/*-
* Copyright (c) 2006,2008-2010 Joseph Koshy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/queue.h>
#include <assert.h>
#include <errno.h>
#include <gelf.h>
#include <libelf.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include "_libelf.h"
ELFTC_VCSID("$Id: elf_scn.c 3177 2015-03-30 18:19:41Z emaste $");
/*
* Load an ELF section table and create a list of Elf_Scn structures.
*/
int
_libelf_load_section_headers(Elf *e, void *ehdr)
{
Elf_Scn *scn;
uint64_t shoff;
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
int ec, swapbytes;
unsigned char *src;
size_t fsz, i, shnum;
int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s,
size_t _c, int _swap);
assert(e != NULL);
assert(ehdr != NULL);
assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0);
#define CHECK_EHDR(E,EH) do { \
if (shoff > e->e_rawsize || \
fsz != (EH)->e_shentsize || \
shnum > SIZE_MAX / fsz || \
fsz * shnum > e->e_rawsize - shoff) { \
LIBELF_SET_ERROR(HEADER, 0); \
return (0); \
} \
} while (0)
ec = e->e_class;
fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
assert(fsz > 0);
shnum = e->e_u.e_elf.e_nscn;
if (ec == ELFCLASS32) {
eh32 = (Elf32_Ehdr *) ehdr;
shoff = (uint64_t) eh32->e_shoff;
CHECK_EHDR(e, eh32);
} else {
eh64 = (Elf64_Ehdr *) ehdr;
shoff = eh64->e_shoff;
CHECK_EHDR(e, eh64);
}
xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
swapbytes = e->e_byteorder != LIBELF_PRIVATE(byteorder);
src = e->e_rawfile + shoff;
/*
* If the file is using extended numbering then section #0
* would have already been read in.
*/
i = 0;
if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) ==
STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next));
i = 1;
src += fsz;
}
for (; i < shnum; i++, src += fsz) {
if ((scn = _libelf_allocate_scn(e, i)) == NULL)
return (0);
(*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr),
src, (size_t) 1, swapbytes);
if (ec == ELFCLASS32) {
scn->s_offset = scn->s_rawoff =
scn->s_shdr.s_shdr32.sh_offset;
scn->s_size = scn->s_shdr.s_shdr32.sh_size;
} else {
scn->s_offset = scn->s_rawoff =
scn->s_shdr.s_shdr64.sh_offset;
scn->s_size = scn->s_shdr.s_shdr64.sh_size;
}
}
e->e_flags |= LIBELF_F_SHDRS_LOADED;
return (1);
}
Elf_Scn *
elf_getscn(Elf *e, size_t index)
{
int ec;
void *ehdr;
Elf_Scn *s;
if (e == NULL || e->e_kind != ELF_K_ELF ||
((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (NULL);
if (e->e_cmd != ELF_C_WRITE &&
(e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
_libelf_load_section_headers(e, ehdr) == 0)
return (NULL);
STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
if (s->s_ndx == index)
return (s);
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
size_t
elf_ndxscn(Elf_Scn *s)
{
if (s == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (SHN_UNDEF);
}
return (s->s_ndx);
}
Elf_Scn *
elf_newscn(Elf *e)
{
int ec;
void *ehdr;
Elf_Scn *scn;
if (e == NULL || e->e_kind != ELF_K_ELF) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
LIBELF_SET_ERROR(CLASS, 0);
return (NULL);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (NULL);
/*
* The application may be asking for a new section descriptor
* on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We
* need to bring in the existing section information before
* appending a new one to the list.
*
* Per the ELF(3) API, an application is allowed to open a
* file using ELF_C_READ, mess with its internal structure and
* use elf_update(...,ELF_C_NULL) to compute its new layout.
*/
if (e->e_cmd != ELF_C_WRITE &&
(e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
_libelf_load_section_headers(e, ehdr) == 0)
return (NULL);
if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(e->e_u.e_elf.e_nscn == 0);
if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) ==
NULL)
return (NULL);
e->e_u.e_elf.e_nscn++;
}
assert(e->e_u.e_elf.e_nscn > 0);
if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL)
return (NULL);
e->e_u.e_elf.e_nscn++;
(void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY);
return (scn);
}
Elf_Scn *
elf_nextscn(Elf *e, Elf_Scn *s)
{
if (e == NULL || (e->e_kind != ELF_K_ELF) ||
(s && s->s_elf != e)) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
return (s == NULL ? elf_getscn(e, (size_t) 1) :
STAILQ_NEXT(s, s_next));
}
