1 /* Return section compression header.
2 Copyright (C) 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 <libelf.h>
34 #include "libelfP.h"
35 #include "common.h"
36
37 #ifndef LIBELFBITS
38 # define LIBELFBITS 32
39 #endif
40
41
ElfW2(LIBELFBITS,Chdr)42 ElfW2(LIBELFBITS,Chdr) *
43 elfw2(LIBELFBITS,getchdr) (Elf_Scn *scn)
44 {
45 ElfW2(LIBELFBITS,Shdr) *shdr = elfw2(LIBELFBITS,getshdr) (scn);
46 if (shdr == NULL)
47 return NULL;
48
49 /* Must have SHF_COMPRESSED flag set. Allocated or no bits sections
50 can never be compressed. */
51 if ((shdr->sh_flags & SHF_ALLOC) != 0)
52 {
53 __libelf_seterrno (ELF_E_INVALID_SECTION_FLAGS);
54 return NULL;
55 }
56
57 if (shdr->sh_type == SHT_NULL
58 || shdr->sh_type == SHT_NOBITS)
59 {
60 __libelf_seterrno (ELF_E_INVALID_SECTION_TYPE);
61 return NULL;
62 }
63
64 if ((shdr->sh_flags & SHF_COMPRESSED) == 0)
65 {
66 __libelf_seterrno (ELF_E_NOT_COMPRESSED);
67 return NULL;
68 }
69
70 /* This makes sure the data is in the correct format, so we don't
71 need to swap fields. */
72 Elf_Data *d = elf_getdata (scn, NULL);
73 if (d == NULL)
74 return NULL;
75
76 if (d->d_size < sizeof (ElfW2(LIBELFBITS,Chdr)) || d->d_buf == NULL)
77 {
78 __libelf_seterrno (ELF_E_INVALID_DATA);
79 return NULL;
80 }
81
82 return (ElfW2(LIBELFBITS,Chdr) *) d->d_buf;
83 }
84