usr.sbin/fstyp/exfat.c

   1 /*
   2  * Copyright (c) 2017 Conrad Meyer <cem@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <stdint.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #include "fstyp.h"
  33
  34 struct exfat_vbr {
  35         char            ev_jmp[3];
  36         char            ev_fsname[8];
  37         char            ev_zeros[53];
  38         uint64_t        ev_part_offset;
  39         uint64_t        ev_vol_length;
  40         uint32_t        ev_fat_offset;
  41         uint32_t        ev_fat_length;
  42         uint32_t        ev_cluster_offset;
  43         uint32_t        ev_cluster_count;
  44         uint32_t        ev_rootdir_cluster;
  45         uint32_t        ev_vol_serial;
  46         uint16_t        ev_fs_revision;
  47         uint16_t        ev_vol_flags;
  48         uint8_t         ev_log_bytes_per_sect;
  49         uint8_t         ev_log_sect_per_clust;
  50         uint8_t         ev_num_fats;
  51         uint8_t         ev_drive_sel;
  52         uint8_t         ev_percent_used;
  53 } __packed;
  54
  55 int
  56 fstyp_exfat(FILE *fp, char *label, size_t size)
  57 {
  58         struct exfat_vbr *ev;
  59
  60         ev = (struct exfat_vbr *)read_buf(fp, 0, 512);
  61         if (ev == NULL || strncmp(ev->ev_fsname, "EXFAT   ", 8) != 0)
  62                 goto fail;
  63
  64         /*
  65          * Reading the volume label requires walking the root directory to look
  66          * for a special label file.  Left as an exercise for the reader.
  67          */
  68         free(ev);
  69         return (0);
  70
  71 fail:
  72         free(ev);
  73         return (1);
  74 }