/* Copyright (C) 2020 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 2001 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1996 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
#include <libc/stubs.h>
#include <utime.h>		/* For utime() */
#include <time.h>		/* For localtime() */
#include <fcntl.h>		/* For open() */
#include <unistd.h>
#include <errno.h>		/* For errno */
#include <go32.h>
#include <dpmi.h>
#include <dos.h>
#include <libc/dosio.h>

/* An implementation of utime() for DJGPP.  The utime() function
   specifies an access time and a modification time.  DOS has only one
   time, so we will (arbitrarily) use the modification time.

   IF LFN is supported, then both times are used.  */
int
utime(const char *path, const struct utimbuf *times)
{
  __dpmi_regs r = {0};
  struct tm *tm;
  time_t modtime;
  int fildes;
  unsigned int dostime, dosdate;
  int retval = 0, e = 0;

  /* NULL times means use current time */
  if (times == NULL)
    modtime = time((time_t *) 0);
  else
    modtime = times->modtime;

  /* Convert UNIX time to DOS date and time */
  tm = localtime(&modtime);
  dosdate = tm->tm_mday + ((tm->tm_mon + 1) << 5) +
    ((tm->tm_year - 80) << 9);
  dostime = tm->tm_sec / 2 + (tm->tm_min << 5) +
    (tm->tm_hour << 11);


  if ((_USE_LFN) &&
      (_os_trueversion == 0x532)) /* LFN and NT (or 2000 or XP) */
  {
    _put_path(path);
    r.x.ds = __tb_segment;  /* DS:DX -> ASCIZ filename */
    r.x.dx = __tb_offset;

    r.x.cx = dostime; /* New time */
    r.x.di = dosdate; /* New date */
    r.x.si = 0x00;    /* Set to zero just in case */

    r.x.ax = 0x7143;  /* LFN API for extended get and set time */
    r.x.bx = 0x03;    /* Set last write date / time */
    __dpmi_int(0x21, &r);

    if (!(r.x.flags & 1))  /* Pass then continue */
    {
      /* Uses date allready in r.x.di */
      r.x.ax = 0x7143;  /* LFN API for extended get and set time */
      r.x.bx = 0x05;    /* Set last access date / time */
      __dpmi_int(0x21, &r);
      if (!(r.x.flags & 1))  /* Pass then continue */
        return 0;
    }
  }

  /* DOS wants the file open */
  fildes = open(path, O_RDONLY);
  if (fildes == -1) return -1;


  /* Set the file timestamp */
  r.h.ah = 0x57; /* DOS FileTimes call */
  r.h.al = 0x01; /* Set date/time request */
  r.x.bx = fildes; /* File handle */
  r.x.cx = dostime; /* New time */
  r.x.dx = dosdate; /* New date */
  __dpmi_int(0x21, &r);
  if (r.x.flags & 1)
  {
    e = EIO;
    retval = -1;
  }
  else if (_USE_LFN && (_os_trueversion == 0x532 || _os_trueversion == 0x700 || _os_trueversion == 0x710))
  {
    /* We can set access time as well on Win95 and above but not on
       FreeDOS or any version of MS-DOS with or without LFN support.  */
    if (times)
      modtime = times->actime;
    tm = localtime(&modtime);
    dosdate = tm->tm_mday + ((tm->tm_mon + 1) << 5) +
      ((tm->tm_year - 80) << 9);
    dostime = tm->tm_sec / 2 + (tm->tm_min << 5) +
      (tm->tm_hour << 11);

    r.x.ax = 0x5705;
    r.x.bx = fildes;
    r.x.cx = _os_trueversion == 0x700 ? 0 : dostime;  /* Acccording to RBIL this must be 0 for Win95 */
    r.x.dx = dosdate;
    __dpmi_int(0x21, &r);
    if (r.x.flags & 1)
    {
      e = EIO;
      retval = -1;
    }
  }

  /* Close the file */
  (void) close(fildes);
  if (e)
    errno = e;

  return retval;
}