1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * time.h - NTFS time conversion functions. Part of the Linux-NTFS project. |
4 | * |
5 | * Copyright (c) 2001-2005 Anton Altaparmakov |
6 | */ |
7 | |
8 | #ifndef _LINUX_NTFS_TIME_H |
9 | #define _LINUX_NTFS_TIME_H |
10 | |
11 | #include <linux/time.h> /* For current_kernel_time(). */ |
12 | #include <asm/div64.h> /* For do_div(). */ |
13 | |
14 | #include "endian.h" |
15 | |
16 | #define NTFS_TIME_OFFSET ((s64)(369 * 365 + 89) * 24 * 3600 * 10000000) |
17 | |
18 | /** |
19 | * utc2ntfs - convert Linux UTC time to NTFS time |
20 | * @ts: Linux UTC time to convert to NTFS time |
21 | * |
22 | * Convert the Linux UTC time @ts to its corresponding NTFS time and return |
23 | * that in little endian format. |
24 | * |
25 | * Linux stores time in a struct timespec64 consisting of a time64_t tv_sec |
26 | * and a long tv_nsec where tv_sec is the number of 1-second intervals since |
27 | * 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second |
28 | * intervals since the value of tv_sec. |
29 | * |
30 | * NTFS uses Microsoft's standard time format which is stored in a s64 and is |
31 | * measured as the number of 100-nano-second intervals since 1st January 1601, |
32 | * 00:00:00 UTC. |
33 | */ |
34 | static inline sle64 utc2ntfs(const struct timespec64 ts) |
35 | { |
36 | /* |
37 | * Convert the seconds to 100ns intervals, add the nano-seconds |
38 | * converted to 100ns intervals, and then add the NTFS time offset. |
39 | */ |
40 | return cpu_to_sle64(x: (s64)ts.tv_sec * 10000000 + ts.tv_nsec / 100 + |
41 | NTFS_TIME_OFFSET); |
42 | } |
43 | |
44 | /** |
45 | * get_current_ntfs_time - get the current time in little endian NTFS format |
46 | * |
47 | * Get the current time from the Linux kernel, convert it to its corresponding |
48 | * NTFS time and return that in little endian format. |
49 | */ |
50 | static inline sle64 get_current_ntfs_time(void) |
51 | { |
52 | struct timespec64 ts; |
53 | |
54 | ktime_get_coarse_real_ts64(ts: &ts); |
55 | return utc2ntfs(ts); |
56 | } |
57 | |
58 | /** |
59 | * ntfs2utc - convert NTFS time to Linux time |
60 | * @time: NTFS time (little endian) to convert to Linux UTC |
61 | * |
62 | * Convert the little endian NTFS time @time to its corresponding Linux UTC |
63 | * time and return that in cpu format. |
64 | * |
65 | * Linux stores time in a struct timespec64 consisting of a time64_t tv_sec |
66 | * and a long tv_nsec where tv_sec is the number of 1-second intervals since |
67 | * 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second |
68 | * intervals since the value of tv_sec. |
69 | * |
70 | * NTFS uses Microsoft's standard time format which is stored in a s64 and is |
71 | * measured as the number of 100 nano-second intervals since 1st January 1601, |
72 | * 00:00:00 UTC. |
73 | */ |
74 | static inline struct timespec64 ntfs2utc(const sle64 time) |
75 | { |
76 | struct timespec64 ts; |
77 | |
78 | /* Subtract the NTFS time offset. */ |
79 | u64 t = (u64)(sle64_to_cpu(x: time) - NTFS_TIME_OFFSET); |
80 | /* |
81 | * Convert the time to 1-second intervals and the remainder to |
82 | * 1-nano-second intervals. |
83 | */ |
84 | ts.tv_nsec = do_div(t, 10000000) * 100; |
85 | ts.tv_sec = t; |
86 | return ts; |
87 | } |
88 | |
89 | #endif /* _LINUX_NTFS_TIME_H */ |
90 | |