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      1 /* Get RELA relocation information at 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 (at) 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 <gelf.h>
     35 #include <string.h>
     36 
     37 #include "libelfP.h"
     38 
     39 
     40 GElf_Rela *
     41 gelf_getrela (Elf_Data *data, int ndx, GElf_Rela *dst)
     42 {
     43   Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
     44   Elf_Scn *scn;
     45   GElf_Rela *result;
     46 
     47   if (data_scn == NULL)
     48     return NULL;
     49 
     50   if (unlikely (data_scn->d.d_type != ELF_T_RELA))
     51     {
     52       __libelf_seterrno (ELF_E_INVALID_HANDLE);
     53       return NULL;
     54     }
     55 
     56   /* This is the one place where we have to take advantage of the fact
     57      that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
     58      The interface is broken so that it requires this hack.  */
     59   scn = data_scn->s;
     60 
     61   rwlock_rdlock (scn->elf->lock);
     62 
     63   if (scn->elf->class == ELFCLASS32)
     64     {
     65       /* We have to convert the data.  */
     66       if (INVALID_NDX (ndx, Elf32_Rela, &data_scn->d))
     67 	{
     68 	  __libelf_seterrno (ELF_E_INVALID_INDEX);
     69 	  result = NULL;
     70 	}
     71       else
     72 	{
     73 	  Elf32_Rela *src = &((Elf32_Rela *) data_scn->d.d_buf)[ndx];
     74 
     75 	  dst->r_offset = src->r_offset;
     76 	  dst->r_info = GELF_R_INFO (ELF32_R_SYM (src->r_info),
     77 				     ELF32_R_TYPE (src->r_info));
     78 	  dst->r_addend = src->r_addend;
     79 
     80 	  result = dst;
     81 	}
     82     }
     83   else
     84     {
     85       /* Simply copy the data after we made sure we are actually getting
     86 	 correct data.  */
     87       if (INVALID_NDX (ndx, Elf64_Rela, &data_scn->d))
     88 	{
     89 	  __libelf_seterrno (ELF_E_INVALID_INDEX);
     90 	  result = NULL;
     91 	}
     92       else
     93 	result = memcpy (dst, &((Elf64_Rela *) data_scn->d.d_buf)[ndx],
     94 			 sizeof (Elf64_Rela));
     95     }
     96 
     97   rwlock_unlock (scn->elf->lock);
     98 
     99   return result;
    100 }
    101