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)