argslen = 0; if (argv != NULL) { p = argv; while (*p != NULL) argslen += strlen (*p++) + 1; args = __alloca (argslen); ap = args; for (p = argv; *p != NULL; ++p) ap = __memccpy (ap, *p, '\0', ULONG_MAX); } else args = NULL;   envlen = 0; if (envp != NULL) { p = envp; while (*p != NULL) envlen += strlen (*p++) + 1; env = __alloca (envlen); ap = env; for (p = envp; *p != NULL; ++p) ap = __memccpy (ap, *p, '\0', ULONG_MAX); } else env = NULL;
if (err = __argz_create (argv, &args, &argslen)) return err; if (err = __argz_create (envp, &env, &envlen)) goto outargs;
_hurd_exec (task_t task, file_t file,	    char *const argv[], char *const envp[]){  error_t err;  char *args, *env, *ap;  size_t argslen, envlen;  int ints[INIT_INT_MAX];  mach_port_t ports[_hurd_nports];  struct hurd_userlink ulink_ports[_hurd_nports];  file_t *dtable;  unsigned int dtablesize, i;  struct hurd_port **dtable_cells;  struct hurd_userlink *ulink_dtable;  char *const *p;  struct hurd_sigstate *ss;  mach_port_t *please_dealloc, *pdp;  /* Pack the arguments into an array with nulls separating the elements.  */  argslen = 0;  if (argv != NULL)    {      p = argv;      while (*p != NULL)	argslen += strlen (*p++) + 1;      args = __alloca (argslen);      ap = args;      for (p = argv; *p != NULL; ++p)	ap = __memccpy (ap, *p, '\0', ULONG_MAX);    }  else    args = NULL;  /* Pack the environment into an array with nulls separating elements.  */  envlen = 0;  if (envp != NULL)    {      p = envp;      while (*p != NULL)	envlen += strlen (*p++) + 1;      env = __alloca (envlen);      ap = env;      for (p = envp; *p != NULL; ++p)	ap = __memccpy (ap, *p, '\0', ULONG_MAX);    }  else    env = NULL;  /* Load up the ports to give to the new program.  */  for (i = 0; i < _hurd_nports; ++i)    if (i == INIT_PORT_PROC && task != __mach_task_self ())      {	/* This is another task, so we need to ask the proc server	   for the right proc server port for it.  */	if (err = __USEPORT (PROC, __proc_task2proc (port, task, &ports[i])))	  {	    while (--i > 0)	      _hurd_port_free (&_hurd_ports[i], &ulink_ports[i], ports[i]);	    return err;	  }      }    else      ports[i] = _hurd_port_get (&_hurd_ports[i], &ulink_ports[i]);  /* Load up the ints to give the new program.  */  for (i = 0; i < INIT_INT_MAX; ++i)    switch (i)      {      case INIT_UMASK:	ints[i] = _hurd_umask;	break;      case INIT_SIGMASK:      case INIT_SIGIGN:      case INIT_SIGPENDING:	/* We will set these all below.  */	break;      default:	ints[i] = 0;      }  ss = _hurd_self_sigstate ();  __spin_lock (&ss->lock);  ints[INIT_SIGMASK] = ss->blocked;  ints[INIT_SIGPENDING] = ss->pending;  ints[INIT_SIGIGN] = 0;  for (i = 1; i < NSIG; ++i)    if (ss->actions[i].sa_handler == SIG_IGN)      ints[INIT_SIGIGN] |= __sigmask (i);  /* We hold the sigstate lock until the exec has failed so that no signal     can arrive between when we pack the blocked and ignored signals, and     when the exec actually happens.  A signal handler could change what     signals are blocked and ignored.  Either the change will be reflected     in the exec, or the signal will never be delivered.  Setting the     critical section flag avoids anything we call trying to acquire the     sigstate lock.  */  ss->critical_section = 1;  __spin_unlock (&ss->lock);  /* Pack up the descriptor table to give the new program.  */  __mutex_lock (&_hurd_dtable_lock);  dtablesize = _hurd_dtable ? _hurd_dtablesize : _hurd_init_dtablesize;  if (task == __mach_task_self ())    /* Request the exec server to deallocate some ports from us if the exec       succeeds.  The init ports and descriptor ports will arrive in the       new program's exec_startup message.  If we failed to deallocate       them, the new program would have duplicate user references for them.       But we cannot deallocate them ourselves, because we must still have       them after a failed exec call.  */    please_dealloc = __alloca ((_hurd_nports + (2 * dtablesize))				* sizeof (mach_port_t));  else    please_dealloc = NULL;  pdp = please_dealloc;  if (_hurd_dtable != NULL)    {      dtable = __alloca (dtablesize * sizeof (dtable[0]));      ulink_dtable = __alloca (dtablesize * sizeof (ulink_dtable[0]));      dtable_cells = __alloca (dtablesize * sizeof (dtable_cells[0]));      for (i = 0; i < dtablesize; ++i)	{	  struct hurd_fd *const d = _hurd_dtable[i];	  if (d == NULL)	    {	      dtable[i] = MACH_PORT_NULL;	      continue;	    }	  __spin_lock (&d->port.lock);	  if (d->flags & FD_CLOEXEC)	    {	      /* This descriptor is marked to be closed on exec.		 So don't pass it to the new program.  */	      dtable[i] = MACH_PORT_NULL;	      if (pdp && d->port.port != MACH_PORT_NULL)		{		  /* We still need to deallocate the ports.  */		  *pdp++ = d->port.port;		  if (d->ctty.port != MACH_PORT_NULL)		    *pdp++ = d->ctty.port;		}	      __spin_unlock (&d->port.lock);	    }	  else	    {	      if (pdp && d->ctty.port != MACH_PORT_NULL)		/* All the elements of DTABLE are added to PLEASE_DEALLOC		   below, so we needn't add the port itself.		   But we must deallocate the ctty port as well as		   the normal port that got installed in DTABLE[I].  */		*pdp++ = d->ctty.port;	      dtable[i] = _hurd_port_locked_get (&d->port, &ulink_dtable[i]);	      dtable_cells[i] = &d->port;	    }	}    }  else    {      dtable = _hurd_init_dtable;      ulink_dtable = NULL;      dtable_cells = NULL;    }  /* The information is all set up now.  Try to exec the file.  */  {    if (pdp)      {	/* Request the exec server to deallocate some ports from us if the exec	   succeeds.  The init ports and descriptor ports will arrive in the	   new program's exec_startup message.  If we failed to deallocate	   them, the new program would have duplicate user references for them.	   But we cannot deallocate them ourselves, because we must still have	   them after a failed exec call.  */	for (i = 0; i < _hurd_nports; ++i)	  *pdp++ = ports[i];	for (i = 0; i < dtablesize; ++i)	  *pdp++ = dtable[i];      }    err = __file_exec (file, task,		       _hurd_exec_flags & EXEC_INHERITED,		       args, argslen, env, envlen,		       dtable, MACH_MSG_TYPE_COPY_SEND, dtablesize,		       ports, MACH_MSG_TYPE_COPY_SEND, _hurd_nports,		       ints, INIT_INT_MAX,		       please_dealloc, pdp - please_dealloc,		       &_hurd_msgport, task == __mach_task_self () ? 1 : 0);  }  /* Release references to the standard ports.  */  for (i = 0; i < _hurd_nports; ++i)    if (i == INIT_PORT_PROC && task != __mach_task_self ())      __mach_port_deallocate (__mach_task_self (), ports[i]);    else      _hurd_port_free (&_hurd_ports[i], &ulink_ports[i], ports[i]);  if (ulink_dtable != NULL)    /* Release references to the file descriptor ports.  */    for (i = 0; i < dtablesize; ++i)      if (dtable[i] != MACH_PORT_NULL)	_hurd_port_free (dtable_cells[i], &ulink_dtable[i], dtable[i]);  /* Release lock on the file descriptor table. */  __mutex_unlock (&_hurd_dtable_lock);  /* Safe to let signals happen now.  */  {    sigset_t pending;    __spin_lock (&ss->lock);    ss->critical_section = 0;    pending = ss->pending & ~ss->blocked;    __spin_unlock (&ss->lock);    if (pending)      __msg_sig_post (_hurd_msgport, 0, __mach_task_self ());  }  return err;}