigprocmask (SIG_UNBLOCK, &sigs, 0);
68 }
69
70 /* Flush all streams. We cannot close them now because the user
71 might have registered a handler for SIGABRT. */
72 if (stage == 1)
73 {
74 ++stage;
75 fflush (NULL);
76 }
77
78 /* Send signal which possibly calls a user handler. */
79 if (stage == 2)
80 {
81 /* This stage is special: we must allow repeated calls of
82 `abort' when a user defined handler for SIGABRT is installed.
83 This is risky since the `raise' implementation might also
84 fail but I don't see another possibility. */
85 int save_stage = stage;
86
87 stage = 0;
88 __libc_lock_unlock_recursive (lock);
89
90 raise (SIGABRT);
91
92 __libc_lock_lock_recursive (lock);
93 stage = save_stage + 1;
94 }
95
96 /* There was a handler installed. Now remove it. */
97 if (stage == 3)
98 {
99 ++stage;
100 memset (&act, '\0', sizeof (struct sigaction));
101 act.sa_handler = SIG_DFL;
102 __sigfillset (&act.sa_mask);
103 act.sa_flags = 0;
104 __sigaction (SIGABRT, &act, NULL);
105 }
106
107 /* Now close the streams which also flushes the output the user
108 defined handler might has produced. */
109 if (stage == 4)
110 {
111 ++stage;
112 __fcloseall ();
113 }
114
115 /* Try again. */
116 if (stage == 5)
117 {
118 ++stage;
119 raise (SIGABRT);
120 }
121
122 /* Now try to abort using the system specific command. */
123 if (stage == 6)
124 {
125 ++stage;
126 ABORT_INSTRUCTION;
127 }
128
129 /* If we can't signal ourselves and the abort instruction failed, exit. */
130 if (stage == 7)
131 {
132 ++stage;
133 _exit (127);
134 }
135
136 /* If even this fails try to use the provided instruction to crash
137 or otherwise make sure we never return. */
138 while (1)
139 /* Try for ever and ever. */
140 ABORT_INSTRUCTION;
141}
142libc_hidden_def (abort)
143