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      1 /* Get RELA relocation information at given index.
      2    Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
      3    Written by Ulrich Drepper <drepper (at) redhat.com>, 2000.
      4 
      5    This program is free software; you can redistribute it and/or modify
      6    it under the terms of the GNU General Public License as published by
      7    the Free Software Foundation, version 2.
      8 
      9    This program is distributed in the hope that it will be useful,
     10    but WITHOUT ANY WARRANTY; without even the implied warranty of
     11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     12    GNU General Public License for more details.
     13 
     14    You should have received a copy of the GNU General Public License
     15    along with this program; if not, write to the Free Software Foundation,
     16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
     17 
     18 #ifdef HAVE_CONFIG_H
     19 # include <config.h>
     20 #endif
     21 
     22 #include <gelf.h>
     23 #include <string.h>
     24 
     25 #include "libelfP.h"
     26 
     27 
     28 GElf_Rela *
     29 gelf_getrela (data, ndx, dst)
     30      Elf_Data *data;
     31      int ndx;
     32      GElf_Rela *dst;
     33 {
     34   Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
     35   Elf_Scn *scn;
     36   GElf_Rela *result;
     37 
     38   if (data_scn == NULL)
     39     return NULL;
     40 
     41   if (unlikely (ndx < 0))
     42     {
     43       __libelf_seterrno (ELF_E_INVALID_INDEX);
     44       return NULL;
     45     }
     46 
     47   if (unlikely (data_scn->d.d_type != ELF_T_RELA))
     48     {
     49       __libelf_seterrno (ELF_E_INVALID_HANDLE);
     50       return NULL;
     51     }
     52 
     53   /* This is the one place where we have to take advantage of the fact
     54      that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
     55      The interface is broken so that it requires this hack.  */
     56   scn = data_scn->s;
     57 
     58   rwlock_rdlock (scn->elf->lock);
     59 
     60   if (scn->elf->class == ELFCLASS32)
     61     {
     62       /* We have to convert the data.  */
     63       if (unlikely ((ndx + 1) * sizeof (Elf32_Rela) > data_scn->d.d_size))
     64 	{
     65 	  __libelf_seterrno (ELF_E_INVALID_INDEX);
     66 	  result = NULL;
     67 	}
     68       else
     69 	{
     70 	  Elf32_Rela *src = &((Elf32_Rela *) data_scn->d.d_buf)[ndx];
     71 
     72 	  dst->r_offset = src->r_offset;
     73 	  dst->r_info = GELF_R_INFO (ELF32_R_SYM (src->r_info),
     74 				     ELF32_R_TYPE (src->r_info));
     75 	  dst->r_addend = src->r_addend;
     76 
     77 	  result = dst;
     78 	}
     79     }
     80   else
     81     {
     82       /* Simply copy the data after we made sure we are actually getting
     83 	 correct data.  */
     84       if (unlikely ((ndx + 1) * sizeof (Elf64_Rela) > data_scn->d.d_size))
     85 	{
     86 	  __libelf_seterrno (ELF_E_INVALID_INDEX);
     87 	  result = NULL;
     88 	}
     89       else
     90 	result = memcpy (dst, &((Elf64_Rela *) data_scn->d.d_buf)[ndx],
     91 			 sizeof (Elf64_Rela));
     92     }
     93 
     94   rwlock_unlock (scn->elf->lock);
     95 
     96   return result;
     97 }
     98