libelf/gelf_getrel.c

/* Get REL relocation information at given index.
   Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, version 2.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <gelf.h>
#include <string.h>

#include "libelfP.h"


GElf_Rel *
gelf_getrel (data, ndx, dst)
     Elf_Data *data;
     int ndx;
     GElf_Rel *dst;
{
  Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
  Elf_Scn *scn;
  GElf_Rel *result;

  if (data_scn == NULL)
    return NULL;

  if (unlikely (ndx < 0))
    {
      __libelf_seterrno (ELF_E_INVALID_INDEX);
      return NULL;
    }

  if (unlikely (data_scn->d.d_type != ELF_T_REL))
    {
      __libelf_seterrno (ELF_E_INVALID_HANDLE);
      return NULL;
    }

  /* This is the one place where we have to take advantage of the fact
     that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
     The interface is broken so that it requires this hack.  */
  scn = data_scn->s;

  rwlock_rdlock (scn->elf->lock);

  if (scn->elf->class == ELFCLASS32)
    {
      /* We have to convert the data.  */
      if (unlikely ((ndx + 1) * sizeof (Elf32_Rel) > data_scn->d.d_size))
	{
	  __libelf_seterrno (ELF_E_INVALID_INDEX);
	  result = NULL;
	}
      else
	{
	  Elf32_Rel *src = &((Elf32_Rel *) data_scn->d.d_buf)[ndx];

	  dst->r_offset = src->r_offset;
	  dst->r_info = GELF_R_INFO (ELF32_R_SYM (src->r_info),
				     ELF32_R_TYPE (src->r_info));

	  result = dst;
	}
    }
  else
    {
      /* Simply copy the data after we made sure we are actually getting
	 correct data.  */
      if (unlikely ((ndx + 1) * sizeof (Elf64_Rel) > data_scn->d.d_size))
	{
	  __libelf_seterrno (ELF_E_INVALID_INDEX);
	  result = NULL;
	}
      else
	result = memcpy (dst, &((Elf64_Rel *) data_scn->d.d_buf)[ndx],
			 sizeof (Elf64_Rel));
    }

  rwlock_unlock (scn->elf->lock);

  return result;
}