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1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Written 1992,1993 by Werner Almesberger
4 * 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
5 * and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
6 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
7 */
8
9 #include <linux/time.h>
10 #include <linux/fs.h>
11 #include <linux/slab.h>
12 #include <linux/buffer_head.h>
13
14 #include "exfat_raw.h"
15 #include "exfat_fs.h"
16
17 /*
18 * exfat_fs_error reports a file system problem that might indicate fa data
19 * corruption/inconsistency. Depending on 'errors' mount option the
20 * panic() is called, or error message is printed FAT and nothing is done,
21 * or filesystem is remounted read-only (default behavior).
22 * In case the file system is remounted read-only, it can be made writable
23 * again by remounting it.
24 */
25 void __exfat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
26 {
27 struct exfat_mount_options *opts = &EXFAT_SB(sb)->options;
28 va_list args;
29 struct va_format vaf;
30
31 if (report) {
32 va_start(args, fmt);
33 vaf.fmt = fmt;
34 vaf.va = &args;
35 exfat_err(sb, "error, %pV", &vaf);
36 va_end(args);
37 }
38
39 if (opts->errors == EXFAT_ERRORS_PANIC) {
40 panic("exFAT-fs (%s): fs panic from previous error\n",
41 sb->s_id);
42 } else if (opts->errors == EXFAT_ERRORS_RO && !sb_rdonly(sb)) {
43 sb->s_flags |= SB_RDONLY;
44 exfat_err(sb, "Filesystem has been set read-only");
45 }
46 }
47
48 /*
49 * exfat_msg() - print preformated EXFAT specific messages.
50 * All logs except what uses exfat_fs_error() should be written by exfat_msg()
51 */
52 void exfat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
53 {
54 struct va_format vaf;
55 va_list args;
56
57 va_start(args, fmt);
58 vaf.fmt = fmt;
59 vaf.va = &args;
60 /* level means KERN_ pacility level */
61 printk("%sexFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
62 va_end(args);
63 }
64
65 #define SECS_PER_MIN (60)
66 #define TIMEZONE_SEC(x) ((x) * 15 * SECS_PER_MIN)
67
68 static void exfat_adjust_tz(struct timespec64 *ts, u8 tz_off)
69 {
70 if (tz_off <= 0x3F)
71 ts->tv_sec -= TIMEZONE_SEC(tz_off);
72 else /* 0x40 <= (tz_off & 0x7F) <=0x7F */
73 ts->tv_sec += TIMEZONE_SEC(0x80 - tz_off);
74 }
75
76 /* Convert a EXFAT time/date pair to a UNIX date (seconds since 1 1 70). */
77 void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
78 u8 tz, __le16 time, __le16 date, u8 time_cs)
79 {
80 u16 t = le16_to_cpu(time);
81 u16 d = le16_to_cpu(date);
82
83 ts->tv_sec = mktime64(1980 + (d >> 9), d >> 5 & 0x000F, d & 0x001F,
84 t >> 11, (t >> 5) & 0x003F, (t & 0x001F) << 1);
85
86
87 /* time_cs field represent 0 ~ 199cs(1990 ms) */
88 if (time_cs) {
89 ts->tv_sec += time_cs / 100;
90 ts->tv_nsec = (time_cs % 100) * 10 * NSEC_PER_MSEC;
91 } else
92 ts->tv_nsec = 0;
93
94 if (tz & EXFAT_TZ_VALID)
95 /* Adjust timezone to UTC0. */
96 exfat_adjust_tz(ts, tz & ~EXFAT_TZ_VALID);
97 else
98 /* Convert from local time to UTC using time_offset. */
99 ts->tv_sec -= sbi->options.time_offset * SECS_PER_MIN;
100 }
101
102 /* Convert linear UNIX date to a EXFAT time/date pair. */
103 void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
104 u8 *tz, __le16 *time, __le16 *date, u8 *time_cs)
105 {
106 struct tm tm;
107 u16 t, d;
108
109 time64_to_tm(ts->tv_sec, 0, &tm);
110 t = (tm.tm_hour << 11) | (tm.tm_min << 5) | (tm.tm_sec >> 1);
111 d = ((tm.tm_year - 80) << 9) | ((tm.tm_mon + 1) << 5) | tm.tm_mday;
112
113 *time = cpu_to_le16(t);
114 *date = cpu_to_le16(d);
115
116 /* time_cs field represent 0 ~ 199cs(1990 ms) */
117 if (time_cs)
118 *time_cs = (tm.tm_sec & 1) * 100 +
119 ts->tv_nsec / (10 * NSEC_PER_MSEC);
120
121 /*
122 * Record 00h value for OffsetFromUtc field and 1 value for OffsetValid
123 * to indicate that local time and UTC are the same.
124 */
125 *tz = EXFAT_TZ_VALID;
126 }
127
128 /*
129 * The timestamp for access_time has double seconds granularity.
130 * (There is no 10msIncrement field for access_time unlike create/modify_time)
131 * atime also has only a 2-second resolution.
132 */
133 void exfat_truncate_atime(struct timespec64 *ts)
134 {
135 ts->tv_sec = round_down(ts->tv_sec, 2);
136 ts->tv_nsec = 0;
137 }
138
139 u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type)
140 {
141 int i;
142 u8 *c = (u8 *)data;
143
144 for (i = 0; i < len; i++, c++) {
145 if (unlikely(type == CS_DIR_ENTRY && (i == 2 || i == 3)))
146 continue;
147 chksum = ((chksum << 15) | (chksum >> 1)) + *c;
148 }
149 return chksum;
150 }
151
152 u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type)
153 {
154 int i;
155 u8 *c = (u8 *)data;
156
157 for (i = 0; i < len; i++, c++) {
158 if (unlikely(type == CS_BOOT_SECTOR &&
159 (i == 106 || i == 107 || i == 112)))
160 continue;
161 chksum = ((chksum << 31) | (chksum >> 1)) + *c;
162 }
163 return chksum;
164 }
165
166 void exfat_update_bh(struct buffer_head *bh, int sync)
167 {
168 set_buffer_uptodate(bh);
169 mark_buffer_dirty(bh);
170
171 if (sync)
172 sync_dirty_buffer(bh);
173 }
174
175 int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync)
176 {
177 int i, err = 0;
178
179 for (i = 0; i < nr_bhs; i++) {
180 set_buffer_uptodate(bhs[i]);
181 mark_buffer_dirty(bhs[i]);
182 if (sync)
183 write_dirty_buffer(bhs[i], 0);
184 }
185
186 for (i = 0; i < nr_bhs && sync; i++) {
187 wait_on_buffer(bhs[i]);
188 if (!err && !buffer_uptodate(bhs[i]))
189 err = -EIO;
190 }
191 return err;
192 }
193
194 void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
195 unsigned int size, unsigned char flags)
196 {
197 ec->dir = dir;
198 ec->size = size;
199 ec->flags = flags;
200 }
201
202 void exfat_chain_dup(struct exfat_chain *dup, struct exfat_chain *ec)
203 {
204 return exfat_chain_set(dup, ec->dir, ec->size, ec->flags);
205 }