1 /* Get information from dynamic table at the 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@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 <assert.h>
35 #include <gelf.h>
36 #include <string.h>
37
38 #include "libelfP.h"
39
40
41 GElf_Dyn *
gelf_getdyn(Elf_Data * data,int ndx,GElf_Dyn * dst)42 gelf_getdyn (Elf_Data *data, int ndx, GElf_Dyn *dst)
43 {
44 Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
45 GElf_Dyn *result = NULL;
46 Elf *elf;
47
48 if (data_scn == NULL)
49 return NULL;
50
51 if (unlikely (data_scn->d.d_type != ELF_T_DYN))
52 {
53 __libelf_seterrno (ELF_E_INVALID_HANDLE);
54 return NULL;
55 }
56
57 elf = data_scn->s->elf;
58
59 rwlock_rdlock (elf->lock);
60
61 /* This is the one place where we have to take advantage of the fact
62 that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
63 The interface is broken so that it requires this hack. */
64 if (elf->class == ELFCLASS32)
65 {
66 Elf32_Dyn *src;
67
68 /* Here it gets a bit more complicated. The format of the symbol
69 table entries has to be adopted. The user better has provided
70 a buffer where we can store the information. While copying the
71 data we are converting the format. */
72 if (INVALID_NDX (ndx, Elf32_Dyn, &data_scn->d))
73 {
74 __libelf_seterrno (ELF_E_INVALID_INDEX);
75 goto out;
76 }
77
78 src = &((Elf32_Dyn *) data_scn->d.d_buf)[ndx];
79
80 /* This might look like a simple copy operation but it's
81 not. There are zero- and sign-extensions going on. */
82 dst->d_tag = src->d_tag;
83 /* It OK to copy `d_val' since `d_ptr' has the same size. */
84 dst->d_un.d_val = src->d_un.d_val;
85 }
86 else
87 {
88 /* If this is a 64 bit object it's easy. */
89 assert (sizeof (GElf_Dyn) == sizeof (Elf64_Dyn));
90
91 /* The data is already in the correct form. Just make sure the
92 index is OK. */
93 if (INVALID_NDX (ndx, GElf_Dyn, &data_scn->d))
94 {
95 __libelf_seterrno (ELF_E_INVALID_INDEX);
96 goto out;
97 }
98
99 *dst = ((GElf_Dyn *) data_scn->d.d_buf)[ndx];
100 }
101
102 result = dst;
103
104 out:
105 rwlock_unlock (elf->lock);
106
107 return result;
108 }
109