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 52 sector0 = NULL; 53 sector = NULL; 54 55 /* Load 1st sector with boot sector and boot parameter block. */ 56 sector0 = (uint8_t *)read_buf(fp, 0, 512); 57 if (sector0 == NULL) 58 return (1); 59 60 /* Check for the FAT boot sector signature. */ 61 if (sector0[510] != 0x55 || sector0[511] != 0xaa) { 62 goto error; 63 } 64 65 /* 66 * Test if this is really a FAT volume and determine the FAT type. 67 */ 68 69 pfat_bsbpb = (FAT_BSBPB *)sector0; 70 pfat32_bsbpb = (FAT32_BSBPB *)sector0; 71 72 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { 73 /* 74 * If the BPB_FATSz16 field is not zero and the string "FAT" is 75 * at the right place, this should be a FAT12 or FAT16 volume. 76 */ 77 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 78 goto error; 79 } 80 81 /* A volume with no name should have "NO NAME " as label. */ 82 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, 83 sizeof(pfat_bsbpb->BS_VolLab)) == 0) { 84 goto endofchecks; 85 } 86 strlcpy(label, pfat_bsbpb->BS_VolLab, 87 MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1)); 88 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 89 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 90 91 /* 92 * If the BPB_FATSz32 field is not zero and the string "FAT" is 93 * at the right place, this should be a FAT32 volume. 94 */ 95 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 96 goto error; 97 } 98 99 /* 100 * If the volume label is not "NO NAME " we're done. 101 */ 102 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 103 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 104 strlcpy(label, pfat32_bsbpb->BS_VolLab, 105 MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1)); 106 goto endofchecks; 107 } 108 109 /* 110 * If the volume label "NO NAME " is in the boot sector, the 111 * label of FAT32 volumes may be stored as a special entry in 112 * the root directory. 113 */ 114 fat_FirstDataSector = 115 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 116 (pfat32_bsbpb->BPB_NumFATs * 117 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 118 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 119 120 // fat_FirstDataSector, fat_BytesPerSector); 121 122 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 123 offset += fat_BytesPerSector) { 124 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); 125 if (sector == NULL) 126 goto error; 127 128 pfat_entry = (FAT_DES *)sector; 129 do { 130 /* No more entries available. */ 131 if (pfat_entry->DIR_Name[0] == 0) { 132 goto endofchecks; 133 } 134 135 /* Skip empty or long name entries. */ 136 if (pfat_entry->DIR_Name[0] == 0xe5 || 137 (pfat_entry->DIR_Attr & 138 FAT_DES_ATTR_LONG_NAME) == 139 FAT_DES_ATTR_LONG_NAME) { 140 continue; 141 } 142 143 /* 144 * The name of the entry is the volume label if 145 * ATTR_VOLUME_ID is set. 146 */ 147 if (pfat_entry->DIR_Attr & 148 FAT_DES_ATTR_VOLUME_ID) { 149 strlcpy(label, pfat_entry->DIR_Name, 150 MIN(size, 151 sizeof(pfat_entry->DIR_Name) + 1)); 152 goto endofchecks; 153 } 154 } while((uint8_t *)(++pfat_entry) < 155 (uint8_t *)(sector + fat_BytesPerSector)); 156 free(sector); 157 } 158 } else { 159 goto error; 160 } 161 162 endofchecks: 163 rtrim(label, size); 164 165 free(sector0); 166 free(sector); 167 168 return (0); 169 170 error: 171 free(sector0); 172 free(sector); 173 174 return (1); 175 } 176