228 lines
6.9 KiB
C
228 lines
6.9 KiB
C
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/*-
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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 <assert.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include "gelf.h"
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#include "libelf.h"
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#include "_libelf.h"
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/*
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* Load an ELF section table and create a list of Elf_Scn structures.
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*/
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static int
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_libelf_load_scn(Elf *e, void *ehdr)
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{
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int ec, swapbytes;
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size_t fsz, i, shnum;
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uint64_t shoff;
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char *src;
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Elf32_Ehdr *eh32;
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Elf64_Ehdr *eh64;
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Elf_Scn *scn;
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void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
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assert(e != NULL);
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assert(ehdr != NULL);
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assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0);
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#define CHECK_EHDR(E,EH) do { \
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if (fsz != (EH)->e_shentsize || \
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shoff + fsz * shnum > e->e_rawsize) { \
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LIBELF_SET_ERROR(HEADER, 0); \
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return (0); \
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} \
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} while (0)
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ec = e->e_class;
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fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
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assert(fsz > 0);
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shnum = e->e_u.e_elf.e_nscn;
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if (ec == ELFCLASS32) {
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eh32 = (Elf32_Ehdr *) ehdr;
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shoff = (uint64_t) eh32->e_shoff;
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CHECK_EHDR(e, eh32);
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} else {
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eh64 = (Elf64_Ehdr *) ehdr;
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shoff = eh64->e_shoff;
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CHECK_EHDR(e, eh64);
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}
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xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
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swapbytes = e->e_byteorder != LIBELF_PRIVATE(byteorder);
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src = e->e_rawfile + shoff;
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/*
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* If the file is using extended numbering then section #0
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* would have already been read in.
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*/
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i = 0;
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if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
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assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) ==
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STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next));
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i = 1;
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src += fsz;
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}
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for (; i < shnum; i++, src += fsz) {
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if ((scn = _libelf_allocate_scn(e, i)) == NULL)
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return (0);
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(*xlator)((char *) &scn->s_shdr, src, (size_t) 1, swapbytes);
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if (ec == ELFCLASS32) {
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scn->s_offset = scn->s_rawoff =
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scn->s_shdr.s_shdr32.sh_offset;
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scn->s_size = scn->s_shdr.s_shdr32.sh_size;
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} else {
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scn->s_offset = scn->s_rawoff =
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scn->s_shdr.s_shdr64.sh_offset;
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scn->s_size = scn->s_shdr.s_shdr64.sh_size;
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}
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}
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e->e_flags |= LIBELF_F_SHDRS_LOADED;
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return (1);
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}
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Elf_Scn *
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elf_getscn(Elf *e, size_t index)
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{
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int ec;
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void *ehdr;
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Elf_Scn *s;
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if (e == NULL || e->e_kind != ELF_K_ELF ||
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((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
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return (NULL);
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if (e->e_cmd != ELF_C_WRITE &&
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(e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
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_libelf_load_scn(e, ehdr) == 0)
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return (NULL);
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STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
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if (s->s_ndx == index)
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return (s);
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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size_t
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elf_ndxscn(Elf_Scn *s)
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{
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if (s == NULL) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (SHN_UNDEF);
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}
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return (s->s_ndx);
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}
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Elf_Scn *
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elf_newscn(Elf *e)
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{
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int ec;
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void *ehdr;
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Elf_Scn *scn;
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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 ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
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LIBELF_SET_ERROR(CLASS, 0);
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return (NULL);
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}
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if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
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return (NULL);
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/*
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* The application may be asking for a new section descriptor
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* on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We
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* need to bring in the existing section information before
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* appending a new one to the list.
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*
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* Per the ELF(3) API, an application is allowed to open a
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* file using ELF_C_READ, mess with its internal structure and
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* use elf_update(...,ELF_C_NULL) to compute its new layout.
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*/
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if (e->e_cmd != ELF_C_WRITE &&
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(e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
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_libelf_load_scn(e, ehdr) == 0)
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return (NULL);
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if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
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assert(e->e_u.e_elf.e_nscn == 0);
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if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) ==
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NULL)
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return (NULL);
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e->e_u.e_elf.e_nscn++;
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}
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assert(e->e_u.e_elf.e_nscn > 0);
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if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL)
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return (NULL);
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e->e_u.e_elf.e_nscn++;
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(void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY);
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return (scn);
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}
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Elf_Scn *
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elf_nextscn(Elf *e, Elf_Scn *s)
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{
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if (e == NULL || (e->e_kind != ELF_K_ELF) ||
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(s && s->s_elf != e)) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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return (s == NULL ? elf_getscn(e, (size_t) 1) :
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STAILQ_NEXT(s, s_next));
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}
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