1 | /*- |
---|
2 | * Copyright (c) 2006,2008 Joseph Koshy |
---|
3 | * All rights reserved. |
---|
4 | * |
---|
5 | * Redistribution and use in source and binary forms, with or without |
---|
6 | * modification, are permitted provided that the following conditions |
---|
7 | * are met: |
---|
8 | * 1. Redistributions of source code must retain the above copyright |
---|
9 | * notice, this list of conditions and the following disclaimer. |
---|
10 | * 2. Redistributions in binary form must reproduce the above copyright |
---|
11 | * notice, this list of conditions and the following disclaimer in the |
---|
12 | * documentation and/or other materials provided with the distribution. |
---|
13 | * |
---|
14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
---|
15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
---|
16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
---|
17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
---|
18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
---|
19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
---|
20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
---|
21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
---|
22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
---|
23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
---|
24 | * SUCH DAMAGE. |
---|
25 | */ |
---|
26 | |
---|
27 | #include <sys/cdefs.h> |
---|
28 | |
---|
29 | #include <gelf.h> |
---|
30 | |
---|
31 | #include "_libelf.h" |
---|
32 | |
---|
33 | LIBELF_VCSID("$Id: libelf_checksum.c 189 2008-07-20 10:38:08Z jkoshy $"); |
---|
34 | |
---|
35 | static unsigned long |
---|
36 | _libelf_sum(unsigned long c, const unsigned char *s, size_t size) |
---|
37 | { |
---|
38 | if (s == NULL || size == 0) |
---|
39 | return (c); |
---|
40 | |
---|
41 | while (size--) |
---|
42 | c += *s++; |
---|
43 | |
---|
44 | return (c); |
---|
45 | } |
---|
46 | |
---|
47 | unsigned long |
---|
48 | _libelf_checksum(Elf *e, int elfclass) |
---|
49 | { |
---|
50 | size_t shn; |
---|
51 | Elf_Scn *scn; |
---|
52 | Elf_Data *d; |
---|
53 | unsigned long checksum; |
---|
54 | GElf_Ehdr eh; |
---|
55 | GElf_Shdr shdr; |
---|
56 | |
---|
57 | if (e == NULL) { |
---|
58 | LIBELF_SET_ERROR(ARGUMENT, 0); |
---|
59 | return (0L); |
---|
60 | } |
---|
61 | |
---|
62 | if (e->e_class != elfclass) { |
---|
63 | LIBELF_SET_ERROR(CLASS, 0); |
---|
64 | return (0L); |
---|
65 | } |
---|
66 | |
---|
67 | if (gelf_getehdr(e, &eh) == NULL) |
---|
68 | return (0); |
---|
69 | |
---|
70 | /* |
---|
71 | * Iterate over all sections in the ELF file, computing the |
---|
72 | * checksum along the way. |
---|
73 | * |
---|
74 | * The first section is always SHN_UNDEF and can be skipped. |
---|
75 | * Non-allocatable sections are skipped, as are sections that |
---|
76 | * could be affected by utilities such as strip(1). |
---|
77 | */ |
---|
78 | |
---|
79 | checksum = 0; |
---|
80 | for (shn = 1; shn < e->e_u.e_elf.e_nscn; shn++) { |
---|
81 | if ((scn = elf_getscn(e, shn)) == NULL) |
---|
82 | return (0); |
---|
83 | if (gelf_getshdr(scn, &shdr) == NULL) |
---|
84 | return (0); |
---|
85 | if ((shdr.sh_flags & SHF_ALLOC) == 0 || |
---|
86 | shdr.sh_type == SHT_DYNAMIC || |
---|
87 | shdr.sh_type == SHT_DYNSYM) |
---|
88 | continue; |
---|
89 | |
---|
90 | d = NULL; |
---|
91 | while ((d = elf_rawdata(scn, d)) != NULL) |
---|
92 | checksum = _libelf_sum(checksum, |
---|
93 | (unsigned char *) d->d_buf, d->d_size); |
---|
94 | } |
---|
95 | |
---|
96 | /* |
---|
97 | * Return a 16-bit checksum compatible with Solaris. |
---|
98 | */ |
---|
99 | return (((checksum >> 16) & 0xFFFFUL) + (checksum & 0xFFFFUL)); |
---|
100 | } |
---|