debug/backtracesymsfd.c

   1 /* Write formatted list with names for addresses in backtrace to a file.
   2    Copyright (C) 1998-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <execinfo.h>
  20 #include <string.h>
  21 #include <sys/uio.h>
  22
  23 #include <_itoa.h>
  24 #include <ldsodefs.h>
  25
  26 #if __ELF_NATIVE_CLASS == 32
  27 # define WORD_WIDTH 8
  28 #else
  29 /* We assume 64bits.  */
  30 # define WORD_WIDTH 16
  31 #endif
  32
  33
  34 void
  35 __backtrace_symbols_fd (void *const *array, int size, int fd)
  36 {
  37   struct iovec iov[9];
  38   int cnt;
  39
  40   for (cnt = 0; cnt < size; ++cnt)
  41     {
  42       char buf[WORD_WIDTH];
  43       char buf2[WORD_WIDTH];
  44       Dl_info info;
  45       struct link_map *map;
  46       size_t last = 0;
  47
  48       if (_dl_addr (array[cnt], &info, &map, NULL)
  49           && info.dli_fname != NULL && info.dli_fname[0] != '\0')
  50         {
  51           /* Name of the file.  */
  52           iov[0].iov_base = (void *) info.dli_fname;
  53           iov[0].iov_len = strlen (info.dli_fname);
  54           last = 1;
  55
  56           if (info.dli_sname != NULL || map->l_addr != 0)
  57             {
  58               size_t diff;
  59
  60               iov[last].iov_base = (void *) "(";
  61               iov[last].iov_len = 1;
  62               ++last;
  63
  64               if (info.dli_sname != NULL)
  65                 {
  66                   /* We have a symbol name.  */
  67                   iov[last].iov_base = (void *) info.dli_sname;
  68                   iov[last].iov_len = strlen (info.dli_sname);
  69                   ++last;
  70                 }
  71               else
  72                 /* We have no symbol, so describe it as relative to the file.
  73                    The load bias is more useful to the user than the load
  74                    address.  The use of these addresses is to calculate an
  75                    address in the ELF file, so its prelinked bias is not
  76                    something we want to subtract out.  */
  77                 info.dli_saddr = (void *) map->l_addr;
  78
  79               if (array[cnt] >= (void *) info.dli_saddr)
  80                 {
  81                   iov[last].iov_base = (void *) "+0x";
  82                   diff = array[cnt] - info.dli_saddr;
  83                 }
  84               else
  85                 {
  86                   iov[last].iov_base = (void *) "-0x";
  87                   diff = info.dli_saddr - array[cnt];
  88                 }
  89               iov[last].iov_len = 3;
  90               ++last;
  91
  92               iov[last].iov_base = _itoa_word ((unsigned long int) diff,
  93                                                &buf2[WORD_WIDTH], 16, 0);
  94               iov[last].iov_len = (&buf2[WORD_WIDTH]
  95                                    - (char *) iov[last].iov_base);
  96               ++last;
  97
  98               iov[last].iov_base = (void *) ")";
  99               iov[last].iov_len = 1;
 100               ++last;
 101             }
 102         }
 103
 104       iov[last].iov_base = (void *) "[0x";
 105       iov[last].iov_len = 3;
 106       ++last;
 107
 108       iov[last].iov_base = _itoa_word ((unsigned long int) array[cnt],
 109                                        &buf[WORD_WIDTH], 16, 0);
 110       iov[last].iov_len = &buf[WORD_WIDTH] - (char *) iov[last].iov_base;
 111       ++last;
 112
 113       iov[last].iov_base = (void *) "]\n";
 114       iov[last].iov_len = 2;
 115       ++last;
 116
 117       __writev (fd, iov, last);
 118     }
 119 }
 120 weak_alias (__backtrace_symbols_fd, backtrace_symbols_fd)
 121 libc_hidden_def (__backtrace_symbols_fd)