/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * time.h - NTFS time conversion functions. Part of the Linux-NTFS project. * * Copyright (c) 2001-2005 Anton Altaparmakov */ #ifndef _LINUX_NTFS_TIME_H #define _LINUX_NTFS_TIME_H #include <linux/time.h> /* For current_kernel_time(). */ #include <asm/div64.h> /* For do_div(). */ #include "endian.h" #define NTFS_TIME_OFFSET ((s64)(369 * 365 + 89) * 24 * 3600 * 10000000) /** * utc2ntfs - convert Linux UTC time to NTFS time * @ts: Linux UTC time to convert to NTFS time * * Convert the Linux UTC time @ts to its corresponding NTFS time and return * that in little endian format. * * Linux stores time in a struct timespec64 consisting of a time64_t tv_sec * and a long tv_nsec where tv_sec is the number of 1-second intervals since * 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second * intervals since the value of tv_sec. * * NTFS uses Microsoft's standard time format which is stored in a s64 and is * measured as the number of 100-nano-second intervals since 1st January 1601, * 00:00:00 UTC. */ static inline sle64 utc2ntfs(const struct timespec64 ts) { /* * Convert the seconds to 100ns intervals, add the nano-seconds * converted to 100ns intervals, and then add the NTFS time offset. */ return cpu_to_sle64((s64)ts.tv_sec * 10000000 + ts.tv_nsec / 100 + NTFS_TIME_OFFSET); } /** * get_current_ntfs_time - get the current time in little endian NTFS format * * Get the current time from the Linux kernel, convert it to its corresponding * NTFS time and return that in little endian format. */ static inline sle64 get_current_ntfs_time(void) { struct timespec64 ts; ktime_get_coarse_real_ts64(&ts); return utc2ntfs(ts); } /** * ntfs2utc - convert NTFS time to Linux time * @time: NTFS time (little endian) to convert to Linux UTC * * Convert the little endian NTFS time @time to its corresponding Linux UTC * time and return that in cpu format. * * Linux stores time in a struct timespec64 consisting of a time64_t tv_sec * and a long tv_nsec where tv_sec is the number of 1-second intervals since * 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second * intervals since the value of tv_sec. * * NTFS uses Microsoft's standard time format which is stored in a s64 and is * measured as the number of 100 nano-second intervals since 1st January 1601, * 00:00:00 UTC. */ static inline struct timespec64 ntfs2utc(const sle64 time) { struct timespec64 ts; /* Subtract the NTFS time offset. */ u64 t = (u64)(sle64_to_cpu(time) - NTFS_TIME_OFFSET); /* * Convert the time to 1-second intervals and the remainder to * 1-nano-second intervals. */ ts.tv_nsec = do_div(t, 10000000) * 100; ts.tv_sec = t; return ts; } #endif /* _LINUX_NTFS_TIME_H */