1 /* Test program for extracting ELF Note headers and getting whole notes.
2 Copyright (C) 2019 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 the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 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
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17
18 #ifdef HAVE_CONFIG_H
19 # include <config.h>
20 #endif
21
22 #include <errno.h>
23 #include <fcntl.h>
24 #include <inttypes.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <unistd.h>
29
30 #include ELFUTILS_HEADER(elf)
31 #include <gelf.h>
32
33 int
main(int argc,char * argv[])34 main (int argc, char *argv[])
35 {
36 if (argc != 2)
37 {
38 printf ("No ELF file given as argument\n");
39 exit (1);
40 }
41
42 const char *fname = argv[1];
43
44 // Initialize libelf.
45 elf_version (EV_CURRENT);
46
47 /* Read the ELF from disk now. */
48 int fd = open (fname, O_RDONLY);
49 if (fd == -1)
50 {
51 printf ("cannot open '%s': %s\n", fname, strerror (errno));
52 exit (1);
53 }
54
55 Elf *elf = elf_begin (fd, ELF_C_READ, NULL);
56 if (elf == NULL)
57 {
58 printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
59 exit (1);
60 }
61
62 GElf_Ehdr ehdr;
63 if (gelf_getehdr (elf, &ehdr) == NULL)
64 {
65 printf ("cannot get Ehdr: %s\n", elf_errmsg (-1));
66 exit (1);
67 }
68
69 /* Search for all SHT_NOTE sections. */
70 Elf_Scn *scn = NULL;
71 while ((scn = elf_nextscn (elf, scn)) != NULL)
72 {
73 /* Get the header. */
74 GElf_Shdr shdr;
75 if (gelf_getshdr (scn, &shdr) == NULL)
76 {
77 printf ("couldn't get shdr: %s\n", elf_errmsg (-1));
78 exit (1);
79 }
80
81 if (shdr.sh_type == SHT_NOTE)
82 {
83 printf ("Notes in section %zd:\n", elf_ndxscn (scn));
84
85 Elf_Data *raw = elf_rawdata (scn, NULL);
86 if (raw == NULL)
87 {
88 printf ("couldn't get raw data: %s\n", elf_errmsg (-1));
89 exit (1);
90 }
91
92 Elf_Data *data = elf_getdata (scn, NULL);
93 if (data == NULL)
94 {
95 printf ("couldn't get data: %s\n", elf_errmsg (-1));
96 exit (1);
97 }
98
99 size_t off = 0;
100 size_t next;
101 GElf_Nhdr nhdr;
102 size_t n_off;
103 size_t d_off;
104 while ((next = gelf_getnote (data, off, &nhdr, &n_off, &d_off)) > 0)
105 {
106 /* Now just get the note header "raw" (don't
107 copy/translate the note data). This only handles
108 traditional GNU ELF Notes, so we still use the next
109 from gelf_getnote (padding is different for new style
110 ELF_T_NHDR8 notes). */
111 Elf32_Nhdr nh;
112 Elf_Data src =
113 {
114 .d_version = EV_CURRENT, .d_type = ELF_T_NHDR,
115 .d_size = sizeof nh
116 };
117 Elf_Data dst = src;
118 src.d_buf = raw->d_buf + off;
119 dst.d_buf = &nh;
120
121 if (elf32_xlatetom (&dst, &src, ehdr.e_ident[EI_DATA]) == NULL)
122 {
123 printf ("couldn't xlate note: %s\n", elf_errmsg (-1));
124 exit (1);
125 }
126
127 printf ("type: %" PRId32 ",%" PRId32
128 ", namesz: %" PRId32 ",%" PRId32
129 ", descsz: %" PRId32 ",%" PRId32 "\n",
130 nhdr.n_type, nh.n_type,
131 nhdr.n_namesz, nh.n_namesz,
132 nhdr.n_descsz, nh.n_descsz);
133
134 if (nhdr.n_type != nh.n_type
135 || nhdr.n_namesz != nh.n_namesz
136 || nhdr.n_descsz != nh.n_descsz)
137 {
138 printf ("Nhdrs not equal!\n");
139 exit (1);
140 }
141
142 off = next;
143 }
144 }
145
146 }
147
148 if (elf_end (elf) != 0)
149 {
150 printf ("failure in elf_end: %s\n", elf_errmsg (-1));
151 exit (1);
152 }
153
154 close (fd);
155
156 return 0;
157 }
158