2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
5 * Copyright (c) 2006 Tobias Reifenberger
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/kernel.h>
36 #include <sys/malloc.h>
38 #include <geom/geom.h>
39 #include <geom/geom_dbg.h>
40 #include <geom/label/g_label.h>
41 #include <geom/label/g_label_msdosfs.h>
43 #define LABEL_NO_NAME "NO NAME "
46 g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size)
48 struct g_provider *pp;
49 FAT_BSBPB *pfat_bsbpb;
50 FAT32_BSBPB *pfat32_bsbpb;
52 uint8_t *sector0, *sector;
54 g_topology_assert_not();
60 /* Check if the sector size of the medium is a valid FAT sector size. */
61 switch(pp->sectorsize) {
68 G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.",
69 pp->name, pp->sectorsize);
73 /* Load 1st sector with boot sector and boot parameter block. */
74 sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL);
78 /* Check for the FAT boot sector signature. */
79 if (sector0[510] != 0x55 || sector0[511] != 0xaa) {
80 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.",
86 * Test if this is really a FAT volume and determine the FAT type.
89 pfat_bsbpb = (FAT_BSBPB *)sector0;
90 pfat32_bsbpb = (FAT32_BSBPB *)sector0;
92 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) {
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.
97 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
99 "MSDOSFS: %s: FAT12/16 volume not valid.",
103 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.",
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) {
110 "MSDOSFS: %s: FAT12/16 volume has no name.",
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;
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.
123 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
124 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.",
128 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.",
132 * If the volume label is not "NO NAME " we're done.
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));
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.
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);
153 "MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d",
154 fat_FirstDataSector, fat_BytesPerSector);
156 for (offset = fat_BytesPerSector * fat_FirstDataSector;;
157 offset += fat_BytesPerSector) {
158 sector = (uint8_t *)g_read_data(cp, offset,
159 fat_BytesPerSector, NULL);
163 pfat_entry = (FAT_DES *)sector;
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.",
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) {
182 * The name of the entry is the volume label if
183 * ATTR_VOLUME_ID is set.
185 if (pfat_entry->DIR_Attr &
186 FAT_DES_ATTR_VOLUME_ID) {
187 strlcpy(label, pfat_entry->DIR_Name,
189 sizeof(pfat_entry->DIR_Name) + 1));
192 } while((uint8_t *)(++pfat_entry) <
193 (uint8_t *)(sector + fat_BytesPerSector));
197 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.",
203 g_label_rtrim(label, size);
212 struct g_label_desc g_label_msdosfs = {
213 .ld_taste = g_label_msdosfs_taste,
214 .ld_dirprefix = "msdosfs/",
218 G_LABEL_INIT(msdosfs, g_label_msdosfs, "Create device nodes for MSDOSFS volumes");