1 /* Return section header.
2 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2005, 2007 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4 Written by Ulrich Drepper <drepper@redhat.com>, 1998.
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 <stdbool.h>
58 #include <unistd.h>
59
60 #include <system.h>
61 #include "libelfP.h"
62 #include "common.h"
63
64 #ifndef LIBELFBITS
65 # define LIBELFBITS 32
66 #endif
67
68
ElfW2(LIBELFBITS,Shdr)69 static ElfW2(LIBELFBITS,Shdr) *
70 load_shdr_wrlock (Elf_Scn *scn)
71 {
72 ElfW2(LIBELFBITS,Shdr) *result;
73
74 /* Read the section header table. */
75 Elf *elf = scn->elf;
76 ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr;
77
78 /* Try again, maybe the data is there now. */
79 result = scn->shdr.ELFW(e,LIBELFBITS);
80 if (result != NULL)
81 goto out;
82
83 size_t shnum;
84 if (__elf_getshnum_rdlock (elf, &shnum) != 0)
85 goto out;
86 size_t size = shnum * sizeof (ElfW2(LIBELFBITS,Shdr));
87
88 /* Allocate memory for the section headers. We know the number
89 of entries from the ELF header. */
90 ElfW2(LIBELFBITS,Shdr) *shdr = elf->state.ELFW(elf,LIBELFBITS).shdr =
91 (ElfW2(LIBELFBITS,Shdr) *) malloc (size);
92 if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL)
93 {
94 __libelf_seterrno (ELF_E_NOMEM);
95 goto out;
96 }
97 elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 1;
98
99 if (elf->map_address != NULL)
100 {
101 ElfW2(LIBELFBITS,Shdr) *notcvt;
102
103 /* All the data is already mapped. If we could use it
104 directly this would already have happened. */
105 void *file_shdr = ((char *) elf->map_address
106 + elf->start_offset + ehdr->e_shoff);
107
108 assert (ehdr->e_ident[EI_DATA] != MY_ELFDATA
109 || (! ALLOW_UNALIGNED
110 && ((uintptr_t) file_shdr
111 & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0));
112
113 /* Now copy the data and at the same time convert the byte order. */
114 if (ehdr->e_ident[EI_DATA] == MY_ELFDATA)
115 {
116 assert (! ALLOW_UNALIGNED);
117 memcpy (shdr, file_shdr, size);
118 }
119 else
120 {
121 if (ALLOW_UNALIGNED
122 || ((uintptr_t) file_shdr
123 & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) == 0)
124 notcvt = (ElfW2(LIBELFBITS,Shdr) *)
125 ((char *) elf->map_address
126 + elf->start_offset + ehdr->e_shoff);
127 else
128 {
129 notcvt = (ElfW2(LIBELFBITS,Shdr) *) alloca (size);
130 memcpy (notcvt, ((char *) elf->map_address
131 + elf->start_offset + ehdr->e_shoff),
132 size);
133 }
134
135 for (size_t cnt = 0; cnt < shnum; ++cnt)
136 {
137 CONVERT_TO (shdr[cnt].sh_name, notcvt[cnt].sh_name);
138 CONVERT_TO (shdr[cnt].sh_type, notcvt[cnt].sh_type);
139 CONVERT_TO (shdr[cnt].sh_flags, notcvt[cnt].sh_flags);
140 CONVERT_TO (shdr[cnt].sh_addr, notcvt[cnt].sh_addr);
141 CONVERT_TO (shdr[cnt].sh_offset, notcvt[cnt].sh_offset);
142 CONVERT_TO (shdr[cnt].sh_size, notcvt[cnt].sh_size);
143 CONVERT_TO (shdr[cnt].sh_link, notcvt[cnt].sh_link);
144 CONVERT_TO (shdr[cnt].sh_info, notcvt[cnt].sh_info);
145 CONVERT_TO (shdr[cnt].sh_addralign,
146 notcvt[cnt].sh_addralign);
147 CONVERT_TO (shdr[cnt].sh_entsize, notcvt[cnt].sh_entsize);
148
149 /* If this is a section with an extended index add a
150 reference in the section which uses the extended
151 index. */
152 if (shdr[cnt].sh_type == SHT_SYMTAB_SHNDX
153 && shdr[cnt].sh_link < shnum)
154 elf->state.ELFW(elf,LIBELFBITS).scns.data[shdr[cnt].sh_link].shndx_index
155 = cnt;
156
157 /* Set the own shndx_index field in case it has not yet
158 been set. */
159 if (elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index == 0)
160 elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index
161 = -1;
162 }
163 }
164 }
165 else if (likely (elf->fildes != -1))
166 {
167 /* Read the header. */
168 ssize_t n = pread_retry (elf->fildes,
169 elf->state.ELFW(elf,LIBELFBITS).shdr, size,
170 elf->start_offset + ehdr->e_shoff);
171 if (unlikely ((size_t) n != size))
172 {
173 /* Severe problems. We cannot read the data. */
174 __libelf_seterrno (ELF_E_READ_ERROR);
175 goto free_and_out;
176 }
177
178 /* If the byte order of the file is not the same as the one
179 of the host convert the data now. */
180 if (ehdr->e_ident[EI_DATA] != MY_ELFDATA)
181 for (size_t cnt = 0; cnt < shnum; ++cnt)
182 {
183 CONVERT (shdr[cnt].sh_name);
184 CONVERT (shdr[cnt].sh_type);
185 CONVERT (shdr[cnt].sh_flags);
186 CONVERT (shdr[cnt].sh_addr);
187 CONVERT (shdr[cnt].sh_offset);
188 CONVERT (shdr[cnt].sh_size);
189 CONVERT (shdr[cnt].sh_link);
190 CONVERT (shdr[cnt].sh_info);
191 CONVERT (shdr[cnt].sh_addralign);
192 CONVERT (shdr[cnt].sh_entsize);
193 }
194 }
195 else
196 {
197 /* The file descriptor was already enabled and not all data was
198 read. Undo the allocation. */
199 __libelf_seterrno (ELF_E_FD_DISABLED);
200
201 free_and_out:
202 free (shdr);
203 elf->state.ELFW(elf,LIBELFBITS).shdr = NULL;
204 elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 0;
205
206 goto out;
207 }
208
209 /* Set the pointers in the `scn's. */
210 for (size_t cnt = 0; cnt < shnum; ++cnt)
211 elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shdr.ELFW(e,LIBELFBITS)
212 = &elf->state.ELFW(elf,LIBELFBITS).shdr[cnt];
213
214 result = scn->shdr.ELFW(e,LIBELFBITS);
215 assert (result != NULL);
216
217 out:
218 return result;
219 }
220
221 static bool
scn_valid(Elf_Scn * scn)222 scn_valid (Elf_Scn *scn)
223 {
224 if (scn == NULL)
225 return false;
226
227 if (unlikely (scn->elf->state.elf.ehdr == NULL))
228 {
229 __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
230 return false;
231 }
232
233 if (unlikely (scn->elf->class != ELFW(ELFCLASS,LIBELFBITS)))
234 {
235 __libelf_seterrno (ELF_E_INVALID_CLASS);
236 return false;
237 }
238
239 return true;
240 }
241
242 ElfW2(LIBELFBITS,Shdr) *
243 __elfw2(LIBELFBITS,getshdr_rdlock) (scn)
244 Elf_Scn *scn;
245 {
246 ElfW2(LIBELFBITS,Shdr) *result;
247
248 if (!scn_valid (scn))
249 return NULL;
250
251 result = scn->shdr.ELFW(e,LIBELFBITS);
252 if (result == NULL)
253 {
254 rwlock_unlock (scn->elf->lock);
255 rwlock_wrlock (scn->elf->lock);
256 result = scn->shdr.ELFW(e,LIBELFBITS);
257 if (result == NULL)
258 result = load_shdr_wrlock (scn);
259 }
260
261 return result;
262 }
263
264 ElfW2(LIBELFBITS,Shdr) *
265 __elfw2(LIBELFBITS,getshdr_wrlock) (scn)
266 Elf_Scn *scn;
267 {
268 ElfW2(LIBELFBITS,Shdr) *result;
269
270 if (!scn_valid (scn))
271 return NULL;
272
273 result = scn->shdr.ELFW(e,LIBELFBITS);
274 if (result == NULL)
275 result = load_shdr_wrlock (scn);
276
277 return result;
278 }
279
280 ElfW2(LIBELFBITS,Shdr) *
281 elfw2(LIBELFBITS,getshdr) (scn)
282 Elf_Scn *scn;
283 {
284 ElfW2(LIBELFBITS,Shdr) *result;
285
286 if (!scn_valid (scn))
287 return NULL;
288
289 rwlock_rdlock (scn->elf->lock);
290 result = __elfw2(LIBELFBITS,getshdr_rdlock) (scn);
291 rwlock_unlock (scn->elf->lock);
292
293 return result;
294 }
295