1 /* Return section index of section header string table.
2 Copyright (C) 2002, 2005 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4 Written by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <errno.h>
57 #include <gelf.h>
58 #include <stddef.h>
59 #include <unistd.h>
60
61 #include <system.h>
62 #include "libelfP.h"
63 #include "common.h"
64
65
66 int
elf_getshstrndx(elf,dst)67 elf_getshstrndx (elf, dst)
68 Elf *elf;
69 size_t *dst;
70 {
71 int result = 0;
72
73 if (elf == NULL)
74 return -1;
75
76 if (unlikely (elf->kind != ELF_K_ELF))
77 {
78 __libelf_seterrno (ELF_E_INVALID_HANDLE);
79 return -1;
80 }
81
82 rwlock_rdlock (elf->lock);
83
84 /* We rely here on the fact that the `elf' element is a common prefix
85 of `elf32' and `elf64'. */
86 assert (offsetof (struct Elf, state.elf.ehdr)
87 == offsetof (struct Elf, state.elf32.ehdr));
88 assert (sizeof (elf->state.elf.ehdr)
89 == sizeof (elf->state.elf32.ehdr));
90 assert (offsetof (struct Elf, state.elf.ehdr)
91 == offsetof (struct Elf, state.elf64.ehdr));
92 assert (sizeof (elf->state.elf.ehdr)
93 == sizeof (elf->state.elf64.ehdr));
94
95 if (unlikely (elf->state.elf.ehdr == NULL))
96 {
97 __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
98 result = -1;
99 }
100 else
101 {
102 Elf32_Word num;
103
104 num = (elf->class == ELFCLASS32
105 ? elf->state.elf32.ehdr->e_shstrndx
106 : elf->state.elf64.ehdr->e_shstrndx);
107
108 /* Determine whether the index is too big to fit in the ELF
109 header. */
110 if (unlikely (num == SHN_XINDEX))
111 {
112 /* Yes. Search the zeroth section header. */
113 if (elf->class == ELFCLASS32)
114 {
115 size_t offset;
116
117 if (elf->state.elf32.scns.data[0].shdr.e32 != NULL)
118 {
119 num = elf->state.elf32.scns.data[0].shdr.e32->sh_link;
120 goto success;
121 }
122
123 offset = elf->state.elf32.ehdr->e_shoff;
124
125 if (elf->map_address != NULL
126 && elf->state.elf32.ehdr->e_ident[EI_DATA] == MY_ELFDATA
127 && (ALLOW_UNALIGNED
128 || (((size_t) ((char *) elf->map_address + offset))
129 & (__alignof__ (Elf32_Shdr) - 1)) == 0))
130 /* We can directly access the memory. */
131 num = ((Elf32_Shdr *) (elf->map_address + offset))->sh_link;
132 else
133 {
134 /* We avoid reading in all the section headers. Just read
135 the first one. */
136 Elf32_Shdr shdr_mem;
137
138 if (unlikely (pread_retry (elf->fildes, &shdr_mem,
139 sizeof (Elf32_Shdr), offset)
140 != sizeof (Elf32_Shdr)))
141 {
142 /* We must be able to read this ELF section header. */
143 __libelf_seterrno (ELF_E_INVALID_FILE);
144 result = -1;
145 goto out;
146 }
147
148 if (elf->state.elf32.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
149 CONVERT (shdr_mem.sh_link);
150 num = shdr_mem.sh_link;
151 }
152 }
153 else
154 {
155 if (elf->state.elf64.scns.data[0].shdr.e64 != NULL)
156 {
157 num = elf->state.elf64.scns.data[0].shdr.e64->sh_link;
158 goto success;
159 }
160
161 size_t offset = elf->state.elf64.ehdr->e_shoff;
162
163 if (elf->map_address != NULL
164 && elf->state.elf64.ehdr->e_ident[EI_DATA] == MY_ELFDATA
165 && (ALLOW_UNALIGNED
166 || (((size_t) ((char *) elf->map_address + offset))
167 & (__alignof__ (Elf64_Shdr) - 1)) == 0))
168 /* We can directly access the memory. */
169 num = ((Elf64_Shdr *) (elf->map_address + offset))->sh_link;
170 else
171 {
172 /* We avoid reading in all the section headers. Just read
173 the first one. */
174 Elf64_Shdr shdr_mem;
175
176 if (unlikely (pread_retry (elf->fildes, &shdr_mem,
177 sizeof (Elf64_Shdr), offset)
178 != sizeof (Elf64_Shdr)))
179 {
180 /* We must be able to read this ELF section header. */
181 __libelf_seterrno (ELF_E_INVALID_FILE);
182 result = -1;
183 goto out;
184 }
185
186 if (elf->state.elf64.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
187 CONVERT (shdr_mem.sh_link);
188 num = shdr_mem.sh_link;
189 }
190 }
191 }
192
193 /* Store the result. */
194 success:
195 *dst = num;
196 }
197
198 out:
199 rwlock_unlock (elf->lock);
200
201 return result;
202 }
203 INTDEF(elf_getshstrndx)
204