cpython/Modules/selectmodule.c

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

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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");
}