libbacktrace/fileline.c

   1 /* fileline.c -- Get file and line number information in a backtrace.
   2    Copyright (C) 2012-2017 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
  41 #include "backtrace.h"
  42 #include "internal.h"
  43
  44 #ifndef HAVE_GETEXECNAME
  45 #define getexecname() NULL
  46 #endif
  47
  48 /* Initialize the fileline information from the executable.  Returns 1
  49    on success, 0 on failure.  */
  50
  51 static int
  52 fileline_initialize (struct backtrace_state *state,
  53                      backtrace_error_callback error_callback, void *data)
  54 {
  55   int failed;
  56   fileline fileline_fn;
  57   int pass;
  58   int called_error_callback;
  59   int descriptor;
  60
  61   if (!state->threaded)
  62     failed = state->fileline_initialization_failed;
  63   else
  64     failed = backtrace_atomic_load_int (&state->fileline_initialization_failed);
  65
  66   if (failed)
  67     {
  68       error_callback (data, "failed to read executable information", -1);
  69       return 0;
  70     }
  71
  72   if (!state->threaded)
  73     fileline_fn = state->fileline_fn;
  74   else
  75     fileline_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
  76   if (fileline_fn != NULL)
  77     return 1;
  78
  79   /* We have not initialized the information.  Do it now.  */
  80
  81   descriptor = -1;
  82   called_error_callback = 0;
  83   for (pass = 0; pass < 4; ++pass)
  84     {
  85       const char *filename;
  86       int does_not_exist;
  87
  88       switch (pass)
  89         {
  90         case 0:
  91           filename = state->filename;
  92           break;
  93         case 1:
  94           filename = getexecname ();
  95           break;
  96         case 2:
  97           filename = "/proc/self/exe";
  98           break;
  99         case 3:
 100           filename = "/proc/curproc/file";
 101           break;
 102         default:
 103           abort ();
 104         }
 105
 106       if (filename == NULL)
 107         continue;
 108
 109       descriptor = backtrace_open (filename, error_callback, data,
 110                                    &does_not_exist);
 111       if (descriptor < 0 && !does_not_exist)
 112         {
 113           called_error_callback = 1;
 114           break;
 115         }
 116       if (descriptor >= 0)
 117         break;
 118     }
 119
 120   if (descriptor < 0)
 121     {
 122       if (!called_error_callback)
 123         {
 124           if (state->filename != NULL)
 125             error_callback (data, state->filename, ENOENT);
 126           else
 127             error_callback (data,
 128                             "libbacktrace could not find executable to open",
 129                             0);
 130         }
 131       failed = 1;
 132     }
 133
 134   if (!failed)
 135     {
 136       if (!backtrace_initialize (state, descriptor, error_callback, data,
 137                                  &fileline_fn))
 138         failed = 1;
 139     }
 140
 141   if (failed)
 142     {
 143       if (!state->threaded)
 144         state->fileline_initialization_failed = 1;
 145       else
 146         backtrace_atomic_store_int (&state->fileline_initialization_failed, 1);
 147       return 0;
 148     }
 149
 150   if (!state->threaded)
 151     state->fileline_fn = fileline_fn;
 152   else
 153     {
 154       backtrace_atomic_store_pointer (&state->fileline_fn, fileline_fn);
 155
 156       /* Note that if two threads initialize at once, one of the data
 157          sets may be leaked.  */
 158     }
 159
 160   return 1;
 161 }
 162
 163 /* Given a PC, find the file name, line number, and function name.  */
 164
 165 int
 166 backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
 167                   backtrace_full_callback callback,
 168                   backtrace_error_callback error_callback, void *data)
 169 {
 170   if (!fileline_initialize (state, error_callback, data))
 171     return 0;
 172
 173   if (state->fileline_initialization_failed)
 174     return 0;
 175
 176   return state->fileline_fn (state, pc, callback, error_callback, data);
 177 }
 178
 179 /* Given a PC, find the symbol for it, and its value.  */
 180
 181 int
 182 backtrace_syminfo (struct backtrace_state *state, uintptr_t pc,
 183                    backtrace_syminfo_callback callback,
 184                    backtrace_error_callback error_callback, void *data)
 185 {
 186   if (!fileline_initialize (state, error_callback, data))
 187     return 0;
 188
 189   if (state->fileline_initialization_failed)
 190     return 0;
 191
 192   state->syminfo_fn (state, pc, callback, error_callback, data);
 193   return 1;
 194 }