1 /*- 2 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3 * Copyright (c) 2006 Tobias Reifenberger 4 * Copyright (c) 2014 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * This software was developed by Edward Tomasz Napierala under sponsorship 8 * from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <stdio.h> 36 #include <stdlib.h> 37 #include <string.h> 38 39 #include "fstyp.h" 40 #include "msdosfs.h" 41 42 #define LABEL_NO_NAME "NO NAME " 43 44 int 45 fstyp_msdosfs(FILE *fp, char *label, size_t size) 46 { 47 FAT_BSBPB *pfat_bsbpb; 48 FAT32_BSBPB *pfat32_bsbpb; 49 FAT_DES *pfat_entry; 50 uint8_t *sector0, *sector; 51 uint32_t i; 52 53 sector0 = NULL; 54 sector = NULL; 55 56 /* Load 1st sector with boot sector and boot parameter block. */ 57 sector0 = (uint8_t *)read_buf(fp, 0, 512); 58 if (sector0 == NULL) 59 return (1); 60 61 /* Check for the FAT boot sector signature. */ 62 if (sector0[510] != 0x55 || sector0[511] != 0xaa) { 63 goto error; 64 } 65 66 /* 67 * Test if this is really a FAT volume and determine the FAT type. 68 */ 69 70 pfat_bsbpb = (FAT_BSBPB *)sector0; 71 pfat32_bsbpb = (FAT32_BSBPB *)sector0; 72 73 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { 74 /* 75 * If the BPB_FATSz16 field is not zero and the string "FAT" is 76 * at the right place, this should be a FAT12 or FAT16 volume. 77 */ 78 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 79 goto error; 80 } 81 82 /* A volume with no name should have "NO NAME " as label. */ 83 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, 84 sizeof(pfat_bsbpb->BS_VolLab)) == 0) { 85 goto endofchecks; 86 } 87 strlcpy(label, pfat_bsbpb->BS_VolLab, 88 MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1)); 89 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 90 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 91 92 /* 93 * If the BPB_FATSz32 field is not zero and the string "FAT" is 94 * at the right place, this should be a FAT32 volume. 95 */ 96 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 97 goto error; 98 } 99 100 /* 101 * If the volume label is not "NO NAME " we're done. 102 */ 103 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 104 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 105 strlcpy(label, pfat32_bsbpb->BS_VolLab, 106 MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1)); 107 goto endofchecks; 108 } 109 110 /* 111 * If the volume label "NO NAME " is in the boot sector, the 112 * label of FAT32 volumes may be stored as a special entry in 113 * the root directory. 114 */ 115 fat_FirstDataSector = 116 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 117 (pfat32_bsbpb->BPB_NumFATs * 118 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 119 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 120 121 // fat_FirstDataSector, fat_BytesPerSector); 122 123 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 124 offset += fat_BytesPerSector) { 125 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); 126 if (sector == NULL) 127 goto error; 128 129 pfat_entry = (FAT_DES *)sector; 130 do { 131 /* No more entries available. */ 132 if (pfat_entry->DIR_Name[0] == 0) { 133 goto endofchecks; 134 } 135 136 /* Skip empty or long name entries. */ 137 if (pfat_entry->DIR_Name[0] == 0xe5 || 138 (pfat_entry->DIR_Attr & 139 FAT_DES_ATTR_LONG_NAME) == 140 FAT_DES_ATTR_LONG_NAME) { 141 continue; 142 } 143 144 /* 145 * The name of the entry is the volume label if 146 * ATTR_VOLUME_ID is set. 147 */ 148 if (pfat_entry->DIR_Attr & 149 FAT_DES_ATTR_VOLUME_ID) { 150 strlcpy(label, pfat_entry->DIR_Name, 151 MIN(size, 152 sizeof(pfat_entry->DIR_Name) + 1)); 153 goto endofchecks; 154 } 155 } while((uint8_t *)(++pfat_entry) < 156 (uint8_t *)(sector + fat_BytesPerSector)); 157 free(sector); 158 } 159 } else { 160 goto error; 161 } 162 163 endofchecks: 164 for (i = size - 1; i > 0; i--) { 165 if (label[i] == '\0') 166 continue; 167 else if (label[i] == ' ') 168 label[i] = '\0'; 169 else 170 break; 171 } 172 173 free(sector0); 174 free(sector); 175 176 return (0); 177 178 error: 179 free(sector0); 180 free(sector); 181 182 return (1); 183 } 184