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 /*
50  * exfat_msg() - print preformated EXFAT specific messages.
51  * All logs except what uses exfat_fs_error() should be written by exfat_msg()
52  */
exfat_msg(struct super_block * sb,const char * level,const char * fmt,...)53 void exfat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
54 {
55 	struct va_format vaf;
56 	va_list args;
57 
58 	va_start(args, fmt);
59 	vaf.fmt = fmt;
60 	vaf.va = &args;
61 	/* level means KERN_ pacility level */
62 	printk("%sexFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
63 	va_end(args);
64 }
65 
66 #define SECS_PER_MIN    (60)
67 #define TIMEZONE_SEC(x)	((x) * 15 * SECS_PER_MIN)
68 
exfat_adjust_tz(struct timespec64 * ts,u8 tz_off)69 static void exfat_adjust_tz(struct timespec64 *ts, u8 tz_off)
70 {
71 	if (tz_off <= 0x3F)
72 		ts->tv_sec -= TIMEZONE_SEC(tz_off);
73 	else /* 0x40 <= (tz_off & 0x7F) <=0x7F */
74 		ts->tv_sec += TIMEZONE_SEC(0x80 - tz_off);
75 }
76 
exfat_tz_offset(struct exfat_sb_info * sbi)77 static inline int exfat_tz_offset(struct exfat_sb_info *sbi)
78 {
79 	if (sbi->options.sys_tz)
80 		return -sys_tz.tz_minuteswest;
81 	return sbi->options.time_offset;
82 }
83 
84 /* 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)85 void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
86 		u8 tz, __le16 time, __le16 date, u8 time_cs)
87 {
88 	u16 t = le16_to_cpu(time);
89 	u16 d = le16_to_cpu(date);
90 
91 	ts->tv_sec = mktime64(1980 + (d >> 9), d >> 5 & 0x000F, d & 0x001F,
92 			      t >> 11, (t >> 5) & 0x003F, (t & 0x001F) << 1);
93 
94 
95 	/* time_cs field represent 0 ~ 199cs(1990 ms) */
96 	if (time_cs) {
97 		ts->tv_sec += time_cs / 100;
98 		ts->tv_nsec = (time_cs % 100) * 10 * NSEC_PER_MSEC;
99 	} else
100 		ts->tv_nsec = 0;
101 
102 	if (tz & EXFAT_TZ_VALID)
103 		/* Adjust timezone to UTC0. */
104 		exfat_adjust_tz(ts, tz & ~EXFAT_TZ_VALID);
105 	else
106 		ts->tv_sec -= exfat_tz_offset(sbi) * SECS_PER_MIN;
107 }
108 
109 /* 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)110 void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
111 		u8 *tz, __le16 *time, __le16 *date, u8 *time_cs)
112 {
113 	struct tm tm;
114 	u16 t, d;
115 
116 	time64_to_tm(ts->tv_sec, 0, &tm);
117 	t = (tm.tm_hour << 11) | (tm.tm_min << 5) | (tm.tm_sec >> 1);
118 	d = ((tm.tm_year - 80) <<  9) | ((tm.tm_mon + 1) << 5) | tm.tm_mday;
119 
120 	*time = cpu_to_le16(t);
121 	*date = cpu_to_le16(d);
122 
123 	/* time_cs field represent 0 ~ 199cs(1990 ms) */
124 	if (time_cs)
125 		*time_cs = (tm.tm_sec & 1) * 100 +
126 			ts->tv_nsec / (10 * NSEC_PER_MSEC);
127 
128 	/*
129 	 * Record 00h value for OffsetFromUtc field and 1 value for OffsetValid
130 	 * to indicate that local time and UTC are the same.
131 	 */
132 	*tz = EXFAT_TZ_VALID;
133 }
134 
135 /*
136  * The timestamp for access_time has double seconds granularity.
137  * (There is no 10msIncrement field for access_time unlike create/modify_time)
138  * atime also has only a 2-second resolution.
139  */
exfat_truncate_atime(struct timespec64 * ts)140 void exfat_truncate_atime(struct timespec64 *ts)
141 {
142 	ts->tv_sec = round_down(ts->tv_sec, 2);
143 	ts->tv_nsec = 0;
144 }
145 
exfat_calc_chksum16(void * data,int len,u16 chksum,int type)146 u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type)
147 {
148 	int i;
149 	u8 *c = (u8 *)data;
150 
151 	for (i = 0; i < len; i++, c++) {
152 		if (unlikely(type == CS_DIR_ENTRY && (i == 2 || i == 3)))
153 			continue;
154 		chksum = ((chksum << 15) | (chksum >> 1)) + *c;
155 	}
156 	return chksum;
157 }
158 
exfat_calc_chksum32(void * data,int len,u32 chksum,int type)159 u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type)
160 {
161 	int i;
162 	u8 *c = (u8 *)data;
163 
164 	for (i = 0; i < len; i++, c++) {
165 		if (unlikely(type == CS_BOOT_SECTOR &&
166 			     (i == 106 || i == 107 || i == 112)))
167 			continue;
168 		chksum = ((chksum << 31) | (chksum >> 1)) + *c;
169 	}
170 	return chksum;
171 }
172 
exfat_update_bh(struct buffer_head * bh,int sync)173 void exfat_update_bh(struct buffer_head *bh, int sync)
174 {
175 	set_buffer_uptodate(bh);
176 	mark_buffer_dirty(bh);
177 
178 	if (sync)
179 		sync_dirty_buffer(bh);
180 }
181 
exfat_update_bhs(struct buffer_head ** bhs,int nr_bhs,int sync)182 int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync)
183 {
184 	int i, err = 0;
185 
186 	for (i = 0; i < nr_bhs; i++) {
187 		set_buffer_uptodate(bhs[i]);
188 		mark_buffer_dirty(bhs[i]);
189 		if (sync)
190 			write_dirty_buffer(bhs[i], REQ_SYNC);
191 	}
192 
193 	for (i = 0; i < nr_bhs && sync; i++) {
194 		wait_on_buffer(bhs[i]);
195 		if (!err && !buffer_uptodate(bhs[i]))
196 			err = -EIO;
197 	}
198 	return err;
199 }
200 
exfat_chain_set(struct exfat_chain * ec,unsigned int dir,unsigned int size,unsigned char flags)201 void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
202 		unsigned int size, unsigned char flags)
203 {
204 	ec->dir = dir;
205 	ec->size = size;
206 	ec->flags = flags;
207 }
208 
exfat_chain_dup(struct exfat_chain * dup,struct exfat_chain * ec)209 void exfat_chain_dup(struct exfat_chain *dup, struct exfat_chain *ec)
210 {
211 	return exfat_chain_set(dup, ec->dir, ec->size, ec->flags);
212 }
213