cpython/Modules/selectmodule.c

/***********************************************************
Copyright 1991, 1992, 1993, 1994 by Stichting Mathematisch Centrum,
Amsterdam, The Netherlands.

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Permission to use, copy, modify, and distribute this software and its 
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THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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******************************************************************/

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

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

#include <sys/types.h>
#include "myselect.h" /* Also includes mytime.h */

static object *SelectError;

static
list2set(list, set, fd2obj)
    object *list;
    fd_set *set;
    object *fd2obj[FD_SETSIZE];
{
    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);
	    DECREF(filenomethod);
	    if ( fno == NULL )
		return -1;
	    if ( !is_intobject(fno) ) {
		err_badarg();
		DECREF(fno);
		return -1;
	    }
	    v = getintvalue(fno);
	    DECREF(fno);
	} else {
	    err_badarg();
	    return -1;
	}
	if ( v < 0 || v >= FD_SETSIZE ) {
	    err_setstr(ValueError, "filedescriptor out of range in select()");
	    return -1;
	}
	if ( v > max ) max = v;
	FD_SET(v, set);
	XDECREF(fd2obj[v]);
	fd2obj[v] = o;
    }
    return max+1;
}

static object *
set2list(set, max, fd2obj)
    fd_set *set;
    int max;
    object *fd2obj[FD_SETSIZE];
{
    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,
			 "filedescriptor out of range returned in select()");
	      return NULL;
	  }
	  o = fd2obj[i];
	  if ( o == NULL ) {
	      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 *fd2obj[FD_SETSIZE];
    object *ifdlist, *ofdlist, *efdlist;
    object *ret, *tout;
    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, "(OOOO)", &ifdlist, &ofdlist, &efdlist, &tout) ) {
	if (tout == None)
	    tvp = (struct timeval *)0;
	else {
	    if (!getargs(tout, "d;timeout must be float or None", &timeout))
		    return NULL;
	    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;
    }

    memset((char *)fd2obj, '\0', sizeof(fd2obj));
    
    /* Convert lists to fd_sets, and get maximum fd number */
    if( (imax=list2set(ifdlist, &ifdset, fd2obj)) < 0 )
      return 0;
    if( (omax=list2set(ofdlist, &ofdset, fd2obj)) < 0 )
      return 0;
    if( (emax=list2set(efdlist, &efdset, fd2obj)) < 0 )
      return 0;
    max = imax;
    if ( omax > max ) max = omax;
    if ( emax > max ) max = emax;

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

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

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

    ifdlist = set2list(&ifdset, imax, fd2obj);
    ofdlist = set2list(&ofdset, omax, fd2obj);
    efdlist = set2list(&efdset, emax, fd2obj);
    ret = mkvalue("OOO", ifdlist, ofdlist, efdlist);
    XDECREF(ifdlist);
    XDECREF(ofdlist);
    XDECREF(efdlist);
    return ret;
}


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");
}