Line data    Source code

       1             : /* Get information from dynamic table at the given index.
       2             :    Copyright (C) 2000, 2001, 2002, 2005, 2009, 2014, 2015 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             :    Written by Ulrich Drepper <drepper@redhat.com>, 2000.
       5             : 
       6             :    This file is free software; you can redistribute it and/or modify
       7             :    it under the terms of either
       8             : 
       9             :      * the GNU Lesser General Public License as published by the Free
      10             :        Software Foundation; either version 3 of the License, or (at
      11             :        your option) any later version
      12             : 
      13             :    or
      14             : 
      15             :      * the GNU General Public License as published by the Free
      16             :        Software Foundation; either version 2 of the License, or (at
      17             :        your option) any later version
      18             : 
      19             :    or both in parallel, as here.
      20             : 
      21             :    elfutils is distributed in the hope that it will be useful, but
      22             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      23             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      24             :    General Public License for more details.
      25             : 
      26             :    You should have received copies of the GNU General Public License and
      27             :    the GNU Lesser General Public License along with this program.  If
      28             :    not, see <http://www.gnu.org/licenses/>.  */
      29             : 
      30             : #ifdef HAVE_CONFIG_H
      31             : # include <config.h>
      32             : #endif
      33             : 
      34             : #include <assert.h>
      35             : #include <gelf.h>
      36             : #include <string.h>
      37             : 
      38             : #include "libelfP.h"
      39             : 
      40             : 
      41             : GElf_Dyn *
      42        6619 : gelf_getdyn (Elf_Data *data, int ndx, GElf_Dyn *dst)
      43             : {
      44        6619 :   Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
      45        6619 :   GElf_Dyn *result = NULL;
      46             :   Elf *elf;
      47             : 
      48        6619 :   if (data_scn == NULL)
      49             :     return NULL;
      50             : 
      51        6619 :   if (unlikely (data_scn->d.d_type != ELF_T_DYN))
      52             :     {
      53           0 :       __libelf_seterrno (ELF_E_INVALID_HANDLE);
      54           0 :       return NULL;
      55             :     }
      56             : 
      57        6619 :   elf = data_scn->s->elf;
      58             : 
      59             :   rwlock_rdlock (elf->lock);
      60             : 
      61             :   /* This is the one place where we have to take advantage of the fact
      62             :      that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
      63             :      The interface is broken so that it requires this hack.  */
      64        6619 :   if (elf->class == ELFCLASS32)
      65             :     {
      66             :       Elf32_Dyn *src;
      67             : 
      68             :       /* Here it gets a bit more complicated.  The format of the symbol
      69             :          table entries has to be adopted.  The user better has provided
      70             :          a buffer where we can store the information.  While copying the
      71             :          data we are converting the format.  */
      72        1924 :       if (INVALID_NDX (ndx, Elf32_Dyn, &data_scn->d))
      73             :         {
      74           0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      75           0 :           goto out;
      76             :         }
      77             : 
      78        1924 :       src = &((Elf32_Dyn *) data_scn->d.d_buf)[ndx];
      79             : 
      80             :       /* This might look like a simple copy operation but it's
      81             :          not.  There are zero- and sign-extensions going on.  */
      82        1924 :       dst->d_tag = src->d_tag;
      83             :       /* It OK to copy `d_val' since `d_ptr' has the same size.  */
      84        1924 :       dst->d_un.d_val = src->d_un.d_val;
      85             :     }
      86             :   else
      87             :     {
      88             :       /* If this is a 64 bit object it's easy.  */
      89             :       assert (sizeof (GElf_Dyn) == sizeof (Elf64_Dyn));
      90             : 
      91             :       /* The data is already in the correct form.  Just make sure the
      92             :          index is OK.  */
      93        4695 :       if (INVALID_NDX (ndx, GElf_Dyn, &data_scn->d))
      94             :         {
      95           0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      96           0 :           goto out;
      97             :         }
      98             : 
      99        4695 :       *dst = ((GElf_Dyn *) data_scn->d.d_buf)[ndx];
     100             :     }
     101             : 
     102             :   result = dst;
     103             : 
     104             :  out:
     105             :   rwlock_unlock (elf->lock);
     106             : 
     107             :   return result;
     108             : }