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