/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

#include "libelf.h"
#include "decl.h"
#include "msg.h"


char *
elf_strptr(Elf * elf, size_t ndx, size_t off)
{
        Elf_Scn         *s;
        Elf_Data        *d;
        char            *rc;

        if (elf == 0)
                return (0);
        if ((s = elf_getscn(elf, ndx)) == 0) {
                _elf_seterr(EREQ_STRSCN, 0);
                return (0);
        }
        READLOCKS(elf, s)
        if (elf->ed_class == ELFCLASS32) {
                Elf32_Shdr* sh = (Elf32_Shdr*)s->s_shdr;

                if ((sh == 0) || (sh->sh_type != SHT_STRTAB)) {
                        _elf_seterr(EREQ_STRSCN, 0);
                        READUNLOCKS(elf, s)
                        return (0);
                }
        } else if (elf->ed_class == ELFCLASS64) {
                Elf64_Shdr* sh = (Elf64_Shdr*)s->s_shdr;

                if ((sh == 0) || (sh->sh_type != SHT_STRTAB)) {
                        _elf_seterr(EREQ_STRSCN, 0);
                        READUNLOCKS(elf, s)
                        return (0);
                }
        } else {
                _elf_seterr(EREQ_STRSCN, 0);
                READUNLOCKS(elf, s)
                return (0);
        }


        /*
         * If the layout bit is set, use the offsets and
         * sizes in the data buffers.  Otherwise, take
         * data buffers in order.
         */

        d = 0;
        if (elf->ed_uflags & ELF_F_LAYOUT) {
                while ((d = _elf_locked_getdata(s, d)) != 0) {
                        if (d->d_buf == 0)
                                continue;
                        if ((off >= d->d_off) &&
                            (off < d->d_off + d->d_size)) {
                                rc = (char *)d->d_buf + off - d->d_off;
                                READUNLOCKS(elf, s)
                                return (rc);
                        }
                }
        } else {
                size_t  sz = 0, j;
                while ((d = _elf_locked_getdata(s, d)) != 0) {
                        if (((j = d->d_align) > 1) && (sz % j != 0)) {
                                j -= sz % j;
                                sz += j;
                                if (off < j)
                                        break;
                                off -= j;
                        }
                        if (d->d_buf != 0) {
                                if (off < d->d_size) {
                                        rc = (char *)d->d_buf + off;
                                        READUNLOCKS(elf, s)
                                        return (rc);
                                }
                        }
                        sz += d->d_size;
                        if (off < d->d_size)
                                break;
                        off -= d->d_size;
                }
        }
        _elf_seterr(EREQ_STROFF, 0);
        READUNLOCKS(elf, s)
        return (0);
}