Modules/selectmodule.c

/***********************************************************
Copyright 1991, 1992 by Stichting Mathematisch Centrum, Amsterdam, The
Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
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STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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******************************************************************/

/* select - Module containing unix select(2) call */

#include "allobjects.h"
#include "modsupport.h"
#include "compile.h"
#include "ceval.h"

#include <sys/types.h>
#include <sys/time.h>
#include <sys/param.h>

/* XXX Maybe you need to define the FD_* macros here when porting this code */

static object *SelectError;

/* XXX This module should be re-entrant! */
static object *fd2obj[FD_SETSIZE];

static
list2set(list, set)
    object *list;
    fd_set *set;
{
    int i, len, v, max=-1;
    object *o, *filenomethod, *fno;
    
    FD_ZERO(set);
    len = getlistsize(list);
    for( i=0; i<len; i++ ) {
	o = getlistitem(list, i);
	if ( is_intobject(o) ) {
	    v = getintvalue(o);
	} else if ( (filenomethod = getattr(o, "fileno")) != NULL ) {
	    fno = call_object(filenomethod, NULL);
	    if ( fno == NULL )
		return -1;
	    if ( !is_intobject(fno) ) {
		err_badarg();
		return -1;
	    }
	    v = getintvalue(fno);
	    DECREF(fno);
	} else {
	    err_badarg();
	    return -1;
	}
	if ( v >= FD_SETSIZE ) {
	    err_setstr(SystemError, "FD_SETSIZE too low in select()");
	    return -1;
	}
	if ( v > max ) max = v;
	FD_SET(v, set);
	fd2obj[v] = o;
    }
    return max+1;
}

static object *
set2list(set, max)
    fd_set *set;
    int max;
{
    int i, num=0;
    object *list, *o;

    for(i=0; i<max; i++)
      if ( FD_ISSET(i,set) )
	num++;
    list = newlistobject(num);
    num = 0;
    for(i=0; i<max; i++)
      if ( FD_ISSET(i,set) ) {
	  if ( i > FD_SETSIZE ) {
	      err_setstr(SystemError, "FD_SETSIZE too low in select()");
	      return NULL;
	  }
	  o = fd2obj[i];
	  if ( o == 0 ) {
	      err_setstr(SystemError,
			 "Bad filedescriptor returned from select()");
	      return NULL;
	  }
	  INCREF(o);
	  setlistitem(list, num, o);
	  num++;
    }
    return list;
}
    
static object *
select_select(self, args)
    object *self;
    object *args;
{
    object *ifdlist, *ofdlist, *efdlist;
    fd_set ifdset, ofdset, efdset;
    double timeout;
    struct timeval tv, *tvp;
    int seconds;
    int imax, omax, emax, max;
    int n;


    /* Get args. Looks funny because of optional timeout argument */
    if ( getargs(args, "(OOOd)", &ifdlist, &ofdlist, &efdlist, &timeout) ) {
	seconds = (int)timeout;
	timeout = timeout - (double)seconds;
	tv.tv_sec = seconds;
	tv.tv_usec = (int)(timeout*1000000.0);
	tvp = &tv;
    } else {
	/* Doesn't have 4 args, that means no timeout */
	err_clear();
	if (!getargs(args, "(OOO)", &ifdlist, &ofdlist, &efdlist) )
	  return 0;
	tvp = (struct timeval *)0;
    }
    if ( !is_listobject(ifdlist) || !is_listobject(ofdlist) ||
	!is_listobject(efdlist) ) {
	err_badarg();
	return 0;
    }

    bzero((char *)fd2obj, sizeof(fd2obj)); /* Not really needed */
    
    /* Convert lists to fd_sets, and get maximum fd number */
    if( (imax=list2set(ifdlist, &ifdset)) < 0 )
      return 0;
    if( (omax=list2set(ofdlist, &ofdset)) < 0 )
      return 0;
    if( (emax=list2set(efdlist, &efdset)) < 0 )
      return 0;
    max = imax;
    if ( omax > max ) max = omax;
    if ( emax > max ) max = emax;

    n = select(max, &ifdset, &ofdset, &efdset, tvp);

    if ( n < 0 ) {
	err_errno(SelectError);
	return 0;
    }

    if ( n == 0 )
      imax = omax = emax = 0; /* Speedup hack */

    ifdlist = set2list(&ifdset, imax);
    ofdlist = set2list(&ofdset, omax);
    efdlist = set2list(&efdset, emax);

    return mkvalue("OOO", ifdlist, ofdlist, efdlist);
}


static struct methodlist select_methods[] = {
    { "select",	select_select },
    { 0,	0 },
};


void
initselect()
{
	object *m, *d;
	m = initmodule("select", select_methods);
	d = getmoduledict(m);
	SelectError = newstringobject("select.error");
	if ( SelectError == NULL || dictinsert(d, "error", SelectError) )
	  fatal("Cannot define select.error");
}