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
fstyp_msdosfs(FILE * fp,char * label,size_t size)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 uint32_t i;
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 strlcpy(label, pfat_bsbpb->BS_VolLab,
88 MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1));
89 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) {
90 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset;
91
92 /*
93 * If the BPB_FATSz32 field is not zero and the string "FAT" is
94 * at the right place, this should be a FAT32 volume.
95 */
96 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
97 goto error;
98 }
99
100 /*
101 * If the volume label is not "NO NAME " we're done.
102 */
103 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME,
104 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) {
105 strlcpy(label, pfat32_bsbpb->BS_VolLab,
106 MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1));
107 goto endofchecks;
108 }
109
110 /*
111 * If the volume label "NO NAME " is in the boot sector, the
112 * label of FAT32 volumes may be stored as a special entry in
113 * the root directory.
114 */
115 fat_FirstDataSector =
116 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) +
117 (pfat32_bsbpb->BPB_NumFATs *
118 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32));
119 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec);
120
121 // fat_FirstDataSector, fat_BytesPerSector);
122
123 for (offset = fat_BytesPerSector * fat_FirstDataSector;;
124 offset += fat_BytesPerSector) {
125 sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector);
126 if (sector == NULL)
127 goto error;
128
129 pfat_entry = (FAT_DES *)sector;
130 do {
131 /* No more entries available. */
132 if (pfat_entry->DIR_Name[0] == 0) {
133 goto endofchecks;
134 }
135
136 /* Skip empty or long name entries. */
137 if (pfat_entry->DIR_Name[0] == 0xe5 ||
138 (pfat_entry->DIR_Attr &
139 FAT_DES_ATTR_LONG_NAME) ==
140 FAT_DES_ATTR_LONG_NAME) {
141 continue;
142 }
143
144 /*
145 * The name of the entry is the volume label if
146 * ATTR_VOLUME_ID is set.
147 */
148 if (pfat_entry->DIR_Attr &
149 FAT_DES_ATTR_VOLUME_ID) {
150 strlcpy(label, pfat_entry->DIR_Name,
151 MIN(size,
152 sizeof(pfat_entry->DIR_Name) + 1));
153 goto endofchecks;
154 }
155 } while((uint8_t *)(++pfat_entry) <
156 (uint8_t *)(sector + fat_BytesPerSector));
157 free(sector);
158 }
159 } else {
160 goto error;
161 }
162
163 endofchecks:
164 for (i = size - 1; i > 0; i--) {
165 if (label[i] == '\0')
166 continue;
167 else if (label[i] == ' ')
168 label[i] = '\0';
169 else
170 break;
171 }
172
173 free(sector0);
174 free(sector);
175
176 return (0);
177
178 error:
179 free(sector0);
180 free(sector);
181
182 return (1);
183 }
184