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      1 /*	$NetBSD: elf_next.c,v 1.7 2026/05/17 21:40:50 jkoshy Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2006,2008 Joseph Koshy
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #if HAVE_NBTOOL_CONFIG_H
     30 # include "nbtool_config.h"
     31 #endif
     32 
     33 #include <sys/cdefs.h>
     34 
     35 #include <ar.h>
     36 #include <assert.h>
     37 #include <libelf.h>
     38 
     39 #include "_libelf.h"
     40 
     41 ELFTC_VCSID("Id: elf_next.c 3977 2022-05-01 06:45:34Z jkoshy");
     42 
     43 __RCSID("$NetBSD: elf_next.c,v 1.7 2026/05/17 21:40:50 jkoshy Exp $");
     44 
     45 Elf_Cmd
     46 elf_next(Elf *e)
     47 {
     48 	off_t next;
     49 	Elf *parent;
     50 
     51 	if (e == NULL)
     52 		return (ELF_C_NULL);
     53 
     54 	 if ((parent = e->e_parent) == NULL) {
     55 		 LIBELF_SET_ERROR(ARGUMENT, 0);
     56 		 return (ELF_C_NULL);
     57 	 }
     58 
     59 	assert(parent->e_kind == ELF_K_AR);
     60 	assert(parent->e_cmd == ELF_C_READ);
     61 	assert(e->e_rawfile > parent->e_rawfile);
     62 
     63 	next = e->e_rawfile - parent->e_rawfile + (off_t) e->e_rawsize;
     64 	next = (next + 1) & ~1;	/* round up to an even boundary */
     65 
     66 	/*
     67 	 * Setup the 'e_next' field of the archive descriptor for the
     68 	 * next call to 'elf_begin()'.
     69 	 */
     70 	parent->e_u.e_ar.e_next = (next >= (off_t) parent->e_rawsize) ?
     71 	    (off_t) 0 : next;
     72 
     73 	/*
     74 	 * Return an error if the 'e_next' field falls outside the current
     75 	 * file.
     76 	 *
     77 	 * This check is performed after updating the parent descriptor's
     78 	 * 'e_next' field so that the next call to elf_begin(3) will terminate
     79 	 * traversal of a too-small archive even if client code forgets to
     80 	 * check the return value from elf_next(3).
     81 	 */
     82 	if (next > (off_t) parent->e_rawsize) {
     83 		LIBELF_SET_ERROR(ARGUMENT, 0);
     84 		return (ELF_C_NULL);
     85 	}
     86 
     87 	return (ELF_C_READ);
     88 }
     89