sysdeps/generic/elf/backtracesyms.c

   1 /* Return list with names for address in backtrace.
   2    Copyright (C) 1998,1999,2000,2001,2003,2009 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library 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 GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <assert.h>
  22 #include <execinfo.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 #include <ldsodefs.h>
  28
  29 #if __ELF_NATIVE_CLASS == 32
  30 # define WORD_WIDTH 8
  31 #else
  32 /* We assyme 64bits.  */
  33 # define WORD_WIDTH 16
  34 #endif
  35
  36
  37 char **
  38 __backtrace_symbols (array, size)
  39      void *const *array;
  40      int size;
  41 {
  42   Dl_info info[size];
  43   int status[size];
  44   int cnt;
  45   size_t total = 0;
  46   char **result;
  47
  48   /* Fill in the information we can get from `dladdr'.  */
  49   for (cnt = 0; cnt < size; ++cnt)
  50     {
  51       struct link_map *map;
  52       status[cnt] = _dl_addr (array[cnt], &info[cnt], &map, NULL);
  53       if (status[cnt] && info[cnt].dli_fname && info[cnt].dli_fname[0] != '\0')
  54         {
  55           /* We have some info, compute the length of the string which will be
  56              "<file-name>(<sym-name>+offset) [address].  */
  57           total += (strlen (info[cnt].dli_fname ?: "")
  58                     + strlen (info[cnt].dli_sname ?: "")
  59                     + 3 + WORD_WIDTH + 3 + WORD_WIDTH + 5);
  60
  61           /* The load bias is more useful to the user than the load
  62              address.  The use of these addresses is to calculate an
  63              address in the ELF file, so its prelinked bias is not
  64              something we want to subtract out.  */
  65           info[cnt].dli_fbase = (void *) map->l_addr;
  66         }
  67       else
  68         total += 5 + WORD_WIDTH;
  69     }
  70
  71   /* Allocate memory for the result.  */
  72   result = (char **) malloc (size * sizeof (char *) + total);
  73   if (result != NULL)
  74     {
  75       char *last = (char *) (result + size);
  76
  77       for (cnt = 0; cnt < size; ++cnt)
  78         {
  79           result[cnt] = last;
  80
  81           if (status[cnt]
  82               && info[cnt].dli_fname != NULL && info[cnt].dli_fname[0] != '\0')
  83             {
  84               if (info[cnt].dli_sname == NULL)
  85                 /* We found no symbol name to use, so describe it as
  86                    relative to the file.  */
  87                 info[cnt].dli_saddr = info[cnt].dli_fbase;
  88
  89               if (info[cnt].dli_sname == NULL && info[cnt].dli_saddr == 0)
  90                 last += 1 + sprintf (last, "%s(%s) [%p]",
  91                                      info[cnt].dli_fname ?: "",
  92                                      info[cnt].dli_sname ?: "",
  93                                      array[cnt]);
  94               else
  95                 {
  96                   char sign;
  97                   ptrdiff_t offset;
  98                   if (array[cnt] >= (void *) info[cnt].dli_saddr)
  99                     {
 100                       sign = '+';
 101                       offset = array[cnt] - info[cnt].dli_saddr;
 102                     }
 103                   else
 104                     {
 105                       sign = '-';
 106                       offset = info[cnt].dli_saddr - array[cnt];
 107                     }
 108
 109                   last += 1 + sprintf (last, "%s(%s%c%#tx) [%p]",
 110                                        info[cnt].dli_fname ?: "",
 111                                        info[cnt].dli_sname ?: "",
 112                                        sign, offset, array[cnt]);
 113                 }
 114             }
 115           else
 116             last += 1 + sprintf (last, "[%p]", array[cnt]);
 117         }
 118       assert (last <= (char *) result + size * sizeof (char *) + total);
 119     }
 120
 121   return result;
 122 }
 123 weak_alias (__backtrace_symbols, backtrace_symbols)