/* $OpenBSD: atomicio.c,v 1.11 2012/12/04 02:24:47 deraadt Exp $ */
/*
* Copyright (c) 2006 Damien Miller. All rights reserved.
* Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.
* Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: atomicio.c,v 1.2 2017/02/06 16:03:40 christos Exp $");

#include <errno.h>
#include <poll.h>
#include <unistd.h>

#include "atomicio.h"

/*
* ensure all of data on socket comes through. f==read || f==vwrite
*/
size_t
atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
{
       char *s = _s;
       size_t pos = 0;
       ssize_t res;
       struct pollfd pfd;

       pfd.fd = fd;
       pfd.events = f == read ? POLLIN : POLLOUT;
       while (n > pos) {
               res = (f) (fd, s + pos, n - pos);
               switch (res) {
               case -1:
                       if (errno == EINTR)
                               continue;
                       if ((errno == EAGAIN) || (errno == ENOBUFS)) {
                               (void)poll(&pfd, 1, -1);
                               continue;
                       }
                       return 0;
               case 0:
                       errno = EPIPE;
                       return pos;
               default:
                       pos += (size_t)res;
               }
       }
       return (pos);
}