/* gspawn-win32.c - Process launching on Win32
 *
 *  Copyright 2000 Red Hat, Inc.
 *  Copyright 2003 Tor Lillqvist
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Implementation details on Win32.
 *
 * - There is no way to set the no-inherit flag for
 *   a "file descriptor" in the MS C runtime. The flag is there,
 *   and the dospawn() function uses it, but unfortunately
 *   this flag can only be set when opening the file.
 * - As there is no fork(), we cannot reliably change directory
 *   before starting the child process. (There might be several threads
 *   running, and the current directory is common for all threads.)
 *
 * Thus, we must in many cases use a helper program to handle closing
 * of (inherited) file descriptors and changing of directory. The
 * helper process is also needed if the standard input, standard
 * output, or standard error of the process to be run are supposed to
 * be redirected somewhere.
 *
 * The structure of the source code in this file is a mess, I know.
 */

/* Define this to get some logging all the time */
/* #define G_SPAWN_WIN32_DEBUG */

#include "config.h"

#include "glib-init.h"
#include "glib-private.h"
#include "glib.h"
#include "glibintl.h"
#include "gprintfint.h"
#include "gspawn-private.h"
#include "gthread.h"

#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#include <windows.h>
#include <errno.h>
#include <fcntl.h>
#include <io.h>
#include <process.h>
#include <direct.h>
#include <wchar.h>

#ifdef _MSC_VER
#ifdef HAVE_VCRUNTIME_H
#include <vcruntime.h> /* for _UCRT */
#endif
#endif

#ifndef GSPAWN_HELPER
#ifdef G_SPAWN_WIN32_DEBUG
  static int debug = 1;
  #define SETUP_DEBUG() /* empty */
#else
  static int debug = -1;
  #define SETUP_DEBUG()					\
    G_STMT_START					\
      {							\
	if (debug == -1)				\
	  {						\
	    if (g_getenv ("G_SPAWN_WIN32_DEBUG") != NULL)	\
	      debug = 1;				\
	    else					\
	      debug = 0;				\
	  }						\
      }							\
    G_STMT_END
#endif
#endif

enum
{
  CHILD_NO_ERROR,
  CHILD_CHDIR_FAILED,
  CHILD_SPAWN_FAILED,
  CHILD_SPAWN_NOENT,
  CHILD_DUP_FAILED,
};

enum {
  ARG_CHILD_ERR_REPORT = 1,
  ARG_HELPER_SYNC,
  ARG_STDIN,
  ARG_STDOUT,
  ARG_STDERR,
  ARG_WORKING_DIRECTORY,
  ARG_CLOSE_DESCRIPTORS,
  ARG_USE_PATH,
  ARG_WAIT,
  ARG_FDS,
  ARG_PROGRAM,
  ARG_COUNT = ARG_PROGRAM
};

#ifndef GSPAWN_HELPER

#ifdef _WIN64
#define HELPER_PROCESS "gspawn-win64-helper"
#else
#define HELPER_PROCESS "gspawn-win32-helper"
#endif

#ifndef _UCRT

/* The wspawn*e functions are thread-safe only in the Universal
 * CRT (UCRT). If we are linking against the MSVCRT.dll or the
 * pre-2015 MSVC runtime (MSVCRXXX.dll), then we have to use a
 * mutex.
 */

static GMutex safe_wspawn_e_mutex;

static intptr_t
safe_wspawnve (int _Mode,
               const wchar_t *_Filename,
               const wchar_t *const *_ArgList,
               const wchar_t *const *_Env)
{
  intptr_t ret_val = -1;

  g_mutex_lock (&safe_wspawn_e_mutex);
  ret_val = _wspawnve (_Mode, _Filename, _ArgList, _Env);
  g_mutex_unlock (&safe_wspawn_e_mutex);

  return ret_val;
}

static intptr_t
safe_wspawnvpe (int _Mode,
                const wchar_t *_Filename,
                const wchar_t *const *_ArgList,
                const wchar_t *const *_Env)
{
  intptr_t ret_val = -1;

  g_mutex_lock (&safe_wspawn_e_mutex);
  ret_val = _wspawnvpe (_Mode, _Filename, _ArgList, _Env);
  g_mutex_unlock (&safe_wspawn_e_mutex);

  return ret_val;
}

#else

/**< private >
 * ensure_cmd_environment:
 *
 * Workaround for an issue in the universal C Runtime library (UCRT). This adds
 * a custom environment variable to this process's environment block that looks
 * like the cmd.exe's shell-related environment variables, i.e the name starts
 * with an equal sign character: '='. This is needed because the UCRT may crash
 * if those environment variables are missing from the calling process's block.
 *
 * Reference:
 *
 * https://developercommunity.visualstudio.com/t/UCRT-Crash-in-_wspawne-functions/10262748
 */
static void
ensure_cmd_environment (void)
{
  static gsize initialization_value = 0;

  if (g_once_init_enter (&initialization_value))
    {
      wchar_t *block = GetEnvironmentStringsW ();
      gboolean have_cmd_environment = FALSE;

      if (block)
        {
          const wchar_t *p = block;

          while (*p != L'\0')
            {
              if (*p == L'=')
                {
                  have_cmd_environment = TRUE;
                  break;
                }

              p += wcslen (p) + 1;
            }

          if (!FreeEnvironmentStringsW (block))
            g_warning ("%s failed with error code %u",
                       "FreeEnvironmentStrings",
                       (guint) GetLastError ());
        }

      if (!have_cmd_environment)
        {
          if (!SetEnvironmentVariableW (L"=GLIB", L"GLIB"))
            {
              g_critical ("%s failed with error code %u",
                          "SetEnvironmentVariable",
                          (guint) GetLastError ());
            }
        }

      g_once_init_leave (&initialization_value, 1);
    }
}

static intptr_t
safe_wspawnve (int                   _mode,
               const wchar_t *       _filename,
               const wchar_t *const *_args,
               const wchar_t *const *_env)
{
  ensure_cmd_environment ();

  return _wspawnve (_mode, _filename, _args, _env);;
}

static intptr_t
safe_wspawnvpe (int                   _mode,
                const wchar_t *       _filename,
                const wchar_t *const *_args,
                const wchar_t *const *_env)
{
  ensure_cmd_environment ();

  return _wspawnvpe (_mode, _filename, _args, _env);
}

#endif /* _UCRT */

/* This logic has a copy for wchar_t in gspawn-win32-helper.c, protect_wargv() */
static gchar *
protect_argv_string (const gchar *string)
{
  const gchar *p = string;
  gchar *retval, *q;
  size_t len = 0;
  size_t pre_bslash = 0;
  gboolean need_dblquotes = FALSE;
  while (*p)
    {
      if (*p == ' ' || *p == '\t')
	need_dblquotes = TRUE;
      /* estimate max len, assuming that all escapable characters will be escaped */
      if (*p == '"' || *p == '\\')
	len += 2;
      else
	len += 1;
      p++;
    }
  
  q = retval = g_malloc (len + need_dblquotes*2 + 1);
  p = string;

  if (need_dblquotes)
    *q++ = '"';
  /* Only quotes and backslashes preceding quotes are escaped:
   * see "Parsing C Command-Line Arguments" at
   * https://docs.microsoft.com/en-us/cpp/c-language/parsing-c-command-line-arguments
   */
  while (*p)
    {
      if (*p == '"')
	{
	  /* Add backslash for escaping quote itself */
	  *q++ = '\\';
	  /* Add backslash for every preceding backslash for escaping it */
	  for (;pre_bslash > 0; --pre_bslash)
	    *q++ = '\\';
	}

      /* Count length of continuous sequence of preceding backslashes. */
      if (*p == '\\')
	++pre_bslash;
      else
	pre_bslash = 0;

      *q++ = *p;
      p++;
    }
  
  if (need_dblquotes)
    {
      /* Add backslash for every preceding backslash for escaping it,
       * do NOT escape quote itself.
       */
      for (;pre_bslash > 0; --pre_bslash)
	*q++ = '\\';
      *q++ = '"';
    }
  *q++ = '\0';

  return retval;
}

static gint
protect_argv (const gchar * const   *argv,
              gchar               ***new_argv)
{
  gint i;
  gint argc = 0;
  
  while (argv[argc])
    ++argc;
  *new_argv = g_new (gchar *, argc+1);

  /* Quote each argv element if necessary, so that it will get
   * reconstructed correctly in the C runtime startup code.  Note that
   * the unquoting algorithm in the C runtime is really weird, and
   * rather different than what Unix shells do. See stdargv.c in the C
   * runtime sources (in the Platform SDK, in src/crt).
   *
   * Note that a new_argv[0] constructed by this function should
   * *not* be passed as the filename argument to a spawn* or exec*
   * family function. That argument should be the real file name
   * without any quoting.
   */
  for (i = 0; i < argc; i++)
    (*new_argv)[i] = protect_argv_string (argv[i]);

  (*new_argv)[argc] = NULL;

  return argc;
}

G_DEFINE_QUARK (g-exec-error-quark, g_spawn_error)
G_DEFINE_QUARK (g-spawn-exit-error-quark, g_spawn_exit_error)

/* Avoids a danger in threaded situations (calling close()
 * on a file descriptor twice, and another thread has
 * re-opened it since the first close)
 */
static void
close_and_invalidate (gint *fd)
{
  if (*fd < 0)
    return;

  close (*fd);
  *fd = -1;
}

typedef enum
{
  READ_FAILED = 0, /* FALSE */
  READ_OK,
  READ_EOF
} ReadResult;

static ReadResult
read_data (GString     *str,
           GIOChannel  *iochannel,
           GError     **error)
{
  GIOStatus giostatus;
  gsize bytes;
  gchar buf[4096];

 again:
  
  giostatus = g_io_channel_read_chars (iochannel, buf, sizeof (buf), &bytes, NULL);

  if (bytes == 0)
    return READ_EOF;
  else if (bytes > 0)
    {
      g_string_append_len (str, buf, bytes);
      return READ_OK;
    }
  else if (giostatus == G_IO_STATUS_AGAIN)
    goto again;
  else if (giostatus == G_IO_STATUS_ERROR)
    {
      g_set_error_literal (error, G_SPAWN_ERROR, G_SPAWN_ERROR_READ,
                           _("Failed to read data from child process"));
      
      return READ_FAILED;
    }
  else
    return READ_OK;
}

static gboolean
make_pipe (gint     p[2],
           GError **error)
{
  if (_pipe (p, 4096, _O_BINARY) < 0)
    {
      int errsv = errno;

      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
                   _("Failed to create pipe for communicating with child process (%s)"),
                   g_strerror (errsv));
      return FALSE;
    }
  else
    return TRUE;
}

/* The helper process writes a status report back to us, through a
 * pipe, consisting of two ints.
 */
static gboolean
read_helper_report (int      fd,
		    gintptr  report[2],
		    GError **error)
{
  gsize bytes = 0;
  
  while (bytes < sizeof(gintptr)*2)
    {
      gint chunk;
      int errsv;

      if (debug)
	g_print ("%s:read_helper_report: read %" G_GSIZE_FORMAT "...\n",
		 __FILE__,
		 sizeof(gintptr)*2 - bytes);

      chunk = read (fd, ((gchar*)report) + bytes,
		    sizeof(gintptr)*2 - bytes);
      errsv = errno;

      if (debug)
	g_print ("...got %d bytes\n", chunk);
          
      if (chunk < 0)
        {
          /* Some weird shit happened, bail out */
          g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
                       _("Failed to read from child pipe (%s)"),
                       g_strerror (errsv));

          return FALSE;
        }
      else if (chunk == 0)
	{
	  g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		       _("Failed to read from child pipe (%s)"),
		       "EOF");
	  break; /* EOF */
	}
      else
	bytes += chunk;
    }

  if (bytes < sizeof(gintptr)*2)
    return FALSE;

  return TRUE;
}

static void
set_child_error (gintptr      report[2],
		 const gchar *working_directory,
		 GError     **error)
{
  switch (report[0])
    {
    case CHILD_CHDIR_FAILED:
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_CHDIR,
		   _("Failed to change to directory “%s” (%s)"),
		   working_directory,
		   g_strerror (report[1]));
      break;
    case CHILD_SPAWN_FAILED:
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Failed to execute child process (%s)"),
		   g_strerror (report[1]));
      break;
    case CHILD_SPAWN_NOENT:
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_NOENT,
                   _("Failed to execute child process (%s)"),
                   g_strerror (report[1]));
      break;
    case CHILD_DUP_FAILED:
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
                   _("Failed to dup() in child process (%s)"),
                   g_strerror (report[1]));
      break;
    default:
      g_assert_not_reached ();
    }
}

static gboolean
utf8_charv_to_wcharv (const gchar * const   *utf8_charv,
                      wchar_t             ***wcharv,
                      int                   *error_index,
                      GError               **error)
{
  wchar_t **retval = NULL;

  *wcharv = NULL;
  if (utf8_charv != NULL)
    {
      int n = 0, i;

      while (utf8_charv[n])
	n++;
      retval = g_new (wchar_t *, n + 1);

      for (i = 0; i < n; i++)
	{
	  retval[i] = g_utf8_to_utf16 (utf8_charv[i], -1, NULL, NULL, error);
	  if (retval[i] == NULL)
	    {
	      if (error_index)
		*error_index = i;
	      while (i)
		g_free (retval[--i]);
	      g_free (retval);
	      return FALSE;
	    }
	}
	    
      retval[n] = NULL;
    }
  *wcharv = retval;
  return TRUE;
}

static gboolean
do_spawn_directly (gint                 *exit_status,
                   gboolean              do_return_handle,
                   GSpawnFlags           flags,
                   const gchar * const  *argv,
                   const gchar * const  *envp,
                   const gchar * const  *protected_argv,
                   GPid                 *child_pid,
                   GError              **error)
{
  const int mode = (exit_status == NULL) ? P_NOWAIT : P_WAIT;
  const gchar * const *new_argv;
  gintptr rc = -1;
  int errsv;
  GError *conv_error = NULL;
  gint conv_error_index;
  wchar_t *wargv0, **wargv, **wenvp;

  g_assert (argv != NULL && argv[0] != NULL);

  new_argv = (flags & G_SPAWN_FILE_AND_ARGV_ZERO) ? protected_argv + 1 : protected_argv;
      
  wargv0 = g_utf8_to_utf16 (argv[0], -1, NULL, NULL, &conv_error);
  if (wargv0 == NULL)
    {
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Invalid program name: %s"),
		   conv_error->message);
      g_error_free (conv_error);
      
      return FALSE;
    }
  
  if (!utf8_charv_to_wcharv (new_argv, &wargv, &conv_error_index, &conv_error))
    {
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Invalid string in argument vector at %d: %s"),
		   conv_error_index, conv_error->message);
      g_error_free (conv_error);
      g_free (wargv0);

      return FALSE;
    }

  if (!utf8_charv_to_wcharv (envp, &wenvp, NULL, &conv_error))
    {
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Invalid string in environment: %s"),
		   conv_error->message);
      g_error_free (conv_error);
      g_free (wargv0);
      g_strfreev ((gchar **) wargv);

      return FALSE;
    }

  if (flags & G_SPAWN_SEARCH_PATH)
    if (wenvp != NULL)
      rc = safe_wspawnvpe (mode, wargv0, (const wchar_t **) wargv, (const wchar_t **) wenvp);
    else
      rc = _wspawnvp (mode, wargv0, (const wchar_t **) wargv);
  else
    if (wenvp != NULL)
      rc = safe_wspawnve (mode, wargv0, (const wchar_t **) wargv, (const wchar_t **) wenvp);
    else
      rc = _wspawnv (mode, wargv0, (const wchar_t **) wargv);

  errsv = errno;

  g_free (wargv0);
  g_strfreev ((gchar **) wargv);
  g_strfreev ((gchar **) wenvp);

  if (rc == -1 && errsv != 0)
    {
      g_set_error (error, G_SPAWN_ERROR, _g_spawn_exec_err_to_g_error (errsv),
		   _("Failed to execute child process (%s)"),
		   g_strerror (errsv));
      return FALSE;
    }

  if (exit_status == NULL)
    {
      if (child_pid && do_return_handle)
	*child_pid = (GPid) rc;
      else
	{
	  CloseHandle ((HANDLE) rc);
	  if (child_pid)
	    *child_pid = 0;
	}
    }
  else
    *exit_status = rc;

  return TRUE;
}

static gboolean
might_be_console_process (void)
{
  // we should always fail to attach ourself to a console (because we're
  // either already attached, or we do not have a console)
  gboolean attached_to_self = AttachConsole (GetCurrentProcessId ());
  g_return_val_if_fail (!attached_to_self, TRUE);

  switch (GetLastError ())
    {
    // current process is already attached to a console
    case ERROR_ACCESS_DENIED:
      return TRUE;
    // current process does not have a console
    case ERROR_INVALID_HANDLE:
      return FALSE;
    // we should not get ERROR_INVALID_PARAMETER
    }

  g_return_val_if_reached (FALSE);
}

static gboolean
fork_exec (gint                  *exit_status,
           gboolean               do_return_handle,
           const gchar           *working_directory,
           const gchar * const   *argv,
           const gchar * const   *envp,
           GSpawnFlags            flags,
           GSpawnChildSetupFunc   child_setup,
           gpointer               user_data,
           GPid                  *child_pid,
           gint                  *stdin_pipe_out,
           gint                  *stdout_pipe_out,
           gint                  *stderr_pipe_out,
           gint                   stdin_fd,
           gint                   stdout_fd,
           gint                   stderr_fd,
           const gint            *source_fds,
           const gint            *target_fds,
           gsize                  n_fds,
           gint                  *err_report,
           GError               **error)
{
  char **protected_argv;
  char args[ARG_COUNT][10];
  char **new_argv;
  int i;
  gintptr rc = -1;
  int errsv;
  int argc;
  int child_err_report_pipe[2] = { -1, -1 };
  int helper_sync_pipe[2] = { -1, -1 };
  gintptr helper_report[2];
  static gboolean warned_about_child_setup = FALSE;
  GError *conv_error = NULL;
  gint conv_error_index;
  gchar *helper_process;
  wchar_t *whelper, **wargv, **wenvp;
  int stdin_pipe[2] = { -1, -1 };
  int stdout_pipe[2] = { -1, -1 };
  int stderr_pipe[2] = { -1, -1 };

  g_assert (argv != NULL && argv[0] != NULL);
  g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
  g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
  g_assert (stderr_pipe_out == NULL || stderr_fd < 0);

  if (child_setup && !warned_about_child_setup)
    {
      warned_about_child_setup = TRUE;
      g_warning ("passing a child setup function to the g_spawn functions is pointless on Windows and it is ignored");
    }

  if (stdin_pipe_out != NULL)
    {
      if (!make_pipe (stdin_pipe, error))
        goto cleanup_and_fail;
      if (_g_spawn_invalid_source_fd (stdin_pipe[0], source_fds, n_fds, error) ||
          _g_spawn_invalid_source_fd (stdin_pipe[1], source_fds, n_fds, error))
        goto cleanup_and_fail;
      stdin_fd = stdin_pipe[0];
    }

  if (stdout_pipe_out != NULL)
    {
      if (!make_pipe (stdout_pipe, error))
        goto cleanup_and_fail;
      if (_g_spawn_invalid_source_fd (stdout_pipe[0], source_fds, n_fds, error) ||
          _g_spawn_invalid_source_fd (stdout_pipe[1], source_fds, n_fds, error))
        goto cleanup_and_fail;
      stdout_fd = stdout_pipe[1];
    }

  if (stderr_pipe_out != NULL)
    {
      if (!make_pipe (stderr_pipe, error))
        goto cleanup_and_fail;
      if (_g_spawn_invalid_source_fd (stderr_pipe[0], source_fds, n_fds, error) ||
          _g_spawn_invalid_source_fd (stderr_pipe[1], source_fds, n_fds, error))
        goto cleanup_and_fail;
      stderr_fd = stderr_pipe[1];
    }

  argc = protect_argv (argv, &protected_argv);

  if (stdin_fd == -1 && stdout_fd == -1 && stderr_fd == -1 &&
      (flags & G_SPAWN_CHILD_INHERITS_STDIN) &&
      !(flags & G_SPAWN_STDOUT_TO_DEV_NULL) &&
      !(flags & G_SPAWN_STDERR_TO_DEV_NULL) &&
      (working_directory == NULL || !*working_directory) &&
      (flags & G_SPAWN_LEAVE_DESCRIPTORS_OPEN) &&
      n_fds == 0)
    {
      /* We can do without the helper process */
      gboolean retval =
	do_spawn_directly (exit_status, do_return_handle, flags,
			   argv, envp, (const gchar * const *) protected_argv,
			   child_pid, error);
      g_strfreev (protected_argv);
      return retval;
    }

  if (!make_pipe (child_err_report_pipe, error))
    goto cleanup_and_fail;
  if (_g_spawn_invalid_source_fd (child_err_report_pipe[0], source_fds, n_fds, error) ||
      _g_spawn_invalid_source_fd (child_err_report_pipe[1], source_fds, n_fds, error))
    goto cleanup_and_fail;
  
  if (!make_pipe (helper_sync_pipe, error))
    goto cleanup_and_fail;
  if (_g_spawn_invalid_source_fd (helper_sync_pipe[0], source_fds, n_fds, error) ||
      _g_spawn_invalid_source_fd (helper_sync_pipe[1], source_fds, n_fds, error))
    goto cleanup_and_fail;
  
  new_argv = g_new (char *, argc + 1 + ARG_COUNT);
  if (might_be_console_process ())
    helper_process = HELPER_PROCESS "-console.exe";
  else
    helper_process = HELPER_PROCESS ".exe";

  helper_process = g_win32_find_helper_executable_path (helper_process, glib_dll);
  new_argv[0] = protect_argv_string (helper_process);

  _g_sprintf (args[ARG_CHILD_ERR_REPORT], "%d", child_err_report_pipe[1]);
  new_argv[ARG_CHILD_ERR_REPORT] = args[ARG_CHILD_ERR_REPORT];
  
  /* Make the read end of the child error report pipe
   * noninherited. Otherwise it will needlessly be inherited by the
   * helper process, and the started actual user process. As such that
   * shouldn't harm, but it is unnecessary.
   */
  child_err_report_pipe[0] = g_win32_reopen_noninherited (
    child_err_report_pipe[0], _O_RDONLY, error);
  if (child_err_report_pipe[0] == -1)
      goto cleanup_and_fail;

  if (flags & G_SPAWN_FILE_AND_ARGV_ZERO)
    {
      /* Overload ARG_CHILD_ERR_REPORT to also encode the
       * G_SPAWN_FILE_AND_ARGV_ZERO functionality.
       */
      strcat (args[ARG_CHILD_ERR_REPORT], "#");
    }
  
  _g_sprintf (args[ARG_HELPER_SYNC], "%d", helper_sync_pipe[0]);
  new_argv[ARG_HELPER_SYNC] = args[ARG_HELPER_SYNC];
  
  /* Make the write end of the sync pipe noninherited. Otherwise the
   * helper process will inherit it, and thus if this process happens
   * to crash before writing the sync byte to the pipe, the helper
   * process won't read but won't get any EOF either, as it has the
   * write end open itself.
   */
  helper_sync_pipe[1] = g_win32_reopen_noninherited (
    helper_sync_pipe[1], _O_WRONLY, error);
  if (helper_sync_pipe[1] == -1)
      goto cleanup_and_fail;

  if (stdin_fd != -1)
    {
      _g_sprintf (args[ARG_STDIN], "%d", stdin_fd);
      new_argv[ARG_STDIN] = args[ARG_STDIN];
    }
  else if (flags & G_SPAWN_CHILD_INHERITS_STDIN)
    {
      /* Let stdin be alone */
      new_argv[ARG_STDIN] = "-";
    }
  else
    {
      /* Keep process from blocking on a read of stdin */
      new_argv[ARG_STDIN] = "z";
    }
  
  if (stdout_fd != -1)
    {
      _g_sprintf (args[ARG_STDOUT], "%d", stdout_fd);
      new_argv[ARG_STDOUT] = args[ARG_STDOUT];
    }
  else if (flags & G_SPAWN_STDOUT_TO_DEV_NULL)
    {
      new_argv[ARG_STDOUT] = "z";
    }
  else
    {
      new_argv[ARG_STDOUT] = "-";
    }
  
  if (stderr_fd != -1)
    {
      _g_sprintf (args[ARG_STDERR], "%d", stderr_fd);
      new_argv[ARG_STDERR] = args[ARG_STDERR];
    }
  else if (flags & G_SPAWN_STDERR_TO_DEV_NULL)
    {
      new_argv[ARG_STDERR] = "z";
    }
  else
    {
      new_argv[ARG_STDERR] = "-";
    }
  
  if (working_directory && *working_directory)
    new_argv[ARG_WORKING_DIRECTORY] = protect_argv_string (working_directory);
  else
    new_argv[ARG_WORKING_DIRECTORY] = g_strdup ("-");
  
  if (!(flags & G_SPAWN_LEAVE_DESCRIPTORS_OPEN))
    new_argv[ARG_CLOSE_DESCRIPTORS] = "y";
  else
    new_argv[ARG_CLOSE_DESCRIPTORS] = "-";

  if (flags & G_SPAWN_SEARCH_PATH)
    new_argv[ARG_USE_PATH] = "y";
  else
    new_argv[ARG_USE_PATH] = "-";

  if (exit_status == NULL)
    new_argv[ARG_WAIT] = "-";
  else
    new_argv[ARG_WAIT] = "w";

  if (n_fds == 0)
    new_argv[ARG_FDS] = g_strdup ("-");
  else
    {
      GString *fds = g_string_new ("");
      gsize n;

      for (n = 0; n < n_fds; n++)
        g_string_append_printf (fds, "%d:%d,", source_fds[n], target_fds[n]);

      /* remove the trailing , */
      g_string_truncate (fds, fds->len - 1);
      new_argv[ARG_FDS] = g_string_free (fds, FALSE);
    }

  for (i = 0; i <= argc; i++)
    new_argv[ARG_PROGRAM + i] = protected_argv[i];

  SETUP_DEBUG();

  if (debug)
    {
      g_print ("calling %s with argv:\n", helper_process);
      for (i = 0; i < argc + 1 + ARG_COUNT; i++)
	g_print ("argv[%d]: %s\n", i, (new_argv[i] ? new_argv[i] : "NULL"));
    }

  if (!utf8_charv_to_wcharv ((const gchar * const *) new_argv, &wargv, &conv_error_index, &conv_error))
    {
      if (conv_error_index == ARG_WORKING_DIRECTORY)
	g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_CHDIR,
		     _("Invalid working directory: %s"),
		     conv_error->message);
      else
	g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		     _("Invalid string in argument vector at %d: %s"),
		     conv_error_index - ARG_PROGRAM, conv_error->message);
      g_error_free (conv_error);
      g_strfreev (protected_argv);
      g_free (new_argv[0]);
      g_free (new_argv[ARG_WORKING_DIRECTORY]);
      g_free (new_argv[ARG_FDS]);
      g_free (new_argv);
      g_free (helper_process);

      goto cleanup_and_fail;
    }

  if (!utf8_charv_to_wcharv (envp, &wenvp, NULL, &conv_error))
    {
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Invalid string in environment: %s"),
		   conv_error->message);
      g_error_free (conv_error);
      g_strfreev (protected_argv);
      g_free (new_argv[0]);
      g_free (new_argv[ARG_WORKING_DIRECTORY]);
      g_free (new_argv[ARG_FDS]);
      g_free (new_argv);
      g_free (helper_process);
      g_strfreev ((gchar **) wargv);
 
      goto cleanup_and_fail;
    }

  whelper = g_utf8_to_utf16 (helper_process, -1, NULL, NULL, NULL);
  g_free (helper_process);

  if (wenvp != NULL)
    rc = safe_wspawnvpe (P_NOWAIT, whelper, (const wchar_t **) wargv, (const wchar_t **) wenvp);
  else
    rc = _wspawnvp (P_NOWAIT, whelper, (const wchar_t **) wargv);

  errsv = errno;

  g_free (whelper);
  g_strfreev ((gchar **) wargv);
  g_strfreev ((gchar **) wenvp);

  /* Close the other process's ends of the pipes in this process,
   * otherwise the reader will never get EOF.
   */
  close_and_invalidate (&child_err_report_pipe[1]);
  close_and_invalidate (&helper_sync_pipe[0]);

  g_strfreev (protected_argv);

  g_free (new_argv[0]);
  g_free (new_argv[ARG_WORKING_DIRECTORY]);
  g_free (new_argv[ARG_FDS]);
  g_free (new_argv);

  /* Check if gspawn-win32-helper couldn't be run */
  if (rc == -1 && errsv != 0)
    {
      g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
		   _("Failed to execute helper program (%s)"),
		   g_strerror (errsv));
      goto cleanup_and_fail;
    }

  if (exit_status != NULL)
    {
      /* Synchronous case. Pass helper's report pipe back to caller,
       * which takes care of reading it after the grandchild has
       * finished.
       */
      g_assert (err_report != NULL);
      *err_report = child_err_report_pipe[0];
      write (helper_sync_pipe[1], " ", 1);
      close_and_invalidate (&helper_sync_pipe[1]);
    }
  else
    {
      /* Asynchronous case. We read the helper's report right away. */
      if (!read_helper_report (child_err_report_pipe[0], helper_report, error))
	goto cleanup_and_fail;
        
      close_and_invalidate (&child_err_report_pipe[0]);

      switch (helper_report[0])
	{
	case CHILD_NO_ERROR:
	  if (child_pid && do_return_handle)
	    {
	      /* rc is our HANDLE for gspawn-win32-helper. It has
	       * told us the HANDLE of its child. Duplicate that into
	       * a HANDLE valid in this process.
	       */
	      if (!DuplicateHandle ((HANDLE) rc, (HANDLE) helper_report[1],
				    GetCurrentProcess (), (LPHANDLE) child_pid,
				    0, TRUE, DUPLICATE_SAME_ACCESS))
		{
		  char *emsg = g_win32_error_message (GetLastError ());
		  g_print ("%s\n", emsg);
		  g_free (emsg);
		  *child_pid = 0;
		}
	    }
	  else if (child_pid)
	    *child_pid = 0;
	  write (helper_sync_pipe[1], " ", 1);
	  close_and_invalidate (&helper_sync_pipe[1]);
	  break;
	  
	default:
	  write (helper_sync_pipe[1], " ", 1);
	  close_and_invalidate (&helper_sync_pipe[1]);
	  set_child_error (helper_report, working_directory, error);
	  goto cleanup_and_fail;
	}
    }

  /* Success against all odds! return the information */
      
  if (rc != -1)
    CloseHandle ((HANDLE) rc);

  /* Close the other process's ends of the pipes in this process,
   * otherwise the reader will never get EOF.
   */
  close_and_invalidate (&stdin_pipe[0]);
  close_and_invalidate (&stdout_pipe[1]);
  close_and_invalidate (&stderr_pipe[1]);

  if (stdin_pipe_out != NULL)
    *stdin_pipe_out = stdin_pipe[1];
  if (stdout_pipe_out != NULL)
    *stdout_pipe_out = stdout_pipe[0];
  if (stderr_pipe_out != NULL)
    *stderr_pipe_out = stderr_pipe[0];

  return TRUE;

 cleanup_and_fail:

  if (rc != -1)
    CloseHandle ((HANDLE) rc);
  if (child_err_report_pipe[0] != -1)
    close (child_err_report_pipe[0]);
  if (child_err_report_pipe[1] != -1)
    close (child_err_report_pipe[1]);
  if (helper_sync_pipe[0] != -1)
    close (helper_sync_pipe[0]);
  if (helper_sync_pipe[1] != -1)
    close (helper_sync_pipe[1]);

  if (stdin_pipe[0] != -1)
    close (stdin_pipe[0]);
  if (stdin_pipe[1] != -1)
    close (stdin_pipe[1]);
  if (stdout_pipe[0] != -1)
    close (stdout_pipe[0]);
  if (stdout_pipe[1] != -1)
    close (stdout_pipe[1]);
  if (stderr_pipe[0] != -1)
    close (stderr_pipe[0]);
  if (stderr_pipe[1] != -1)
    close (stderr_pipe[1]);

  return FALSE;
}

gboolean
g_spawn_sync_impl (const gchar           *working_directory,
                   gchar                **argv,
                   gchar                **envp,
                   GSpawnFlags            flags,
                   GSpawnChildSetupFunc   child_setup,
                   gpointer               user_data,
                   gchar                **standard_output,
                   gchar                **standard_error,
                   gint                  *wait_status,
                   GError               **error)
{
  gint outpipe = -1;
  gint errpipe = -1;
  gint reportpipe = -1;
  GIOChannel *outchannel = NULL;
  GIOChannel *errchannel = NULL;
  GPollFD outfd = { -1, 0, 0 }, errfd = { -1, 0, 0 };
  GPollFD fds[2];
  gint nfds;
  gint outindex = -1;
  gint errindex = -1;
  gint ret;
  GString *outstr = NULL;
  GString *errstr = NULL;
  gboolean failed;
  gint status;
  
  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
  g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
  g_return_val_if_fail (standard_output == NULL ||
                        !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
  g_return_val_if_fail (standard_error == NULL ||
                        !(flags & G_SPAWN_STDERR_TO_DEV_NULL), FALSE);
  
  /* Just to ensure segfaults if callers try to use
   * these when an error is reported.
   */
  if (standard_output)
    *standard_output = NULL;

  if (standard_error)
    *standard_error = NULL;

  if (!fork_exec (&status,
                  FALSE,
                  working_directory,
                  (const gchar * const *) argv,
                  (const gchar * const *) envp,
                  flags,
                  child_setup,
                  user_data,
                  NULL,
                  NULL,
                  standard_output ? &outpipe : NULL,
                  standard_error ? &errpipe : NULL,
                  -1,
                  -1,
                  -1,
                  NULL, NULL, 0,
                  &reportpipe,
                  error))
    return FALSE;

  /* Read data from child. */
  
  failed = FALSE;

  if (outpipe >= 0)
    {
      outstr = g_string_new (NULL);
      outchannel = g_io_channel_win32_new_fd (outpipe);
      g_io_channel_set_encoding (outchannel, NULL, NULL);
      g_io_channel_set_buffered (outchannel, FALSE);
      g_io_channel_win32_make_pollfd (outchannel,
				      G_IO_IN | G_IO_ERR | G_IO_HUP,
				      &outfd);
      if (debug)
	g_print ("outfd=%p\n", (HANDLE) outfd.fd);
    }
      
  if (errpipe >= 0)
    {
      errstr = g_string_new (NULL);
      errchannel = g_io_channel_win32_new_fd (errpipe);
      g_io_channel_set_encoding (errchannel, NULL, NULL);
      g_io_channel_set_buffered (errchannel, FALSE);
      g_io_channel_win32_make_pollfd (errchannel,
				      G_IO_IN | G_IO_ERR | G_IO_HUP,
				      &errfd);
      if (debug)
	g_print ("errfd=%p\n", (HANDLE) errfd.fd);
    }

  /* Read data until we get EOF on all pipes. */
  while (!failed && (outpipe >= 0 || errpipe >= 0))
    {
      nfds = 0;
      if (outpipe >= 0)
	{
	  fds[nfds] = outfd;
	  outindex = nfds;
	  nfds++;
	}
      if (errpipe >= 0)
	{
	  fds[nfds] = errfd;
	  errindex = nfds;
	  nfds++;
	}

      if (debug)
	g_print ("g_spawn_sync: calling g_io_channel_win32_poll, nfds=%d\n",
		 nfds);

      ret = g_io_channel_win32_poll (fds, nfds, -1);

      if (ret < 0)
        {
          failed = TRUE;

          g_set_error_literal (error, G_SPAWN_ERROR, G_SPAWN_ERROR_READ,
                               _("Unexpected error in g_io_channel_win32_poll() reading data from a child process"));
	  
          break;
        }

      if (outpipe >= 0 && (fds[outindex].revents & G_IO_IN))
        {
          switch (read_data (outstr, outchannel, error))
            {
            case READ_FAILED:
	      if (debug)
		g_print ("g_spawn_sync: outchannel: READ_FAILED\n");
              failed = TRUE;
              break;
            case READ_EOF:
	      if (debug)
		g_print ("g_spawn_sync: outchannel: READ_EOF\n");
              g_io_channel_unref (outchannel);
	      outchannel = NULL;
              close_and_invalidate (&outpipe);
              break;
            default:
	      if (debug)
		g_print ("g_spawn_sync: outchannel: OK\n");
              break;
            }

          if (failed)
            break;
        }

      if (errpipe >= 0 && (fds[errindex].revents & G_IO_IN))
        {
          switch (read_data (errstr, errchannel, error))
            {
            case READ_FAILED:
	      if (debug)
		g_print ("g_spawn_sync: errchannel: READ_FAILED\n");
              failed = TRUE;
              break;
            case READ_EOF:
	      if (debug)
		g_print ("g_spawn_sync: errchannel: READ_EOF\n");
	      g_io_channel_unref (errchannel);
	      errchannel = NULL;
              close_and_invalidate (&errpipe);
              break;
            default:
	      if (debug)
		g_print ("g_spawn_sync: errchannel: OK\n");
              break;
            }

          if (failed)
            break;
        }
    }

  if (reportpipe == -1)
    {
      /* No helper process, exit status of actual spawned process
       * already available.
       */
      if (wait_status)
        *wait_status = status;
    }
  else
    {
      /* Helper process was involved. Read its report now after the
       * grandchild has finished.
       */
      gintptr helper_report[2];

      if (!read_helper_report (reportpipe, helper_report, error))
	failed = TRUE;
      else
	{
	  switch (helper_report[0])
	    {
	    case CHILD_NO_ERROR:
	      if (wait_status)
		*wait_status = helper_report[1];
	      break;
	    default:
	      set_child_error (helper_report, working_directory, error);
	      failed = TRUE;
	      break;
	    }
	}
      close_and_invalidate (&reportpipe);
    }


  /* These should only be open still if we had an error.  */
  
  if (outchannel != NULL)
    g_io_channel_unref (outchannel);
  if (errchannel != NULL)
    g_io_channel_unref (errchannel);
  if (outpipe >= 0)
    close_and_invalidate (&outpipe);
  if (errpipe >= 0)
    close_and_invalidate (&errpipe);
  
  if (failed)
    {
      if (outstr)
        g_string_free (outstr, TRUE);
      if (errstr)
        g_string_free (errstr, TRUE);

      return FALSE;
    }
  else
    {
      if (standard_output)        
        *standard_output = g_string_free (outstr, FALSE);

      if (standard_error)
        *standard_error = g_string_free (errstr, FALSE);

      return TRUE;
    }
}

gboolean
g_spawn_async_with_pipes_and_fds_impl (const gchar           *working_directory,
                                       const gchar * const   *argv,
                                       const gchar * const   *envp,
                                       GSpawnFlags            flags,
                                       GSpawnChildSetupFunc   child_setup,
                                       gpointer               user_data,
                                       gint                   stdin_fd,
                                       gint                   stdout_fd,
                                       gint                   stderr_fd,
                                       const gint            *source_fds,
                                       const gint            *target_fds,
                                       gsize                  n_fds,
                                       GPid                  *child_pid_out,
                                       gint                  *stdin_pipe_out,
                                       gint                  *stdout_pipe_out,
                                       gint                  *stderr_pipe_out,
                                       GError               **error)
{
  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
  g_return_val_if_fail (stdout_pipe_out == NULL ||
                        !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
  g_return_val_if_fail (stderr_pipe_out == NULL ||
                        !(flags & G_SPAWN_STDERR_TO_DEV_NULL), FALSE);
  /* can't inherit stdin if we have an input pipe. */
  g_return_val_if_fail (stdin_pipe_out == NULL ||
                        !(flags & G_SPAWN_CHILD_INHERITS_STDIN), FALSE);
  /* can’t use pipes and stdin/stdout/stderr FDs */
  g_return_val_if_fail (stdin_pipe_out == NULL || stdin_fd < 0, FALSE);
  g_return_val_if_fail (stdout_pipe_out == NULL || stdout_fd < 0, FALSE);
  g_return_val_if_fail (stderr_pipe_out == NULL || stderr_fd < 0, FALSE);

  return fork_exec (NULL,
                    (flags & G_SPAWN_DO_NOT_REAP_CHILD),
                    working_directory,
                    argv,
                    envp,
                    flags,
                    child_setup,
                    user_data,
                    child_pid_out,
                    stdin_pipe_out,
                    stdout_pipe_out,
                    stderr_pipe_out,
                    stdin_fd,
                    stdout_fd,
                    stderr_fd,
                    source_fds,
                    target_fds,
                    n_fds,
                    NULL,
                    error);
}

void
g_spawn_close_pid_impl (GPid pid)
{
  /* CRT functions such as _wspawn* return (HANDLE)-1
   * on failure, so check also for that value. */
  if (pid != NULL && pid != (HANDLE) -1)
    CloseHandle (pid);
}

gboolean
g_spawn_check_wait_status_impl (gint     wait_status,
                                GError **error)
{
  gboolean ret = FALSE;

  if (wait_status != 0)
    {
      /* On Windows, the wait status is just the exit status: the
       * difference between the two that exists on Unix is not relevant */
      g_set_error (error, G_SPAWN_EXIT_ERROR, wait_status,
		   _("Child process exited with code %ld"),
		   (long) wait_status);
      goto out;
    }

  ret = TRUE;
 out:
  return ret;
}

#ifdef G_OS_WIN32

/* Binary compatibility versions. Not for newly compiled code. */

_GLIB_EXTERN gboolean g_spawn_async_utf8              (const gchar           *working_directory,
                                                       gchar                **argv,
                                                       gchar                **envp,
                                                       GSpawnFlags            flags,
                                                       GSpawnChildSetupFunc   child_setup,
                                                       gpointer               user_data,
                                                       GPid                  *child_pid,
                                                       GError               **error);
_GLIB_EXTERN gboolean g_spawn_async_with_pipes_utf8   (const gchar           *working_directory,
                                                       gchar                **argv,
                                                       gchar                **envp,
                                                       GSpawnFlags            flags,
                                                       GSpawnChildSetupFunc   child_setup,
                                                       gpointer               user_data,
                                                       GPid                  *child_pid,
                                                       gint                  *standard_input,
                                                       gint                  *standard_output,
                                                       gint                  *standard_error,
                                                       GError               **error);
_GLIB_EXTERN gboolean g_spawn_sync_utf8               (const gchar           *working_directory,
                                                       gchar                **argv,
                                                       gchar                **envp,
                                                       GSpawnFlags            flags,
                                                       GSpawnChildSetupFunc   child_setup,
                                                       gpointer               user_data,
                                                       gchar                **standard_output,
                                                       gchar                **standard_error,
                                                       gint                  *wait_status,
                                                       GError               **error);
_GLIB_EXTERN gboolean g_spawn_command_line_sync_utf8  (const gchar           *command_line,
                                                       gchar                **standard_output,
                                                       gchar                **standard_error,
                                                       gint                  *wait_status,
                                                       GError               **error);
_GLIB_EXTERN gboolean g_spawn_command_line_async_utf8 (const gchar           *command_line,
                                                       GError               **error);

gboolean
g_spawn_async_utf8 (const gchar          *working_directory,
                    gchar               **argv,
                    gchar               **envp,
                    GSpawnFlags           flags,
                    GSpawnChildSetupFunc  child_setup,
                    gpointer              user_data,
                    GPid                 *child_pid,
                    GError              **error)
{
  return g_spawn_async (working_directory,
                        argv,
                        envp,
                        flags,
                        child_setup,
                        user_data,
                        child_pid,
                        error);
}

gboolean
g_spawn_async_with_pipes_utf8 (const gchar          *working_directory,
                               gchar               **argv,
                               gchar               **envp,
                               GSpawnFlags           flags,
                               GSpawnChildSetupFunc  child_setup,
                               gpointer              user_data,
                               GPid                 *child_pid,
                               gint                 *standard_input,
                               gint                 *standard_output,
                               gint                 *standard_error,
                               GError              **error)
{
  return g_spawn_async_with_pipes (working_directory,
                                   argv,
                                   envp,
                                   flags,
                                   child_setup,
                                   user_data,
                                   child_pid,
                                   standard_input,
                                   standard_output,
                                   standard_error,
                                   error);
}

gboolean
g_spawn_sync_utf8 (const gchar          *working_directory,
                   gchar               **argv,
                   gchar               **envp,
                   GSpawnFlags           flags,
                   GSpawnChildSetupFunc  child_setup,
                   gpointer              user_data,
                   gchar               **standard_output,
                   gchar               **standard_error,
                   gint                 *wait_status,
                   GError              **error)
{
  return g_spawn_sync (working_directory,
                       argv,
                       envp,
                       flags,
                       child_setup,
                       user_data,
                       standard_output,
                       standard_error,
                       wait_status,
                       error);
}

gboolean
g_spawn_command_line_sync_utf8 (const gchar  *command_line,
                                gchar       **standard_output,
                                gchar       **standard_error,
                                gint         *wait_status,
                                GError      **error)
{
  return g_spawn_command_line_sync (command_line,
                                    standard_output,
                                    standard_error,
                                    wait_status,
                                    error);
}

gboolean
g_spawn_command_line_async_utf8 (const gchar *command_line,
                                 GError     **error)
{
  return g_spawn_command_line_async (command_line, error);
}

#endif /* G_OS_WIN32 */

#endif /* !GSPAWN_HELPER */
