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Remove XXX comment and just close received fd if calloc() fails.

If this happens the imsg may no longer be usable as there may be queued
messages, but this is a) already the case with the code now, and b)
would be the case if recvmsg() fails anyway, so we can document that -1
from imsg_read() invalidates the struct imsgbuf.

discussed with and ok eric

/*	$OpenBSD: imsg.c,v 1.2 2010/04/07 18:09:39 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/param.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/uio.h>

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

#include "imsg.h"

int	 imsg_get_fd(struct imsgbuf *);

void
imsg_init(struct imsgbuf *ibuf, int fd)
{
	msgbuf_init(&ibuf->w);
	bzero(&ibuf->r, sizeof(ibuf->r));
	ibuf->fd = fd;
	ibuf->w.fd = fd;
	ibuf->pid = getpid();
	TAILQ_INIT(&ibuf->fds);
}

ssize_t
imsg_read(struct imsgbuf *ibuf)
{
	struct msghdr		 msg;
	struct cmsghdr		*cmsg;
	union {
		struct cmsghdr hdr;
		char	buf[CMSG_SPACE(sizeof(int) * 16)];
	} cmsgbuf;
	struct iovec		 iov;
	ssize_t			 n;
	int			 fd;
	struct imsg_fd		*ifd;

	bzero(&msg, sizeof(msg));

	iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
	iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = &cmsgbuf.buf;
	msg.msg_controllen = sizeof(cmsgbuf.buf);

	if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
		if (errno != EINTR && errno != EAGAIN) {
			return (-1);
		}
		return (-2);
	}

	ibuf->r.wpos += n;

	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
		if (cmsg->cmsg_level == SOL_SOCKET &&
		    cmsg->cmsg_type == SCM_RIGHTS) {
			fd = (*(int *)CMSG_DATA(cmsg));
			if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL) {
				close(fd);
				return (-1);
			}
			ifd->fd = fd;
			TAILQ_INSERT_TAIL(&ibuf->fds, ifd, entry);
		}
		/* we do not handle other ctl data level */
	}

	return (n);
}

ssize_t
imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
{
	size_t			 av, left, datalen;

	av = ibuf->r.wpos;

	if (IMSG_HEADER_SIZE > av)
		return (0);

	memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
	if (imsg->hdr.len < IMSG_HEADER_SIZE ||
	    imsg->hdr.len > MAX_IMSGSIZE) {
		errno = ERANGE;
		return (-1);
	}
	if (imsg->hdr.len > av)
		return (0);
	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
	ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
	if ((imsg->data = malloc(datalen)) == NULL)
		return (-1);

	if (imsg->hdr.flags & IMSGF_HASFD)
		imsg->fd = imsg_get_fd(ibuf);
	else
		imsg->fd = -1;

	memcpy(imsg->data, ibuf->r.rptr, datalen);

	if (imsg->hdr.len < av) {
		left = av - imsg->hdr.len;
		memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
		ibuf->r.wpos = left;
	} else
		ibuf->r.wpos = 0;

	return (datalen + IMSG_HEADER_SIZE);
}

int
imsg_compose(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, int fd, void *data, u_int16_t datalen)
{
	struct buf	*wbuf;

	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
		return (-1);

	if (imsg_add(wbuf, data, datalen) == -1)
		return (-1);

	wbuf->fd = fd;

	imsg_close(ibuf, wbuf);

	return (1);
}

int
imsg_composev(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, int fd, const struct iovec *iov, int iovcnt)
{
	struct buf	*wbuf;
	int		 i, datalen = 0;

	for (i = 0; i < iovcnt; i++)
		datalen += iov[i].iov_len;

	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
		return (-1);

	for (i = 0; i < iovcnt; i++)
		if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
			return (-1);

	wbuf->fd = fd;

	imsg_close(ibuf, wbuf);

	return (1);
}

/* ARGSUSED */
struct buf *
imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, u_int16_t datalen)
{
	struct buf	*wbuf;
	struct imsg_hdr	 hdr;

	datalen += IMSG_HEADER_SIZE;
	if (datalen > MAX_IMSGSIZE) {
		errno = ERANGE;
		return (NULL);
	}

	hdr.type = type;
	hdr.flags = 0;
	hdr.peerid = peerid;
	if ((hdr.pid = pid) == 0)
		hdr.pid = ibuf->pid;
	if ((wbuf = buf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
		return (NULL);
	}
	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
		return (NULL);

	return (wbuf);
}

int
imsg_add(struct buf *msg, void *data, u_int16_t datalen)
{
	if (datalen)
		if (buf_add(msg, data, datalen) == -1) {
			buf_free(msg);
			return (-1);
		}
	return (datalen);
}

void
imsg_close(struct imsgbuf *ibuf, struct buf *msg)
{
	struct imsg_hdr	*hdr;

	hdr = (struct imsg_hdr *)msg->buf;

	hdr->flags &= ~IMSGF_HASFD;
	if (msg->fd != -1)
		hdr->flags |= IMSGF_HASFD;

	hdr->len = (u_int16_t)msg->wpos;

	buf_close(&ibuf->w, msg);
}

void
imsg_free(struct imsg *imsg)
{
	free(imsg->data);
}

int
imsg_get_fd(struct imsgbuf *ibuf)
{
	int		 fd;
	struct imsg_fd	*ifd;

	if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
		return (-1);

	fd = ifd->fd;
	TAILQ_REMOVE(&ibuf->fds, ifd, entry);
	free(ifd);

	return (fd);
}

int
imsg_flush(struct imsgbuf *ibuf)
{
	while (ibuf->w.queued)
		if (msgbuf_write(&ibuf->w) < 0)
			return (-1);
	return (0);
}

void
imsg_clear(struct imsgbuf *ibuf)
{
	int	fd;

	msgbuf_clear(&ibuf->w);
	while ((fd = imsg_get_fd(ibuf)) != -1)
		close(fd);
}