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