1 /* Copyright (C) 2006-2021 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
has_gfortran_prefix(const char * s)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
error_callback(void * data,const char * msg,int errnum)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 const char *p = gfc_itoa (errnum, errbuf, sizeof (errbuf));
101 iov[3].iov_base = (char*) p;
102 iov[3].iov_len = strlen (p);
103 iov[4].iov_base = (char*) "\n";
104 iov[4].iov_len = 1;
105 estr_writev (iov, 5);
106 }
107 else
108 st_printf (ERRHDR "%s: %s\n", msg,
109 gf_strerror (errnum, errbuf, sizeof (errbuf)));
110 }
111 }
112
113 static int
simple_callback(void * data,uintptr_t pc)114 simple_callback (void *data, uintptr_t pc)
115 {
116 struct mystate *state = (struct mystate *) data;
117 st_printf ("#%d 0x%lx\n", state->frame, (unsigned long) pc);
118 (state->frame)++;
119 return 0;
120 }
121
122 static int
full_callback(void * data,uintptr_t pc,const char * filename,int lineno,const char * function)123 full_callback (void *data, uintptr_t pc, const char *filename,
124 int lineno, const char *function)
125 {
126 struct mystate *state = (struct mystate *) data;
127
128 if (has_gfortran_prefix (function))
129 return 0;
130
131 st_printf ("#%d 0x%lx in %s\n", state->frame,
132 (unsigned long) pc, function == NULL ? "???" : function);
133 if (filename || lineno != 0)
134 st_printf ("\tat %s:%d\n", filename == NULL ? "???" : filename, lineno);
135 (state->frame)++;
136
137 if (function != NULL && strcmp (function, "main") == 0)
138 return 1;
139
140 return 0;
141 }
142
143
144 /* Display the backtrace. */
145
146 void
show_backtrace(bool in_signal_handler)147 show_backtrace (bool in_signal_handler)
148 {
149 /* Note that libbacktrace allows the state to be accessed from
150 multiple threads, so we don't need to use a TLS variable for the
151 state here. */
152 static struct backtrace_state *lbstate_saved;
153 struct backtrace_state *lbstate;
154 struct mystate state = { 0, false, in_signal_handler };
155
156 lbstate = __atomic_load_n (&lbstate_saved, __ATOMIC_RELAXED);
157 if (!lbstate)
158 {
159 lbstate = backtrace_create_state (NULL, __gthread_active_p (),
160 error_callback, NULL);
161 if (lbstate)
162 __atomic_store_n (&lbstate_saved, lbstate, __ATOMIC_RELAXED);
163 else
164 return;
165 }
166
167 if (!BACKTRACE_SUPPORTED || (in_signal_handler && BACKTRACE_USES_MALLOC))
168 {
169 /* If symbolic backtrace is not supported on this target, or would
170 require malloc() and we are in a signal handler, go with a
171 simple backtrace. */
172
173 backtrace_simple (lbstate, 0, simple_callback, error_callback, &state);
174 }
175 else
176 {
177 /* libbacktrace uses mmap, which is safe to call from a signal handler
178 (in practice, if not in theory). Thus we can generate a symbolic
179 backtrace, if debug symbols are available. */
180
181 backtrace_full (lbstate, 0, full_callback, error_callback, &state);
182 if (state.try_simple)
183 backtrace_simple (lbstate, 0, simple_callback, error_callback, &state);
184 }
185 }
186
187
188
189 /* Function called by the front-end translating the BACKTRACE intrinsic. */
190
191 extern void backtrace (void);
192 export_proto (backtrace);
193
194 void
backtrace(void)195 backtrace (void)
196 {
197 show_backtrace (false);
198 }
199
200