1be3a49eeSEdward Tomasz Napierala /*-
2be3a49eeSEdward Tomasz Napierala * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3be3a49eeSEdward Tomasz Napierala * Copyright (c) 2006 Tobias Reifenberger
4be3a49eeSEdward Tomasz Napierala * Copyright (c) 2014 The FreeBSD Foundation
5be3a49eeSEdward Tomasz Napierala * All rights reserved.
6be3a49eeSEdward Tomasz Napierala *
7be3a49eeSEdward Tomasz Napierala * This software was developed by Edward Tomasz Napierala under sponsorship
8be3a49eeSEdward Tomasz Napierala * from the FreeBSD Foundation.
9be3a49eeSEdward Tomasz Napierala *
10be3a49eeSEdward Tomasz Napierala * Redistribution and use in source and binary forms, with or without
11be3a49eeSEdward Tomasz Napierala * modification, are permitted provided that the following conditions
12be3a49eeSEdward Tomasz Napierala * are met:
13be3a49eeSEdward Tomasz Napierala * 1. Redistributions of source code must retain the above copyright
14be3a49eeSEdward Tomasz Napierala * notice, this list of conditions and the following disclaimer.
15be3a49eeSEdward Tomasz Napierala * 2. Redistributions in binary form must reproduce the above copyright
16be3a49eeSEdward Tomasz Napierala * notice, this list of conditions and the following disclaimer in the
17be3a49eeSEdward Tomasz Napierala * documentation and/or other materials provided with the distribution.
18be3a49eeSEdward Tomasz Napierala *
19be3a49eeSEdward Tomasz Napierala * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
20be3a49eeSEdward Tomasz Napierala * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21be3a49eeSEdward Tomasz Napierala * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22be3a49eeSEdward Tomasz Napierala * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
23be3a49eeSEdward Tomasz Napierala * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24be3a49eeSEdward Tomasz Napierala * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25be3a49eeSEdward Tomasz Napierala * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26be3a49eeSEdward Tomasz Napierala * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27be3a49eeSEdward Tomasz Napierala * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28be3a49eeSEdward Tomasz Napierala * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29be3a49eeSEdward Tomasz Napierala * SUCH DAMAGE.
30be3a49eeSEdward Tomasz Napierala */
31be3a49eeSEdward Tomasz Napierala
32be3a49eeSEdward Tomasz Napierala #include <sys/cdefs.h>
33be3a49eeSEdward Tomasz Napierala #include <stdio.h>
34be3a49eeSEdward Tomasz Napierala #include <stdlib.h>
35be3a49eeSEdward Tomasz Napierala #include <string.h>
36be3a49eeSEdward Tomasz Napierala
37be3a49eeSEdward Tomasz Napierala #include "fstyp.h"
38be3a49eeSEdward Tomasz Napierala #include "msdosfs.h"
39be3a49eeSEdward Tomasz Napierala
40be3a49eeSEdward Tomasz Napierala #define LABEL_NO_NAME "NO NAME "
41be3a49eeSEdward Tomasz Napierala
42868c1b84SEd Maste /*
43868c1b84SEd Maste * XXX the signature 0x55 0xAA as the last two bytes of 512 is not required
44868c1b84SEd Maste * by specifications, but was historically required by fstyp. This check
45868c1b84SEd Maste * should be removed, with a more comprehensive BPB validation instead.
46868c1b84SEd Maste */
47868c1b84SEd Maste static bool
check_signature(uint8_t sector0[512])48868c1b84SEd Maste check_signature(uint8_t sector0[512])
49868c1b84SEd Maste {
50868c1b84SEd Maste /* Check for the FAT boot sector signature. */
51868c1b84SEd Maste if (sector0[510] == 0x55 && sector0[511] == 0xaa)
52868c1b84SEd Maste return (true);
53*27c2f016SEd Maste /* Special case for Raspberry Pi Pico bootloader. */
54868c1b84SEd Maste if (sector0[510] == 0 && sector0[511] == 0 &&
55868c1b84SEd Maste sector0[0] == 0xeb && sector0[1] == 0x3c && sector0[2] == 0x90)
56868c1b84SEd Maste return (true);
57868c1b84SEd Maste return (false);
58868c1b84SEd Maste }
59868c1b84SEd Maste
60be3a49eeSEdward Tomasz Napierala int
fstyp_msdosfs(FILE * fp,char * label,size_t size)61be3a49eeSEdward Tomasz Napierala fstyp_msdosfs(FILE *fp, char *label, size_t size)
62be3a49eeSEdward Tomasz Napierala {
63be3a49eeSEdward Tomasz Napierala FAT_BSBPB *pfat_bsbpb;
64be3a49eeSEdward Tomasz Napierala FAT32_BSBPB *pfat32_bsbpb;
65be3a49eeSEdward Tomasz Napierala FAT_DES *pfat_entry;
66be3a49eeSEdward Tomasz Napierala uint8_t *sector0, *sector;
6734fb1c13SJessica Clarke size_t copysize;
68be3a49eeSEdward Tomasz Napierala
69be3a49eeSEdward Tomasz Napierala sector0 = NULL;
70be3a49eeSEdward Tomasz Napierala sector = NULL;
71be3a49eeSEdward Tomasz Napierala
72be3a49eeSEdward Tomasz Napierala /* Load 1st sector with boot sector and boot parameter block. */
73be3a49eeSEdward Tomasz Napierala sector0 = (uint8_t *)read_buf(fp, 0, 512);
74be3a49eeSEdward Tomasz Napierala if (sector0 == NULL)
75be3a49eeSEdward Tomasz Napierala return (1);
76be3a49eeSEdward Tomasz Napierala
77868c1b84SEd Maste if (!check_signature(sector0)) {
78be3a49eeSEdward Tomasz Napierala goto error;
79be3a49eeSEdward Tomasz Napierala }
80be3a49eeSEdward Tomasz Napierala
81be3a49eeSEdward Tomasz Napierala /*
82be3a49eeSEdward Tomasz Napierala * Test if this is really a FAT volume and determine the FAT type.
83be3a49eeSEdward Tomasz Napierala */
84be3a49eeSEdward Tomasz Napierala
85be3a49eeSEdward Tomasz Napierala pfat_bsbpb = (FAT_BSBPB *)sector0;
86be3a49eeSEdward Tomasz Napierala pfat32_bsbpb = (FAT32_BSBPB *)sector0;
87be3a49eeSEdward Tomasz Napierala
88be3a49eeSEdward Tomasz Napierala if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) {
89be3a49eeSEdward Tomasz Napierala /*
90be3a49eeSEdward Tomasz Napierala * If the BPB_FATSz16 field is not zero and the string "FAT" is
91be3a49eeSEdward Tomasz Napierala * at the right place, this should be a FAT12 or FAT16 volume.
92be3a49eeSEdward Tomasz Napierala */
93be3a49eeSEdward Tomasz Napierala if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
94be3a49eeSEdward Tomasz Napierala goto error;
95be3a49eeSEdward Tomasz Napierala }
96be3a49eeSEdward Tomasz Napierala
97be3a49eeSEdward Tomasz Napierala /* A volume with no name should have "NO NAME " as label. */
98be3a49eeSEdward Tomasz Napierala if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME,
99be3a49eeSEdward Tomasz Napierala sizeof(pfat_bsbpb->BS_VolLab)) == 0) {
100be3a49eeSEdward Tomasz Napierala goto endofchecks;
101be3a49eeSEdward Tomasz Napierala }
10234fb1c13SJessica Clarke copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab));
10334fb1c13SJessica Clarke memcpy(label, pfat_bsbpb->BS_VolLab, copysize);
10434fb1c13SJessica Clarke label[copysize] = '\0';
105be3a49eeSEdward Tomasz Napierala } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) {
106be3a49eeSEdward Tomasz Napierala uint32_t fat_FirstDataSector, fat_BytesPerSector, offset;
107be3a49eeSEdward Tomasz Napierala
108be3a49eeSEdward Tomasz Napierala /*
109be3a49eeSEdward Tomasz Napierala * If the BPB_FATSz32 field is not zero and the string "FAT" is
110be3a49eeSEdward Tomasz Napierala * at the right place, this should be a FAT32 volume.
111be3a49eeSEdward Tomasz Napierala */
112be3a49eeSEdward Tomasz Napierala if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
113be3a49eeSEdward Tomasz Napierala goto error;
114be3a49eeSEdward Tomasz Napierala }
115be3a49eeSEdward Tomasz Napierala
116be3a49eeSEdward Tomasz Napierala /*
117be3a49eeSEdward Tomasz Napierala * If the volume label is not "NO NAME " we're done.
118be3a49eeSEdward Tomasz Napierala */
119be3a49eeSEdward Tomasz Napierala if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME,
120be3a49eeSEdward Tomasz Napierala sizeof(pfat32_bsbpb->BS_VolLab)) != 0) {
12134fb1c13SJessica Clarke copysize = MIN(size - 1,
12263d24336SJessica Clarke sizeof(pfat32_bsbpb->BS_VolLab));
12334fb1c13SJessica Clarke memcpy(label, pfat32_bsbpb->BS_VolLab, copysize);
12434fb1c13SJessica Clarke label[copysize] = '\0';
125be3a49eeSEdward Tomasz Napierala goto endofchecks;
126be3a49eeSEdward Tomasz Napierala }
127be3a49eeSEdward Tomasz Napierala
128be3a49eeSEdward Tomasz Napierala /*
129be3a49eeSEdward Tomasz Napierala * If the volume label "NO NAME " is in the boot sector, the
130be3a49eeSEdward Tomasz Napierala * label of FAT32 volumes may be stored as a special entry in
131be3a49eeSEdward Tomasz Napierala * the root directory.
132be3a49eeSEdward Tomasz Napierala */
133be3a49eeSEdward Tomasz Napierala fat_FirstDataSector =
134be3a49eeSEdward Tomasz Napierala UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) +
135be3a49eeSEdward Tomasz Napierala (pfat32_bsbpb->BPB_NumFATs *
136be3a49eeSEdward Tomasz Napierala UINT32BYTES(pfat32_bsbpb->BPB_FATSz32));
137be3a49eeSEdward Tomasz Napierala fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec);
138be3a49eeSEdward Tomasz Napierala
139be3a49eeSEdward Tomasz Napierala // fat_FirstDataSector, fat_BytesPerSector);
140be3a49eeSEdward Tomasz Napierala
141be3a49eeSEdward Tomasz Napierala for (offset = fat_BytesPerSector * fat_FirstDataSector;;
142be3a49eeSEdward Tomasz Napierala offset += fat_BytesPerSector) {
143be3a49eeSEdward Tomasz Napierala sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector);
144be3a49eeSEdward Tomasz Napierala if (sector == NULL)
145be3a49eeSEdward Tomasz Napierala goto error;
146be3a49eeSEdward Tomasz Napierala
147be3a49eeSEdward Tomasz Napierala pfat_entry = (FAT_DES *)sector;
148be3a49eeSEdward Tomasz Napierala do {
149be3a49eeSEdward Tomasz Napierala /* No more entries available. */
150be3a49eeSEdward Tomasz Napierala if (pfat_entry->DIR_Name[0] == 0) {
151be3a49eeSEdward Tomasz Napierala goto endofchecks;
152be3a49eeSEdward Tomasz Napierala }
153be3a49eeSEdward Tomasz Napierala
154be3a49eeSEdward Tomasz Napierala /* Skip empty or long name entries. */
155be3a49eeSEdward Tomasz Napierala if (pfat_entry->DIR_Name[0] == 0xe5 ||
156be3a49eeSEdward Tomasz Napierala (pfat_entry->DIR_Attr &
157be3a49eeSEdward Tomasz Napierala FAT_DES_ATTR_LONG_NAME) ==
158be3a49eeSEdward Tomasz Napierala FAT_DES_ATTR_LONG_NAME) {
159be3a49eeSEdward Tomasz Napierala continue;
160be3a49eeSEdward Tomasz Napierala }
161be3a49eeSEdward Tomasz Napierala
162be3a49eeSEdward Tomasz Napierala /*
163be3a49eeSEdward Tomasz Napierala * The name of the entry is the volume label if
164be3a49eeSEdward Tomasz Napierala * ATTR_VOLUME_ID is set.
165be3a49eeSEdward Tomasz Napierala */
166be3a49eeSEdward Tomasz Napierala if (pfat_entry->DIR_Attr &
167be3a49eeSEdward Tomasz Napierala FAT_DES_ATTR_VOLUME_ID) {
16834fb1c13SJessica Clarke copysize = MIN(size - 1,
16934fb1c13SJessica Clarke sizeof(pfat_entry->DIR_Name));
17034fb1c13SJessica Clarke memcpy(label, pfat_entry->DIR_Name,
17134fb1c13SJessica Clarke copysize);
17234fb1c13SJessica Clarke label[copysize] = '\0';
173be3a49eeSEdward Tomasz Napierala goto endofchecks;
174be3a49eeSEdward Tomasz Napierala }
175be3a49eeSEdward Tomasz Napierala } while((uint8_t *)(++pfat_entry) <
176be3a49eeSEdward Tomasz Napierala (uint8_t *)(sector + fat_BytesPerSector));
177be3a49eeSEdward Tomasz Napierala free(sector);
178be3a49eeSEdward Tomasz Napierala }
179be3a49eeSEdward Tomasz Napierala } else {
180be3a49eeSEdward Tomasz Napierala goto error;
181be3a49eeSEdward Tomasz Napierala }
182be3a49eeSEdward Tomasz Napierala
183be3a49eeSEdward Tomasz Napierala endofchecks:
184628b7128SEdward Tomasz Napierala rtrim(label, size);
185be3a49eeSEdward Tomasz Napierala
186be3a49eeSEdward Tomasz Napierala free(sector0);
187be3a49eeSEdward Tomasz Napierala free(sector);
188be3a49eeSEdward Tomasz Napierala
189be3a49eeSEdward Tomasz Napierala return (0);
190be3a49eeSEdward Tomasz Napierala
191be3a49eeSEdward Tomasz Napierala error:
192be3a49eeSEdward Tomasz Napierala free(sector0);
193be3a49eeSEdward Tomasz Napierala free(sector);
194be3a49eeSEdward Tomasz Napierala
195be3a49eeSEdward Tomasz Napierala return (1);
196be3a49eeSEdward Tomasz Napierala }
197