cpython/Modules/selectmodule.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

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/* select - Module containing unix select(2) call.
Under Unix, the file descriptors are small integers.
Under Win32, select only exists for sockets, and sockets may
have any value except INVALID_SOCKET.
*/

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

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <sys/types.h>

#ifdef MS_WINDOWS
#include <winsock.h>
#else
#include "myselect.h" /* Also includes mytime.h */
#define SOCKET int
#endif

static object *SelectError;

typedef struct {	/* list of Python objects and their file descriptor */
	object *obj;
	SOCKET fd;
} pylist;

static int
list2set(list, set, fd2obj)
    object *list;
    fd_set *set;
    pylist fd2obj[FD_SETSIZE + 3];
{
    int i, len, index, max = -1;
    object *o, *filenomethod, *fno;
    SOCKET v;

    index = 0;
    fd2obj[0].obj = (object*)0;	/* set list to zero size */
    
    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;
	}
#ifdef _MSC_VER
	max = 0;	/* not used for Win32 */
#else
	if ( v < 0 || v >= FD_SETSIZE ) {
	    err_setstr(ValueError, "filedescriptor out of range in select()");
	    return -1;
	}
	if ( v > max ) max = v;
#endif
	FD_SET(v, set);
	/* add object and its file descriptor to the list */
	if ( index >= FD_SETSIZE ) {
	    err_setstr(ValueError, "too many file descriptors in select()");
	    return -1;
	}
	fd2obj[index].obj = o;
	fd2obj[index].fd = v;
	fd2obj[++index].obj = (object *)0;	/* sentinel */
    }
    return max+1;
}

static object *
set2list(set, fd2obj)
    fd_set *set;
    pylist fd2obj[FD_SETSIZE + 3];
{
    int j, num=0;
    object *list, *o;
    SOCKET fd;

    for(j=0; fd2obj[j].obj; j++)
      if ( FD_ISSET(fd2obj[j].fd, set) )
	num++;
    list = newlistobject(num);
    num = 0;
    for(j=0; fd2obj[j].obj; j++) {
      fd = fd2obj[j].fd;
      if ( FD_ISSET(fd, set) ) {
#ifndef _MSC_VER
	  if ( fd > FD_SETSIZE ) {
	      err_setstr(SystemError,
			 "filedescriptor out of range returned in select()");
	      return NULL;
	  }
#endif
          o = fd2obj[j].obj;
	  INCREF(o);
	  setlistitem(list, num, o);
	  num++;
      }
    }
    return list;
}
    
static object *
select_select(self, args)
    object *self;
    object *args;
{
    pylist rfd2obj[FD_SETSIZE + 3], wfd2obj[FD_SETSIZE + 3], efd2obj[FD_SETSIZE + 3];
    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;
    }

    /* Convert lists to fd_sets, and get maximum fd number */
    if( (imax=list2set(ifdlist, &ifdset, rfd2obj)) < 0 )
      return 0;
    if( (omax=list2set(ofdlist, &ofdset, wfd2obj)) < 0 )
      return 0;
    if( (emax=list2set(efdlist, &efdset, efd2obj)) < 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 ) { /* Speedup hack */
      ifdlist = newlistobject(0);
      ret = mkvalue("OOO", ifdlist, ifdlist, ifdlist);
      XDECREF(ifdlist);
      return ret;
    }

    ifdlist = set2list(&ifdset, rfd2obj);
    ofdlist = set2list(&ofdset, wfd2obj);
    efdlist = set2list(&efdset, efd2obj);
    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");
}