/* Utility and Unix shadow routines for GNU Emacs support programs on NT.

Copyright (C) 1994, 2001-2016 Free Software Foundation, Inc.

Author: Geoff Voelker (voelker@cs.washington.edu)
Created: 10-8-94

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <direct.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <ctype.h>
#include <sys/timeb.h>
#include <mbstring.h>

#include "ntlib.h"

/* MinGW64 defines _TIMEZONE_DEFINED and defines 'struct timespec' in
   its system headers.  */
#ifndef _TIMEZONE_DEFINED
struct timezone
{
  int		tz_minuteswest;	/* minutes west of Greenwich */
  int		tz_dsttime;	/* type of dst correction */
};
#endif

#define MAXPATHLEN _MAX_PATH

/* Emulate sleep...we could have done this with a define, but that
   would necessitate including windows.h in the files that used it.
   This is much easier.  */
unsigned
sleep (unsigned seconds)
{
  Sleep (seconds * 1000);
  return 0;
}

/* Get the current working directory.  */
char *
getwd (char *dir)
{
  if (GetCurrentDirectory (MAXPATHLEN, dir) > 0)
    return dir;
  return NULL;
}

static HANDLE getppid_parent;
static int    getppid_ppid;

int
getppid (void)
{
  char *ppid;
  DWORD result;

  ppid = getenv ("EM_PARENT_PROCESS_ID");
  if (!ppid)
    {
      printf ("no pid.\n");
      return 0;
    }
  else
    {
      getppid_ppid = atoi (ppid);
    }

  if (!getppid_parent)
    {
      getppid_parent = OpenProcess (SYNCHRONIZE, FALSE, atoi (ppid));
      if (!getppid_parent)
	{
	  printf ("Failed to open handle to parent process: %d\n",
		 GetLastError ());
	  exit (1);
	}
    }

  result = WaitForSingleObject (getppid_parent, 0);
  switch (result)
    {
    case WAIT_TIMEOUT:
      /* The parent is still alive.  */
      return getppid_ppid;
    case WAIT_OBJECT_0:
      /* The parent is gone.  Return the pid of Unix init (1).  */
      return 1;
    case WAIT_FAILED:
    default:
      printf ("Checking parent status failed: %d\n", GetLastError ());
      exit (1);
    }
}

char *
getlogin (void)
{
  static char user_name[256];
  DWORD  length = sizeof (user_name);

  if (GetUserName (user_name, &length))
    return user_name;
  return NULL;
}

char *
cuserid (char * s)
{
  char * name = getlogin ();
  if (s)
    return strcpy (s, name ? name : "");
  return name;
}

unsigned
getuid (void)
{
  return 0;
}

unsigned
geteuid (void)
{
  return getuid ();
}

unsigned
getgid (void)
{
  return 0;
}

unsigned
getegid (void)
{
  return 0;
}

int
setuid (unsigned uid)
{
  return 0;
}

int
setregid (unsigned rgid, unsigned gid)
{
  return 0;
}

struct passwd *
getpwuid (unsigned uid)
{
  return NULL;
}

char *
getpass (const char * prompt)
{
  static char input[256];
  HANDLE in;
  HANDLE err;
  DWORD  count;

  in = GetStdHandle (STD_INPUT_HANDLE);
  err = GetStdHandle (STD_ERROR_HANDLE);

  if (in == INVALID_HANDLE_VALUE || err == INVALID_HANDLE_VALUE)
    return NULL;

  if (WriteFile (err, prompt, strlen (prompt), &count, NULL))
    {
      int istty = (GetFileType (in) == FILE_TYPE_CHAR);
      DWORD old_flags;
      int rc;

      if (istty)
	{
	  if (GetConsoleMode (in, &old_flags))
	    SetConsoleMode (in, ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
	  else
	    istty = 0;
	}
      rc = ReadFile (in, input, sizeof (input), &count, NULL);
      if (count >= 2 && input[count - 2] == '\r')
	input[count - 2] = '\0';
      else
	{
	  char buf[256];
	  while (ReadFile (in, buf, sizeof (buf), &count, NULL) > 0)
	    if (count >= 2 && buf[count - 2] == '\r')
	      break;
	}
      WriteFile (err, "\r\n", 2, &count, NULL);
      if (istty)
	SetConsoleMode (in, old_flags);
      if (rc)
	return input;
    }

  return NULL;
}

/* This is needed because lib/gettime.c calls gettimeofday, which MSVC
   doesn't have.  Copied from w32.c.  */
void
gettimeofday (struct timeval *tv, struct timezone *tz)
{
  struct _timeb tb;
  _ftime (&tb);

  tv->tv_sec = tb.time;
  tv->tv_usec = tb.millitm * 1000L;
  /* Implementation note: _ftime sometimes doesn't update the dstflag
     according to the new timezone when the system timezone is
     changed.  We could fix that by using GetSystemTime and
     GetTimeZoneInformation, but that doesn't seem necessary, since
     Emacs always calls gettimeofday with the 2nd argument NULL (see
     current_emacs_time).  */
  if (tz)
    {
      tz->tz_minuteswest = tb.timezone;	/* minutes west of Greenwich  */
      tz->tz_dsttime = tb.dstflag;	/* type of dst correction  */
    }
}

int
fchown (int fd, unsigned uid, unsigned gid)
{
  return 0;
}

/* Place a wrapper around the MSVC version of ctime.  It returns NULL
   on network directories, so we handle that case here.
   (Ulrich Leodolter, 1/11/95).  */
char *
sys_ctime (const time_t *t)
{
  char *str = (char *) ctime (t);
  return (str ? str : "Sun Jan 01 00:00:00 1970");
}

FILE *
sys_fopen (const char * path, const char * mode)
{
  return fopen (path, mode);
}

int
sys_chdir (const char * path)
{
  return _chdir (path);
}

static FILETIME utc_base_ft;
static long double utc_base;
static int init = 0;

static time_t
convert_time (FILETIME ft)
{
  long double ret;

  if (CompareFileTime (&ft, &utc_base_ft) < 0)
    return 0;

  ret = (long double) ft.dwHighDateTime
    * 4096.0L * 1024.0L * 1024.0L + ft.dwLowDateTime;
  ret -= utc_base;
  return (time_t) (ret * 1e-7L);
}

static int
is_exec (const char * name)
{
  char * p = strrchr (name, '.');
  return
    (p != NULL
     && (stricmp (p, ".exe") == 0 ||
	 stricmp (p, ".com") == 0 ||
	 stricmp (p, ".bat") == 0 ||
	 stricmp (p, ".cmd") == 0));
}

/* FIXME?  This is in configure.ac now - is this still needed?  */
#define IS_DIRECTORY_SEP(x) ((x) == '/' || (x) == '\\')

/* We need this because nt/inc/sys/stat.h defines struct stat that is
   incompatible with the MS run-time libraries.  */
int
stat (const char * path, struct stat * buf)
{
  WIN32_FIND_DATA wfd;
  HANDLE fh;
  int permission;
  int len;
  int rootdir = FALSE;
  char *name = alloca (FILENAME_MAX);

  if (!init)
    {
      /* Determine the delta between 1-Jan-1601 and 1-Jan-1970. */
      SYSTEMTIME st;

      st.wYear = 1970;
      st.wMonth = 1;
      st.wDay = 1;
      st.wHour = 0;
      st.wMinute = 0;
      st.wSecond = 0;
      st.wMilliseconds = 0;

      SystemTimeToFileTime (&st, &utc_base_ft);
      utc_base = (long double) utc_base_ft.dwHighDateTime
	* 4096.0L * 1024.0L * 1024.0L + utc_base_ft.dwLowDateTime;
      init = 1;
    }

  if (path == NULL || buf == NULL || *path == '\0')
    {
      errno = EFAULT;
      return -1;
    }
  if (_mbspbrk (path, "*?|<>\""))
    {
      errno = ENOENT;
      return -1;
    }

  strcpy (name, path);
  /* Remove trailing directory separator, unless name is the root
     directory of a drive in which case ensure there is a trailing
     separator. */
  len = strlen (name);
  rootdir = IS_DIRECTORY_SEP (name[0])
    || (len == 3 && name[1] == ':' && IS_DIRECTORY_SEP (name[2]));
  if (rootdir)
    {
      if (GetDriveType (name) < 2)
	{
	  errno = ENOENT;
	  return -1;
	}
      memset (&wfd, 0, sizeof (wfd));
      wfd.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
      wfd.ftCreationTime = utc_base_ft;
      wfd.ftLastAccessTime = utc_base_ft;
      wfd.ftLastWriteTime = utc_base_ft;
      strcpy (wfd.cFileName, name);
    }
  else
    {
      if (IS_DIRECTORY_SEP (name[len-1]))
	name[len - 1] = 0;

      fh = FindFirstFile (name, &wfd);
      if (fh == INVALID_HANDLE_VALUE)
	{
	  errno = ENOENT;
	  return -1;
	}
      FindClose (fh);
    }
  buf->st_mode = (wfd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ?
    S_IFDIR : S_IFREG;
  buf->st_nlink = 1;
  buf->st_ino = 0;

  if (name[0] && name[1] == ':')
    buf->st_dev = tolower (name[0]) - 'a' + 1;
  else
    buf->st_dev = _getdrive ();
  buf->st_rdev = buf->st_dev;

  buf->st_size = wfd.nFileSizeLow;

  /* Convert timestamps to Unix format. */
  buf->st_mtime = convert_time (wfd.ftLastWriteTime);
  buf->st_atime = convert_time (wfd.ftLastAccessTime);
  if (buf->st_atime == 0) buf->st_atime = buf->st_mtime;
  buf->st_ctime = convert_time (wfd.ftCreationTime);
  if (buf->st_ctime == 0) buf->st_ctime = buf->st_mtime;

  /* determine rwx permissions */
  if (wfd.dwFileAttributes & FILE_ATTRIBUTE_READONLY)
    permission = S_IREAD;
  else
    permission = S_IREAD | S_IWRITE;

  if (wfd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
    permission |= S_IEXEC;
  else if (is_exec (name))
    permission |= S_IEXEC;

  buf->st_mode |= permission | (permission >> 3) | (permission >> 6);

  return 0;
}

int
lstat (const char * path, struct stat * buf)
{
  return stat (path, buf);
}

/* Implementation of mkostemp for MS-Windows, to avoid race conditions
   when using mktemp.  Copied from w32.c.

   This is used only in update-game-score.c.  It is overkill for that
   use case, since update-game-score renames the temporary file into
   the game score file, which isn't atomic on MS-Windows anyway, when
   the game score already existed before running the program, which it
   almost always does.  But using a simpler implementation just to
   make a point is uneconomical...  */

int
mkostemp (char * template, int flags)
{
  char * p;
  int i, fd = -1;
  unsigned uid = GetCurrentThreadId ();
  int save_errno = errno;
  static char first_char[] = "abcdefghijklmnopqrstuvwyz0123456789!%-_@#";

  errno = EINVAL;
  if (template == NULL)
    return -1;

  p = template + strlen (template);
  i = 5;
  /* replace up to the last 5 X's with uid in decimal */
  while (--p >= template && p[0] == 'X' && --i >= 0)
    {
      p[0] = '0' + uid % 10;
      uid /= 10;
    }

  if (i < 0 && p[0] == 'X')
    {
      i = 0;
      do
	{
	  p[0] = first_char[i];
	  if ((fd = open (template,
			  flags | _O_CREAT | _O_EXCL | _O_RDWR,
			  S_IRUSR | S_IWUSR)) >= 0
	      || errno != EEXIST)
	    {
	      if (fd >= 0)
		errno = save_errno;
	      return fd;
	    }
	}
      while (++i < sizeof (first_char));
    }

  /* Template is badly formed or else we can't generate a unique name.  */
  return -1;
}

/* On Windows, you cannot rename into an existing file.  */
int
sys_rename (const char *from, const char *to)
{
  int retval = rename (from, to);

  if (retval < 0 && errno == EEXIST)
    {
      if (unlink (to) == 0)
	retval = rename (from, to);
    }
  return retval;
}