2 * Copyright (c) 2006,2008 Joseph Koshy
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
27 #include <sys/param.h>
34 ELFTC_VCSID("$Id: elf_strptr.c 2271 2011-12-03 17:06:35Z jkoshy $");
37 * Convert an ELF section#,offset pair to a string pointer.
41 elf_strptr(Elf *e, size_t scndx, size_t offset)
45 size_t alignment, count;
48 if (e == NULL || e->e_kind != ELF_K_ELF) {
49 LIBELF_SET_ERROR(ARGUMENT, 0);
53 if ((s = elf_getscn(e, scndx)) == NULL ||
54 gelf_getshdr(s, &shdr) == NULL)
57 if (shdr.sh_type != SHT_STRTAB ||
58 offset >= shdr.sh_size) {
59 LIBELF_SET_ERROR(ARGUMENT, 0);
64 if (e->e_flags & ELF_F_LAYOUT) {
67 * The application is taking responsibility for the
68 * ELF object's layout, so we can directly translate
69 * an offset to a `char *' address using the `d_off'
70 * members of Elf_Data descriptors.
72 while ((d = elf_getdata(s, d)) != NULL) {
74 if (d->d_buf == 0 || d->d_size == 0)
77 if (d->d_type != ELF_T_BYTE) {
78 LIBELF_SET_ERROR(DATA, 0);
82 if (offset >= d->d_off &&
83 offset < d->d_off + d->d_size)
84 return ((char *) d->d_buf + offset - d->d_off);
88 * Otherwise, the `d_off' members are not useable and
89 * we need to compute offsets ourselves, taking into
90 * account 'holes' in coverage of the section introduced
91 * by alignment requirements.
93 count = (size_t) 0; /* cumulative count of bytes seen */
94 while ((d = elf_getdata(s, d)) != NULL && count <= offset) {
96 if (d->d_buf == NULL || d->d_size == 0)
99 if (d->d_type != ELF_T_BYTE) {
100 LIBELF_SET_ERROR(DATA, 0);
104 if ((alignment = d->d_align) > 1) {
105 if ((alignment & (alignment - 1)) != 0) {
106 LIBELF_SET_ERROR(DATA, 0);
109 count = roundup2(count, alignment);
112 if (offset < count) {
113 /* offset starts in the 'hole' */
114 LIBELF_SET_ERROR(ARGUMENT, 0);
118 if (offset < count + d->d_size) {
119 if (d->d_buf != NULL)
120 return ((char *) d->d_buf +
122 LIBELF_SET_ERROR(DATA, 0);
130 LIBELF_SET_ERROR(ARGUMENT, 0);