/****************************************************************************
 *                                                                          *
 *                         GNAT RUN-TIME COMPONENTS                         *
 *                                                                          *
 *                            T E R M I N A L S                             *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *                     Copyright (C) 2008-2021, AdaCore                     *
 *                                                                          *
 * GNAT is free software;  you can  redistribute it  and/or modify it under *
 * terms of the  GNU General Public License as published  by the Free Soft- *
 * ware  Foundation;  either version 3,  or (at your option) any later ver- *
 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
 * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
 * or FITNESS FOR A PARTICULAR PURPOSE.                                     *
 *                                                                          *
 * As a special exception under Section 7 of GPL version 3, you are granted *
 * additional permissions described in the GCC Runtime Library Exception,   *
 * version 3.1, as published by the Free Software Foundation.               *
 *                                                                          *
 * You should have received a copy of the GNU General Public License and    *
 * a copy of the GCC Runtime Library Exception along with this program;     *
 * see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    *
 * <http://www.gnu.org/licenses/>.                                          *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

#define ATTRIBUTE_UNUSED __attribute__((unused))

/* First all usupported platforms. Add stubs for exported routines. */

#if defined (VMS) || defined (__vxworks) || defined (__Lynx__) \
  || defined (__ANDROID__) || defined (__PikeOS__) || defined(__DJGPP__)

void *
__gnat_new_tty (void)
{
  return (void*)0;
}

char *
__gnat_tty_name (void* t ATTRIBUTE_UNUSED)
{
  return (char*)0;
}

int
__gnat_interrupt_pid (int pid ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_interrupt_process (void* desc ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_setup_communication (void** desc ATTRIBUTE_UNUSED)
{
  return -1;
}

void
__gnat_setup_parent_communication (void *d ATTRIBUTE_UNUSED,
				   int *i ATTRIBUTE_UNUSED,
				   int *o ATTRIBUTE_UNUSED,
				   int *e ATTRIBUTE_UNUSED,
				   int *p ATTRIBUTE_UNUSED)
{
}

int
__gnat_setup_child_communication (void *d ATTRIBUTE_UNUSED,
				  char **n ATTRIBUTE_UNUSED,
				  int u ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_terminate_process (void *desc ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_terminate_pid (int pid ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_tty_fd (void* t ATTRIBUTE_UNUSED)
{
  return -1;
}

int
__gnat_tty_supported (void)
{
  return 0;
}

int
__gnat_tty_waitpid (void *desc ATTRIBUTE_UNUSED, int blocking)
{
  return 1;
}

void
__gnat_close_tty (void* t ATTRIBUTE_UNUSED)
{
}

void
__gnat_free_process (void** process ATTRIBUTE_UNUSED)
{
}

void
__gnat_reset_tty (void* t ATTRIBUTE_UNUSED)
{
}

void
__gnat_send_header (void* d ATTRIBUTE_UNUSED,
		    char h[5] ATTRIBUTE_UNUSED,
		    int s ATTRIBUTE_UNUSED,
		    int *r ATTRIBUTE_UNUSED)
{
}

void
__gnat_setup_winsize (void *desc ATTRIBUTE_UNUSED,
		      int rows ATTRIBUTE_UNUSED,
		      int columns ATTRIBUTE_UNUSED)
{
}

/* For Windows platforms. */

#elif defined(_WIN32)

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

#include <windows.h>
#include <winternl.h>
#include <io.h>

#define MAXPATHLEN 1024

#define NILP(x) ((x) == 0)
#define Qnil 0
#define report_file_error(x, y) fprintf (stderr, "Error: %s\n", x);
#define INTEGERP(x) 1
#define XINT(x) x

struct TTY_Process {
  int pid;           /* Number of this process */
  PROCESS_INFORMATION procinfo;
  HANDLE w_infd, w_outfd;
  HANDLE w_forkin, w_forkout;
  BOOL usePipe;
};

/* Control whether create_child cause the process to inherit GNAT Studio'
   error mode setting.  The default is 1, to minimize the possibility of
   subprocesses blocking when accessing unmounted drives.  */
static int Vw32_start_process_inherit_error_mode = 1;

/* Control whether spawnve quotes arguments as necessary to ensure
   correct parsing by child process.  Because not all uses of spawnve
   are careful about constructing argv arrays, we make this behavior
   conditional (off by default, since a similar operation is already done
   in g-expect.adb by calling Normalize_Argument). */
static int Vw32_quote_process_args = 0;

static DWORD AbsoluteSeek(HANDLE, DWORD);
static VOID  ReadBytes(HANDLE, LPVOID, DWORD);

#define XFER_BUFFER_SIZE 2048

/* This tell if the executable we're about to launch uses a GUI interface. */
/* if we can't determine it, we will return true */
static int
is_gui_app (char *exe)
{
  HANDLE hImage;

  DWORD  CoffHeaderOffset;
  DWORD  MoreDosHeader[16];
  CHAR   *file;
  size_t nlen;

  ULONG  ntSignature;

  IMAGE_DOS_HEADER      image_dos_header;
  IMAGE_FILE_HEADER     image_file_header;
  IMAGE_OPTIONAL_HEADER image_optional_header;

  /*
   *  Open the reference file.
  */
  nlen = strlen (exe);
  file = exe;
  if (nlen > 2) {
    if (exe[0] == '"') {
      /* remove quotes */
      nlen -= 2;
      file = malloc ((nlen + 1) * sizeof (char));
      memcpy (file, &exe[1], nlen);
      file [nlen] = '\0';
    }
  }
  hImage = CreateFile(file,
                      GENERIC_READ,
                      FILE_SHARE_READ,
                      NULL,
                      OPEN_EXISTING,
                      FILE_ATTRIBUTE_NORMAL,
                      NULL);

  if (file != exe) {
    free (file);
  }

  if (INVALID_HANDLE_VALUE == hImage)
    {
      report_file_error ("Could not open exe: ", Qnil);
      report_file_error (exe, Qnil);
      report_file_error ("\n", Qnil);
      CloseHandle (hImage);
      return -1;
    }

  /*
   *  Read the MS-DOS image header.
   */
  ReadBytes(hImage, &image_dos_header, sizeof(IMAGE_DOS_HEADER));

  if (IMAGE_DOS_SIGNATURE != image_dos_header.e_magic)
    {
      report_file_error("Sorry, I do not understand this file.\n", Qnil);
      CloseHandle (hImage);
      return -1;
    }

  /*
   *  Read more MS-DOS header.       */
  ReadBytes(hImage, MoreDosHeader, sizeof(MoreDosHeader));
   /*
   *  Get actual COFF header.
   */
  CoffHeaderOffset = AbsoluteSeek(hImage, image_dos_header.e_lfanew) +
                     sizeof(ULONG);
  if (CoffHeaderOffset == (DWORD) -1) {
    CloseHandle (hImage);
    return -1;
  }

  ReadBytes (hImage, &ntSignature, sizeof(ULONG));

  if (IMAGE_NT_SIGNATURE != ntSignature)
    {
      report_file_error ("Missing NT signature. Unknown file type.\n", Qnil);
      CloseHandle (hImage);
      return -1;
    }

  ReadBytes(hImage, &image_file_header, IMAGE_SIZEOF_FILE_HEADER);

  /*
   *  Read optional header.
   */
  ReadBytes(hImage,
            &image_optional_header,
            IMAGE_SIZEOF_NT_OPTIONAL_HEADER);

  CloseHandle (hImage);

  switch (image_optional_header.Subsystem)
    {
    case IMAGE_SUBSYSTEM_UNKNOWN:
        return 1;

    case IMAGE_SUBSYSTEM_NATIVE:
        return 1;

    case IMAGE_SUBSYSTEM_WINDOWS_GUI:
        return 1;

    case IMAGE_SUBSYSTEM_WINDOWS_CUI:
        return 0;

    case IMAGE_SUBSYSTEM_OS2_CUI:
        return 0;

    case IMAGE_SUBSYSTEM_POSIX_CUI:
        return 0;

    default:
        /* Unknown, return GUI app to be preservative: if yes, it will be
           correctly launched, if no, it will be launched, and a console will
           be also displayed, which is not a big deal */
        return 1;
    }

}

static DWORD
AbsoluteSeek (HANDLE hFile, DWORD offset)
{
    DWORD newOffset;

    newOffset = SetFilePointer (hFile, offset, NULL, FILE_BEGIN);

    if (newOffset == 0xFFFFFFFF)
      return -1;
    else
      return newOffset;
}

static VOID
ReadBytes (HANDLE hFile, LPVOID buffer, DWORD size)
{
  DWORD bytes;

  if (!ReadFile(hFile, buffer, size, &bytes, NULL))
    {
      size = 0;
      return;
    }
  else if (size != bytes)
    {
      return;
    }
}

static int
nt_spawnve (char *exe ATTRIBUTE_UNUSED, char **argv, char *env,
            struct TTY_Process *process)
{
  STARTUPINFO start;
  SECURITY_ATTRIBUTES sec_attrs;
  SECURITY_DESCRIPTOR sec_desc;
  DWORD flags;
  int pid;
  int is_gui, use_cmd;
  char *cmdline, *parg, **targ;
  int do_quoting = 0;
  char escape_char = 0;
  int arglen;

  /* we have to do some conjuring here to put argv and envp into the
     form CreateProcess wants...  argv needs to be a space separated/null
     terminated list of parameters, and envp is a null
     separated/double-null terminated list of parameters.

     Additionally, zero-length args and args containing whitespace or
     quote chars need to be wrapped in double quotes - for this to work,
     embedded quotes need to be escaped as well.  The aim is to ensure
     the child process reconstructs the argv array we start with
     exactly, so we treat quotes at the beginning and end of arguments
     as embedded quotes.

     Note that using backslash to escape embedded quotes requires
     additional special handling if an embedded quote is already
     preceded by backslash, or if an arg requiring quoting ends with
     backslash.  In such cases, the run of escape characters needs to be
     doubled.  For consistency, we apply this special handling as long
     as the escape character is not quote.

     Since we have no idea how large argv and envp are likely to be we
     figure out list lengths on the fly and allocate them.  */

  if (!NILP (Vw32_quote_process_args))
    {
      do_quoting = 1;
      /* Override escape char by binding w32-quote-process-args to
	 desired character, or use t for auto-selection.  */
      if (INTEGERP (Vw32_quote_process_args))
	escape_char = XINT (Vw32_quote_process_args);
      else
	escape_char = '\\';
    }

  /* do argv...  */
  arglen = 0;
  targ = argv;
  while (*targ)
    {
      char *p = *targ;
      int need_quotes = 0;
      int escape_char_run = 0;

      if (*p == 0)
	need_quotes = 1;
      for ( ; *p; p++)
	{
	  if (*p == '"')
	    {
	      /* allow for embedded quotes to be escaped */
	      arglen++;
	      need_quotes = 1;
	      /* handle the case where the embedded quote is already escaped */
	      if (escape_char_run > 0)
		{
		  /* To preserve the arg exactly, we need to double the
		     preceding escape characters (plus adding one to
		     escape the quote character itself).  */
		  arglen += escape_char_run;
		}
	    }
	  else if (*p == ' ' || *p == '\t')
	    {
	      need_quotes = 1;
	    }

	  if (*p == escape_char && escape_char != '"')
	    escape_char_run++;
	  else
	    escape_char_run = 0;
	}
      if (need_quotes)
	{
	  arglen += 2;
	  /* handle the case where the arg ends with an escape char - we
	     must not let the enclosing quote be escaped.  */
	  if (escape_char_run > 0)
	    arglen += escape_char_run;
	}
      arglen += strlen (*targ) + 1;
      targ++;
    }

  is_gui = is_gui_app (argv[0]);
  use_cmd = FALSE;

  if (is_gui == -1) {
    /* could not determine application type. Try launching with "cmd /c" */
    is_gui = FALSE;
    arglen += 7;
    use_cmd = TRUE;
  }

  cmdline = (char*)malloc (arglen + 1);
  targ = argv;
  parg = cmdline;

  if (use_cmd == TRUE) {
    strcpy (parg, "cmd /c ");
    parg += 7;
  }

  while (*targ)
    {
      char * p = *targ;
      int need_quotes = 0;

      if (*p == 0)
	need_quotes = 1;

      if (do_quoting)
	{
	  for ( ; *p; p++)
	    if (*p == ' ' || *p == '\t' || *p == '"')
	      need_quotes = 1;
	}
      if (need_quotes)
	{
	  int escape_char_run = 0;

	  p = *targ;
	  *parg++ = '"';
	  for ( ; *p; p++)
	    {
	      if (*p == '"')
		{
		  /* double preceding escape chars if any */
		  while (escape_char_run > 0)
		    {
		      *parg++ = escape_char;
		      escape_char_run--;
		    }
		  /* escape all quote chars, even at beginning or end */
		  *parg++ = escape_char;
		}
	      *parg++ = *p;

	      if (*p == escape_char && escape_char != '"')
		escape_char_run++;
	      else
		escape_char_run = 0;
	    }
	  /* double escape chars before enclosing quote */
	  while (escape_char_run > 0)
	    {
	      *parg++ = escape_char;
	      escape_char_run--;
	    }
	  *parg++ = '"';
	}
      else
	{
	  strcpy (parg, *targ);
	  parg += strlen (*targ);
	}
      *parg++ = ' ';
      targ++;
    }
  *--parg = '\0';

  memset (&start, 0, sizeof (start));
  start.cb = sizeof (start);

  if (process->usePipe == TRUE) {
    start.dwFlags = STARTF_USESTDHANDLES;
    start.hStdInput = process->w_forkin;
    start.hStdOutput = process->w_forkout;
    /* child's stderr is always redirected to outfd */
    start.hStdError = process->w_forkout;
  } else {
    start.dwFlags = STARTF_USESTDHANDLES;
    /* We only need to redirect stderr/stdout here. Stdin will be forced to
       the spawned process console by explaunch */
    start.hStdInput = NULL;
    start.hStdOutput = process->w_forkout;
    start.hStdError = process->w_forkout;
  }

  /* Explicitly specify no security */
  if (!InitializeSecurityDescriptor (&sec_desc, SECURITY_DESCRIPTOR_REVISION))
    goto EH_Fail;
  if (!SetSecurityDescriptorDacl (&sec_desc, TRUE, NULL, FALSE))
    goto EH_Fail;
  sec_attrs.nLength = sizeof (sec_attrs);
  sec_attrs.lpSecurityDescriptor = &sec_desc;
  sec_attrs.bInheritHandle = FALSE;

  /* creating a new console allow easier close. Do not use
     CREATE_NEW_PROCESS_GROUP as this results in disabling Ctrl+C */
  flags = CREATE_NEW_CONSOLE;
  if (NILP (Vw32_start_process_inherit_error_mode))
    flags |= CREATE_DEFAULT_ERROR_MODE;

  /* if app is not a gui application, hide the console */
  if (is_gui == FALSE) {
    start.dwFlags |= STARTF_USESHOWWINDOW;
    start.wShowWindow = SW_HIDE;
  }

  /* Set initial directory to null character to use current directory */
  if (!CreateProcess (NULL, cmdline, &sec_attrs, NULL, TRUE,
		      flags, env, NULL, &start, &process->procinfo))
    goto EH_Fail;

  pid = (int) (intptr_t) process->procinfo.hProcess;
  process->pid = pid;

  return pid;

 EH_Fail:
  return -1;
}

/*************************
 ** __gnat_send_header ()
 *************************/

#define EXP_SLAVE_CREATE 'c'
#define EXP_SLAVE_KEY    'k'
#define EXP_SLAVE_MOUSE  'm'
#define EXP_SLAVE_WRITE  'w'
#define EXP_SLAVE_KILL   'x'

#define EXP_KILL_TERMINATE  0x1
#define EXP_KILL_CTRL_C     0x2
#define EXP_KILL_CTRL_BREAK 0x4

void
__gnat_send_header (struct TTY_Process* p, char header[5], int size, int *ret)
{
  if (p->usePipe == FALSE) {
    header[0] = EXP_SLAVE_WRITE;
    header[1] = size & 0xff;
    header[2] = (size & 0xff00) >> 8;
    header[3] = (size & 0xff0000) >> 16;
    header[4] = (size & 0xff000000) >> 24;
    *ret = 1;
  } else {
    *ret = 0;
  }
}

/**********************************
 **  __gnat_setup_communication ()
 **********************************/

int
__gnat_setup_communication (struct TTY_Process** process_out) /* output param */
{
  struct TTY_Process* process;

  process = (struct TTY_Process*)malloc (sizeof (struct TTY_Process));
  ZeroMemory (process, sizeof (struct TTY_Process));
  *process_out = process;

  return 0;
}

#define EXP_PIPE_BASENAME "\\\\.\\pipe\\ExpectPipe"

int
__gnat_setup_child_communication
  (struct TTY_Process* process,
   char** argv,
   int Use_Pipes)
{
  int cpid;
  SECURITY_ATTRIBUTES sec_attrs;
  char slavePath [MAX_PATH];
  char **nargv;
  int argc;
  int i;
  char pipeNameIn[100];
  HANDLE hSlaveInDrv = NULL; /* Handle to communicate with slave driver */

  /* Set inheritance for the pipe handles */
  sec_attrs.nLength = sizeof (SECURITY_ATTRIBUTES);
  sec_attrs.bInheritHandle = TRUE;
  sec_attrs.lpSecurityDescriptor = NULL;

  if (Use_Pipes) {
    /* Create in and out pipes */
    if (!CreatePipe (&process->w_forkin, &process->w_infd, &sec_attrs, 0))
      report_file_error ("Creation of child's IN handle", Qnil);
    if (!CreatePipe (&process->w_outfd, &process->w_forkout, &sec_attrs, 0))
      report_file_error ("Creation of child's OUT handle", Qnil);

    /* Do not inherit the parent's side of the pipes */
    SetHandleInformation (&process->w_infd, HANDLE_FLAG_INHERIT, 0);
    SetHandleInformation (&process->w_outfd, HANDLE_FLAG_INHERIT, 0);

    /* use native argv */
    nargv = argv;
    process->usePipe = TRUE;

  } else {
    static int pipeNameId = 0;

    process->w_infd = NULL;

    /* We create a named pipe for Input, as we handle input by sending special
       commands to the explaunch process, that uses it to feed the actual input
       of the process */
    sprintf(pipeNameIn, "%sIn%08lx_%08x", EXP_PIPE_BASENAME,
	    GetCurrentProcessId(), pipeNameId);
    pipeNameId++;

    hSlaveInDrv = CreateNamedPipe(pipeNameIn,
				  PIPE_ACCESS_OUTBOUND,
				  PIPE_TYPE_BYTE | PIPE_WAIT, 1, 8192, 8192,
				  20000, NULL);
    if (hSlaveInDrv == NULL)  goto end;

    if (!CreatePipe (&process->w_outfd, &process->w_forkout, &sec_attrs, 0))
      report_file_error ("Creation of child's OUT handle", Qnil);

    if (SearchPath (NULL, "explaunch.exe", NULL,
                    MAX_PATH, slavePath, NULL) == 0) goto end;

    for (argc=0; argv[argc] != NULL; argc++) ;
    nargv = (char **) malloc (sizeof (char*) * (argc + 3));
    nargv[0] = slavePath;
    nargv[1] = pipeNameIn;

    for (i = 0; i <= argc; i++) nargv[i + 2] = argv[i];
    process->usePipe = FALSE;
  }

  /* Spawn the child. */
  cpid = nt_spawnve (nargv[0], nargv, NULL, process);

  /* close the duplicated handles passed to the child */
  CloseHandle (process->w_forkout);

  if (process->usePipe == TRUE) {
    CloseHandle (process->w_forkin);

  } else {
    UCHAR buf[8];		/* enough space for child status info */
    DWORD count;
    BOOL bRet;
    DWORD dwRet;

    /*
     * Wait for connection with the slave driver
     */
    bRet = ConnectNamedPipe(hSlaveInDrv, NULL);
    if (bRet == FALSE) {
      dwRet = GetLastError();
      if (dwRet == ERROR_PIPE_CONNECTED) {
	;
      } else {
	goto end;
      }
    }

    process->w_infd = hSlaveInDrv;

    /*
     * wait for slave driver to initialize before allowing user to send to it
     */
    bRet = ReadFile(process->w_outfd, buf, 8, &count, NULL);
    if (bRet == FALSE) {
      cpid = -1;
    }

    dwRet = buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
    if (dwRet != 0) {
      cpid = -1;
    }

    cpid = buf[4] | (buf[5] << 8) | (buf[6] << 16) | (buf[7] << 24);
    process->pid = cpid;
  }

  if (cpid == -1)
    /* An error occurred while trying to spawn the process.  */
    report_file_error ("Spawning child process", Qnil);

  return cpid;
 end:
  if (hSlaveInDrv != NULL)
    CloseHandle (hSlaveInDrv);
  return -1;
}

void
__gnat_setup_parent_communication
  (struct TTY_Process* process,
   int* in,
   int* out,
   int* err,
   int* pid)
{
  *in = _open_osfhandle ((intptr_t) process->w_infd, 0);
  *out = _open_osfhandle ((intptr_t) process->w_outfd, 0);
  /* child's stderr is always redirected to outfd */
  *err = *out;
  *pid = process->pid;
}

typedef struct _child_process
{
  HWND                 hwnd;
  PROCESS_INFORMATION *procinfo;
} child_process;

/* The major and minor versions of NT.  */
static int w32_major_version;
static int w32_minor_version;

/* Distinguish between Windows NT and Windows 95.  */
static enum {OS_UNKNOWN, OS_WIN95, OS_NT} os_subtype = OS_UNKNOWN;

/* Cache information describing the NT system for later use.  */
static void
cache_system_info (void)
{
  union
    {
      struct info
        {
          char  major;
          char  minor;
          short platform;
        } info;
      DWORD data;
    } version;

  /* Cache the version of the operating system.  */
  version.data = GetVersion ();
  w32_major_version = version.info.major;
  w32_minor_version = version.info.minor;

  if (version.info.platform & 0x8000)
    os_subtype = OS_WIN95;
  else
    os_subtype = OS_NT;
}

static WINBOOL CALLBACK
find_child_console (HWND hwnd, LPARAM param)
{
  child_process *cp = (child_process *) param;
  DWORD process_id;

  (void) GetWindowThreadProcessId (hwnd, &process_id);
  if (process_id == cp->procinfo->dwProcessId)
    {
      char window_class[32];

      GetClassName (hwnd, window_class, sizeof (window_class));
      if (strcmp (window_class,
                  (os_subtype == OS_WIN95)
                  ? "tty"
                  : "ConsoleWindowClass") == 0)
        {
          cp->hwnd = hwnd;
          return FALSE;
        }
    }
  /* keep looking */
  return TRUE;
}

int
__gnat_interrupt_pid (int pid)
{
  volatile child_process cp;
  int rc = 0;

  cp.procinfo = (LPPROCESS_INFORMATION) malloc (sizeof (PROCESS_INFORMATION));
  cp.procinfo->dwProcessId = pid;

  if (os_subtype == OS_UNKNOWN)
    cache_system_info ();

  /* Try to locate console window for process. */
  EnumWindows ((WNDENUMPROC) find_child_console, (LPARAM) &cp);

  if (cp.hwnd)
    {
      BYTE control_scan_code = (BYTE) MapVirtualKey (VK_CONTROL, 0);
      /* Retrieve Ctrl-C scancode */
      BYTE vk_break_code = 'C';
      BYTE break_scan_code = (BYTE) MapVirtualKey (vk_break_code, 0);
      HWND foreground_window;

      foreground_window = GetForegroundWindow ();
      if (foreground_window)
        {
          /* NT 5.0, and apparently also Windows 98, will not allow
             a Window to be set to foreground directly without the
             user's involvement. The workaround is to attach
             ourselves to the thread that owns the foreground
             window, since that is the only thread that can set the
             foreground window.  */
          DWORD foreground_thread, child_thread;

          foreground_thread =
            GetWindowThreadProcessId (foreground_window, NULL);
          if (foreground_thread == GetCurrentThreadId ()
              || !AttachThreadInput (GetCurrentThreadId (),
                                     foreground_thread, TRUE))
            foreground_thread = 0;

          child_thread = GetWindowThreadProcessId (cp.hwnd, NULL);
          if (child_thread == GetCurrentThreadId ()
              || !AttachThreadInput (GetCurrentThreadId (),
                                     child_thread, TRUE))
            child_thread = 0;

          /* Set the foreground window to the child.  */
          if (SetForegroundWindow (cp.hwnd))
            {
              /* Generate keystrokes as if user had typed Ctrl-Break or
                 Ctrl-C.  */
              keybd_event (VK_CONTROL, control_scan_code, 0, 0);
              keybd_event (vk_break_code, break_scan_code,
                (vk_break_code == 'C' ? 0 : KEYEVENTF_EXTENDEDKEY), 0);
              keybd_event (vk_break_code, break_scan_code,
                (vk_break_code == 'C' ? 0 : KEYEVENTF_EXTENDEDKEY)
                 | KEYEVENTF_KEYUP, 0);
              keybd_event (VK_CONTROL, control_scan_code, KEYEVENTF_KEYUP, 0);

              /* Sleep for a bit to give time for the main frame to respond
              to focus change events.  */
              Sleep (100);

              SetForegroundWindow (foreground_window);
            }
          /* Detach from the foreground and child threads now that
             the foreground switching is over.  */
          if (foreground_thread)
	    AttachThreadInput (GetCurrentThreadId (), foreground_thread, FALSE);
	  if (child_thread)
            AttachThreadInput (GetCurrentThreadId (), child_thread, FALSE);
        }
    }
  /* Ctrl-Break is NT equivalent of SIGINT.  */
  else if (!GenerateConsoleCtrlEvent
             (CTRL_BREAK_EVENT, cp.procinfo->dwProcessId))
    {
      errno = EINVAL;
      rc = -1;
    }

  free (cp.procinfo);
  return rc;
}

int
__gnat_interrupt_process (struct TTY_Process* p)
{
  char buf[2];
  DWORD written;
  BOOL bret;

  if (p->usePipe == TRUE) {
    bret = FALSE;
  } else {
    buf[0] = EXP_SLAVE_KILL;
    buf[1] = EXP_KILL_CTRL_C;
    bret = WriteFile (p->w_infd, buf, 2, &written, NULL);
  }

  if (bret == FALSE) {
    return __gnat_interrupt_pid (p->procinfo.dwProcessId);
  }
  return 0;
}

/* kill a process, as this implementation use CreateProcess on Win32 we need
   to use Win32 TerminateProcess API */
int
__gnat_terminate_process (struct TTY_Process* p)
{
  char buf[2];
  DWORD written;
  BOOL bret;

  if (p->usePipe == TRUE) {
    bret = FALSE;
  } else {
    buf[0] = EXP_SLAVE_KILL;
    buf[1] = EXP_KILL_TERMINATE;
    bret = WriteFile (p->w_infd, buf, 2, &written, NULL);
  }

  if (bret == FALSE) {
    if (!TerminateProcess (p->procinfo.hProcess, 1))
      return -1;
    else
      return 0;
  } else
    return 0;
}

typedef struct {
  DWORD dwProcessId;
  HANDLE hwnd;
} pid_struct;

static WINBOOL CALLBACK
find_process_handle (HWND hwnd, LPARAM param)
{
  pid_struct *ps = (pid_struct *) param;
  DWORD process_id;

  (void) GetWindowThreadProcessId (hwnd, &process_id);
  if (process_id == ps->dwProcessId)
    {
      ps->hwnd = hwnd;
      return FALSE;
    }
  /* keep looking */
  return TRUE;
}

int
__gnat_terminate_pid (int pid)
{
  pid_struct ps;

  ps.dwProcessId = pid;
  ps.hwnd = 0;
  EnumWindows ((WNDENUMPROC) find_process_handle, (LPARAM) &ps);

  if (ps.hwnd)
    {
      if (!TerminateProcess (ps.hwnd, 1))
	return -1;
      else
	return 0;
    }

  return -1;
}

/* wait for process pid to terminate and return the process status. This
   implementation is different from the adaint.c one for Windows as it uses
   the Win32 API instead of the C one. */

int
__gnat_tty_waitpid (struct TTY_Process* p, int blocking)
{
  DWORD exitcode;
  HANDLE hprocess = p->procinfo.hProcess;

  if (blocking) {
     /* Wait is needed on Windows only in blocking mode. */
     WaitForSingleObject (hprocess, 0);
  }

  GetExitCodeProcess (hprocess, &exitcode);

  if (exitcode == STILL_ACTIVE) {
     /* If process is still active return -1. */
     exitcode = -1;
  } else {
     /* Process is dead, so handle to process and main thread can be closed. */
     CloseHandle (p->procinfo.hThread);
     CloseHandle (hprocess);
  }

  /* No need to close the handles: they were closed on the ada side */
  return (int) exitcode;
}

/********************************
 **  __gnat_free_process ()
 ********************************/

void
__gnat_free_process (struct TTY_Process** process)
{
  free (*process);
  *process = NULL;
}

/* TTY handling */

typedef struct {
  int tty_fd;        /* descriptor for the tty */
  char tty_name[24]; /* Name of TTY device */
} TTY_Handle;

int
__gnat_tty_supported (void)
{
  return 0;
}

/* Return the tty name associated with p */

char *
__gnat_tty_name (TTY_Handle* t)
{
  return t->tty_name;
}

int
__gnat_tty_fd (TTY_Handle* t)
{
  return t->tty_fd;
}

TTY_Handle*
__gnat_new_tty (void)
{
  return (TTY_Handle*)0;
}

void
__gnat_reset_tty (TTY_Handle* t ATTRIBUTE_UNUSED)
{
}

void
__gnat_close_tty (TTY_Handle* t)
{
  free (t);
}

void
__gnat_setup_winsize (void *desc ATTRIBUTE_UNUSED,
  int rows ATTRIBUTE_UNUSED, int columns ATTRIBUTE_UNUSED)
{
}

#else /* defined(_WIN32, implementatin for all UNIXes */

/* First defined some macro to identify easily some systems */
#if defined (__FreeBSD__) \
 || defined (__OpenBSD__) \
 || defined (__NetBSD__)  \
 || defined (__DragonFly__)
#   define BSD
#endif

/* Include every system header we need */
#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#if defined (__sun__)
#   include <sys/stropts.h>
#endif
#if defined (BSD) || defined (__sun__)
#   include <sys/signal.h>
#endif
#if defined (__hpux__)
#   include <sys/stropts.h>
#endif

#define CDISABLE _POSIX_VDISABLE

/* On HP-UX and Sun system, there is a bzero function but with a different
   signature. Use memset instead */
#if defined (__hpux__) || defined (__sun__) || defined (_AIX)
#   define bzero(s,n) memset (s,0,n)
#endif

/* POSIX does not specify how to open the master side of a terminal.Several
   methods are available (system specific):
      1- using a cloning device (USE_CLONE_DEVICE)
      2- getpt                  (USE_GETPT)
      3- openpty                (USE_OPENPTY)

   When using the cloning device method, the macro USE_CLONE_DEVICE should
   contains a full path to the adequate device.

   When a new system is about to be supported, one of the previous macro should
   be set otherwise allocate_pty_desc will return an error
*/

/* Configurable part */
#if defined (__APPLE__) || defined (BSD)
#define USE_OPENPTY
#elif defined (__linux__)
#define USE_GETPT
#elif defined (__sun__)
#define USE_CLONE_DEVICE "/dev/ptmx"
#elif defined (_AIX)
#define USE_CLONE_DEVICE "/dev/ptc"
#elif defined (__hpux__)
/* On HP-UX we use the streamed version. Using the non streamed version is not
   recommanded (through "/dev/ptym/clone"). Indeed it seems that there are
   issues to detect process terminations. */
#define USE_CLONE_DEVICE "/dev/ptmx"
#endif

/* structure that holds information about the terminal used and the process
   connected on the slave side */
typedef struct pty_desc_struct {
   int  master_fd;     /* fd of the master side if the terminal */
   int  slave_fd;      /* fd of the slave side */
   char slave_name[32];   /* filename of the slave side */
   int  child_pid;     /* PID of the child process connected to the slave side
                         of the terminal */
} pty_desc;

/* allocate_pty_desc - allocate a pseudo terminal
 *
 * PARAMETERS
 *   out desc  returned pointer to a pty_desc structure containing information
 *             about the opened pseudo terminal
 * RETURN VALUE
 *   -1        if failed
 *    0        if ok
 * COMMENTS
 *   If the function is successful we should have at least the master side fd
 *   and the slave side filename. On some system, the slave side will also be
 *   opened. If this is not the case the slave side will be open once we are in
 *   the child process (note that opening the slave side at this stage will
 *   failed...).
 */

extern char* ptsname (int);

static int
allocate_pty_desc (pty_desc **desc) {

   pty_desc *result;
   int  status      =  0;
   int  slave_fd    = -1;
   int  master_fd   = -1;
   char *slave_name = NULL;

#ifdef USE_GETPT
  master_fd = getpt ();
#elif defined (USE_OPENPTY)
  status = openpty (&master_fd, &slave_fd, NULL, NULL, NULL);
#elif defined (USE_CLONE_DEVICE)
  master_fd = open (USE_CLONE_DEVICE, O_RDWR | O_NONBLOCK, 0);
#else
  printf ("[error]: terminal support is not configured\n");
  return -1;
#endif

  /* at this stage we should have the master side fd and status should be 0 */
  if (status != 0 || master_fd < 0)
    {
      /* If this is not the case close all opened files and return -1 */
      printf ("[error]: cannot allocate master side of the pty\n");
      if (master_fd >= 0) close (master_fd);
      if (slave_fd  >= 0) close (slave_fd);
      *desc = NULL;
      return -1;
    }

  /* retrieve the file name of the slave side if necessary */
  if (slave_name == NULL) slave_name = (char *) ptsname (master_fd);

  /* Now we should have slave file name */
  if (slave_name == NULL)
    {
      /* If not the case close any opened file and return - 1 */
      printf ("[error]: cannot allocate slave side of the pty\n");
      if (master_fd >= 0) close (master_fd);
      if (slave_fd  >= 0) close (slave_fd);
      *desc = NULL;
      return -1;
    }

#if !defined(__rtems__)
  /* grant access to the slave side */
  grantpt (master_fd);
  /* unlock the terminal */
  unlockpt (master_fd);
#endif

  /* set desc and return 0 */
  result = malloc (sizeof (pty_desc));
  result->master_fd  = master_fd;
  result->slave_fd   = slave_fd;
  /* the string returned by ptsname or _getpty is a static allocated string. So
     we should make a copy */
  strncpy (result->slave_name, slave_name, sizeof (result->slave_name) - 1);
  result->slave_name[sizeof (result->slave_name) - 1] = '\0';
  result->child_pid  = -1;
  *desc=result;
  return 0;
}

/* some utility macro that make the code of child_setup_tty easier to read */
#define __enable(a, b) ((a) |= (b))
#define __disable(a, b) ((a) &= ~(b))

/* some properties do not exist on all systems. Set their value to 0 in that
   case */
#ifndef IUCLC
#define IUCLC 0
#endif
#ifndef OLCUC
#define OLCUC 0
#endif
#ifndef NLDLY
#define NLDLY 0
#define CRDLY 0
#define TABDLY 0
#define BSDLY 0
#define VTDLY 0
#define FFDLY 0
#endif

/* child_setup_tty - set terminal properties
 *
 * PARAMETERS
 *   file descriptor of the slave side of the terminal
 *
 * RETURN VALUE
 *   0 if success, any other value if failed.
 *
 * COMMENTS
 *   None
 */
static int
child_setup_tty (int fd)
{
  struct termios s;
  int    status;

  /* ensure that s is filled with 0 */
  bzero (&s, sizeof (s));

  /* Get the current terminal settings */
  status = tcgetattr (fd, &s);
  if (status != 0) return -1;

  /* Adjust input modes */
  __disable (s.c_iflag, IUCLC);    /* don't transform to lower case */
  __disable (s.c_iflag, ISTRIP);   /* don't delete 8th bit */

  /* Adjust output modes */
  __enable  (s.c_oflag, OPOST);    /* enable postprocessing */
  __disable (s.c_oflag, ONLCR);    /* don't map LF to CR-LF */
  __disable (s.c_oflag, NLDLY|CRDLY|TABDLY|BSDLY|VTDLY|FFDLY);
                                   /* disable delays */
  __disable (s.c_oflag, OLCUC);    /* don't transform to upper case */

  /* Adjust control modes */
  s.c_cflag = (s.c_cflag & ~CSIZE) | CS8; /* Don't strip 8th bit */

  /* Adjust local modes */
  __disable (s.c_lflag, ECHO);     /* disable echo */
  __enable  (s.c_lflag, ISIG);     /* enable signals */
  __enable  (s.c_lflag, ICANON);   /* erase/kill/eof processing */

  /* Adjust control characters */
  /* IMPORTANT: we need to ensure that Ctrl-C will trigger an interrupt signal
     otherwise send_signal_via_characters will fail */
  s.c_cc[VEOF]   = 04;         /* insure that EOF is Control-D */
  s.c_cc[VERASE] = CDISABLE;   /* disable erase processing */
  s.c_cc[VKILL]  = CDISABLE;   /* disable kill processing */
  s.c_cc[VQUIT]  = 28;         /* Control-\ */
  s.c_cc[VINTR]  = 03;         /* Control-C */
  s.c_cc[VEOL]   = CDISABLE;
  s.c_cc[VSUSP]  = 26;         /* Control-Z */

  /* push our changes */
  status = tcsetattr (fd, TCSADRAIN, &s);
  return status;
}

/* __gnat_setup_communication - interface to the external world. Should be
 * called before forking. On Unixes this function only call allocate_pty_desc.
 * The Windows implementation (in different part of this file) is very
 * different.
 *
 * PARAMETERS
 *  out desc   returned pointer to a pty_desc structure
 * RETURN VALUE
 *  0 if success, -1 otherwise
 */
int __gnat_setup_communication (pty_desc** desc) {
  return allocate_pty_desc (desc);
}

/* __gnat_setup_parent_communication - interface to the external world. Should
 * be called after forking in the parent process
 *
 * PARAMETERS
 *   out in_fd
     out out_fd
     out err_fd fds corresponding to the parent side of the
                terminal
     in pid_out child process pid
 * RETRUN VALUE
 *  0
 */
void
__gnat_setup_parent_communication
  (pty_desc *desc,
   int*     in_fd,  /* input */
   int*     out_fd, /* output */
   int*     err_fd, /* error */
   int*     pid_out)
{

  *in_fd = desc->master_fd;
  *out_fd= desc->master_fd;
  *err_fd= desc->master_fd;
  desc->child_pid = *pid_out;
}

/* __gnat_setup_winsize - Sets up the size of the terminal
 * This lets the process know the size of the terminal
 */

void __gnat_setup_winsize (pty_desc *desc, int rows, int columns) {
#ifdef TIOCGWINSZ
  struct winsize s;
  s.ws_row = (unsigned short)rows;
  s.ws_col = (unsigned short)columns;
  s.ws_xpixel = 0;
  s.ws_ypixel = 0;
  ioctl (desc->master_fd, TIOCSWINSZ, &s);
#ifdef SIGWINCH
  if (desc->child_pid > 0) {
     /* Let the process know about the change in size */
     kill (desc->child_pid, SIGWINCH);
  }
#endif
#endif
}

/* __gnat_setup_child_communication - interface to external world. Should be
 * called after forking in the child process. On Unixes, this function
 * first adjust the line setting, set standard output, input and error and
 * then spawn the program.
 *
 * PARAMETERS
 *   desc      a pty_desc structure containing the pty parameters
 *   new_argv  argv of the program to be spawned
 * RETURN VALUE
 *   this function should not return
 */
int
__gnat_setup_child_communication
   (pty_desc *desc,
    char **new_argv,
    int Use_Pipes ATTRIBUTE_UNUSED)
{
  int status;
  int pid = getpid ();

  setsid ();

  /* open the slave side of the terminal if necessary */
  if (desc->slave_fd == -1)
#if defined (_AIX)
    /* On AIX, if the slave process is not opened with O_NDELAY or O_NONBLOCK
       then we might have some processes hanging on I/O system calls. Not sure
       we can do that for all platforms so do it only on AIX for the moment.
       On AIX O_NONBLOCK and O_NDELAY have slightly different meanings. When
       reading on the slave fd, in case there is no data available, if O_NDELAY
       is set then 0 is returned. If O_NON_BLOCK is -1 is returned. It seems
       that interactive programs such as GDB prefer the O_NDELAY behavior.
       We chose O_NONBLOCK because it allows us to make the distinction
       between a true EOF and an EOF returned because there is no data
       available to be read.  */
    desc->slave_fd = open (desc->slave_name, O_RDWR | O_NONBLOCK, 0);
#else
    desc->slave_fd = open (desc->slave_name, O_RDWR, 0);
#endif

#if defined (__sun__) || defined (__hpux__)
  /* On systems such as Solaris we are using stream. We need to push the right
     "modules" in order to get the expected terminal behaviors. Otherwise
     functionalities such as termios are not available.  */
  ioctl (desc->slave_fd, I_PUSH, "ptem");
  ioctl (desc->slave_fd, I_PUSH, "ldterm");
  ioctl (desc->slave_fd, I_PUSH, "ttcompat");
#endif

#ifdef TIOCSCTTY
  /* make the tty the controlling terminal */
  if ((status = ioctl (desc->slave_fd, TIOCSCTTY, 0)) == -1)
    _exit (1);
#endif

  /* adjust tty settings */
  child_setup_tty (desc->slave_fd);
  __gnat_setup_winsize (desc, 24, 80); /* To prevent errors in some shells */

  /* stdin, stdout and stderr should be now our tty */
  dup2 (desc->slave_fd, 0);
  dup2 (desc->slave_fd, 1);
  dup2 (desc->slave_fd, 2);
  if (desc->slave_fd > 2) close (desc->slave_fd);

  /* adjust process group settings */
  /* ignore failures of the following two commands as the context might not
   * allow making those changes. */
  setpgid (pid, pid);
  tcsetpgrp (0, pid);

  /* launch the program */
  execvp (new_argv[0], new_argv);

  _exit (1);
}

/* send_signal_via_characters - Send a characters that will trigger a signal
 * in the child process.
 *
 * PARAMETERS
 *  desc  a pty_desc structure containing terminal information
 *  int   a signal number
 * RETURN VALUE
 *  None
 */
static void
send_signal_via_characters
  (pty_desc *desc,
   int signal_number)
{
  char ctrl_c         = 03;
  char ctrl_backslash = 28;
  char ctrl_Z         = 26;

  switch (signal_number)
    {
      case SIGINT:
	write (desc->master_fd, &ctrl_c, 1); return;
      case SIGQUIT:
	write (desc->master_fd, &ctrl_backslash, 1); return;
      case SIGTSTP:
	write (desc->master_fd, &ctrl_Z, 1); return;
    }
}

/* __gnat_interrupt_process - interrupt the child process
 *
 * PARAMETERS
 *   desc a pty_desc structure
 */
int
__gnat_interrupt_process (pty_desc *desc)
{
  send_signal_via_characters (desc, SIGINT);
  return 0;
}

/* __gnat_interrupt_pid - interrupt a process group
 *
 * PARAMETERS
 *   pid  pid of the process to interrupt
 */
int
__gnat_interrupt_pid (int pid)
{
  kill (-pid, SIGINT);
  return 0;
}

/* __gnat_terminate_process - kill a child process
 *
 * PARAMETERS
 *   desc pty_desc structure
 */
int __gnat_terminate_process (pty_desc *desc)
{
  return kill (desc->child_pid, SIGKILL);
}

/* __gnat_terminate_pid - kill a process
 *
 * PARAMETERS
 *   pid unix process id
 */
int
__gnat_terminate_pid (int pid)
{
  return kill (pid, SIGKILL);
}

/* __gnat_tty_waitpid - wait for the child process to die
 *
 * PARAMETERS
 *   desc pty_desc structure
 * RETURN VALUE
 *   exit status of the child process
 */
int
__gnat_tty_waitpid (pty_desc *desc, int blocking)
{
  int status = -1;
  int options = 0;

  if (blocking) {
     options = 0;
  } else {
     options = WNOHANG;
  }
  waitpid (desc->child_pid, &status, options);
  if WIFEXITED (status) {
     status = WEXITSTATUS (status);
  }
  return status;
}

/* __gnat_tty_supported - Are tty supported ?
 *
 * RETURN VALUE
 *   always 1 on Unix systems
 */
int
__gnat_tty_supported (void)
{
  return 1;
}

/* __gnat_free_process - free a pty_desc structure
 *
 * PARAMETERS
 *   in out desc: a pty desc structure
 */
void
__gnat_free_process (pty_desc** desc)
{
  free (*desc);
  *desc = NULL;
}

/* __gnat_send_header - dummy function. this interface is only used on Windows */
void
__gnat_send_header (pty_desc* desc ATTRIBUTE_UNUSED,
		    char header[5] ATTRIBUTE_UNUSED,
		    int size ATTRIBUTE_UNUSED,
		    int *ret ATTRIBUTE_UNUSED)
{
  *ret = 0;
}

/* __gnat_reset_tty - reset line setting
 *
 * PARAMETERS
 *   desc: a pty_desc structure
 */
void
__gnat_reset_tty (pty_desc* desc)
{
  child_setup_tty (desc->master_fd);
}

/* __gnat_new_tty - allocate a new terminal
 *
 * RETURN VALUE
 *   a pty_desc structure
 */
pty_desc *
__gnat_new_tty (void)
{
  int status;
  pty_desc* desc = NULL;
  if ((status = allocate_pty_desc (&desc)))
    child_setup_tty (desc->master_fd);
  return desc;
}

/* __gnat_close_tty - close a terminal
 *
 * PARAMETERS
 *   desc  a pty_desc strucure
 */
void __gnat_close_tty (pty_desc* desc)
{
  if (desc->master_fd >= 0) { close (desc->master_fd); desc->master_fd = -1; }
  if (desc->slave_fd  >= 0) { close (desc->slave_fd);  desc->slave_fd  = -1; }
}

/* __gnat_tty_name - return slave side device name
 *
 * PARAMETERS
 *   desc  a pty_desc strucure
 * RETURN VALUE
 *   a string
 */
char *
__gnat_tty_name (pty_desc* desc)
{
  return desc->slave_name;
}

/* __gnat_tty_name - return master side fd
 *
 * PARAMETERS
 *   desc  a pty_desc strucure
 * RETURN VALUE
 *   a fd
 */
int
__gnat_tty_fd (pty_desc* desc)
{
  return desc->master_fd;
}

#endif /* WIN32 */