FreeBSD/Linux Kernel Cross Reference
sys/sys/poll.h

     /*-
      * Copyright (c) 1997 Peter Wemm <peter@freebsd.org>
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #ifndef _SYS_POLL_H_
    #define _SYS_POLL_H_
    
    /*
     * This file is intended to be compatable with the traditional poll.h.
     */
    
    /*
     * This structure is passed as an array to poll(2).
     */
    struct pollfd {
            int     fd;             /* which file descriptor to poll */
            short   events;         /* events we are interested in */
            short   revents;        /* events found on return */
    };
    
    /*
     * Requestable events.  If poll(2) finds any of these set, they are
     * copied to revents on return.
     * XXX Note that FreeBSD doesn't make much distinction between POLLPRI
     * and POLLRDBAND since none of the file types have distinct priority
     * bands - and only some have an urgent "mode".
     * XXX Note POLLIN isn't really supported in true SVSV terms.  Under SYSV
     * POLLIN includes all of normal, band and urgent data.  Most poll handlers
     * on FreeBSD only treat it as "normal" data.
     */
    #define POLLIN          0x0001          /* any readable data available */
    #define POLLPRI         0x0002          /* OOB/Urgent readable data */
    #define POLLOUT         0x0004          /* file descriptor is writeable */
    #define POLLRDNORM      0x0040          /* non-OOB/URG data available */
    #define POLLWRNORM      POLLOUT         /* no write type differentiation */
    #define POLLRDBAND      0x0080          /* OOB/Urgent readable data */
    #define POLLWRBAND      0x0100          /* OOB/Urgent data can be written */
    
    /*
     * FreeBSD extensions: polling on a regular file might return one
     * of these events (currently only supported on UFS).
     */
    #define POLLEXTEND      0x0200          /* file may have been extended */
    #define POLLATTRIB      0x0400          /* file attributes may have changed */
    #define POLLNLINK       0x0800          /* (un)link/rename may have happened */
    #define POLLWRITE       0x1000          /* file's contents may have changed */
    
    /*
     * These events are set if they occur regardless of whether they were
     * requested.
     */
    #define POLLERR         0x0008          /* some poll error occurred */
    #define POLLHUP         0x0010          /* file descriptor was "hung up" */
    #define POLLNVAL        0x0020          /* requested events "invalid" */
    
    #define POLLSTANDARD    (POLLIN|POLLPRI|POLLOUT|POLLRDNORM|POLLRDBAND|\
                             POLLWRBAND|POLLERR|POLLHUP|POLLNVAL)
    
    /*
     * Request that poll() wait forever.
     * XXX in SYSV, this is defined in stropts.h, which is not included
     * by poll.h.
     */
    #define INFTIM          (-1)
    
    #ifndef _KERNEL
    
    #include <sys/cdefs.h>
    
    __BEGIN_DECLS
    /*
     * XXX logically, poll() should be declared in <poll.h>, but SVR4 at
     * least has it here in <sys/poll.h>.
    * XXX poll() has "unsigned long" nfds on SVR4, not unsigned as on the
    * other BSDs.
    */
   int     poll __P((struct pollfd *_pfd, unsigned int _nfds, int _timeout));
   __END_DECLS
   
   #endif /* !_KERNEL */
   
   #endif /* !_SYS_POLL_H_ */

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