/* $OpenBSD: atomicio.c,v 1.2 2024/11/21 13:25:30 claudio 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/uio.h>

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

#include <sys/queue.h>
#include <imsg.h>

#include "atomicio.h"

/*
 * ensure all of data on socket comes through. f==read || f==vwrite
 */
size_t
atomicio6(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n,
    int (*cb)(void *, size_t), void *cb_arg)
{
        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) {
                                (void)poll(&pfd, 1, -1);
                                continue;
                        }
                        return 0;
                case 0:
                        errno = EPIPE;
                        return pos;
                default:
                        pos += (size_t)res;
                        if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {
                                errno = EINTR;
                                return pos;
                        }
                }
        }
        return pos;
}

size_t
atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
{
        return atomicio6(f, fd, _s, n, NULL, NULL);
}

/*
 * ensure all of data on socket comes through. f==readv || f==writev
 */
size_t
atomiciov6(ssize_t (*f) (int, const struct iovec *, int), int fd,
    const struct iovec *_iov, int iovcnt,
    int (*cb)(void *, size_t), void *cb_arg)
{
        size_t pos = 0, rem;
        ssize_t res;
        struct iovec iov_array[IOV_MAX], *iov = iov_array;
        struct pollfd pfd;

        if (iovcnt < 0 || iovcnt > IOV_MAX) {
                errno = EINVAL;
                return 0;
        }
        /* Make a copy of the iov array because we may modify it below */
        memcpy(iov, _iov, (size_t)iovcnt * sizeof(*_iov));

        pfd.fd = fd;
        pfd.events = f == readv ? POLLIN : POLLOUT;
        for (; iovcnt > 0 && iov[0].iov_len > 0;) {
                res = (f) (fd, iov, iovcnt);
                switch (res) {
                case -1:
                        if (errno == EINTR)
                                continue;
                        if (errno == EAGAIN) {
                                (void)poll(&pfd, 1, -1);
                                continue;
                        }
                        return 0;
                case 0:
                        errno = EPIPE;
                        return pos;
                default:
                        rem = (size_t)res;
                        pos += rem;
                        /* skip completed iov entries */
                        while (iovcnt > 0 && rem >= iov[0].iov_len) {
                                rem -= iov[0].iov_len;
                                iov++;
                                iovcnt--;
                        }
                        /* This shouldn't happen... */
                        if (rem > 0 && (iovcnt <= 0 || rem > iov[0].iov_len)) {
                                errno = EFAULT;
                                return 0;
                        }
                        if (iovcnt == 0)
                                break;
                        /* update pointer in partially complete iov */
                        iov[0].iov_base = ((char *)iov[0].iov_base) + rem;
                        iov[0].iov_len -= rem;
                }
                if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {
                        errno = EINTR;
                        return pos;
                }
        }
        return pos;
}

size_t
atomiciov(ssize_t (*f) (int, const struct iovec *, int), int fd,
    const struct iovec *_iov, int iovcnt)
{
        return atomiciov6(f, fd, _iov, iovcnt, NULL, NULL);
}

int
imsgbuf_read_one(struct imsgbuf *imsgbuf, struct imsg *imsg)
{
        struct pollfd pfd;
        int dopoll = 0;

        pfd.fd = imsgbuf->fd;
        pfd.events = POLLIN;
        while (1) {
                switch (imsg_get(imsgbuf, imsg)) {
                case -1:
                        return (-1);
                case 0:
                        if (dopoll)
                                (void)poll(&pfd, 1, -1);
                        break;
                default:
                        return (1);
                }
                dopoll = 1;

                switch (imsgbuf_read(imsgbuf)) {
                case -1:
                        return (-1);
                case 0:
                        return (0);
                }
        }
}