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134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/*-
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* Copyright (c) 2006 Joseph Koshy
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <assert.h>
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#include <gelf.h>
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#include "_libelf.h"
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/*
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* Convert an ELF section#,offset pair to a string pointer.
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*/
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char *
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elf_strptr(Elf *e, size_t scndx, size_t offset)
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{
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Elf_Scn *s;
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Elf_Data *d;
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size_t alignment, count;
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GElf_Shdr shdr;
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if (e == NULL || e->e_kind != ELF_K_ELF) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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if ((s = elf_getscn(e, scndx)) == NULL ||
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gelf_getshdr(s, &shdr) == NULL)
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return (NULL);
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if (shdr.sh_type != SHT_STRTAB ||
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offset >= shdr.sh_size) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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d = NULL;
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if (e->e_flags & ELF_F_LAYOUT) {
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/*
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* The application is taking responsibility for the
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* ELF object's layout, so we can directly translate
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* an offset to a `char *' address using the `d_off'
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* members of Elf_Data descriptors.
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*/
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while ((d = elf_getdata(s, d)) != NULL) {
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if (d->d_buf == 0 || d->d_size == 0)
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continue;
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if (d->d_type != ELF_T_BYTE) {
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LIBELF_SET_ERROR(DATA, 0);
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return (NULL);
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}
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if (offset >= d->d_off &&
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offset < d->d_off + d->d_size)
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return ((char *) d->d_buf + offset - d->d_off);
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}
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} else {
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/*
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* Otherwise, the `d_off' members are not useable and
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* we need to compute offsets ourselves, taking into
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* account 'holes' in coverage of the section introduced
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* by alignment requirements.
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*/
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count = (size_t) 0; /* cumulative count of bytes seen */
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while ((d = elf_getdata(s, d)) != NULL && count <= offset) {
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if (d->d_buf == NULL || d->d_size == 0)
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continue;
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if (d->d_type != ELF_T_BYTE) {
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LIBELF_SET_ERROR(DATA, 0);
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return (NULL);
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}
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if ((alignment = d->d_align) > 1) {
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if ((alignment & (alignment - 1)) != 0) {
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LIBELF_SET_ERROR(DATA, 0);
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return (NULL);
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}
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count = roundup2(count, alignment);
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}
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if (offset < count) {
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/* offset starts in the 'hole' */
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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if (offset < count + d->d_size) {
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if (d->d_buf != NULL)
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return ((char *) d->d_buf +
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offset - count);
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LIBELF_SET_ERROR(DATA, 0);
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return (NULL);
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}
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count += d->d_size;
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}
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}
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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