/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2014 The FreeBSD Foundation
 *
 * 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/capsicum.h>
#include <sys/disk.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <capsicum_helpers.h>
#include <err.h>
#include <errno.h>
#ifdef WITH_ICONV
#include <iconv.h>
#endif
#include <locale.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vis.h>

#include "fstyp.h"

#define LABEL_LEN       256

bool show_label = false;

typedef int (*fstyp_function)(FILE *, char *, size_t);

/*
 * The ordering of fstypes[] is not arbitrary.
 *
 * fstyp checks the existence of a file system header to determine the
 * type of file system on a given device. For different file systems,
 * these headers reside at different offsets within the device.
 *
 * For example, the header for an MS-DOS file system begins at offset 0,
 * whereas a header for UFS *normally* begins at offset 64k. If a device
 * was constructed as MS-DOS and then repurposed as UFS (via newfs), it
 * is possible the MS-DOS header will still be intact. To prevent
 * misidentifying the file system, it is desirable to check the header
 * with the largest offset first (i.e., UFS before MS-DOS).
 */
static struct {
        const char      *name;
        fstyp_function  function;
        bool            unmountable;
        const char      *precache_encoding;
} fstypes[] = {
        /* last sector of geli device */
        { "geli", &fstyp_geli, true, NULL },
        /*
         * ufs headers have four different areas, searched in this order:
         * offsets: 64k, 8k, 0k, 256k + 8192 bytes
         */
        { "ufs", &fstyp_ufs, false, NULL },
        /* offset 32768 + 512 bytes */
        { "cd9660", &fstyp_cd9660, false, NULL },
        /* offset 1024 + 512 bytes */
        { "hfs+", &fstyp_hfsp, false, NULL },
        /* offset 1024 + 512 bytes */
        { "ext2fs", &fstyp_ext2fs, false, NULL },
        /* offset 512 + 36 bytes */
        { "befs", &fstyp_befs, false, NULL },
        /* offset 0 + 40 bytes */
        { "apfs", &fstyp_apfs, true, NULL },
        /* offset 0 + 512 bytes (for initial signature check) */
        { "exfat", &fstyp_exfat, false, EXFAT_ENC },
        /* offset 0 + 1928 bytes */
        { "hammer", &fstyp_hammer, true, NULL },
        /* offset 0 + 65536 bytes (for initial signature check) */
        { "hammer2", &fstyp_hammer2, true, NULL },
        /* offset 0 + 512 bytes (for initial signature check) */
        { "msdosfs", &fstyp_msdosfs, false, NULL },
        /* offset 0 + 512 bytes (for initial signature check) */
        { "ntfs", &fstyp_ntfs, false, NTFS_ENC },
#ifdef HAVE_ZFS
        /* offset 0 + 256k */
        { "zfs", &fstyp_zfs, true, NULL },
#endif
        { NULL, NULL, NULL, NULL }
};

void *
read_buf(FILE *fp, off_t off, size_t len)
{
        int error;
        size_t nread;
        void *buf;

        error = fseek(fp, off, SEEK_SET);
        if (error != 0) {
                warn("cannot seek to %jd", (uintmax_t)off);
                return (NULL);
        }

        buf = malloc(len);
        if (buf == NULL) {
                warn("cannot malloc %zd bytes of memory", len);
                return (NULL);
        }

        nread = fread(buf, len, 1, fp);
        if (nread != 1) {
                free(buf);
                if (feof(fp) == 0)
                        warn("fread");
                return (NULL);
        }

        return (buf);
}

char *
checked_strdup(const char *s)
{
        char *c;

        c = strdup(s);
        if (c == NULL)
                err(1, "strdup");
        return (c);
}

void
rtrim(char *label, size_t size)
{
        ptrdiff_t i;

        for (i = size - 1; i >= 0; i--) {
                if (label[i] == '\0')
                        continue;
                else if (label[i] == ' ')
                        label[i] = '\0';
                else
                        break;
        }
}

static void
usage(void)
{

        fprintf(stderr, "usage: fstyp [-l] [-s] [-u] special\n");
        exit(1);
}

static void
type_check(const char *path, FILE *fp)
{
        int error, fd;
        off_t mediasize;
        struct stat sb;

        fd = fileno(fp);

        error = fstat(fd, &sb);
        if (error != 0)
                err(1, "%s: fstat", path);

        if (S_ISREG(sb.st_mode))
                return;

        error = ioctl(fd, DIOCGMEDIASIZE, &mediasize);
        if (error != 0)
                errx(1, "%s: not a disk", path);
}

int
main(int argc, char **argv)
{
        int ch, error, i, nbytes;
        bool ignore_type = false, show_unmountable = false;
        char label[LABEL_LEN + 1], strvised[LABEL_LEN * 4 + 1];
        char *path;
        FILE *fp;
        fstyp_function fstyp_f;

        while ((ch = getopt(argc, argv, "lsu")) != -1) {
                switch (ch) {
                case 'l':
                        show_label = true;
                        break;
                case 's':
                        ignore_type = true;
                        break;
                case 'u':
                        show_unmountable = true;
                        break;
                default:
                        usage();
                }
        }

        argc -= optind;
        argv += optind;
        if (argc != 1)
                usage();

        path = argv[0];

        if (setlocale(LC_CTYPE, "") == NULL)
                err(1, "setlocale");
        caph_cache_catpages();

#ifdef WITH_ICONV
        /* Cache iconv conversion data before entering capability mode. */
        if (show_label) {
                for (i = 0; i < (int)nitems(fstypes); i++) {
                        iconv_t cd;

                        if (fstypes[i].precache_encoding == NULL)
                                continue;
                        cd = iconv_open("", fstypes[i].precache_encoding);
                        if (cd == (iconv_t)-1)
                                err(1, "%s: iconv_open %s", fstypes[i].name,
                                    fstypes[i].precache_encoding);
                        /* Iconv keeps a small cache of unused encodings. */
                        iconv_close(cd);
                }
        }
#endif

        fp = fopen(path, "r");
        if (fp == NULL)
                err(1, "%s", path);

        if (caph_enter() < 0)
                err(1, "cap_enter");

        if (ignore_type == false)
                type_check(path, fp);

        memset(label, '\0', sizeof(label));

        for (i = 0;; i++) {
                if (show_unmountable == false && fstypes[i].unmountable == true)
                        continue;
                fstyp_f = fstypes[i].function;
                if (fstyp_f == NULL)
                        break;

                error = fstyp_f(fp, label, sizeof(label));
                if (error == 0)
                        break;
        }

        if (fstypes[i].name == NULL) {
                warnx("%s: filesystem not recognized", path);
                return (1);
        }

        if (show_label && label[0] != '\0') {
                /*
                 * XXX: I'd prefer VIS_HTTPSTYLE, but it unconditionally
                 *      encodes spaces.
                 */
                nbytes = strsnvis(strvised, sizeof(strvised), label,
                    VIS_GLOB | VIS_NL, "\"'$");
                if (nbytes == -1)
                        err(1, "strsnvis");

                printf("%s %s\n", fstypes[i].name, strvised);
        } else {
                printf("%s\n", fstypes[i].name);
        }

        return (0);
}