debug/backtracesymsfd.c

   1 /* Write formatted list with names for addresses in backtrace to a file.
   2    Copyright (C) 1998-2019 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, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <execinfo.h>
  21 #include <string.h>
  22 #include <sys/uio.h>
  23
  24 #include <_itoa.h>
  25 #include <ldsodefs.h>
  26
  27 #if __ELF_NATIVE_CLASS == 32
  28 # define WORD_WIDTH 8
  29 #else
  30 /* We assume 64bits.  */
  31 # define WORD_WIDTH 16
  32 #endif
  33
  34
  35 void
  36 __backtrace_symbols_fd (void *const *array, int size, int fd)
  37 {
  38   struct iovec iov[9];
  39   int cnt;
  40
  41   for (cnt = 0; cnt < size; ++cnt)
  42     {
  43       char buf[WORD_WIDTH];
  44       char buf2[WORD_WIDTH];
  45       Dl_info info;
  46       struct link_map *map;
  47       size_t last = 0;
  48
  49       if (_dl_addr (array[cnt], &info, &map, NULL)
  50           && info.dli_fname != NULL && info.dli_fname[0] != '\0')
  51         {
  52           /* Name of the file.  */
  53           iov[0].iov_base = (void *) info.dli_fname;
  54           iov[0].iov_len = strlen (info.dli_fname);
  55           last = 1;
  56
  57           if (info.dli_sname != NULL || map->l_addr != 0)
  58             {
  59               size_t diff;
  60
  61               iov[last].iov_base = (void *) "(";
  62               iov[last].iov_len = 1;
  63               ++last;
  64
  65               if (info.dli_sname != NULL)
  66                 {
  67                   /* We have a symbol name.  */
  68                   iov[last].iov_base = (void *) info.dli_sname;
  69                   iov[last].iov_len = strlen (info.dli_sname);
  70                   ++last;
  71                 }
  72               else
  73                 /* We have no symbol, so describe it as relative to the file.
  74                    The load bias is more useful to the user than the load
  75                    address.  The use of these addresses is to calculate an
  76                    address in the ELF file, so its prelinked bias is not
  77                    something we want to subtract out.  */
  78                 info.dli_saddr = (void *) map->l_addr;
  79
  80               if (array[cnt] >= (void *) info.dli_saddr)
  81                 {
  82                   iov[last].iov_base = (void *) "+0x";
  83                   diff = array[cnt] - info.dli_saddr;
  84                 }
  85               else
  86                 {
  87                   iov[last].iov_base = (void *) "-0x";
  88                   diff = info.dli_saddr - array[cnt];
  89                 }
  90               iov[last].iov_len = 3;
  91               ++last;
  92
  93               iov[last].iov_base = _itoa_word ((unsigned long int) diff,
  94                                                &buf2[WORD_WIDTH], 16, 0);
  95               iov[last].iov_len = (&buf2[WORD_WIDTH]
  96                                    - (char *) iov[last].iov_base);
  97               ++last;
  98
  99               iov[last].iov_base = (void *) ")";
 100               iov[last].iov_len = 1;
 101               ++last;
 102             }
 103         }
 104
 105       iov[last].iov_base = (void *) "[0x";
 106       iov[last].iov_len = 3;
 107       ++last;
 108
 109       iov[last].iov_base = _itoa_word ((unsigned long int) array[cnt],
 110                                        &buf[WORD_WIDTH], 16, 0);
 111       iov[last].iov_len = &buf[WORD_WIDTH] - (char *) iov[last].iov_base;
 112       ++last;
 113
 114       iov[last].iov_base = (void *) "]\n";
 115       iov[last].iov_len = 2;
 116       ++last;
 117
 118       __writev (fd, iov, last);
 119     }
 120 }
 121 weak_alias (__backtrace_symbols_fd, backtrace_symbols_fd)
 122 libc_hidden_def (__backtrace_symbols_fd)