/*      $OpenBSD: imsg-buffer.c,v 1.7 2015/07/12 18:40:49 nicm Exp $    */

/*
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/uio.h>

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

#include "imsg.h"

int     ibuf_realloc(struct ibuf *, size_t);
void    ibuf_enqueue(struct msgbuf *, struct ibuf *);
void    ibuf_dequeue(struct msgbuf *, struct ibuf *);

struct ibuf *
ibuf_open(size_t len)
{
        struct ibuf     *buf;

        if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
                return (NULL);
        if ((buf->buf = malloc(len)) == NULL) {
                free(buf);
                return (NULL);
        }
        buf->size = buf->max = len;
        buf->fd = -1;

        return (buf);
}

struct ibuf *
ibuf_dynamic(size_t len, size_t max)
{
        struct ibuf     *buf;

        if (max < len)
                return (NULL);

        if ((buf = ibuf_open(len)) == NULL)
                return (NULL);

        if (max > 0)
                buf->max = max;

        return (buf);
}

int
ibuf_realloc(struct ibuf *buf, size_t len)
{
        u_char  *b;

        /* on static buffers max is eq size and so the following fails */
        if (buf->wpos + len > buf->max) {
                errno = ERANGE;
                return (-1);
        }

        b = realloc(buf->buf, buf->wpos + len);
        if (b == NULL)
                return (-1);
        buf->buf = b;
        buf->size = buf->wpos + len;

        return (0);
}

int
ibuf_add(struct ibuf *buf, const void *data, size_t len)
{
        if (buf->wpos + len > buf->size)
                if (ibuf_realloc(buf, len) == -1)
                        return (-1);

        memcpy(buf->buf + buf->wpos, data, len);
        buf->wpos += len;
        return (0);
}

void *
ibuf_reserve(struct ibuf *buf, size_t len)
{
        void    *b;

        if (buf->wpos + len > buf->size)
                if (ibuf_realloc(buf, len) == -1)
                        return (NULL);

        b = buf->buf + buf->wpos;
        buf->wpos += len;
        return (b);
}

void *
ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
{
        /* only allowed to seek in already written parts */
        if (pos + len > buf->wpos)
                return (NULL);

        return (buf->buf + pos);
}

size_t
ibuf_size(struct ibuf *buf)
{
        return (buf->wpos);
}

size_t
ibuf_left(struct ibuf *buf)
{
        return (buf->max - buf->wpos);
}

void
ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
{
        ibuf_enqueue(msgbuf, buf);
}

int
ibuf_write(struct msgbuf *msgbuf)
{
        struct iovec     iov[IOV_MAX];
        struct ibuf     *buf;
        unsigned int     i = 0;
        ssize_t n;

        memset(&iov, 0, sizeof(iov));
        TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
                if (i >= IOV_MAX)
                        break;
                iov[i].iov_base = buf->buf + buf->rpos;
                iov[i].iov_len = buf->wpos - buf->rpos;
                i++;
        }

again:
        if ((n = writev(msgbuf->fd, iov, i)) == -1) {
                if (errno == EINTR)
                        goto again;
                if (errno == ENOBUFS)
                        errno = EAGAIN;
                return (-1);
        }

        if (n == 0) {                   /* connection closed */
                errno = 0;
                return (0);
        }

        msgbuf_drain(msgbuf, n);

        return (1);
}

void
ibuf_free(struct ibuf *buf)
{
        free(buf->buf);
        free(buf);
}

void
msgbuf_init(struct msgbuf *msgbuf)
{
        msgbuf->queued = 0;
        msgbuf->fd = -1;
        TAILQ_INIT(&msgbuf->bufs);
}

void
msgbuf_drain(struct msgbuf *msgbuf, size_t n)
{
        struct ibuf     *buf, *next;

        for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
            buf = next) {
                next = TAILQ_NEXT(buf, entry);
                if (buf->rpos + n >= buf->wpos) {
                        n -= buf->wpos - buf->rpos;
                        ibuf_dequeue(msgbuf, buf);
                } else {
                        buf->rpos += n;
                        n = 0;
                }
        }
}

void
msgbuf_clear(struct msgbuf *msgbuf)
{
        struct ibuf     *buf;

        while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
                ibuf_dequeue(msgbuf, buf);
}

int
msgbuf_write(struct msgbuf *msgbuf)
{
        struct iovec     iov[IOV_MAX];
        struct ibuf     *buf;
        unsigned int     i = 0;
        ssize_t          n;
        struct msghdr    msg;
        struct cmsghdr  *cmsg;
        union {
                struct cmsghdr  hdr;
                char            buf[CMSG_SPACE(sizeof(int))];
        } cmsgbuf;

        memset(&iov, 0, sizeof(iov));
        memset(&msg, 0, sizeof(msg));
        memset(&cmsgbuf, 0, sizeof(cmsgbuf));
        TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
                if (i >= IOV_MAX)
                        break;
                iov[i].iov_base = buf->buf + buf->rpos;
                iov[i].iov_len = buf->wpos - buf->rpos;
                i++;
                if (buf->fd != -1)
                        break;
        }

        msg.msg_iov = iov;
        msg.msg_iovlen = i;

        if (buf != NULL && buf->fd != -1) {
                msg.msg_control = (caddr_t)&cmsgbuf.buf;
                msg.msg_controllen = sizeof(cmsgbuf.buf);
                cmsg = CMSG_FIRSTHDR(&msg);
                cmsg->cmsg_len = CMSG_LEN(sizeof(int));
                cmsg->cmsg_level = SOL_SOCKET;
                cmsg->cmsg_type = SCM_RIGHTS;
                *(int *)CMSG_DATA(cmsg) = buf->fd;
        }

again:
        if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
                if (errno == EINTR)
                        goto again;
                if (errno == ENOBUFS)
                        errno = EAGAIN;
                return (-1);
        }

        if (n == 0) {                   /* connection closed */
                errno = 0;
                return (0);
        }

        /*
         * assumption: fd got sent if sendmsg sent anything
         * this works because fds are passed one at a time
         */
        if (buf != NULL && buf->fd != -1) {
                close(buf->fd);
                buf->fd = -1;
        }

        msgbuf_drain(msgbuf, n);

        return (1);
}

void
ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
{
        TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
        msgbuf->queued++;
}

void
ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
{
        TAILQ_REMOVE(&msgbuf->bufs, buf, entry);

        if (buf->fd != -1)
                close(buf->fd);

        msgbuf->queued--;
        ibuf_free(buf);
}