elf/dl-addr.c

   1 /* Locate the shared object symbol nearest a given address.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <dlfcn.h>
  21 #include <stddef.h>
  22 #include <ldsodefs.h>
  23
  24
  25 int
  26 internal_function
  27 _dl_addr (const void *address, Dl_info *info)
  28 {
  29   const ElfW(Addr) addr = (ElfW(Addr)) address;
  30   struct link_map *l, *match;
  31   const ElfW(Sym) *symtab, *matchsym;
  32   const char *strtab;
  33
  34   /* Find the highest-addressed object that ADDRESS is not below.  */
  35   match = NULL;
  36   for (l = _dl_loaded; l; l = l->l_next)
  37     if (addr >= l->l_map_start && addr < l->l_map_end)
  38       {
  39         match = l;
  40         break;
  41       }
  42
  43   if (__builtin_expect (match != NULL, 1))
  44     {
  45       /* We know ADDRESS lies within MATCH if in any shared object.
  46          Make sure it isn't past the end of MATCH's segments.  */
  47       size_t n = match->l_phnum;
  48       if (n > 0)
  49         {
  50           do
  51             --n;
  52           while (match->l_phdr[n].p_type != PT_LOAD);
  53           if (addr >= (match->l_addr +
  54                        match->l_phdr[n].p_vaddr + match->l_phdr[n].p_memsz))
  55             /* Off the end of the highest-addressed shared object.  */
  56             return 0;
  57         }
  58     }
  59   else
  60     return 0;
  61
  62   /* Now we know what object the address lies in.  */
  63   info->dli_fname = match->l_name;
  64   info->dli_fbase = (void *) match->l_addr;
  65
  66   /* If this is the main program the information is incomplete.  */
  67   if (__builtin_expect (info->dli_fbase == NULL, 0))
  68     {
  69       info->dli_fname = _dl_argv[0];
  70       info->dli_fbase = (void *) match->l_map_start;
  71     }
  72
  73   symtab = (const void *) D_PTR (match, l_info[DT_SYMTAB]);
  74   strtab = (const void *) D_PTR (match, l_info[DT_STRTAB]);
  75
  76   /* We assume that the string table follows the symbol table, because
  77      there is no way in ELF to know the size of the dynamic symbol table!!  */
  78   for (matchsym = NULL; (void *) symtab < (void *) strtab; ++symtab)
  79     if (addr >= match->l_addr + symtab->st_value
  80         && (!matchsym
  81             || (matchsym->st_value < symtab->st_value
  82                 && (ELFW(ST_BIND) (symtab->st_info) == STB_GLOBAL
  83                     || ELFW(ST_BIND) (symtab->st_info) == STB_WEAK))))
  84       matchsym = symtab;
  85
  86   if (matchsym)
  87     {
  88       /* We found a symbol close by.  Fill in its name and exact address.  */
  89       info->dli_sname = strtab + matchsym->st_name;
  90       info->dli_saddr = (void *) (match->l_addr + matchsym->st_value);
  91     }
  92   else
  93     {
  94       /* No symbol matches.  We return only the containing object.  */
  95       info->dli_sname = NULL;
  96       info->dli_saddr = NULL;
  97     }
  98
  99   return 1;
 100 }