1 /* fileline.c -- Get file and line number information in a backtrace. 2 Copyright (C) 2012-2018 Free Software Foundation, Inc. 3 Written by Ian Lance Taylor, Google. 4 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions are 7 met: 8 9 (1) Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 12 (2) Redistributions in binary form must reproduce the above copyright 13 notice, this list of conditions and the following disclaimer in 14 the documentation and/or other materials provided with the 15 distribution. 16 17 (3) The name of the author may not be used to 18 endorse or promote products derived from this software without 19 specific prior written permission. 20 21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, 25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 POSSIBILITY OF SUCH DAMAGE. */ 32 33 #include "config.h" 34 35 #include <sys/types.h> 36 #include <sys/stat.h> 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <stdlib.h> 40 #include <unistd.h> 41 42 #include "backtrace.h" 43 #include "internal.h" 44 45 #ifndef HAVE_GETEXECNAME 46 #define getexecname() NULL 47 #endif 48 49 /* Initialize the fileline information from the executable. Returns 1 50 on success, 0 on failure. */ 51 52 static int 53 fileline_initialize (struct backtrace_state *state, 54 backtrace_error_callback error_callback, void *data) 55 { 56 int failed; 57 fileline fileline_fn; 58 int pass; 59 int called_error_callback; 60 int descriptor; 61 const char *filename; 62 char buf[64]; 63 64 if (!state->threaded) 65 failed = state->fileline_initialization_failed; 66 else 67 failed = backtrace_atomic_load_int (&state->fileline_initialization_failed); 68 69 if (failed) 70 { 71 error_callback (data, "failed to read executable information", -1); 72 return 0; 73 } 74 75 if (!state->threaded) 76 fileline_fn = state->fileline_fn; 77 else 78 fileline_fn = backtrace_atomic_load_pointer (&state->fileline_fn); 79 if (fileline_fn != NULL) 80 return 1; 81 82 /* We have not initialized the information. Do it now. */ 83 84 descriptor = -1; 85 called_error_callback = 0; 86 for (pass = 0; pass < 5; ++pass) 87 { 88 int does_not_exist; 89 90 switch (pass) 91 { 92 case 0: 93 filename = state->filename; 94 break; 95 case 1: 96 filename = getexecname (); 97 break; 98 case 2: 99 filename = "/proc/self/exe"; 100 break; 101 case 3: 102 filename = "/proc/curproc/file"; 103 break; 104 case 4: 105 snprintf (buf, sizeof (buf), "/proc/%ld/object/a.out", 106 (long) getpid ()); 107 filename = buf; 108 break; 109 default: 110 abort (); 111 } 112 113 if (filename == NULL) 114 continue; 115 116 descriptor = backtrace_open (filename, error_callback, data, 117 &does_not_exist); 118 if (descriptor < 0 && !does_not_exist) 119 { 120 called_error_callback = 1; 121 break; 122 } 123 if (descriptor >= 0) 124 break; 125 } 126 127 if (descriptor < 0) 128 { 129 if (!called_error_callback) 130 { 131 if (state->filename != NULL) 132 error_callback (data, state->filename, ENOENT); 133 else 134 error_callback (data, 135 "libbacktrace could not find executable to open", 136 0); 137 } 138 failed = 1; 139 } 140 141 if (!failed) 142 { 143 if (!backtrace_initialize (state, filename, descriptor, error_callback, 144 data, &fileline_fn)) 145 failed = 1; 146 } 147 148 if (failed) 149 { 150 if (!state->threaded) 151 state->fileline_initialization_failed = 1; 152 else 153 backtrace_atomic_store_int (&state->fileline_initialization_failed, 1); 154 return 0; 155 } 156 157 if (!state->threaded) 158 state->fileline_fn = fileline_fn; 159 else 160 { 161 backtrace_atomic_store_pointer (&state->fileline_fn, fileline_fn); 162 163 /* Note that if two threads initialize at once, one of the data 164 sets may be leaked. */ 165 } 166 167 return 1; 168 } 169 170 /* Given a PC, find the file name, line number, and function name. */ 171 172 int 173 backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc, 174 backtrace_full_callback callback, 175 backtrace_error_callback error_callback, void *data) 176 { 177 if (!fileline_initialize (state, error_callback, data)) 178 return 0; 179 180 if (state->fileline_initialization_failed) 181 return 0; 182 183 return state->fileline_fn (state, pc, callback, error_callback, data); 184 } 185 186 /* Given a PC, find the symbol for it, and its value. */ 187 188 int 189 backtrace_syminfo (struct backtrace_state *state, uintptr_t pc, 190 backtrace_syminfo_callback callback, 191 backtrace_error_callback error_callback, void *data) 192 { 193 if (!fileline_initialize (state, error_callback, data)) 194 return 0; 195 196 if (state->fileline_initialization_failed) 197 return 0; 198 199 state->syminfo_fn (state, pc, callback, error_callback, data); 200 return 1; 201 } 202