/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2005 Takanori Watanabe
 * Copyright (c) 2014 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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/cdefs.h>
#include <err.h>
#ifdef WITH_ICONV
#include <iconv.h>
#endif
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "fstyp.h"

#define NTFS_A_VOLUMENAME       0x60
#define NTFS_FILEMAGIC          ((uint32_t)(0x454C4946))
#define NTFS_VOLUMEINO          3

struct ntfs_attr {
        uint32_t        a_type;
        uint32_t        reclen;
        uint8_t         a_flag;
        uint8_t         a_namelen;
        uint8_t         a_nameoff;
        uint8_t         reserved1;
        uint8_t         a_compression;
        uint8_t         reserved2;
        uint16_t        a_index;
        uint16_t        a_datalen;
        uint16_t        reserved3;
        uint16_t        a_dataoff;
        uint16_t        a_indexed;
} __packed;

struct ntfs_filerec {
        uint32_t        fr_hdrmagic;
        uint16_t        fr_hdrfoff;
        uint16_t        fr_hdrfnum;
        uint8_t         reserved[8];
        uint16_t        fr_seqnum;
        uint16_t        fr_nlink;
        uint16_t        fr_attroff;
        uint16_t        fr_flags;
        uint32_t        fr_size;
        uint32_t        fr_allocated;
        uint64_t        fr_mainrec;
        uint16_t        fr_attrnum;
} __packed;

struct ntfs_bootfile {
        uint8_t         reserved1[3];
        uint8_t         bf_sysid[8];
        uint16_t        bf_bps;
        uint8_t         bf_spc;
        uint8_t         reserved2[7];
        uint8_t         bf_media;
        uint8_t         reserved3[2];
        uint16_t        bf_spt;
        uint16_t        bf_heads;
        uint8_t         reserver4[12];
        uint64_t        bf_spv;
        uint64_t        bf_mftcn;
        uint64_t        bf_mftmirrcn;
        int8_t          bf_mftrecsz;
        uint32_t        bf_ibsz;
        uint32_t        bf_volsn;
} __packed;

#ifdef WITH_ICONV
static void
convert_label(const void *label /* LE */, size_t labellen, char *label_out,
    size_t label_sz)
{
        char *label_out_orig;
        iconv_t cd;
        size_t rc;

        /* dstname="" means convert to the current locale. */
        cd = iconv_open("", NTFS_ENC);
        if (cd == (iconv_t)-1) {
                warn("ntfs: Could not open iconv");
                return;
        }

        label_out_orig = label_out;

        rc = iconv(cd, __DECONST(char **, &label), &labellen, &label_out,
            &label_sz);
        if (rc == (size_t)-1) {
                warn("ntfs: iconv()");
                *label_out_orig = '\0';
        } else {
                /* NUL-terminate result (iconv advances label_out). */
                if (label_sz == 0)
                        label_out--;
                *label_out = '\0';
        }

        iconv_close(cd);
}
#endif

int
fstyp_ntfs(FILE *fp, char *label, size_t size)
{
        struct ntfs_bootfile *bf;
        char *filerecp;
#ifdef WITH_ICONV
        struct ntfs_filerec *fr;
        struct ntfs_attr *atr;
        off_t voloff;
        int8_t mftrecsz;
        size_t recsize;
#endif /* WITH_ICONV */

        filerecp = NULL;

        bf = (struct ntfs_bootfile *)read_buf(fp, 0, 512);
        if (bf == NULL || strncmp(bf->bf_sysid, "NTFS    ", 8) != 0)
                goto fail;
#ifdef WITH_ICONV
        if (!show_label)
                goto ok;

        mftrecsz = bf->bf_mftrecsz;
        recsize = (mftrecsz > 0) ?
            (mftrecsz * bf->bf_bps * bf->bf_spc) : (1 << -mftrecsz);

        voloff = bf->bf_mftcn * bf->bf_spc * bf->bf_bps +
            recsize * NTFS_VOLUMEINO;

        filerecp = read_buf(fp, voloff, recsize);
        if (filerecp == NULL)
                goto fail;
        fr = (struct ntfs_filerec *)filerecp;

        if (fr->fr_hdrmagic != NTFS_FILEMAGIC)
                goto fail;

        for (size_t ioff = fr->fr_attroff;
            ioff + sizeof(struct ntfs_attr) < recsize;
            ioff += atr->reclen) {
                atr = (struct ntfs_attr *)(filerecp + ioff);
                if ((int)atr->a_type == -1)
                        goto ok;
                if (atr->a_type == NTFS_A_VOLUMENAME) {
                        if ((size_t)atr->a_dataoff + atr->a_datalen > recsize) {
                                warnx("ntfs: Volume name attribute overflow");
                                goto fail;
                        }
                        convert_label(filerecp + ioff + atr->a_dataoff,
                            atr->a_datalen, label, size);
                        goto ok;
                }
                if (atr->reclen == 0) {
                        warnx("ntfs: Invalid attribute record length");
                        goto fail;
                }
        }
        warnx("ntfs: Volume name not found");
        goto fail;

ok:
#else
        if (show_label) {
                warnx("label not available without iconv support");
                memset(label, 0, size);
        }
#endif /* WITH_ICONV */
        free(bf);
        free(filerecp);

        return (0);

fail:
        free(bf);
        free(filerecp);

        return (1);
}