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 <sys/param.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 38 #include "fstyp.h" 39 #include "msdosfs.h" 40 41 #define LABEL_NO_NAME "NO NAME " 42 43 int 44 fstyp_msdosfs(FILE *fp, char *label, size_t size, const char *devpath) 45 { 46 FAT_BSBPB *pfat_bsbpb; 47 FAT32_BSBPB *pfat32_bsbpb; 48 FAT_DES *pfat_entry; 49 uint8_t *sector0, *sector; 50 size_t copysize; 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 copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab)); 87 memcpy(label, pfat_bsbpb->BS_VolLab, copysize); 88 label[copysize] = '\0'; 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 copysize = MIN(size - 1, 106 sizeof(pfat32_bsbpb->BS_VolLab)); 107 memcpy(label, pfat32_bsbpb->BS_VolLab, copysize); 108 label[copysize] = '\0'; 109 goto endofchecks; 110 } 111 112 /* 113 * If the volume label "NO NAME " is in the boot sector, the 114 * label of FAT32 volumes may be stored as a special entry in 115 * the root directory. 116 */ 117 fat_FirstDataSector = 118 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 119 (pfat32_bsbpb->BPB_NumFATs * 120 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 121 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 122 123 // fat_FirstDataSector, fat_BytesPerSector); 124 125 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 126 offset += fat_BytesPerSector) { 127 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); 128 if (sector == NULL) 129 goto error; 130 131 pfat_entry = (FAT_DES *)sector; 132 do { 133 /* No more entries available. */ 134 if (pfat_entry->DIR_Name[0] == 0) { 135 goto endofchecks; 136 } 137 138 /* Skip empty or long name entries. */ 139 if (pfat_entry->DIR_Name[0] == 0xe5 || 140 (pfat_entry->DIR_Attr & 141 FAT_DES_ATTR_LONG_NAME) == 142 FAT_DES_ATTR_LONG_NAME) { 143 continue; 144 } 145 146 /* 147 * The name of the entry is the volume label if 148 * ATTR_VOLUME_ID is set. 149 */ 150 if (pfat_entry->DIR_Attr & 151 FAT_DES_ATTR_VOLUME_ID) { 152 copysize = MIN(size - 1, 153 sizeof(pfat_entry->DIR_Name)); 154 memcpy(label, pfat_entry->DIR_Name, 155 copysize); 156 label[copysize] = '\0'; 157 goto endofchecks; 158 } 159 } while((uint8_t *)(++pfat_entry) < 160 (uint8_t *)(sector + fat_BytesPerSector)); 161 free(sector); 162 } 163 } else { 164 goto error; 165 } 166 167 endofchecks: 168 rtrim(label, size); 169 170 free(sector0); 171 free(sector); 172 173 return (0); 174 175 error: 176 free(sector0); 177 free(sector); 178 179 return (1); 180 } 181