1 /* Get information from auxiliary vector at the given index.
2 Copyright (C) 2007, 2015 Red Hat, Inc.
3 This file is part of elfutils.
4
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
7
8 * the GNU Lesser General Public License as published by the Free
9 Software Foundation; either version 3 of the License, or (at
10 your option) any later version
11
12 or
13
14 * the GNU General Public License as published by the Free
15 Software Foundation; either version 2 of the License, or (at
16 your option) any later version
17
18 or both in parallel, as here.
19
20 elfutils is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
24
25 You should have received copies of the GNU General Public License and
26 the GNU Lesser General Public License along with this program. If
27 not, see <http://www.gnu.org/licenses/>. */
28
29 #ifdef HAVE_CONFIG_H
30 # include <config.h>
31 #endif
32
33 #include <assert.h>
34 #include <gelf.h>
35 #include <string.h>
36
37 #include "libelfP.h"
38
39
40 GElf_auxv_t *
gelf_getauxv(Elf_Data * data,int ndx,GElf_auxv_t * dst)41 gelf_getauxv (Elf_Data *data, int ndx, GElf_auxv_t *dst)
42 {
43 Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
44 GElf_auxv_t *result = NULL;
45 Elf *elf;
46
47 if (data_scn == NULL)
48 return NULL;
49
50 if (unlikely (data_scn->d.d_type != ELF_T_AUXV))
51 {
52 __libelf_seterrno (ELF_E_INVALID_HANDLE);
53 return NULL;
54 }
55
56 elf = data_scn->s->elf;
57
58 rwlock_rdlock (elf->lock);
59
60 /* This is the one place where we have to take advantage of the fact
61 that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
62 The interface is broken so that it requires this hack. */
63 if (elf->class == ELFCLASS32)
64 {
65 Elf32_auxv_t *src;
66
67 /* Here it gets a bit more complicated. The format of the vector
68 entries has to be converted. The user better have provided a
69 buffer where we can store the information. While copying the data
70 we convert the format. */
71 if (unlikely ((ndx + 1) * sizeof (Elf32_auxv_t) > data_scn->d.d_size))
72 {
73 __libelf_seterrno (ELF_E_INVALID_INDEX);
74 goto out;
75 }
76
77 src = &((Elf32_auxv_t *) data_scn->d.d_buf)[ndx];
78
79 /* This might look like a simple copy operation but it's
80 not. There are zero- and sign-extensions going on. */
81 dst->a_type = src->a_type;
82 dst->a_un.a_val = src->a_un.a_val;
83 }
84 else
85 {
86 /* If this is a 64 bit object it's easy. */
87 assert (sizeof (GElf_auxv_t) == sizeof (Elf64_auxv_t));
88
89 /* The data is already in the correct form. Just make sure the
90 index is OK. */
91 if (unlikely ((ndx + 1) * sizeof (GElf_auxv_t) > data_scn->d.d_size))
92 {
93 __libelf_seterrno (ELF_E_INVALID_INDEX);
94 goto out;
95 }
96
97 memcpy (dst, data_scn->d.d_buf + ndx * sizeof (GElf_auxv_t),
98 sizeof (GElf_auxv_t));
99 }
100
101 result = dst;
102
103 out:
104 rwlock_unlock (elf->lock);
105
106 return result;
107 }
108