(_sys_read_ahead): Handle sleep here.

[bpt/emacs.git] / src / w32.c

/* Utility and Unix shadow routines for GNU Emacs on Windows NT.
   Copyright (C) 1994, 1995 Free Software Foundation, Inc.

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 2, 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; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.

   Geoff Voelker (voelker@cs.washington.edu)                         7-29-94
*/


#include <stdlib.h>
#include <stdio.h>
#include <io.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <signal.h>
#include <sys/time.h>

/* must include CRT headers *before* config.h */
#include "config.h"
#undef access
#undef chdir
#undef chmod
#undef creat
#undef ctime
#undef fopen
#undef link
#undef mkdir
#undef mktemp
#undef open
#undef rename
#undef rmdir
#undef unlink

#undef close
#undef dup
#undef dup2
#undef pipe
#undef read
#undef write

#define getwd _getwd
#include "lisp.h"
#undef getwd

#include <pwd.h>

#include <windows.h>

#ifdef HAVE_SOCKETS     /* TCP connection support, if kernel can do it */
#include <sys/socket.h>
#undef socket
#undef bind
#undef connect
#undef htons
#undef ntohs
#undef inet_addr
#undef gethostname
#undef gethostbyname
#undef getservbyname
#endif

#include "nt.h"
#include "ndir.h"
#include "ntheap.h"

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

#ifndef HAVE_SOCKETS
/* Emulate gethostname.  */
int
gethostname (char *buffer, int size)
{
  /* NT only allows small host names, so the buffer is 
     certainly large enough.  */
  return !GetComputerName (buffer, &size);
}
#endif /* HAVE_SOCKETS */

/* Emulate getloadavg.  */
int
getloadavg (double loadavg[], int nelem)
{
  int i;

  /* A faithful emulation is going to have to be saved for a rainy day.  */
  for (i = 0; i < nelem; i++) 
    {
      loadavg[i] = 0.0;
    }
  return i;
}

/* Emulate the Unix directory procedures opendir, closedir, 
   and readdir.  We can't use the procedures supplied in sysdep.c,
   so we provide them here.  */

struct direct dir_static;       /* simulated directory contents */
static HANDLE dir_find_handle = INVALID_HANDLE_VALUE;
static int    dir_is_fat;
static char   dir_pathname[MAXPATHLEN+1];

DIR *
opendir (char *filename)
{
  DIR *dirp;

  /* Opening is done by FindFirstFile.  However, a read is inherent to
     this operation, so we defer the open until read time.  */

  if (!(dirp = (DIR *) malloc (sizeof (DIR))))
    return NULL;
  if (dir_find_handle != INVALID_HANDLE_VALUE)
    return NULL;

  dirp->dd_fd = 0;
  dirp->dd_loc = 0;
  dirp->dd_size = 0;

  strncpy (dir_pathname, filename, MAXPATHLEN);
  dir_pathname[MAXPATHLEN] = '\0';
  dir_is_fat = is_fat_volume (filename, NULL);

  return dirp;
}

void
closedir (DIR *dirp)
{
  /* If we have a find-handle open, close it.  */
  if (dir_find_handle != INVALID_HANDLE_VALUE)
    {
      FindClose (dir_find_handle);
      dir_find_handle = INVALID_HANDLE_VALUE;
    }
  xfree ((char *) dirp);
}

struct direct *
readdir (DIR *dirp)
{
  WIN32_FIND_DATA find_data;
  
  /* If we aren't dir_finding, do a find-first, otherwise do a find-next. */
  if (dir_find_handle == INVALID_HANDLE_VALUE)
    {
      char filename[MAXNAMLEN + 3];
      int ln;

      strcpy (filename, dir_pathname);
      ln = strlen (filename) - 1;
      if (!IS_DIRECTORY_SEP (filename[ln]))
        strcat (filename, "\\");
      strcat (filename, "*");

      dir_find_handle = FindFirstFile (filename, &find_data);

      if (dir_find_handle == INVALID_HANDLE_VALUE)
        return NULL;
    }
  else
    {
      if (!FindNextFile (dir_find_handle, &find_data))
        return NULL;
    }
  
  /* Emacs never uses this value, so don't bother making it match
     value returned by stat().  */
  dir_static.d_ino = 1;
  
  dir_static.d_reclen = sizeof (struct direct) - MAXNAMLEN + 3 +
    dir_static.d_namlen - dir_static.d_namlen % 4;
  
  dir_static.d_namlen = strlen (find_data.cFileName);
  strcpy (dir_static.d_name, find_data.cFileName);
  if (dir_is_fat)
    _strlwr (dir_static.d_name);
  
  return &dir_static;
}

/* Emulate getpwuid, getpwnam and others.  */

#define PASSWD_FIELD_SIZE 256

static char the_passwd_name[PASSWD_FIELD_SIZE];
static char the_passwd_passwd[PASSWD_FIELD_SIZE];
static char the_passwd_gecos[PASSWD_FIELD_SIZE];
static char the_passwd_dir[PASSWD_FIELD_SIZE];
static char the_passwd_shell[PASSWD_FIELD_SIZE];

static struct passwd the_passwd = 
{
  the_passwd_name,
  the_passwd_passwd,
  0,
  0,
  0,
  the_passwd_gecos,
  the_passwd_dir,
  the_passwd_shell,
};

int 
getuid () 
{ 
  return the_passwd.pw_uid;
}

int 
geteuid () 
{ 
  /* I could imagine arguing for checking to see whether the user is
     in the Administrators group and returning a UID of 0 for that
     case, but I don't know how wise that would be in the long run.  */
  return getuid (); 
}

int 
getgid () 
{ 
  return the_passwd.pw_gid;
}

int 
getegid () 
{ 
  return getgid ();
}

struct passwd *
getpwuid (int uid)
{
  if (uid == the_passwd.pw_uid)
    return &the_passwd;
  return NULL;
}

struct passwd *
getpwnam (char *name)
{
  struct passwd *pw;
  
  pw = getpwuid (getuid ());
  if (!pw)
    return pw;

  if (stricmp (name, pw->pw_name))
    return NULL;

  return pw;
}

void
init_user_info ()
{
  /* Find the user's real name by opening the process token and
     looking up the name associated with the user-sid in that token.

     Use the relative portion of the identifier authority value from
     the user-sid as the user id value (same for group id using the
     primary group sid from the process token). */

  char            user_sid[256], name[256], domain[256];
  DWORD           length = sizeof (name), dlength = sizeof (domain), trash;
  HANDLE          token = NULL;
  SID_NAME_USE    user_type;

  if (OpenProcessToken (GetCurrentProcess (), TOKEN_QUERY, &token)
      && GetTokenInformation (token, TokenUser,
                              (PVOID) user_sid, sizeof (user_sid), &trash)
      && LookupAccountSid (NULL, *((PSID *) user_sid), name, &length,
                           domain, &dlength, &user_type))
    {
      strcpy (the_passwd.pw_name, name);
      /* Determine a reasonable uid value. */
      if (stricmp ("administrator", name) == 0)
        {
          the_passwd.pw_uid = 0;
          the_passwd.pw_gid = 0;
        }
      else
        {
          SID_IDENTIFIER_AUTHORITY * pSIA;

          pSIA = GetSidIdentifierAuthority (*((PSID *) user_sid));
          /* I believe the relative portion is the last 4 bytes (of 6)
             with msb first. */
          the_passwd.pw_uid = ((pSIA->Value[2] << 24) +
                               (pSIA->Value[3] << 16) +
                               (pSIA->Value[4] << 8)  +
                               (pSIA->Value[5] << 0));
          /* restrict to conventional uid range for normal users */
          the_passwd.pw_uid = the_passwd.pw_uid % 60001;

          /* Get group id */
          if (GetTokenInformation (token, TokenPrimaryGroup,
                                   (PVOID) user_sid, sizeof (user_sid), &trash))
            {
              SID_IDENTIFIER_AUTHORITY * pSIA;

              pSIA = GetSidIdentifierAuthority (*((PSID *) user_sid));
              the_passwd.pw_gid = ((pSIA->Value[2] << 24) +
                                   (pSIA->Value[3] << 16) +
                                   (pSIA->Value[4] << 8)  +
                                   (pSIA->Value[5] << 0));
              /* I don't know if this is necessary, but for safety... */
              the_passwd.pw_gid = the_passwd.pw_gid % 60001;
            }
          else
            the_passwd.pw_gid = the_passwd.pw_uid;
        }
    }
  /* If security calls are not supported (presumably because we
       are running under Windows 95), fallback to this. */
  else if (GetUserName (name, &length))
    {
      strcpy (the_passwd.pw_name, name);
      if (stricmp ("administrator", name) == 0)
        the_passwd.pw_uid = 0;
      else
        the_passwd.pw_uid = 123;
      the_passwd.pw_gid = the_passwd.pw_uid;
    }
  else
    {
      strcpy (the_passwd.pw_name, "unknown");
      the_passwd.pw_uid = 123;
      the_passwd.pw_gid = 123;
    }

  /* Ensure HOME and SHELL are defined. */
  if (getenv ("HOME") == NULL)
    putenv ("HOME=c:/");
  if (getenv ("SHELL") == NULL)
    putenv ((GetVersion () & 0x80000000) ? "SHELL=command" : "SHELL=cmd");

  /* Set dir and shell from environment variables. */
  strcpy (the_passwd.pw_dir, getenv ("HOME"));
  strcpy (the_passwd.pw_shell, getenv ("SHELL"));

  if (token)
    CloseHandle (token);
}

int
random ()
{
  /* rand () on NT gives us 15 random bits...hack together 30 bits.  */
  return ((rand () << 15) | rand ());
}

void
srandom (int seed)
{
  srand (seed);
}

/* Destructively turn backslashes into slashes.  */
void
dostounix_filename (p)
     register char *p;
{
  while (*p)
    {
      if (*p == '\\')
        *p = '/';
      p++;
    }
}

/* Destructively turn slashes into backslashes.  */
void
unixtodos_filename (p)
     register char *p;
{
  while (*p)
    {
      if (*p == '/')
        *p = '\\';
      p++;
    }
}

/* Remove all CR's that are followed by a LF.
   (From msdos.c...probably should figure out a way to share it,
   although this code isn't going to ever change.)  */
int
crlf_to_lf (n, buf)
     register int n;
     register unsigned char *buf;
{
  unsigned char *np = buf;
  unsigned char *startp = buf;
  unsigned char *endp = buf + n;

  if (n == 0)
    return n;
  while (buf < endp - 1)
    {
      if (*buf == 0x0d)
        {
          if (*(++buf) != 0x0a)
            *np++ = 0x0d;
        }
      else
        *np++ = *buf++;
    }
  if (buf < endp)
    *np++ = *buf++;
  return np - startp;
}

/* Routines that are no-ops on NT but are defined to get Emacs to compile.  */

int 
sigsetmask (int signal_mask) 
{ 
  return 0;
}

int 
sigblock (int sig) 
{ 
  return 0;
}

int 
setpgrp (int pid, int gid) 
{ 
  return 0;
}

int 
alarm (int seconds) 
{ 
  return 0;
}

int 
unrequest_sigio (void) 
{ 
  return 0;
}

int 
request_sigio (void) 
{ 
  return 0;
}

#define REG_ROOT "SOFTWARE\\GNU\\Emacs"

LPBYTE 
nt_get_resource (key, lpdwtype)
    char *key;
    LPDWORD lpdwtype;
{
  LPBYTE lpvalue;
  HKEY hrootkey = NULL;
  DWORD cbData;
  BOOL ok = FALSE;
  
  /* Check both the current user and the local machine to see if 
     we have any resources.  */
  
  if (RegOpenKeyEx (HKEY_CURRENT_USER, REG_ROOT, 0, KEY_READ, &hrootkey) == ERROR_SUCCESS)
    {
      lpvalue = NULL;

      if (RegQueryValueEx (hrootkey, key, NULL, NULL, NULL, &cbData) == ERROR_SUCCESS 
          && (lpvalue = (LPBYTE) xmalloc (cbData)) != NULL 
          && RegQueryValueEx (hrootkey, key, NULL, lpdwtype, lpvalue, &cbData) == ERROR_SUCCESS)
        {
          return (lpvalue);
        }

      if (lpvalue) xfree (lpvalue);
        
      RegCloseKey (hrootkey);
    } 
  
  if (RegOpenKeyEx (HKEY_LOCAL_MACHINE, REG_ROOT, 0, KEY_READ, &hrootkey) == ERROR_SUCCESS)
    {
      lpvalue = NULL;
        
      if (RegQueryValueEx (hrootkey, key, NULL, NULL, NULL, &cbData) == ERROR_SUCCESS &&
          (lpvalue = (LPBYTE) xmalloc (cbData)) != NULL &&
          RegQueryValueEx (hrootkey, key, NULL, lpdwtype, lpvalue, &cbData) == ERROR_SUCCESS)
        {
          return (lpvalue);
        }
        
      if (lpvalue) xfree (lpvalue);
        
      RegCloseKey (hrootkey);
    } 
  
  return (NULL);
}

void
init_environment ()
{
  /* Check for environment variables and use registry if they don't exist */
  {
    int i;
    LPBYTE lpval;
    DWORD dwType;

    static char * env_vars[] = 
    {
      "HOME",
      "emacs_dir",
      "EMACSLOADPATH",
      "SHELL",
      "EMACSDATA",
      "EMACSPATH",
      "EMACSLOCKDIR",
      "INFOPATH",
      "EMACSDOC",
      "TERM",
    };

    for (i = 0; i < (sizeof (env_vars) / sizeof (env_vars[0])); i++) 
      {
        if (!getenv (env_vars[i]) &&
            (lpval = nt_get_resource (env_vars[i], &dwType)) != NULL)
          {
            if (dwType == REG_EXPAND_SZ)
              {
                char buf1[500], buf2[500];

                ExpandEnvironmentStrings ((LPSTR) lpval, buf1, 500);
                _snprintf (buf2, 499, "%s=%s", env_vars[i], buf1);
                putenv (strdup (buf2));
              }
            else if (dwType == REG_SZ)
              {
                char buf[500];
                  
                _snprintf (buf, 499, "%s=%s", env_vars[i], lpval);
                putenv (strdup (buf));
              }

            xfree (lpval);
          }
      }
  }

  init_user_info ();
}

/* We don't have scripts to automatically determine the system configuration
   for Emacs before it's compiled, and we don't want to have to make the
   user enter it, so we define EMACS_CONFIGURATION to invoke this runtime
   routine.  */

static char configuration_buffer[32];

char *
get_emacs_configuration (void)
{
  char *arch, *oem, *os;

  /* Determine the processor type.  */
  switch (get_processor_type ()) 
    {

#ifdef PROCESSOR_INTEL_386
    case PROCESSOR_INTEL_386:
    case PROCESSOR_INTEL_486:
    case PROCESSOR_INTEL_PENTIUM:
      arch = "i386";
      break;
#endif

#ifdef PROCESSOR_INTEL_860
    case PROCESSOR_INTEL_860:
      arch = "i860";
      break;
#endif

#ifdef PROCESSOR_MIPS_R2000
    case PROCESSOR_MIPS_R2000:
    case PROCESSOR_MIPS_R3000:
    case PROCESSOR_MIPS_R4000:
      arch = "mips";
      break;
#endif

#ifdef PROCESSOR_ALPHA_21064
    case PROCESSOR_ALPHA_21064:
      arch = "alpha";
      break;
#endif

    default:
      arch = "unknown";
      break;
    }

  /* Let oem be "*" until we figure out how to decode the OEM field.  */
  oem = "*";

  os = (GetVersion () & 0x80000000) ? "win95" : "nt";

  sprintf (configuration_buffer, "%s-%s-%s%d.%d", arch, oem, os,
           get_nt_major_version (), get_nt_minor_version ());
  return configuration_buffer;
}

#include <sys/timeb.h>

/* Emulate gettimeofday (Ulrich Leodolter, 1/11/95).  */
void 
gettimeofday (struct timeval *tv, struct timezone *tz)
{
  struct _timeb tb;
  _ftime (&tb);

  tv->tv_sec = tb.time;
  tv->tv_usec = tb.millitm * 1000L;
  if (tz) 
    {
      tz->tz_minuteswest = tb.timezone; /* minutes west of Greenwich  */
      tz->tz_dsttime = tb.dstflag;      /* type of dst correction  */
    }
}

/* ------------------------------------------------------------------------- */
/* IO support and wrapper functions for Win32 API. */
/* ------------------------------------------------------------------------- */

/* 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");
}

/* 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.  */
void
sys_sleep (int seconds)
{
  Sleep (seconds * 1000);
}

/* Internal MSVC data and functions for low-level descriptor munging */
#if (_MSC_VER == 900)
extern char _osfile[];
#endif
extern int __cdecl _set_osfhnd (int fd, long h);
extern int __cdecl _free_osfhnd (int fd);

/* parallel array of private info on file handles */
filedesc fd_info [ MAXDESC ];

static struct {
  DWORD     serialnum;
  DWORD     maxcomp;
  DWORD     flags;
  char      name[32];
  char      type[32];
} volume_info;

/* Get information on the volume where name is held; set path pointer to
   start of pathname in name (past UNC header\volume header if present).  */
int
get_volume_info (const char * name, const char ** pPath)
{
  char temp[MAX_PATH];
  char *rootname = NULL;  /* default to current volume */

  if (name == NULL)
    return FALSE;

  /* find the root name of the volume if given */
  if (isalpha (name[0]) && name[1] == ':')
    {
      rootname = temp;
      temp[0] = *name++;
      temp[1] = *name++;
      temp[2] = '\\';
      temp[3] = 0;
    }
  else if (IS_DIRECTORY_SEP (name[0]) && IS_DIRECTORY_SEP (name[1]))
    {
      char *str = temp;
      int slashes = 4;
      rootname = temp;
      do
        {
          if (IS_DIRECTORY_SEP (*name) && --slashes == 0)
            break;
          *str++ = *name++;
        }
      while ( *name );

      if (slashes > 1)
        return FALSE;

      *str++ = '\\';
      *str = 0;
    }

  if (pPath)
    *pPath = name;
    
  if (GetVolumeInformation (rootname,
                            volume_info.name, 32,
                            &volume_info.serialnum,
                            &volume_info.maxcomp,
                            &volume_info.flags,
                            volume_info.type, 32))
    {
      return TRUE;
    }
  return FALSE;
}

/* Determine if volume is FAT format (ie. only supports short 8.3
   names); also set path pointer to start of pathname in name.  */
int
is_fat_volume (const char * name, const char ** pPath)
{
  if (get_volume_info (name, pPath))
    return (volume_info.maxcomp == 12);
  return FALSE;
}

/* Map filename to a legal 8.3 name if necessary. */
const char *
map_win32_filename (const char * name, const char ** pPath)
{
  static char shortname[MAX_PATH];
  char * str = shortname;
  char c;
  char * path;

  if (is_fat_volume (name, &path)) /* truncate to 8.3 */
    {
      register int left = 8;    /* maximum number of chars in part */
      register int extn = 0;    /* extension added? */
      register int dots = 2;    /* maximum number of dots allowed */

      while (name < path)
        *str++ = *name++;       /* skip past UNC header */

      while ((c = *name++))
        {
          switch ( c )
            {
            case '\\':
            case '/':
              *str++ = '\\';
              extn = 0;         /* reset extension flags */
              dots = 2;         /* max 2 dots */
              left = 8;         /* max length 8 for main part */
              break;
            case ':':
              *str++ = ':';
              extn = 0;         /* reset extension flags */
              dots = 2;         /* max 2 dots */
              left = 8;         /* max length 8 for main part */
              break;
            case '.':
              if ( dots )
                {
                  /* Convert path components of the form .xxx to _xxx,
                     but leave . and .. as they are.  This allows .emacs
                     to be read as _emacs, for example.  */

                  if (! *name ||
                      *name == '.' ||
                      IS_DIRECTORY_SEP (*name))
                    {
                      *str++ = '.';
                      dots--;
                    }
                  else
                    {
                      *str++ = '_';
                      left--;
                      dots = 0;
                    }
                }
              else if ( !extn )
                {
                  *str++ = '.';
                  extn = 1;             /* we've got an extension */
                  left = 3;             /* 3 chars in extension */
                }
              else
                {
                  /* any embedded dots after the first are converted to _ */
                  *str++ = '_';
                }
              break;
            case '~':
            case '#':                   /* don't lose these, they're important */
              if ( ! left )
                str[-1] = c;            /* replace last character of part */
              /* FALLTHRU */
            default:
              if ( left )
                {
                  *str++ = tolower (c); /* map to lower case (looks nicer) */
                  left--;
                  dots = 0;             /* started a path component */
                }
              break;
            }
        }
      *str = '\0';
    }
  else
    {
      strcpy (shortname, name);
      unixtodos_filename (shortname);
    }

  if (pPath)
    *pPath = shortname + (path - name);

  return shortname;
}


/* Shadow some MSVC runtime functions to map requests for long filenames
   to reasonable short names if necessary.  This was originally added to
   permit running Emacs on NT 3.1 on a FAT partition, which doesn't support 
   long file names.  */

int
sys_access (const char * path, int mode)
{
  return _access (map_win32_filename (path, NULL), mode);
}

int
sys_chdir (const char * path)
{
  return _chdir (map_win32_filename (path, NULL));
}

int
sys_chmod (const char * path, int mode)
{
  return _chmod (map_win32_filename (path, NULL), mode);
}

int
sys_creat (const char * path, int mode)
{
  return _creat (map_win32_filename (path, NULL), mode);
}

FILE *
sys_fopen(const char * path, const char * mode)
{
  int fd;
  int oflag;
  const char * mode_save = mode;

  /* Force all file handles to be non-inheritable.  This is necessary to
     ensure child processes don't unwittingly inherit handles that might
     prevent future file access. */

  if (mode[0] == 'r')
    oflag = O_RDONLY;
  else if (mode[0] == 'w' || mode[0] == 'a')
    oflag = O_WRONLY | O_CREAT | O_TRUNC;
  else
    return NULL;

  /* Only do simplistic option parsing. */
  while (*++mode)
    if (mode[0] == '+')
      {
        oflag &= ~(O_RDONLY | O_WRONLY);
        oflag |= O_RDWR;
      }
    else if (mode[0] == 'b')
      {
        oflag &= ~O_TEXT;
        oflag |= O_BINARY;
      }
    else if (mode[0] == 't')
      {
        oflag &= ~O_BINARY;
        oflag |= O_TEXT;
      }
    else break;

  fd = _open (map_win32_filename (path, NULL), oflag | _O_NOINHERIT, 0644);
  if (fd < 0)
    return NULL;

  return fdopen (fd, mode_save);
}

int
sys_link (const char * path1, const char * path2)
{
  errno = EINVAL;
  return -1;
}

int
sys_mkdir (const char * path)
{
  return _mkdir (map_win32_filename (path, NULL));
}

char *
sys_mktemp (char * template)
{
  return (char *) map_win32_filename ((const char *) _mktemp (template), NULL);
}

int
sys_open (const char * path, int oflag, int mode)
{
  /* Force all file handles to be non-inheritable. */
  return _open (map_win32_filename (path, NULL), oflag | _O_NOINHERIT, mode);
}

int
sys_rename (const char * oldname, const char * newname)
{
  char temp[MAX_PATH];

  /* MoveFile on Win95 doesn't correctly change the short file name
     alias when oldname has a three char extension and newname has the
     same first three chars in its extension.  To avoid problems, on
     Win95 we rename to a temporary name first.  */

  strcpy (temp, map_win32_filename (oldname, NULL));

  if (GetVersion () & 0x80000000)
    {
      char * p;

      unixtodos_filename (temp);
      if (p = strrchr (temp, '\\'))
        p++;
      else
        p = temp;
      strcpy (p, "__XXXXXX");
      _mktemp (temp);
      if (rename (map_win32_filename (oldname, NULL), temp) < 0)
        return -1;
    }

  /* Emulate Unix behaviour - newname is deleted if it already exists
     (at least if it is a file; don't do this for directories). */
  newname = map_win32_filename (newname, NULL);
  if (GetFileAttributes (newname) != -1)
    {
      _chmod (newname, 0666);
      _unlink (newname);
    }

  return rename (temp, newname);
}

int
sys_rmdir (const char * path)
{
  return _rmdir (map_win32_filename (path, NULL));
}

int
sys_unlink (const char * path)
{
  return _unlink (map_win32_filename (path, NULL));
}

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 (!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 * 1024 * 1024 + utc_base_ft.dwLowDateTime;
      init = 1;
    }

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

  ret = (long double) ft.dwHighDateTime * 4096 * 1024 * 1024 + ft.dwLowDateTime;
  ret -= utc_base;
  return (time_t) (ret * 1e-7);
}

#if 0
/* in case we ever have need of this */
void
convert_from_time_t (time_t time, FILETIME * pft)
{
  long double tmp;

  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 * 1024 * 1024 + utc_base_ft.dwLowDateTime;
      init = 1;
    }

  /* time in 100ns units since 1-Jan-1601 */
  tmp = (long double) time * 1e7 + utc_base;
  pft->dwHighDateTime = (DWORD) (tmp / (4096.0 * 1024 * 1024));
  pft->dwLowDateTime = (DWORD) (tmp - pft->dwHighDateTime);
}
#endif

/*  "PJW" algorithm (see the "Dragon" compiler book). */
static unsigned
hashval (const char * str)
{
  unsigned h = 0;
  unsigned g;
  while (*str)
    {
      h = (h << 4) + *str++;
      if ((g = h & 0xf0000000) != 0)
        h = (h ^ (g >> 24)) & 0x0fffffff;
    }
  return h;
}

/* Return the hash value of the canonical pathname, excluding the
   drive/UNC header, to get a hopefully unique inode number. */
static _ino_t
generate_inode_val (const char * name)
{
  char fullname[ MAX_PATH ];
  char * p;
  unsigned hash;

  GetFullPathName (name, sizeof (fullname), fullname, &p);
  get_volume_info (fullname, &p);
  /* Normal Win32 filesystems are still case insensitive. */
  _strlwr (p);
  hash = hashval (p);
  return (_ino_t) (hash ^ (hash >> 16));
}

/* MSVC stat function can't cope with UNC names and has other bugs, so
   replace it with our own.  This also allows us to calculate consistent
   inode values without hacks in the main Emacs code. */
int
stat (const char * path, struct stat * buf)
{
  char * name;
  WIN32_FIND_DATA wfd;
  HANDLE fh;
  int permission;
  int len;
  int rootdir = FALSE;

  if (path == NULL || buf == NULL)
    {
      errno = EFAULT;
      return -1;
    }

  name = (char *) map_win32_filename (path, &path);
  /* must be valid filename, no wild cards */
  if (strchr (name, '*') || strchr (name, '?'))
    {
      errno = ENOENT;
      return -1;
    }

  /* Remove trailing directory separator, unless name is the root
     directory of a drive or UNC volume in which case ensure there
     is a trailing separator. */
  len = strlen (name);
  rootdir = (path >= name + len - 1
             && (IS_DIRECTORY_SEP (*path) || *path == 0));
  name = strcpy (alloca (len + 2), name);

  if (rootdir)
    {
      if (!IS_DIRECTORY_SEP (name[len-1]))
        strcat (name, "\\");
      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);
    }

  if (wfd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
    {
      buf->st_mode = _S_IFDIR;
      buf->st_nlink = 2;        /* doesn't really matter */
    }
  else
    {
#if 0
      /* This is more accurate in terms of gettting the correct number
         of links, but is quite slow (it is noticable when Emacs is
         making a list of file name completions). */
      BY_HANDLE_FILE_INFORMATION info;

      fh = CreateFile (name, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE,
                       NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

      if (GetFileInformationByHandle (fh, &info))
        {
          switch (GetFileType (fh))
            {
            case FILE_TYPE_DISK:
              buf->st_mode = _S_IFREG;
              break;
            case FILE_TYPE_PIPE:
              buf->st_mode = _S_IFIFO;
              break;
            case FILE_TYPE_CHAR:
            case FILE_TYPE_UNKNOWN:
            default:
              buf->st_mode = _S_IFCHR;
            }
          buf->st_nlink = info.nNumberOfLinks;
          /* Could use file index, but this is not guaranteed to be
             unique unless we keep a handle open all the time. */
          /* buf->st_ino = info.nFileIndexLow ^ info.nFileIndexHigh; */
          CloseHandle (fh);
        }
      else
        {
          errno = EACCES;
          return -1;
        }
#else
      buf->st_mode = _S_IFREG;
      buf->st_nlink = 1;
#endif
    }

  /* consider files to belong to current user */
  buf->st_uid = the_passwd.pw_uid;
  buf->st_gid = the_passwd.pw_gid;

  /* volume_info is set indirectly by map_win32_filename */
  buf->st_dev = volume_info.serialnum;
  buf->st_rdev = volume_info.serialnum;

  buf->st_ino = generate_inode_val (name);

  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
    {
      char * p = strrchr (name, '.');
      if (p != NULL &&
          (stricmp (p, ".exe") == 0 ||
           stricmp (p, ".com") == 0 ||
           stricmp (p, ".bat") == 0 ||
           stricmp (p, ".cmd") == 0))
        permission |= _S_IEXEC;
    }

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

  return 0;
}

#ifdef HAVE_SOCKETS

/* Wrappers for  winsock functions to map between our file descriptors
   and winsock's handles; also set h_errno for convenience.

   To allow Emacs to run on systems which don't have winsock support
   installed, we dynamically link to winsock on startup if present, and
   otherwise provide the minimum necessary functionality
   (eg. gethostname). */

/* function pointers for relevant socket functions */
int (PASCAL *pfn_WSAStartup) (WORD wVersionRequired, LPWSADATA lpWSAData);
void (PASCAL *pfn_WSASetLastError) (int iError);
int (PASCAL *pfn_WSAGetLastError) (void);
int (PASCAL *pfn_socket) (int af, int type, int protocol);
int (PASCAL *pfn_bind) (SOCKET s, const struct sockaddr *addr, int namelen);
int (PASCAL *pfn_connect) (SOCKET s, const struct sockaddr *addr, int namelen);
int (PASCAL *pfn_ioctlsocket) (SOCKET s, long cmd, u_long *argp);
int (PASCAL *pfn_recv) (SOCKET s, char * buf, int len, int flags);
int (PASCAL *pfn_send) (SOCKET s, const char * buf, int len, int flags);
int (PASCAL *pfn_closesocket) (SOCKET s);
int (PASCAL *pfn_shutdown) (SOCKET s, int how);
int (PASCAL *pfn_WSACleanup) (void);

u_short (PASCAL *pfn_htons) (u_short hostshort);
u_short (PASCAL *pfn_ntohs) (u_short netshort);
unsigned long (PASCAL *pfn_inet_addr) (const char * cp);
int (PASCAL *pfn_gethostname) (char * name, int namelen);
struct hostent * (PASCAL *pfn_gethostbyname) (const char * name);
struct servent * (PASCAL *pfn_getservbyname) (const char * name, const char * proto);

static int have_winsock;
static HANDLE winsock_lib;

static void
term_winsock (void)
{
  if (have_winsock)
    {
      pfn_WSACleanup ();
      FreeLibrary (winsock_lib);
    }
}

static void
init_winsock ()
{
  WSADATA  winsockData;

  winsock_lib = LoadLibrary ("wsock32.dll");

  if (winsock_lib != NULL)
    {
      /* dynamically link to socket functions */

#define LOAD_PROC(fn) \
      if ((pfn_##fn = (void *) GetProcAddress (winsock_lib, #fn)) == NULL) \
        goto fail;

      LOAD_PROC( WSAStartup );
      LOAD_PROC( WSASetLastError );
      LOAD_PROC( WSAGetLastError );
      LOAD_PROC( socket );
      LOAD_PROC( bind );
      LOAD_PROC( connect );
      LOAD_PROC( ioctlsocket );
      LOAD_PROC( recv );
      LOAD_PROC( send );
      LOAD_PROC( closesocket );
      LOAD_PROC( shutdown );
      LOAD_PROC( htons );
      LOAD_PROC( ntohs );
      LOAD_PROC( inet_addr );
      LOAD_PROC( gethostname );
      LOAD_PROC( gethostbyname );
      LOAD_PROC( getservbyname );
      LOAD_PROC( WSACleanup );

      /* specify version 1.1 of winsock */
      if (pfn_WSAStartup (0x101, &winsockData) == 0)
        {
          have_winsock = TRUE;
          return;
        }

    fail:
      FreeLibrary (winsock_lib);
    }
  have_winsock = FALSE;
}


int h_errno = 0;

/* function to set h_errno for compatability; map winsock error codes to
   normal system codes where they overlap (non-overlapping definitions
   are already in <sys/socket.h> */
static void set_errno ()
{
  if (!have_winsock)
    h_errno = EINVAL;
  else
    h_errno = pfn_WSAGetLastError ();

  switch (h_errno)
    {
    case WSAEACCES:             h_errno = EACCES; break;
    case WSAEBADF:              h_errno = EBADF; break;
    case WSAEFAULT:             h_errno = EFAULT; break;
    case WSAEINTR:              h_errno = EINTR; break;
    case WSAEINVAL:             h_errno = EINVAL; break;
    case WSAEMFILE:             h_errno = EMFILE; break;
    case WSAENAMETOOLONG:       h_errno = ENAMETOOLONG; break;
    case WSAENOTEMPTY:          h_errno = ENOTEMPTY; break;
    }
  errno = h_errno;
}

static void check_errno ()
{
  if (h_errno == 0 && have_winsock)
    pfn_WSASetLastError (0);
}

/* [andrewi 3-May-96] I've had conflicting results using both methods,
   but I believe the method of keeping the socket handle separate (and
   insuring it is not inheritable) is the correct one. */

//#define SOCK_REPLACE_HANDLE

#ifdef SOCK_REPLACE_HANDLE
#define SOCK_HANDLE(fd) ((SOCKET) _get_osfhandle (fd))
#else
#define SOCK_HANDLE(fd) ((SOCKET) fd_info[fd].hnd)
#endif

int
sys_socket(int af, int type, int protocol)
{
  int fd;
  long s;
  child_process * cp;

  if (!have_winsock)
    {
      h_errno = ENETDOWN;
      return INVALID_SOCKET;
    }

  check_errno ();

  /* call the real socket function */
  s = (long) pfn_socket (af, type, protocol);
  
  if (s != INVALID_SOCKET)
    {
      /* Although under NT 3.5 _open_osfhandle will accept a socket
         handle, if opened with SO_OPENTYPE == SO_SYNCHRONOUS_NONALERT,
         that does not work under NT 3.1.  However, we can get the same
         effect by using a backdoor function to replace an existing
         descriptor handle with the one we want. */

      /* allocate a file descriptor (with appropriate flags) */
      fd = _open ("NUL:", _O_RDWR);
      if (fd >= 0)
        {
#ifdef SOCK_REPLACE_HANDLE
          /* now replace handle to NUL with our socket handle */
          CloseHandle ((HANDLE) _get_osfhandle (fd));
          _free_osfhnd (fd);
          _set_osfhnd (fd, s);
          /* setmode (fd, _O_BINARY); */
#else
          /* Make a non-inheritable copy of the socket handle. */
          {
            HANDLE parent;
            HANDLE new_s = INVALID_HANDLE_VALUE;

            parent = GetCurrentProcess ();

            DuplicateHandle (parent,
                             (HANDLE) s,
                             parent,
                             &new_s,
                             0,
                             FALSE,
                             DUPLICATE_SAME_ACCESS);
            pfn_closesocket (s);
            fd_info[fd].hnd = new_s;
            s = (SOCKET) new_s;
          }
#endif

          /* set our own internal flags */
          fd_info[fd].flags = FILE_SOCKET | FILE_BINARY | FILE_READ | FILE_WRITE;

          cp = new_child ();
          if (cp)
            {
              cp->fd = fd;
              cp->status = STATUS_READ_ACKNOWLEDGED;

              /* attach child_process to fd_info */
              if (fd_info[ fd ].cp != NULL)
                {
                  DebPrint (("sys_socket: fd_info[%d] apparently in use!\n", fd));
                  abort ();
                }

              fd_info[ fd ].cp = cp;

              /* success! */
              return fd;
            }

          /* clean up */
          _close (fd);
        }
      pfn_closesocket (s);
      h_errno = EMFILE;
    }
  set_errno ();

  return -1;
}


int
sys_bind (int s, const struct sockaddr * addr, int namelen)
{
  if (!have_winsock)
    {
      h_errno = ENOTSOCK;
      return SOCKET_ERROR;
    }

  check_errno ();
  if (fd_info[s].flags & FILE_SOCKET)
    {
      int rc = pfn_bind (SOCK_HANDLE (s), addr, namelen);
      if (rc == SOCKET_ERROR)
        set_errno ();
      return rc;
    }
  h_errno = ENOTSOCK;
  return SOCKET_ERROR;
}


int
sys_connect (int s, const struct sockaddr * name, int namelen)
{
  if (!have_winsock)
    {
      h_errno = ENOTSOCK;
      return SOCKET_ERROR;
    }

  check_errno ();
  if (fd_info[s].flags & FILE_SOCKET)
    {
      int rc = pfn_connect (SOCK_HANDLE (s), name, namelen);
      if (rc == SOCKET_ERROR)
        set_errno ();
      return rc;
    }
  h_errno = ENOTSOCK;
  return SOCKET_ERROR;
}

u_short
sys_htons (u_short hostshort)
{
  return (have_winsock) ?
    pfn_htons (hostshort) : hostshort;
}

u_short
sys_ntohs (u_short netshort)
{
  return (have_winsock) ?
    pfn_ntohs (netshort) : netshort;
}

unsigned long
sys_inet_addr (const char * cp)
{
  return (have_winsock) ?
    pfn_inet_addr (cp) : INADDR_NONE;
}

int
sys_gethostname (char * name, int namelen)
{
  if (have_winsock)
    return pfn_gethostname (name, namelen);

  if (namelen > MAX_COMPUTERNAME_LENGTH)
    return !GetComputerName (name, &namelen);

  h_errno = EFAULT;
  return SOCKET_ERROR;
}

struct hostent *
sys_gethostbyname(const char * name)
{
  struct hostent * host;

  if (!have_winsock)
    {
      h_errno = ENETDOWN;
      return NULL;
    }

  check_errno ();
  host = pfn_gethostbyname (name);
  if (!host)
    set_errno ();
  return host;
}

struct servent *
sys_getservbyname(const char * name, const char * proto)
{
  struct servent * serv;

  if (!have_winsock)
    {
      h_errno = ENETDOWN;
      return NULL;
    }

  check_errno ();
  serv = pfn_getservbyname (name, proto);
  if (!serv)
    set_errno ();
  return serv;
}

#endif /* HAVE_SOCKETS */


/* Shadow main io functions: we need to handle pipes and sockets more
   intelligently, and implement non-blocking mode as well. */

int
sys_close (int fd)
{
  int rc;

  if (fd < 0 || fd >= MAXDESC)
    {
      errno = EBADF;
      return -1;
    }

  if (fd_info[fd].cp)
    {
      child_process * cp = fd_info[fd].cp;

      fd_info[fd].cp = NULL;

      if (CHILD_ACTIVE (cp))
        {
          /* if last descriptor to active child_process then cleanup */
          int i;
          for (i = 0; i < MAXDESC; i++)
            {
              if (i == fd)
                continue;
              if (fd_info[i].cp == cp)
                break;
            }
          if (i == MAXDESC)
            {
#if defined (HAVE_SOCKETS) && !defined (SOCK_REPLACE_HANDLE)
              if (fd_info[fd].flags & FILE_SOCKET)
                {
                  if (!have_winsock) abort ();

                  pfn_shutdown (SOCK_HANDLE (fd), 2);
                  rc = pfn_closesocket (SOCK_HANDLE (fd));
                }
#endif
              delete_child (cp);
            }
        }
    }

  /* Note that sockets do not need special treatment here (at least on
     NT and Win95 using the standard tcp/ip stacks) - it appears that
     closesocket is equivalent to CloseHandle, which is to be expected
     because socket handles are fully fledged kernel handles. */
  rc = _close (fd);

  if (rc == 0)
    fd_info[fd].flags = 0;

  return rc;
}

int
sys_dup (int fd)
{
  int new_fd;

  new_fd = _dup (fd);
  if (new_fd >= 0)
    {
      /* duplicate our internal info as well */
      fd_info[new_fd] = fd_info[fd];
    }
  return new_fd;
}


int
sys_dup2 (int src, int dst)
{
  int rc;

  if (dst < 0 || dst >= MAXDESC)
    {
      errno = EBADF;
      return -1;
    }

  /* make sure we close the destination first if it's a pipe or socket */
  if (src != dst && fd_info[dst].flags != 0)
    sys_close (dst);
  
  rc = _dup2 (src, dst);
  if (rc == 0)
    {
      /* duplicate our internal info as well */
      fd_info[dst] = fd_info[src];
    }
  return rc;
}

/* From callproc.c  */
extern Lisp_Object Vbinary_process_input;
extern Lisp_Object Vbinary_process_output;

/* Unix pipe() has only one arg */
int
sys_pipe (int * phandles)
{
  int rc;
  unsigned flags;
  child_process * cp;

  /* make pipe handles non-inheritable; when we spawn a child,
     we replace the relevant handle with an inheritable one. */
  rc = _pipe (phandles, 0, _O_NOINHERIT);

  if (rc == 0)
    {
      /* set internal flags, and put read and write handles into binary
         mode as necessary; if not in binary mode, set the MSVC internal
         FDEV (0x40) flag to prevent _read from treating ^Z as eof (this
         could otherwise allow Emacs to hang because it then waits
         indefinitely for the child process to exit, when it might not be
         finished). */
      flags = FILE_PIPE | FILE_READ;
      if (!NILP (Vbinary_process_output))
        {
          flags |= FILE_BINARY;
          setmode (phandles[0], _O_BINARY);
        }
#if (_MSC_VER == 900)
      else
        _osfile[phandles[0]] |= 0x40;
#endif

      fd_info[phandles[0]].flags = flags;

      flags = FILE_PIPE | FILE_WRITE;
      if (!NILP (Vbinary_process_input))
        {
          flags |= FILE_BINARY;
          setmode (phandles[1], _O_BINARY);
        }
#if (_MSC_VER == 900)
      else
        _osfile[phandles[1]] |= 0x40;
#endif

      fd_info[phandles[1]].flags = flags;
    }

  return rc;
}

/* From ntproc.c */
extern Lisp_Object Vwin32_pipe_read_delay;

/* Function to do blocking read of one byte, needed to implement
   select.  It is only allowed on sockets and pipes. */
int
_sys_read_ahead (int fd)
{
  child_process * cp;
  int rc;

  if (fd < 0 || fd >= MAXDESC)
    return STATUS_READ_ERROR;

  cp = fd_info[fd].cp;

  if (cp == NULL || cp->fd != fd || cp->status != STATUS_READ_READY)
    return STATUS_READ_ERROR;

  if ((fd_info[fd].flags & (FILE_PIPE | FILE_SOCKET)) == 0
      || (fd_info[fd].flags & FILE_READ) == 0)
    {
      DebPrint (("_sys_read_ahead: internal error: fd %d is not a pipe or socket!\n", fd));
      abort ();
    }
  
  cp->status = STATUS_READ_IN_PROGRESS;
  
  if (fd_info[fd].flags & FILE_PIPE)
    {
      /* Use read to get CRLF translation */
      rc = _read (fd, &cp->chr, sizeof (char));

      /* Give subprocess time to buffer some more output for us before
         reporting that input is available; we need this because Win95
         connects DOS programs to pipes by making the pipe appear to be
         the normal console stdout - as a result most DOS programs will
         write to stdout without buffering, ie.  one character at a
         time.  Even some Win32 programs do this - "dir" in a command
         shell on NT is very slow if we don't do this. */
      if (rc > 0)
        {
          int wait = XINT (Vwin32_pipe_read_delay);

          if (wait > 0)
            Sleep (wait);
          else if (wait < 0)
            while (++wait <= 0)
              /* Yield remainder of our time slice, effectively giving a
                 temporary priority boost to the child process. */
              Sleep (0);
        }
    }
#ifdef HAVE_SOCKETS
  else if (fd_info[fd].flags & FILE_SOCKET)
    rc = pfn_recv (SOCK_HANDLE (fd), &cp->chr, sizeof (char), 0);
#endif
  
  if (rc == sizeof (char))
    cp->status = STATUS_READ_SUCCEEDED;
  else
    cp->status = STATUS_READ_FAILED;

  return cp->status;
}

int
sys_read (int fd, char * buffer, unsigned int count)
{
  int nchars;
  int extra = 0;
  int to_read;
  DWORD waiting;

  if (fd < 0 || fd >= MAXDESC)
    {
      errno = EBADF;
      return -1;
    }

  if (fd_info[fd].flags & (FILE_PIPE | FILE_SOCKET))
    {
      child_process *cp = fd_info[fd].cp;

      if ((fd_info[fd].flags & FILE_READ) == 0)
        {
          errno = EBADF;
          return -1;
        }

      /* presence of a child_process structure means we are operating in
         non-blocking mode - otherwise we just call _read directly.
         Note that the child_process structure might be missing because
         reap_subprocess has been called; in this case the pipe is
         already broken, so calling _read on it is okay. */
      if (cp)
        {
          int current_status = cp->status;

          switch (current_status)
            {
            case STATUS_READ_FAILED:
            case STATUS_READ_ERROR:
              /* report normal EOF */
              return 0;

            case STATUS_READ_READY:
            case STATUS_READ_IN_PROGRESS:
              DebPrint (("sys_read called when read is in progress\n"));
              errno = EWOULDBLOCK;
              return -1;

            case STATUS_READ_SUCCEEDED:
              /* consume read-ahead char */
              *buffer++ = cp->chr;
              count--;
              extra = 1;
              cp->status = STATUS_READ_ACKNOWLEDGED;
              ResetEvent (cp->char_avail);

            case STATUS_READ_ACKNOWLEDGED:
              break;

            default:
              DebPrint (("sys_read: bad status %d\n", current_status));
              errno = EBADF;
              return -1;
            }

          if (fd_info[fd].flags & FILE_PIPE)
            {
              PeekNamedPipe ((HANDLE) _get_osfhandle (fd), NULL, 0, NULL, &waiting, NULL);
              to_read = min (waiting, (DWORD) count);
      
              /* Use read to get CRLF translation */
              nchars = _read (fd, buffer, to_read);
            }
#ifdef HAVE_SOCKETS
          else /* FILE_SOCKET */
            {
              if (!have_winsock) abort ();

              /* do the equivalent of a non-blocking read */
              pfn_ioctlsocket (SOCK_HANDLE (fd), FIONREAD, &waiting);
              if (waiting == 0 && extra == 0)
                {
                  h_errno = errno = EWOULDBLOCK;
                  return -1;
                }

              nchars = 0;
              if (waiting)
                {
                  /* always use binary mode for sockets */
                  nchars = pfn_recv (SOCK_HANDLE (fd), buffer, count, 0);
                  if (nchars == SOCKET_ERROR)
                    {
                      DebPrint(("sys_read.recv failed with error %d on socket %ld\n",
                                pfn_WSAGetLastError (), SOCK_HANDLE (fd)));
                      if (extra == 0)
                        {
                          set_errno ();
                          return -1;
                        }
                      nchars = 0;
                    }
                }
            }
#endif
        }
      else
        nchars = _read (fd, buffer, count);
    }
  else
    nchars = _read (fd, buffer, count);

  return nchars + extra;
}

/* For now, don't bother with a non-blocking mode */
int
sys_write (int fd, const void * buffer, unsigned int count)
{
  int nchars;

  if (fd < 0 || fd >= MAXDESC)
    {
      errno = EBADF;
      return -1;
    }

  if (fd_info[fd].flags & (FILE_PIPE | FILE_SOCKET))
    if ((fd_info[fd].flags & FILE_WRITE) == 0)
      {
        errno = EBADF;
        return -1;
      }
#ifdef HAVE_SOCKETS
  if (fd_info[fd].flags & FILE_SOCKET)
    {
      if (!have_winsock) abort ();
      nchars =  pfn_send (SOCK_HANDLE (fd), buffer, count, 0);
      if (nchars == SOCKET_ERROR)
        {
          DebPrint(("sys_read.send failed with error %d on socket %ld\n",
                    pfn_WSAGetLastError (), SOCK_HANDLE (fd)));
          set_errno ();
        }
    }
  else
#endif
    nchars = _write (fd, buffer, count);

  return nchars;
}


void
term_ntproc ()
{
#ifdef HAVE_SOCKETS
  /* shutdown the socket interface if necessary */
  term_winsock ();
#endif
}

extern BOOL can_run_dos_process;
extern BOOL dos_process_running;

void
init_ntproc ()
{
#ifdef HAVE_SOCKETS
  /* initialise the socket interface if available */
  init_winsock ();
#endif

  /* Initial preparation for subprocess support: replace our standard
     handles with non-inheritable versions. */
  {
    HANDLE parent;
    HANDLE stdin_save =  INVALID_HANDLE_VALUE;
    HANDLE stdout_save = INVALID_HANDLE_VALUE;
    HANDLE stderr_save = INVALID_HANDLE_VALUE;

    parent = GetCurrentProcess ();

    /* ignore errors when duplicating and closing; typically the
       handles will be invalid when running as a gui program. */
    DuplicateHandle (parent, 
                     GetStdHandle (STD_INPUT_HANDLE), 
                     parent,
                     &stdin_save, 
                     0, 
                     FALSE, 
                     DUPLICATE_SAME_ACCESS);
    
    DuplicateHandle (parent,
                     GetStdHandle (STD_OUTPUT_HANDLE),
                     parent,
                     &stdout_save,
                     0,
                     FALSE,
                     DUPLICATE_SAME_ACCESS);
    
    DuplicateHandle (parent,
                     GetStdHandle (STD_ERROR_HANDLE),
                     parent,
                     &stderr_save,
                     0,
                     FALSE,
                     DUPLICATE_SAME_ACCESS);
    
    fclose (stdin);
    fclose (stdout);
    fclose (stderr);

    if (stdin_save != INVALID_HANDLE_VALUE)
      _open_osfhandle ((long) stdin_save, O_TEXT);
    else
      open ("nul", O_TEXT | O_NOINHERIT | O_RDONLY);
    fdopen (0, "r");

    if (stdout_save != INVALID_HANDLE_VALUE)
      _open_osfhandle ((long) stdout_save, O_TEXT);
    else
      open ("nul", O_TEXT | O_NOINHERIT | O_WRONLY);
    fdopen (1, "w");

    if (stderr_save != INVALID_HANDLE_VALUE)
      _open_osfhandle ((long) stderr_save, O_TEXT);
    else
      open ("nul", O_TEXT | O_NOINHERIT | O_WRONLY);
    fdopen (2, "w");
  }

  /* Only allow Emacs to run DOS programs on Win95. */
  can_run_dos_process = (GetVersion () & 0x80000000);
  dos_process_running = FALSE;

  /* unfortunately, atexit depends on implementation of malloc */
  /* atexit (term_ntproc); */
  signal (SIGABRT, term_ntproc);
}

/* end of nt.c */