1 /* Get information from dynamic table at the given index.
2 Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
3 Written by Ulrich Drepper <drepper@redhat.com>, 2000.
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, version 2.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
17
18 #ifdef HAVE_CONFIG_H
19 # include <config.h>
20 #endif
21
22 #include <assert.h>
23 #include <gelf.h>
24 #include <string.h>
25
26 #include "libelfP.h"
27
28
29 GElf_Dyn *
gelf_getdyn(data,ndx,dst)30 gelf_getdyn (data, ndx, dst)
31 Elf_Data *data;
32 int ndx;
33 GElf_Dyn *dst;
34 {
35 Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
36 GElf_Dyn *result = NULL;
37 Elf *elf;
38
39 if (data_scn == NULL)
40 return NULL;
41
42 if (unlikely (data_scn->d.d_type != ELF_T_DYN))
43 {
44 __libelf_seterrno (ELF_E_INVALID_HANDLE);
45 return NULL;
46 }
47
48 elf = data_scn->s->elf;
49
50 rwlock_rdlock (elf->lock);
51
52 /* This is the one place where we have to take advantage of the fact
53 that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
54 The interface is broken so that it requires this hack. */
55 if (elf->class == ELFCLASS32)
56 {
57 Elf32_Dyn *src;
58
59 /* Here it gets a bit more complicated. The format of the symbol
60 table entries has to be adopted. The user better has provided
61 a buffer where we can store the information. While copying the
62 data we are converting the format. */
63 if (unlikely ((ndx + 1) * sizeof (Elf32_Dyn) > data_scn->d.d_size))
64 {
65 __libelf_seterrno (ELF_E_INVALID_INDEX);
66 goto out;
67 }
68
69 src = &((Elf32_Dyn *) data_scn->d.d_buf)[ndx];
70
71 /* This might look like a simple copy operation but it's
72 not. There are zero- and sign-extensions going on. */
73 dst->d_tag = src->d_tag;
74 /* It OK to copy `d_val' since `d_ptr' has the same size. */
75 dst->d_un.d_val = src->d_un.d_val;
76 }
77 else
78 {
79 /* If this is a 64 bit object it's easy. */
80 assert (sizeof (GElf_Dyn) == sizeof (Elf64_Dyn));
81
82 /* The data is already in the correct form. Just make sure the
83 index is OK. */
84 if (unlikely ((ndx + 1) * sizeof (GElf_Dyn) > data_scn->d.d_size))
85 {
86 __libelf_seterrno (ELF_E_INVALID_INDEX);
87 goto out;
88 }
89
90 *dst = ((GElf_Dyn *) data_scn->d.d_buf)[ndx];
91 }
92
93 result = dst;
94
95 out:
96 rwlock_unlock (elf->lock);
97
98 return result;
99 }
100