2 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * Copyright (c) 2006 Tobias Reifenberger
4 * Copyright (c) 2014 The FreeBSD Foundation
7 * This software was developed by Edward Tomasz Napierala under sponsorship
8 * from the FreeBSD Foundation.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
42 #define LABEL_NO_NAME "NO NAME "
45 * XXX the signature 0x55 0xAA as the last two bytes of 512 is not required
46 * by specifications, but was historically required by fstyp. This check
47 * should be removed, with a more comprehensive BPB validation instead.
50 check_signature(uint8_t sector0[512])
52 /* Check for the FAT boot sector signature. */
53 if (sector0[510] == 0x55 && sector0[511] == 0xaa)
55 /* Special case for Raspberry Pi Pico bootloader. */
56 if (sector0[510] == 0 && sector0[511] == 0 &&
57 sector0[0] == 0xeb && sector0[1] == 0x3c && sector0[2] == 0x90)
63 fstyp_msdosfs(FILE *fp, char *label, size_t size)
65 FAT_BSBPB *pfat_bsbpb;
66 FAT32_BSBPB *pfat32_bsbpb;
68 uint8_t *sector0, *sector;
74 /* Load 1st sector with boot sector and boot parameter block. */
75 sector0 = (uint8_t *)read_buf(fp, 0, 512);
79 if (!check_signature(sector0)) {
84 * Test if this is really a FAT volume and determine the FAT type.
87 pfat_bsbpb = (FAT_BSBPB *)sector0;
88 pfat32_bsbpb = (FAT32_BSBPB *)sector0;
90 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) {
92 * If the BPB_FATSz16 field is not zero and the string "FAT" is
93 * at the right place, this should be a FAT12 or FAT16 volume.
95 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
99 /* A volume with no name should have "NO NAME " as label. */
100 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME,
101 sizeof(pfat_bsbpb->BS_VolLab)) == 0) {
104 copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab));
105 memcpy(label, pfat_bsbpb->BS_VolLab, copysize);
106 label[copysize] = '\0';
107 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) {
108 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset;
111 * If the BPB_FATSz32 field is not zero and the string "FAT" is
112 * at the right place, this should be a FAT32 volume.
114 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
119 * If the volume label is not "NO NAME " we're done.
121 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME,
122 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) {
123 copysize = MIN(size - 1,
124 sizeof(pfat32_bsbpb->BS_VolLab));
125 memcpy(label, pfat32_bsbpb->BS_VolLab, copysize);
126 label[copysize] = '\0';
131 * If the volume label "NO NAME " is in the boot sector, the
132 * label of FAT32 volumes may be stored as a special entry in
133 * the root directory.
135 fat_FirstDataSector =
136 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) +
137 (pfat32_bsbpb->BPB_NumFATs *
138 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32));
139 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec);
141 // fat_FirstDataSector, fat_BytesPerSector);
143 for (offset = fat_BytesPerSector * fat_FirstDataSector;;
144 offset += fat_BytesPerSector) {
145 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector);
149 pfat_entry = (FAT_DES *)sector;
151 /* No more entries available. */
152 if (pfat_entry->DIR_Name[0] == 0) {
156 /* Skip empty or long name entries. */
157 if (pfat_entry->DIR_Name[0] == 0xe5 ||
158 (pfat_entry->DIR_Attr &
159 FAT_DES_ATTR_LONG_NAME) ==
160 FAT_DES_ATTR_LONG_NAME) {
165 * The name of the entry is the volume label if
166 * ATTR_VOLUME_ID is set.
168 if (pfat_entry->DIR_Attr &
169 FAT_DES_ATTR_VOLUME_ID) {
170 copysize = MIN(size - 1,
171 sizeof(pfat_entry->DIR_Name));
172 memcpy(label, pfat_entry->DIR_Name,
174 label[copysize] = '\0';
177 } while((uint8_t *)(++pfat_entry) <
178 (uint8_t *)(sector + fat_BytesPerSector));