libbacktrace/fileline.c

   1 /* fileline.c -- Get file and line number information in a backtrace.
   2    Copyright (C) 2012-2021 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 #if defined (HAVE_KERN_PROC_ARGS) || defined (HAVE_KERN_PROC)
  43 #include <sys/sysctl.h>
  44 #endif
  45
  46 #ifdef HAVE_MACH_O_DYLD_H
  47 #include <mach-o/dyld.h>
  48 #endif
  49
  50 #include "backtrace.h"
  51 #include "internal.h"
  52
  53 #ifndef HAVE_GETEXECNAME
  54 #define getexecname() NULL
  55 #endif
  56
  57 #if !defined (HAVE_KERN_PROC_ARGS) && !defined (HAVE_KERN_PROC)
  58
  59 #define sysctl_exec_name1(state, error_callback, data) NULL
  60 #define sysctl_exec_name2(state, error_callback, data) NULL
  61
  62 #else /* defined (HAVE_KERN_PROC_ARGS) || |defined (HAVE_KERN_PROC) */
  63
  64 static char *
  65 sysctl_exec_name (struct backtrace_state *state,
  66                   int mib0, int mib1, int mib2, int mib3,
  67                   backtrace_error_callback error_callback, void *data)
  68 {
  69   int mib[4];
  70   size_t len;
  71   char *name;
  72   size_t rlen;
  73
  74   mib[0] = mib0;
  75   mib[1] = mib1;
  76   mib[2] = mib2;
  77   mib[3] = mib3;
  78
  79   if (sysctl (mib, 4, NULL, &len, NULL, 0) < 0)
  80     return NULL;
  81   name = (char *) backtrace_alloc (state, len, error_callback, data);
  82   if (name == NULL)
  83     return NULL;
  84   rlen = len;
  85   if (sysctl (mib, 4, name, &rlen, NULL, 0) < 0)
  86     {
  87       backtrace_free (state, name, len, error_callback, data);
  88       return NULL;
  89     }
  90   return name;
  91 }
  92
  93 #ifdef HAVE_KERN_PROC_ARGS
  94
  95 static char *
  96 sysctl_exec_name1 (struct backtrace_state *state,
  97                    backtrace_error_callback error_callback, void *data)
  98 {
  99   /* This variant is used on NetBSD.  */
 100   return sysctl_exec_name (state, CTL_KERN, KERN_PROC_ARGS, -1,
 101                            KERN_PROC_PATHNAME, error_callback, data);
 102 }
 103
 104 #else
 105
 106 #define sysctl_exec_name1(state, error_callback, data) NULL
 107
 108 #endif
 109
 110 #ifdef HAVE_KERN_PROC
 111
 112 static char *
 113 sysctl_exec_name2 (struct backtrace_state *state,
 114                    backtrace_error_callback error_callback, void *data)
 115 {
 116   /* This variant is used on FreeBSD.  */
 117   return sysctl_exec_name (state, CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1,
 118                            error_callback, data);
 119 }
 120
 121 #else
 122
 123 #define sysctl_exec_name2(state, error_callback, data) NULL
 124
 125 #endif
 126
 127 #endif /* defined (HAVE_KERN_PROC_ARGS) || |defined (HAVE_KERN_PROC) */
 128
 129 #ifdef HAVE_MACH_O_DYLD_H
 130
 131 static char *
 132 macho_get_executable_path (struct backtrace_state *state,
 133                            backtrace_error_callback error_callback, void *data)
 134 {
 135   uint32_t len;
 136   char *name;
 137
 138   len = 0;
 139   if (_NSGetExecutablePath (NULL, &len) == 0)
 140     return NULL;
 141   name = (char *) backtrace_alloc (state, len, error_callback, data);
 142   if (name == NULL)
 143     return NULL;
 144   if (_NSGetExecutablePath (name, &len) != 0)
 145     {
 146       backtrace_free (state, name, len, error_callback, data);
 147       return NULL;
 148     }
 149   return name;
 150 }
 151
 152 #else /* !defined (HAVE_MACH_O_DYLD_H) */
 153
 154 #define macho_get_executable_path(state, error_callback, data) NULL
 155
 156 #endif /* !defined (HAVE_MACH_O_DYLD_H) */
 157
 158 /* Initialize the fileline information from the executable.  Returns 1
 159    on success, 0 on failure.  */
 160
 161 static int
 162 fileline_initialize (struct backtrace_state *state,
 163                      backtrace_error_callback error_callback, void *data)
 164 {
 165   int failed;
 166   fileline fileline_fn;
 167   int pass;
 168   int called_error_callback;
 169   int descriptor;
 170   const char *filename;
 171   char buf[64];
 172
 173   if (!state->threaded)
 174     failed = state->fileline_initialization_failed;
 175   else
 176     failed = backtrace_atomic_load_int (&state->fileline_initialization_failed);
 177
 178   if (failed)
 179     {
 180       error_callback (data, "failed to read executable information", -1);
 181       return 0;
 182     }
 183
 184   if (!state->threaded)
 185     fileline_fn = state->fileline_fn;
 186   else
 187     fileline_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
 188   if (fileline_fn != NULL)
 189     return 1;
 190
 191   /* We have not initialized the information.  Do it now.  */
 192
 193   descriptor = -1;
 194   called_error_callback = 0;
 195   for (pass = 0; pass < 8; ++pass)
 196     {
 197       int does_not_exist;
 198
 199       switch (pass)
 200         {
 201         case 0:
 202           filename = state->filename;
 203           break;
 204         case 1:
 205           filename = getexecname ();
 206           break;
 207         case 2:
 208           filename = "/proc/self/exe";
 209           break;
 210         case 3:
 211           filename = "/proc/curproc/file";
 212           break;
 213         case 4:
 214           snprintf (buf, sizeof (buf), "/proc/%ld/object/a.out",
 215                     (long) getpid ());
 216           filename = buf;
 217           break;
 218         case 5:
 219           filename = sysctl_exec_name1 (state, error_callback, data);
 220           break;
 221         case 6:
 222           filename = sysctl_exec_name2 (state, error_callback, data);
 223           break;
 224         case 7:
 225           filename = macho_get_executable_path (state, error_callback, data);
 226           break;
 227         default:
 228           abort ();
 229         }
 230
 231       if (filename == NULL)
 232         continue;
 233
 234       descriptor = backtrace_open (filename, error_callback, data,
 235                                    &does_not_exist);
 236       if (descriptor < 0 && !does_not_exist)
 237         {
 238           called_error_callback = 1;
 239           break;
 240         }
 241       if (descriptor >= 0)
 242         break;
 243     }
 244
 245   if (descriptor < 0)
 246     {
 247       if (!called_error_callback)
 248         {
 249           if (state->filename != NULL)
 250             error_callback (data, state->filename, ENOENT);
 251           else
 252             error_callback (data,
 253                             "libbacktrace could not find executable to open",
 254                             0);
 255         }
 256       failed = 1;
 257     }
 258
 259   if (!failed)
 260     {
 261       if (!backtrace_initialize (state, filename, descriptor, error_callback,
 262                                  data, &fileline_fn))
 263         failed = 1;
 264     }
 265
 266   if (failed)
 267     {
 268       if (!state->threaded)
 269         state->fileline_initialization_failed = 1;
 270       else
 271         backtrace_atomic_store_int (&state->fileline_initialization_failed, 1);
 272       return 0;
 273     }
 274
 275   if (!state->threaded)
 276     state->fileline_fn = fileline_fn;
 277   else
 278     {
 279       backtrace_atomic_store_pointer (&state->fileline_fn, fileline_fn);
 280
 281       /* Note that if two threads initialize at once, one of the data
 282          sets may be leaked.  */
 283     }
 284
 285   return 1;
 286 }
 287
 288 /* Given a PC, find the file name, line number, and function name.  */
 289
 290 int
 291 backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
 292                   backtrace_full_callback callback,
 293                   backtrace_error_callback error_callback, void *data)
 294 {
 295   if (!fileline_initialize (state, error_callback, data))
 296     return 0;
 297
 298   if (state->fileline_initialization_failed)
 299     return 0;
 300
 301   return state->fileline_fn (state, pc, callback, error_callback, data);
 302 }
 303
 304 /* Given a PC, find the symbol for it, and its value.  */
 305
 306 int
 307 backtrace_syminfo (struct backtrace_state *state, uintptr_t pc,
 308                    backtrace_syminfo_callback callback,
 309                    backtrace_error_callback error_callback, void *data)
 310 {
 311   if (!fileline_initialize (state, error_callback, data))
 312     return 0;
 313
 314   if (state->fileline_initialization_failed)
 315     return 0;
 316
 317   state->syminfo_fn (state, pc, callback, error_callback, data);
 318   return 1;
 319 }
 320
 321 /* A backtrace_syminfo_callback that can call into a
 322    backtrace_full_callback, used when we have a symbol table but no
 323    debug info.  */
 324
 325 void
 326 backtrace_syminfo_to_full_callback (void *data, uintptr_t pc,
 327                                     const char *symname,
 328                                     uintptr_t symval ATTRIBUTE_UNUSED,
 329                                     uintptr_t symsize ATTRIBUTE_UNUSED)
 330 {
 331   struct backtrace_call_full *bdata = (struct backtrace_call_full *) data;
 332
 333   bdata->ret = bdata->full_callback (bdata->full_data, pc, NULL, 0, symname);
 334 }
 335
 336 /* An error callback that corresponds to
 337    backtrace_syminfo_to_full_callback.  */
 338
 339 void
 340 backtrace_syminfo_to_full_error_callback (void *data, const char *msg,
 341                                           int errnum)
 342 {
 343   struct backtrace_call_full *bdata = (struct backtrace_call_full *) data;
 344
 345   bdata->full_error_callback (bdata->full_data, msg, errnum);
 346 }