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      1 /* Get section at specific index.
      2    Copyright (C) 2005, 2008 Red Hat, Inc.
      3    This file is part of Red Hat elfutils.
      4    Contributed by Ulrich Drepper <drepper (at) redhat.com>, 2005.
      5 
      6    Red Hat elfutils is free software; you can redistribute it and/or modify
      7    it under the terms of the GNU General Public License as published by the
      8    Free Software Foundation; version 2 of the License.
      9 
     10    Red Hat elfutils is distributed in the hope that it will be useful, but
     11    WITHOUT ANY WARRANTY; without even the implied warranty of
     12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13    General Public License for more details.
     14 
     15    You should have received a copy of the GNU General Public License along
     16    with Red Hat elfutils; if not, write to the Free Software Foundation,
     17    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
     18 
     19    In addition, as a special exception, Red Hat, Inc. gives You the
     20    additional right to link the code of Red Hat elfutils with code licensed
     21    under any Open Source Initiative certified open source license
     22    (http://www.opensource.org/licenses/index.php) which requires the
     23    distribution of source code with any binary distribution and to
     24    distribute linked combinations of the two.  Non-GPL Code permitted under
     25    this exception must only link to the code of Red Hat elfutils through
     26    those well defined interfaces identified in the file named EXCEPTION
     27    found in the source code files (the "Approved Interfaces").  The files
     28    of Non-GPL Code may instantiate templates or use macros or inline
     29    functions from the Approved Interfaces without causing the resulting
     30    work to be covered by the GNU General Public License.  Only Red Hat,
     31    Inc. may make changes or additions to the list of Approved Interfaces.
     32    Red Hat's grant of this exception is conditioned upon your not adding
     33    any new exceptions.  If you wish to add a new Approved Interface or
     34    exception, please contact Red Hat.  You must obey the GNU General Public
     35    License in all respects for all of the Red Hat elfutils code and other
     36    code used in conjunction with Red Hat elfutils except the Non-GPL Code
     37    covered by this exception.  If you modify this file, you may extend this
     38    exception to your version of the file, but you are not obligated to do
     39    so.  If you do not wish to provide this exception without modification,
     40    you must delete this exception statement from your version and license
     41    this file solely under the GPL without exception.
     42 
     43    Red Hat elfutils is an included package of the Open Invention Network.
     44    An included package of the Open Invention Network is a package for which
     45    Open Invention Network licensees cross-license their patents.  No patent
     46    license is granted, either expressly or impliedly, by designation as an
     47    included package.  Should you wish to participate in the Open Invention
     48    Network licensing program, please visit www.openinventionnetwork.com
     49    <http://www.openinventionnetwork.com>.  */
     50 
     51 #ifdef HAVE_CONFIG_H
     52 # include <config.h>
     53 #endif
     54 
     55 #include <assert.h>
     56 #include <stddef.h>
     57 #include <stdlib.h>
     58 
     59 #include "libelfP.h"
     60 
     61 #ifndef LIBELFBITS
     62 # define LIBELFBITS 32
     63 #endif
     64 
     65 
     66 Elf_Scn *
     67 elfw2(LIBELFBITS,offscn) (elf, offset)
     68      Elf *elf;
     69      ElfW2(LIBELFBITS,Off) offset;
     70 {
     71   if (elf == NULL)
     72     return NULL;
     73 
     74   if (unlikely (elf->kind != ELF_K_ELF))
     75     {
     76       __libelf_seterrno (ELF_E_INVALID_HANDLE);
     77       return NULL;
     78     }
     79 
     80   Elf_ScnList *runp = &elf->state.ELFW(elf,LIBELFBITS).scns;
     81 
     82   /* If we have not looked at section headers before,
     83      we might need to read them in first.  */
     84   if (runp->cnt > 0
     85       && unlikely (runp->data[0].shdr.ELFW(e,LIBELFBITS) == NULL)
     86       && unlikely (elfw2(LIBELFBITS,getshdr) (&runp->data[0]) == NULL))
     87     return NULL;
     88 
     89   rwlock_rdlock (elf->lock);
     90 
     91   Elf_Scn *result = NULL;
     92 
     93   /* Find the section in the list.  */
     94   while (1)
     95     {
     96       for (unsigned int i = 0; i < runp->cnt; ++i)
     97 	if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_offset == offset)
     98 	  {
     99 	    result = &runp->data[i];
    100 
    101 	    /* If this section is empty, the following one has the same
    102 	       sh_offset.  We presume the caller is looking for a nonempty
    103 	       section, so keep looking if this one is empty.  */
    104 	    if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_size != 0)
    105 	      goto out;
    106 	  }
    107 
    108       runp = runp->next;
    109       if (runp == NULL)
    110 	{
    111 	  __libelf_seterrno (ELF_E_INVALID_OFFSET);
    112 	  break;
    113 	}
    114     }
    115 
    116  out:
    117   rwlock_unlock (elf->lock);
    118 
    119   return result;
    120 }
    121 INTDEF(elfw2(LIBELFBITS,offscn))
    122