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