1/* Get section at specific index.
2   Copyright (C) 2005, 2008, 2015 Red Hat, Inc.
3   This file is part of elfutils.
4   Contributed by Ulrich Drepper <drepper@redhat.com>, 2005.
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 <stddef.h>
36#include <stdlib.h>
37
38#include "libelfP.h"
39
40#ifndef LIBELFBITS
41# define LIBELFBITS 32
42#endif
43
44
45Elf_Scn *
46elfw2(LIBELFBITS,offscn) (Elf *elf, ElfW2(LIBELFBITS,Off) offset)
47{
48  if (elf == NULL)
49    return NULL;
50
51  if (unlikely (elf->kind != ELF_K_ELF))
52    {
53      __libelf_seterrno (ELF_E_INVALID_HANDLE);
54      return NULL;
55    }
56
57  Elf_ScnList *runp = &elf->state.ELFW(elf,LIBELFBITS).scns;
58
59  /* If we have not looked at section headers before,
60     we might need to read them in first.  */
61  if (runp->cnt > 0
62      && unlikely (runp->data[0].shdr.ELFW(e,LIBELFBITS) == NULL)
63      && unlikely (elfw2(LIBELFBITS,getshdr) (&runp->data[0]) == NULL))
64    return NULL;
65
66  rwlock_rdlock (elf->lock);
67
68  Elf_Scn *result = NULL;
69
70  /* Find the section in the list.  */
71  while (1)
72    {
73      for (unsigned int i = 0; i < runp->cnt; ++i)
74	if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_offset == offset)
75	  {
76	    result = &runp->data[i];
77
78	    /* If this section is empty, the following one has the same
79	       sh_offset.  We presume the caller is looking for a nonempty
80	       section, so keep looking if this one is empty.  */
81	    if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_size != 0
82		&& runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_type != SHT_NOBITS)
83	      goto out;
84	  }
85
86      runp = runp->next;
87      if (runp == NULL)
88	{
89	  __libelf_seterrno (ELF_E_INVALID_OFFSET);
90	  break;
91	}
92    }
93
94 out:
95  rwlock_unlock (elf->lock);
96
97  return result;
98}
99INTDEF(elfw2(LIBELFBITS,offscn))
100