1 /*- 2 * Copyright (c) 2016 The DragonFly Project 3 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 4 * Copyright (c) 2006 Tobias Reifenberger 5 * Copyright (c) 2014 The FreeBSD Foundation 6 * All rights reserved. 7 * 8 * This software was developed by Edward Tomasz Napierala under sponsorship 9 * from the FreeBSD Foundation. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 37 #include "fstyp.h" 38 #include "msdosfs.h" 39 40 #define LABEL_NO_NAME "NO NAME " 41 42 int 43 fstyp_msdosfs(FILE *fp, char *label, size_t size) 44 { 45 FAT_BSBPB *pfat_bsbpb; 46 FAT32_BSBPB *pfat32_bsbpb; 47 FAT_DES *pfat_entry; 48 uint8_t *sector0, *sector; 49 50 sector0 = NULL; 51 sector = NULL; 52 53 /* Load 1st sector with boot sector and boot parameter block. */ 54 sector0 = (uint8_t *)read_buf(fp, 0, 512); 55 if (sector0 == NULL) 56 return (1); 57 58 /* Check for the FAT boot sector signature. */ 59 if (sector0[510] != 0x55 || sector0[511] != 0xaa) { 60 goto error; 61 } 62 63 /* 64 * Test if this is really a FAT volume and determine the FAT type. 65 */ 66 67 pfat_bsbpb = (FAT_BSBPB *)sector0; 68 pfat32_bsbpb = (FAT32_BSBPB *)sector0; 69 70 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { 71 /* 72 * If the BPB_FATSz16 field is not zero and the string "FAT" is 73 * at the right place, this should be a FAT12 or FAT16 volume. 74 */ 75 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 76 goto error; 77 } 78 79 /* A volume with no name should have "NO NAME " as label. */ 80 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, 81 sizeof(pfat_bsbpb->BS_VolLab)) == 0) { 82 goto endofchecks; 83 } 84 strlcpy(label, pfat_bsbpb->BS_VolLab, 85 MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1)); 86 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 87 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 88 89 /* 90 * If the BPB_FATSz32 field is not zero and the string "FAT" is 91 * at the right place, this should be a FAT32 volume. 92 */ 93 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 94 goto error; 95 } 96 97 /* 98 * If the volume label is not "NO NAME " we're done. 99 */ 100 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 101 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 102 strlcpy(label, pfat32_bsbpb->BS_VolLab, 103 MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1)); 104 goto endofchecks; 105 } 106 107 /* 108 * If the volume label "NO NAME " is in the boot sector, the 109 * label of FAT32 volumes may be stored as a special entry in 110 * the root directory. 111 */ 112 fat_FirstDataSector = 113 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 114 (pfat32_bsbpb->BPB_NumFATs * 115 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 116 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 117 118 // fat_FirstDataSector, fat_BytesPerSector); 119 120 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 121 offset += fat_BytesPerSector) { 122 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); 123 if (sector == NULL) 124 goto error; 125 126 pfat_entry = (FAT_DES *)sector; 127 do { 128 /* No more entries available. */ 129 if (pfat_entry->DIR_Name[0] == 0) { 130 goto endofchecks; 131 } 132 133 /* Skip empty or long name entries. */ 134 if (pfat_entry->DIR_Name[0] == 0xe5 || 135 (pfat_entry->DIR_Attr & 136 FAT_DES_ATTR_LONG_NAME) == 137 FAT_DES_ATTR_LONG_NAME) { 138 continue; 139 } 140 141 /* 142 * The name of the entry is the volume label if 143 * ATTR_VOLUME_ID is set. 144 */ 145 if (pfat_entry->DIR_Attr & 146 FAT_DES_ATTR_VOLUME_ID) { 147 strlcpy(label, pfat_entry->DIR_Name, 148 MIN(size, 149 sizeof(pfat_entry->DIR_Name) + 1)); 150 goto endofchecks; 151 } 152 } while((uint8_t *)(++pfat_entry) < 153 (uint8_t *)(sector + fat_BytesPerSector)); 154 free(sector); 155 } 156 } else { 157 goto error; 158 } 159 160 endofchecks: 161 rtrim(label, size); 162 163 free(sector0); 164 free(sector); 165 166 return (0); 167 168 error: 169 free(sector0); 170 free(sector); 171 172 return (1); 173 } 174