1/* Copyright (C) 1991-2020 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 <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. */
35struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
36libc_hidden_def (__abort_msg)
37
38/* We must avoid to run in circles. Therefore we remember how far we
39 already got. */
40static 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. */
47void
48abort (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}
123libc_hidden_def (abort)
124