1 /*- 2 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3 * Copyright (c) 2006 Tobias Reifenberger 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/kernel.h> 34 #include <sys/malloc.h> 35 36 #include <geom/geom.h> 37 #include <geom/label/g_label.h> 38 #include <geom/label/g_label_msdosfs.h> 39 40 #define G_LABEL_MSDOSFS_DIR "msdosfs" 41 #define LABEL_NO_NAME "NO NAME " 42 43 static void 44 g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size) 45 { 46 struct g_provider *pp; 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 g_topology_assert_not(); 54 pp = cp->provider; 55 sector0 = NULL; 56 sector = NULL; 57 bzero(label, size); 58 59 /* Check if the sector size of the medium is a valid FAT sector size. */ 60 switch(pp->sectorsize) { 61 case 512: 62 case 1024: 63 case 2048: 64 case 4096: 65 break; 66 default: 67 G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.", 68 pp->name, pp->sectorsize); 69 return; 70 } 71 72 /* Load 1st sector with boot sector and boot parameter block. */ 73 sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL); 74 if (sector0 == NULL) 75 return; 76 77 /* Check for the FAT boot sector signature. */ 78 if (sector0[510] != 0x55 || sector0[511] != 0xaa) { 79 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.", 80 pp->name); 81 goto error; 82 } 83 84 85 /* 86 * Test if this is really a FAT volume and determine the FAT type. 87 */ 88 89 pfat_bsbpb = (FAT_BSBPB *)sector0; 90 pfat32_bsbpb = (FAT32_BSBPB *)sector0; 91 92 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { 93 /* 94 * If the BPB_FATSz16 field is not zero and the string "FAT" is 95 * at the right place, this should be a FAT12 or FAT16 volume. 96 */ 97 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 98 G_LABEL_DEBUG(1, 99 "MSDOSFS: %s: FAT12/16 volume not valid.", 100 pp->name); 101 goto error; 102 } 103 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.", 104 pp->name); 105 106 /* A volume with no name should have "NO NAME " as label. */ 107 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, 108 sizeof(pfat_bsbpb->BS_VolLab)) == 0) { 109 G_LABEL_DEBUG(1, 110 "MSDOSFS: %s: FAT12/16 volume has no name.", 111 pp->name); 112 goto error; 113 } 114 strlcpy(label, pfat_bsbpb->BS_VolLab, 115 MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1)); 116 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 117 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 118 119 /* 120 * If the BPB_FATSz32 field is not zero and the string "FAT" is 121 * at the right place, this should be a FAT32 volume. 122 */ 123 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 124 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.", 125 pp->name); 126 goto error; 127 } 128 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.", 129 pp->name); 130 131 /* 132 * If the volume label is not "NO NAME " we're done. 133 */ 134 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 135 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 136 strlcpy(label, pfat32_bsbpb->BS_VolLab, 137 MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1)); 138 goto endofchecks; 139 } 140 141 /* 142 * If the volume label "NO NAME " is in the boot sector, the 143 * label of FAT32 volumes may be stored as a special entry in 144 * the root directory. 145 */ 146 fat_FirstDataSector = 147 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 148 (pfat32_bsbpb->BPB_NumFATs * 149 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 150 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 151 152 G_LABEL_DEBUG(2, 153 "MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d", 154 fat_FirstDataSector, fat_BytesPerSector); 155 156 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 157 offset += fat_BytesPerSector) { 158 sector = (uint8_t *)g_read_data(cp, offset, 159 fat_BytesPerSector, NULL); 160 if (sector == NULL) 161 goto error; 162 163 pfat_entry = (FAT_DES *)sector; 164 do { 165 /* No more entries available. */ 166 if (pfat_entry->DIR_Name[0] == 0) { 167 G_LABEL_DEBUG(1, "MSDOSFS: %s: " 168 "FAT32 volume has no name.", 169 pp->name); 170 goto error; 171 } 172 173 /* Skip empty or long name entries. */ 174 if (pfat_entry->DIR_Name[0] == 0xe5 || 175 (pfat_entry->DIR_Attr & 176 FAT_DES_ATTR_LONG_NAME) == 177 FAT_DES_ATTR_LONG_NAME) { 178 continue; 179 } 180 181 /* 182 * The name of the entry is the volume label if 183 * ATTR_VOLUME_ID is set. 184 */ 185 if (pfat_entry->DIR_Attr & 186 FAT_DES_ATTR_VOLUME_ID) { 187 strlcpy(label, pfat_entry->DIR_Name, 188 MIN(size, 189 sizeof(pfat_entry->DIR_Name) + 1)); 190 goto endofchecks; 191 } 192 } while((uint8_t *)(++pfat_entry) < 193 (uint8_t *)(sector + fat_BytesPerSector)); 194 g_free(sector); 195 } 196 } else { 197 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.", 198 pp->name); 199 goto error; 200 } 201 202 endofchecks: 203 for (i = size - 1; i > 0; i--) { 204 if (label[i] == '\0') 205 continue; 206 else if (label[i] == ' ') 207 label[i] = '\0'; 208 else 209 break; 210 } 211 212 error: 213 if (sector0 != NULL) 214 g_free(sector0); 215 if (sector != NULL) 216 g_free(sector); 217 } 218 219 const struct g_label_desc g_label_msdosfs = { 220 .ld_taste = g_label_msdosfs_taste, 221 .ld_dir = G_LABEL_MSDOSFS_DIR 222 }; 223