fs/cifsd/netmisc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *   Copyright (c) International Business Machines  Corp., 2002,2008
   4  *   Author(s): Steve French (sfrench@us.ibm.com)
   5  *
   6  *   Error mapping routines from Samba libsmb/errormap.c
   7  *   Copyright (C) Andrew Tridgell 2001
   8  */
   9
  10 #include "glob.h"
  11 #include "smberr.h"
  12 #include "nterr.h"
  13 #include "time_wrappers.h"
  14
  15 /*
  16  * Convert the NT UTC (based 1601-01-01, in hundred nanosecond units)
  17  * into Unix UTC (based 1970-01-01, in seconds).
  18  */
  19 struct timespec64 ksmbd_NTtimeToUnix(__le64 ntutc)
  20 {
  21         struct timespec64 ts;
  22
  23         /* Subtract the NTFS time offset, then convert to 1s intervals. */
  24         s64 t = le64_to_cpu(ntutc) - NTFS_TIME_OFFSET;
  25         u64 abs_t;
  26
  27         /*
  28          * Unfortunately can not use normal 64 bit division on 32 bit arch, but
  29          * the alternative, do_div, does not work with negative numbers so have
  30          * to special case them
  31          */
  32         if (t < 0) {
  33                 abs_t = -t;
  34                 ts.tv_nsec = do_div(abs_t, 10000000) * 100;
  35                 ts.tv_nsec = -ts.tv_nsec;
  36                 ts.tv_sec = -abs_t;
  37         } else {
  38                 abs_t = t;
  39                 ts.tv_nsec = do_div(abs_t, 10000000) * 100;
  40                 ts.tv_sec = abs_t;
  41         }
  42
  43         return ts;
  44 }