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 size_t copysize; 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 copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab)); 88 memcpy(label, pfat_bsbpb->BS_VolLab, copysize); 89 label[copysize] = '\0'; 90 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 91 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 92 93 /* 94 * If the BPB_FATSz32 field is not zero and the string "FAT" is 95 * at the right place, this should be a FAT32 volume. 96 */ 97 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 98 goto error; 99 } 100 101 /* 102 * If the volume label is not "NO NAME " we're done. 103 */ 104 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 105 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 106 copysize = MIN(size - 1, 107 sizeof(pfat32_bsbpb->BS_VolLab)); 108 memcpy(label, pfat32_bsbpb->BS_VolLab, copysize); 109 label[copysize] = '\0'; 110 goto endofchecks; 111 } 112 113 /* 114 * If the volume label "NO NAME " is in the boot sector, the 115 * label of FAT32 volumes may be stored as a special entry in 116 * the root directory. 117 */ 118 fat_FirstDataSector = 119 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 120 (pfat32_bsbpb->BPB_NumFATs * 121 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 122 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 123 124 // fat_FirstDataSector, fat_BytesPerSector); 125 126 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 127 offset += fat_BytesPerSector) { 128 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); 129 if (sector == NULL) 130 goto error; 131 132 pfat_entry = (FAT_DES *)sector; 133 do { 134 /* No more entries available. */ 135 if (pfat_entry->DIR_Name[0] == 0) { 136 goto endofchecks; 137 } 138 139 /* Skip empty or long name entries. */ 140 if (pfat_entry->DIR_Name[0] == 0xe5 || 141 (pfat_entry->DIR_Attr & 142 FAT_DES_ATTR_LONG_NAME) == 143 FAT_DES_ATTR_LONG_NAME) { 144 continue; 145 } 146 147 /* 148 * The name of the entry is the volume label if 149 * ATTR_VOLUME_ID is set. 150 */ 151 if (pfat_entry->DIR_Attr & 152 FAT_DES_ATTR_VOLUME_ID) { 153 copysize = MIN(size - 1, 154 sizeof(pfat_entry->DIR_Name)); 155 memcpy(label, pfat_entry->DIR_Name, 156 copysize); 157 label[copysize] = '\0'; 158 goto endofchecks; 159 } 160 } while((uint8_t *)(++pfat_entry) < 161 (uint8_t *)(sector + fat_BytesPerSector)); 162 free(sector); 163 } 164 } else { 165 goto error; 166 } 167 168 endofchecks: 169 rtrim(label, size); 170 171 free(sector0); 172 free(sector); 173 174 return (0); 175 176 error: 177 free(sector0); 178 free(sector); 179 180 return (1); 181 } 182