1 /* Copyright (C) 2012 Red Hat, Inc.
2    This file is part of elfutils.
3 
4    This file is free software; you can redistribute it and/or modify
5    it under the terms of the GNU General Public License as published by
6    the Free Software Foundation; either version 3 of the License, or
7    (at your option) any later version.
8 
9    elfutils is distributed in the hope that it will be useful, but
10    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, see <http://www.gnu.org/licenses/>.  */
16 
17 #ifdef HAVE_CONFIG_H
18 # include <config.h>
19 #endif
20 
21 #include <sys/types.h>
22 #include <sys/stat.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <unistd.h>
26 #include <errno.h>
27 #include <string.h>
28 #include <fcntl.h>
29 #include <gelf.h>
30 #include <libelf.h>
31 #include <stdbool.h>
32 #include <inttypes.h>
33 
34 int
35 main (int argc, char *argv[])
36 {
37   if (argc != 3)
38     {
39       fprintf (stderr, "Needs two arguments.\n");
40       fprintf (stderr, "First needs to be 'READ', 'MMAP' or 'FDREAD'\n");
41       fprintf (stderr, "Second is the ELF file to read.\n");
42       exit (2); /* user error */
43     }
44 
45   bool do_mmap = false;
46   bool close_fd = false;
47   if (strcmp (argv[1], "READ") == 0)
48     {
49       do_mmap = false;
50       close_fd = false;
51     }
52   else if (strcmp (argv[1], "MMAP") == 0)
53     {
54       do_mmap = true;
55       close_fd = false;
56     }
57   else if  (strcmp (argv[1], "FDREAD") == 0)
58     {
59       do_mmap = false;
60       close_fd = true;
61     }
62   else
63     {
64       fprintf (stderr, "First arg needs to be 'READ', 'MMAP' or 'FDREAD'\n");
65       exit (2); /* user error */
66     }
67 
68   elf_version (EV_CURRENT);
69 
70   int fd = open (argv[2], O_RDONLY);
71   if (fd < 0)
72     {
73       fprintf (stderr, "Cannot open input file %s: %s\n", argv[2],
74 	       strerror (errno));
75       exit (2);
76     }
77 
78   Elf *elf = elf_begin (fd, do_mmap ? ELF_C_READ_MMAP : ELF_C_READ, NULL);
79   if (elf == NULL)
80     {
81       fprintf (stderr, "elf_begin failed for %s: %s\n", argv[2],
82 	       elf_errmsg (-1));
83       exit (2);
84     }
85 
86   if (! do_mmap && close_fd)
87     {
88       if (elf_cntl (elf, ELF_C_FDREAD) < 0)
89 	{
90 	  fprintf (stderr, "elf_cntl failed for %s: %s\n", argv[2],
91 		   elf_errmsg (-1));
92 	  exit (1);
93 	}
94       close (fd);
95     }
96 
97   Elf_Scn *scn = NULL;
98   while ((scn = elf_nextscn (elf, scn)) != NULL)
99     {
100       GElf_Shdr shdr_mem;
101       GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
102       printf ("Section at offset %#0" PRIx64 "\n", shdr->sh_offset);
103     }
104 
105   elf_end (elf);
106   exit (0);
107 }
108