151 lines
3.3 KiB
C
151 lines
3.3 KiB
C
/*
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* strptr.c - implementation of the elf_strptr(3) function.
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* Copyright (C) 1995 - 2007 Michael Riepe
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#include <private.h>
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#ifndef lint
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static const char rcsid[] = "@(#) $Id: strptr.c,v 1.12 2008/05/23 08:15:35 michael Exp $";
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#endif /* lint */
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char*
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elf_strptr(Elf *elf, size_t section, size_t offset) {
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Elf_Data *data;
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Elf_Scn *scn;
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size_t n;
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char *s;
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if (!elf) {
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return NULL;
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}
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elf_assert(elf->e_magic == ELF_MAGIC);
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if (!(scn = elf_getscn(elf, section))) {
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return NULL;
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}
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if (scn->s_index == SHN_UNDEF) {
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seterr(ERROR_NOSTRTAB);
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return NULL;
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}
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/*
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* checking the section header is more appropriate
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*/
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if (elf->e_class == ELFCLASS32) {
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if (scn->s_shdr32.sh_type != SHT_STRTAB) {
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seterr(ERROR_NOSTRTAB);
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return NULL;
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}
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}
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#if __LIBELF64
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else if (elf->e_class == ELFCLASS64) {
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if (scn->s_shdr64.sh_type != SHT_STRTAB) {
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seterr(ERROR_NOSTRTAB);
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return NULL;
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}
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}
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#endif /* __LIBELF64 */
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else if (valid_class(elf->e_class)) {
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seterr(ERROR_UNIMPLEMENTED);
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return NULL;
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}
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else {
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seterr(ERROR_UNKNOWN_CLASS);
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return NULL;
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}
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/*
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* Find matching buffer
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*/
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n = 0;
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data = NULL;
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if (elf->e_elf_flags & ELF_F_LAYOUT) {
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/*
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* Programmer is responsible for d_off
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* Note: buffers may be in any order!
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*/
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while ((data = elf_getdata(scn, data))) {
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n = data->d_off;
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if (offset >= n && offset - n < data->d_size) {
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/*
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* Found it
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*/
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break;
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}
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}
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}
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else {
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/*
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* Calculate offsets myself
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*/
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while ((data = elf_getdata(scn, data))) {
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if (data->d_align > 1) {
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n += data->d_align - 1;
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n -= n % data->d_align;
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}
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if (offset < n) {
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/*
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* Invalid offset: points into a hole
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*/
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seterr(ERROR_BADSTROFF);
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return NULL;
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}
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if (offset - n < data->d_size) {
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/*
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* Found it
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*/
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break;
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}
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n += data->d_size;
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}
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}
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if (data == NULL) {
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/*
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* Not found
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*/
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seterr(ERROR_BADSTROFF);
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return NULL;
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}
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if (data->d_buf == NULL) {
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/*
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* Buffer is NULL (usually the programmers' fault)
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*/
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seterr(ERROR_NULLBUF);
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return NULL;
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}
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offset -= n;
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s = (char*)data->d_buf;
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if (!(_elf_sanity_checks & SANITY_CHECK_STRPTR)) {
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return s + offset;
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}
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/*
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* Perform extra sanity check
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*/
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for (n = offset; n < data->d_size; n++) {
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if (s[n] == '\0') {
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/*
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* Return properly NUL terminated string
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*/
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return s + offset;
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}
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}
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/*
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* String is not NUL terminated
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* Return error to avoid SEGV in application
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*/
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seterr(ERROR_UNTERM);
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return NULL;
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}
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