1 /* Copyright (C) 2006-2023 Free Software Foundation, Inc.
2 Contributed by François-Xavier Coudert
3
4 This file is part of the GNU Fortran runtime library (libgfortran).
5
6 Libgfortran is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
10
11 Libgfortran is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
19
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
24
25 #include "libgfortran.h"
26
27 #include <gthr.h>
28
29 #include <string.h>
30 #include <errno.h>
31
32 #ifdef HAVE_UNISTD_H
33 #include <unistd.h>
34 #endif
35
36 #include "backtrace-supported.h"
37 #include "backtrace.h"
38
39
40 /* Store our own state while backtracing. */
41 struct mystate
42 {
43 int frame;
44 bool try_simple;
45 bool in_signal_handler;
46 };
47
48
49 /* Does a function name have "_gfortran_" or "_gfortrani_" prefix, possibly
50 with additional underscore(s) at the beginning? Cannot use strncmp()
51 because we might be called from a signal handler. */
52
53 static int
54 has_gfortran_prefix (const char *s)
55 {
56 if (!s)
57 return 0;
58
59 while (*s == '_')
60 s++;
61
62 return (s[0] == 'g' && s[1] == 'f' && s[2] == 'o' && s[3] == 'r'
63 && s[4] == 't' && s[5] == 'r' && s[6] == 'a' && s[7] == 'n'
64 && (s[8] == '_' || (s[8] == 'i' && s[9] == '_')));
65 }
66
67 static void
68 error_callback (void *data, const char *msg, int errnum)
69 {
70 struct mystate *state = (struct mystate *) data;
71 struct iovec iov[5];
72 #define ERRHDR "\nCould not print backtrace: "
73
74 if (errnum < 0)
75 {
76 state->try_simple = true;
77 return;
78 }
79 else if (errnum == 0)
80 {
81 iov[0].iov_base = (char*) ERRHDR;
82 iov[0].iov_len = strlen (ERRHDR);
83 iov[1].iov_base = (char*) msg;
84 iov[1].iov_len = strlen (msg);
85 iov[2].iov_base = (char*) "\n";
86 iov[2].iov_len = 1;
87 estr_writev (iov, 3);
88 }
89 else
90 {
91 char errbuf[256];
92 if (state->in_signal_handler)
93 {
94 iov[0].iov_base = (char*) ERRHDR;
95 iov[0].iov_len = strlen (ERRHDR);
96 iov[1].iov_base = (char*) msg;
97 iov[1].iov_len = strlen (msg);
98 iov[2].iov_base = (char*) ", errno: ";
99 iov[2].iov_len = strlen (iov[2].iov_base);
100 /* Async-signal-safe function, errnum must be positive. */
101 const char *p = gfc_itoa (errnum, errbuf, sizeof (errbuf));
102 iov[3].iov_base = (char*) p;
103 iov[3].iov_len = strlen (p);
104 iov[4].iov_base = (char*) "\n";
105 iov[4].iov_len = 1;
106 estr_writev (iov, 5);
107 }
108 else
109 st_printf (ERRHDR "%s: %s\n", msg,
110 gf_strerror (errnum, errbuf, sizeof (errbuf)));
111 }
112 }
113
114 static int
115 simple_callback (void *data, uintptr_t pc)
116 {
117 struct mystate *state = (struct mystate *) data;
118 st_printf ("#%d 0x%lx\n", state->frame, (unsigned long) pc);
119 (state->frame)++;
120 return 0;
121 }
122
123 static int
124 full_callback (void *data, uintptr_t pc, const char *filename,
125 int lineno, const char *function)
126 {
127 struct mystate *state = (struct mystate *) data;
128
129 if (has_gfortran_prefix (function))
130 return 0;
131
132 st_printf ("#%d 0x%lx in %s\n", state->frame,
133 (unsigned long) pc, function == NULL ? "???" : function);
134 if (filename || lineno != 0)
135 st_printf ("\tat %s:%d\n", filename == NULL ? "???" : filename, lineno);
136 (state->frame)++;
137
138 if (function != NULL && strcmp (function, "main") == 0)
139 return 1;
140
141 return 0;
142 }
143
144
145 /* Display the backtrace. */
146
147 void
148 show_backtrace (bool in_signal_handler)
149 {
150 /* Note that libbacktrace allows the state to be accessed from
151 multiple threads, so we don't need to use a TLS variable for the
152 state here. */
153 static struct backtrace_state *lbstate_saved;
154 struct backtrace_state *lbstate;
155 struct mystate state = { 0, false, in_signal_handler };
156
157 lbstate = __atomic_load_n (&lbstate_saved, __ATOMIC_RELAXED);
158 if (!lbstate)
159 {
160 lbstate = backtrace_create_state (NULL, __gthread_active_p (),
161 error_callback, NULL);
162 if (lbstate)
163 __atomic_store_n (&lbstate_saved, lbstate, __ATOMIC_RELAXED);
164 else
165 return;
166 }
167
168 if (!BACKTRACE_SUPPORTED || (in_signal_handler && BACKTRACE_USES_MALLOC))
169 {
170 /* If symbolic backtrace is not supported on this target, or would
171 require malloc() and we are in a signal handler, go with a
172 simple backtrace. */
173
174 backtrace_simple (lbstate, 0, simple_callback, error_callback, &state);
175 }
176 else
177 {
178 /* libbacktrace uses mmap, which is safe to call from a signal handler
179 (in practice, if not in theory). Thus we can generate a symbolic
180 backtrace, if debug symbols are available. */
181
182 backtrace_full (lbstate, 0, full_callback, error_callback, &state);
183 if (state.try_simple)
184 backtrace_simple (lbstate, 0, simple_callback, error_callback, &state);
185 }
186 }
187
188
189
190 /* Function called by the front-end translating the BACKTRACE intrinsic. */
191
192 extern void backtrace (void);
193 export_proto (backtrace);
194
195 void
196 backtrace (void)
197 {
198 show_backtrace (false);
199 }
200