imsg.patch

diff --git a/.gitignore b/.gitignore
index eb37b56..73d6801 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,7 +20,6 @@ Makefile.in
 /autoscan-*.log
 /aclocal.m4
 /compile
-/config.h.in
 /config.guess
 /config.sub
 /configure
diff --git a/Makefile.am b/Makefile.am
index 5847975..85a6562 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -29,6 +29,7 @@ i3lock_CPPFLAGS = \
 	$(CODE_COVERAGE_CPPFLAGS)
 
 i3lock_LDADD = \
+	$(LIBOBJS) \
 	$(XCB_LIBS) \
 	$(XCB_IMAGE_LIBS) \
 	$(XCB_UTIL_LIBS) \
@@ -38,6 +39,7 @@ i3lock_LDADD = \
 	$(CODE_COVERAGE_LDFLAGS)
 
 i3lock_SOURCES = \
+	compat.h \
 	cursors.h \
 	dpi.c \
 	dpi.h \
@@ -50,6 +52,8 @@ i3lock_SOURCES = \
 	xcb.c \
 	xcb.h
 
+dist_EXTRA_i3lock_SOURCES = compat/*.[ch]
+
 EXTRA_DIST = \
 	$(pamd_files) \
 	CHANGELOG \
diff --git a/compat.h b/compat.h
new file mode 100644
index 0000000..c43f335
--- /dev/null
+++ b/compat.h
@@ -0,0 +1,62 @@
+/*
+ *  Copyright (c) 2007 Nicholas Marriott <[email protected]>
+ *
+ * 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 MIND, 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.
+ */
+#ifndef COMPAT_H
+#define COMPAT_H
+
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include <limits.h>
+#include <stdio.h>
+
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#else
+#include <inttypes.h>
+#endif
+
+#ifdef HAVE_QUEUE_H
+#include <sys/queue.h>
+#else
+#include "compat/queue.h"
+#endif
+
+#ifdef HAVE_LIBUTIL_H
+#include <libutil.h>
+#endif
+
+#ifndef HAVE_GETDTABLECOUNT
+/* getdtablecount.c */
+int		 getdtablecount(void);
+#endif
+
+#ifndef HAVE_FREEZERO
+/* freezero.c */
+void		 freezero(void *, size_t);
+#endif
+
+#ifndef HAVE_RECALLOCARRAY
+/* recallocarray.c */
+void		*recallocarray(void *, size_t, size_t, size_t);
+#endif
+
+#ifdef HAVE_IMSG
+#include <imsg.h>
+#else
+#include "compat/imsg.h"
+#endif
+
+#endif /* COMPAT_H */
diff --git a/compat/freezero.c b/compat/freezero.c
new file mode 100644
index 0000000..711a10c
--- /dev/null
+++ b/compat/freezero.c
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2017 Nicholas Marriott <[email protected]>
+ *
+ * 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 MIND, 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 <stdlib.h>
+#include <string.h>
+
+#include "compat.h"
+
+void
+freezero(void *ptr, size_t size)
+{
+	if (ptr != NULL) {
+		memset(ptr, 0, size);
+		free(ptr);
+	}
+}
diff --git a/compat/getdtablecount.c b/compat/getdtablecount.c
new file mode 100644
index 0000000..7d2b499
--- /dev/null
+++ b/compat/getdtablecount.c
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2017 Nicholas Marriott <[email protected]>
+ *
+ * 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 MIND, 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 <err.h>
+#include <glob.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "compat.h"
+
+#ifdef HAVE_PROC_PID
+int
+getdtablecount(void)
+{
+	char	path[PATH_MAX];
+	glob_t	g;
+	int	n = 0;
+
+	if (snprintf(path, sizeof path, "/proc/%ld/fd/*", (long)getpid()) < 0)
+		err(EXIT_FAILURE, "snprintf overflow");
+	if (glob(path, 0, NULL, &g) == 0)
+		n = g.gl_pathc;
+	globfree(&g);
+	return (n);
+}
+#else
+int
+getdtablecount(void)
+{
+	return (0);
+}
+#endif
diff --git a/compat/imsg-buffer.c b/compat/imsg-buffer.c
new file mode 100644
index 0000000..814591f
--- /dev/null
+++ b/compat/imsg-buffer.c
@@ -0,0 +1,309 @@
+/*	$OpenBSD: imsg-buffer.c,v 1.11 2017/12/14 09:27:44 kettenis Exp $	*/
+
+/*
+ * Copyright (c) 2003, 2004 Henning Brauer <[email protected]>
+ *
+ * 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/socket.h>
+#include <sys/uio.h>
+
+#include <limits.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "compat.h"
+#include "imsg.h"
+
+static int	ibuf_realloc(struct ibuf *, size_t);
+static void	ibuf_enqueue(struct msgbuf *, struct ibuf *);
+static 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);
+}
+
+static 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 = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
+	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)
+{
+	if (buf == NULL)
+		return;
+	freezero(buf->buf, buf->size);
+	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);
+}
+
+static void
+ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
+{
+	TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
+	msgbuf->queued++;
+}
+
+static 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);
+}
diff --git a/compat/imsg.c b/compat/imsg.c
new file mode 100644
index 0000000..54ac7e5
--- /dev/null
+++ b/compat/imsg.c
@@ -0,0 +1,302 @@
+/*	$OpenBSD: imsg.c,v 1.16 2017/12/14 09:27:44 kettenis Exp $	*/
+
+/*
+ * Copyright (c) 2003, 2004 Henning Brauer <[email protected]>
+ *
+ * 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/socket.h>
+#include <sys/uio.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "compat.h"
+#include "imsg.h"
+
+int	 imsg_fd_overhead = 0;
+
+static int	 imsg_get_fd(struct imsgbuf *);
+
+void
+imsg_init(struct imsgbuf *ibuf, int fd)
+{
+	msgbuf_init(&ibuf->w);
+	memset(&ibuf->r, 0, 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) * 1)];
+	} cmsgbuf;
+	struct iovec		 iov;
+	ssize_t			 n = -1;
+	int			 fd;
+	struct imsg_fd		*ifd;
+
+	memset(&msg, 0, sizeof(msg));
+	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
+
+	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 ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
+		return (-1);
+
+again:
+	if (getdtablecount() + imsg_fd_overhead +
+	    (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
+	    >= getdtablesize()) {
+		errno = EAGAIN;
+		free(ifd);
+		return (-1);
+	}
+
+	if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
+		if (errno == EINTR)
+			goto again;
+		goto fail;
+	}
+
+	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) {
+			int i;
+			int j;
+
+			/*
+			 * We only accept one file descriptor.  Due to C
+			 * padding rules, our control buffer might contain
+			 * more than one fd, and we must close them.
+			 */
+			j = ((char *)cmsg + cmsg->cmsg_len -
+			    (char *)CMSG_DATA(cmsg)) / sizeof(int);
+			for (i = 0; i < j; i++) {
+				fd = ((int *)CMSG_DATA(cmsg))[i];
+				if (ifd != NULL) {
+					ifd->fd = fd;
+					TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
+					    entry);
+					ifd = NULL;
+				} else
+					close(fd);
+			}
+		}
+		/* we do not handle other ctl data level */
+	}
+
+fail:
+	free(ifd);
+	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 (datalen == 0)
+		imsg->data = NULL;
+	else 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, uint32_t type, uint32_t peerid, pid_t pid,
+    int fd, const void *data, uint16_t datalen)
+{
+	struct ibuf	*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, uint32_t type, uint32_t peerid, pid_t pid,
+    int fd, const struct iovec *iov, int iovcnt)
+{
+	struct ibuf	*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 ibuf *
+imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
+    uint16_t datalen)
+{
+	struct ibuf	*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 = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
+		return (NULL);
+	}
+	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
+		return (NULL);
+
+	return (wbuf);
+}
+
+int
+imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
+{
+	if (datalen)
+		if (ibuf_add(msg, data, datalen) == -1) {
+			ibuf_free(msg);
+			return (-1);
+		}
+	return (datalen);
+}
+
+void
+imsg_close(struct imsgbuf *ibuf, struct ibuf *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 = (uint16_t)msg->wpos;
+
+	ibuf_close(&ibuf->w, msg);
+}
+
+void
+imsg_free(struct imsg *imsg)
+{
+	freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
+}
+
+static 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);
+}
diff --git a/compat/imsg.h b/compat/imsg.h
new file mode 100644
index 0000000..8bf9414
--- /dev/null
+++ b/compat/imsg.h
@@ -0,0 +1,111 @@
+/*	$OpenBSD: imsg.h,v 1.4 2017/03/24 09:34:12 nicm Exp $	*/
+
+/*
+ * Copyright (c) 2006, 2007 Pierre-Yves Ritschard <[email protected]>
+ * Copyright (c) 2006, 2007, 2008 Reyk Floeter <[email protected]>
+ * Copyright (c) 2003, 2004 Henning Brauer <[email protected]>
+ *
+ * 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.
+ */
+
+#ifndef _IMSG_H_
+#define _IMSG_H_
+
+#define IBUF_READ_SIZE		65535
+#define IMSG_HEADER_SIZE	sizeof(struct imsg_hdr)
+#define MAX_IMSGSIZE		16384
+
+struct ibuf {
+	TAILQ_ENTRY(ibuf)	 entry;
+	u_char			*buf;
+	size_t			 size;
+	size_t			 max;
+	size_t			 wpos;
+	size_t			 rpos;
+	int			 fd;
+};
+
+struct msgbuf {
+	TAILQ_HEAD(, ibuf)	 bufs;
+	uint32_t		 queued;
+	int			 fd;
+};
+
+struct ibuf_read {
+	u_char			 buf[IBUF_READ_SIZE];
+	u_char			*rptr;
+	size_t			 wpos;
+};
+
+struct imsg_fd {
+	TAILQ_ENTRY(imsg_fd)	entry;
+	int			fd;
+};
+
+struct imsgbuf {
+	TAILQ_HEAD(, imsg_fd)	 fds;
+	struct ibuf_read	 r;
+	struct msgbuf		 w;
+	int			 fd;
+	pid_t			 pid;
+};
+
+#define IMSGF_HASFD	1
+
+struct imsg_hdr {
+	uint32_t	 type;
+	uint16_t	 len;
+	uint16_t	 flags;
+	uint32_t	 peerid;
+	uint32_t	 pid;
+};
+
+struct imsg {
+	struct imsg_hdr	 hdr;
+	int		 fd;
+	void		*data;
+};
+
+
+/* buffer.c */
+struct ibuf	*ibuf_open(size_t);
+struct ibuf	*ibuf_dynamic(size_t, size_t);
+int		 ibuf_add(struct ibuf *, const void *, size_t);
+void		*ibuf_reserve(struct ibuf *, size_t);
+void		*ibuf_seek(struct ibuf *, size_t, size_t);
+size_t		 ibuf_size(struct ibuf *);
+size_t		 ibuf_left(struct ibuf *);
+void		 ibuf_close(struct msgbuf *, struct ibuf *);
+int		 ibuf_write(struct msgbuf *);
+void		 ibuf_free(struct ibuf *);
+void		 msgbuf_init(struct msgbuf *);
+void		 msgbuf_clear(struct msgbuf *);
+int		 msgbuf_write(struct msgbuf *);
+void		 msgbuf_drain(struct msgbuf *, size_t);
+
+/* imsg.c */
+void	 imsg_init(struct imsgbuf *, int);
+ssize_t	 imsg_read(struct imsgbuf *);
+ssize_t	 imsg_get(struct imsgbuf *, struct imsg *);
+int	 imsg_compose(struct imsgbuf *, uint32_t, uint32_t, pid_t, int,
+	    const void *, uint16_t);
+int	 imsg_composev(struct imsgbuf *, uint32_t, uint32_t,  pid_t, int,
+	    const struct iovec *, int);
+struct ibuf *imsg_create(struct imsgbuf *, uint32_t, uint32_t, pid_t, uint16_t);
+int	 imsg_add(struct ibuf *, const void *, uint16_t);
+void	 imsg_close(struct imsgbuf *, struct ibuf *);
+void	 imsg_free(struct imsg *);
+int	 imsg_flush(struct imsgbuf *);
+void	 imsg_clear(struct imsgbuf *);
+
+#endif
diff --git a/compat/queue.h b/compat/queue.h
new file mode 100644
index 0000000..a20532c
--- /dev/null
+++ b/compat/queue.h
@@ -0,0 +1,533 @@
+/*	$OpenBSD: queue.h,v 1.44 2016/09/09 20:31:46 millert Exp $	*/
+/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/
+
+/*
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  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. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
+
+/*
+ * This file defines five types of data structures: singly-linked lists,
+ * lists, simple queues, tail queues and XOR simple queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * An XOR simple queue is used in the same way as a regular simple queue.
+ * The difference is that the head structure also includes a "cookie" that
+ * is XOR'd with the queue pointer (first, last or next) to generate the
+ * real pointer value.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
+#define _Q_INVALIDATE(a) (a) = ((void *)-1)
+#else
+#define _Q_INVALIDATE(a)
+#endif
+
+/*
+ * Singly-linked List definitions.
+ */
+#define SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_END(head)		NULL
+#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = SLIST_FIRST(head);					\
+	    (var) != SLIST_END(head);					\
+	    (var) = SLIST_NEXT(var, field))
+
+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SLIST_FIRST(head);				\
+	    (var) && ((tvar) = SLIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) {						\
+	SLIST_FIRST(head) = SLIST_END(head);				\
+}
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (0)
+
+#define	SLIST_REMOVE_AFTER(elm, field) do {				\
+	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (0)
+
+#define SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->slh_first;		\
+									\
+		while (curelm->field.sle_next != (elm))			\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+	}								\
+	_Q_INVALIDATE((elm)->field.sle_next);				\
+} while (0)
+
+/*
+ * List definitions.
+ */
+#define LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define LIST_ENTRY(type)						\
+struct {								\
+	struct type *le_next;	/* next element */			\
+	struct type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List access methods.
+ */
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_END(head)			NULL
+#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+#define LIST_FOREACH(var, head, field)					\
+	for((var) = LIST_FIRST(head);					\
+	    (var)!= LIST_END(head);					\
+	    (var) = LIST_NEXT(var, field))
+
+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = LIST_FIRST(head);				\
+	    (var) && ((tvar) = LIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * List functions.
+ */
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST(head) = LIST_END(head);				\
+} while (0)
+
+#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
+		(listelm)->field.le_next->field.le_prev =		\
+		    &(elm)->field.le_next;				\
+	(listelm)->field.le_next = (elm);				\
+	(elm)->field.le_prev = &(listelm)->field.le_next;		\
+} while (0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {				\
+	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
+		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
+	(head)->lh_first = (elm);					\
+	(elm)->field.le_prev = &(head)->lh_first;			\
+} while (0)
+
+#define LIST_REMOVE(elm, field) do {					\
+	if ((elm)->field.le_next != NULL)				\
+		(elm)->field.le_next->field.le_prev =			\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = (elm)->field.le_next;			\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+#define LIST_REPLACE(elm, elm2, field) do {				\
+	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
+		(elm2)->field.le_next->field.le_prev =			\
+		    &(elm2)->field.le_next;				\
+	(elm2)->field.le_prev = (elm)->field.le_prev;			\
+	*(elm2)->field.le_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+/*
+ * Simple queue definitions.
+ */
+#define SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
+}
+
+/*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
+#define	SIMPLEQ_END(head)	    NULL
+#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
+#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
+
+#define SIMPLEQ_FOREACH(var, head, field)				\
+	for((var) = SIMPLEQ_FIRST(head);				\
+	    (var) != SIMPLEQ_END(head);					\
+	    (var) = SIMPLEQ_NEXT(var, field))
+
+#define	SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (0)
+
+#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (0)
+
+#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (0)
+
+#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (0)
+
+#define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
+	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (0)
+
+#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
+	    == NULL)							\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+} while (0)
+
+#define SIMPLEQ_CONCAT(head1, head2) do {				\
+	if (!SIMPLEQ_EMPTY((head2))) {					\
+		*(head1)->sqh_last = (head2)->sqh_first;		\
+		(head1)->sqh_last = (head2)->sqh_last;			\
+		SIMPLEQ_INIT((head2));					\
+	}								\
+} while (0)
+
+/*
+ * XOR Simple queue definitions.
+ */
+#define XSIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqx_first;	/* first element */			\
+	struct type **sqx_last;	/* addr of last next element */		\
+	unsigned long sqx_cookie;					\
+}
+
+#define XSIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqx_next;	/* next element */			\
+}
+
+/*
+ * XOR Simple queue access methods.
+ */
+#define XSIMPLEQ_XOR(head, ptr)	    ((__typeof(ptr))((head)->sqx_cookie ^ \
+					(unsigned long)(ptr)))
+#define	XSIMPLEQ_FIRST(head)	    XSIMPLEQ_XOR(head, ((head)->sqx_first))
+#define	XSIMPLEQ_END(head)	    NULL
+#define	XSIMPLEQ_EMPTY(head)	    (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
+#define	XSIMPLEQ_NEXT(head, elm, field)    XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
+
+
+#define XSIMPLEQ_FOREACH(var, head, field)				\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) != XSIMPLEQ_END(head);				\
+	    (var) = XSIMPLEQ_NEXT(head, var, field))
+
+#define	XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1);	\
+	    (var) = (tvar))
+
+/*
+ * XOR Simple queue functions.
+ */
+#define	XSIMPLEQ_INIT(head) do {					\
+	arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, NULL);			\
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = (head)->sqx_first) ==		\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, (elm));			\
+} while (0)
+
+#define XSIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL);		\
+	*(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqx_next = (listelm)->field.sqx_next) ==	\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm));		\
+} while (0)
+
+#define XSIMPLEQ_REMOVE_HEAD(head, field) do {				\
+	if (((head)->sqx_first = XSIMPLEQ_XOR(head,			\
+	    (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) \
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
+} while (0)
+
+#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head,			\
+	    (elm)->field.sqx_next)->field.sqx_next)			\
+	    == XSIMPLEQ_XOR(head, NULL))				\
+		(head)->sqx_last = 					\
+		    XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);		\
+} while (0)
+
+
+/*
+ * Tail queue definitions.
+ */
+#define TAILQ_HEAD(name, type)						\
+struct name {								\
+	struct type *tqh_first;	/* first element */			\
+	struct type **tqh_last;	/* addr of last next element */		\
+}
+
+#define TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
+#define TAILQ_ENTRY(type)						\
+struct {								\
+	struct type *tqe_next;	/* next element */			\
+	struct type **tqe_prev;	/* address of previous next element */	\
+}
+
+/*
+ * Tail queue access methods.
+ */
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_END(head)			NULL
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#define TAILQ_LAST(head, headname)					\
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+/* XXX */
+#define TAILQ_PREV(elm, headname, field)				\
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+#define	TAILQ_EMPTY(head)						\
+	(TAILQ_FIRST(head) == TAILQ_END(head))
+
+#define TAILQ_FOREACH(var, head, field)					\
+	for((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_NEXT(var, field))
+
+#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_NEXT(var, field), 1);			\
+	    (var) = (tvar))
+
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for((var) = TAILQ_LAST(head, headname);				\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_PREV(var, headname, field))
+
+#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
+	for ((var) = TAILQ_LAST(head, headname);			\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_PREV(var, headname, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Tail queue functions.
+ */
+#define	TAILQ_INIT(head) do {						\
+	(head)->tqh_first = NULL;					\
+	(head)->tqh_last = &(head)->tqh_first;				\
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
+		(head)->tqh_first->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(head)->tqh_first = (elm);					\
+	(elm)->field.tqe_prev = &(head)->tqh_first;			\
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.tqe_next = NULL;					\
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
+	*(head)->tqh_last = (elm);					\
+	(head)->tqh_last = &(elm)->field.tqe_next;			\
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(listelm)->field.tqe_next = (elm);				\
+	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
+} while (0)
+
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (0)
+
+#define TAILQ_REMOVE(head, elm, field) do {				\
+	if (((elm)->field.tqe_next) != NULL)				\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    (elm)->field.tqe_prev;				\
+	else								\
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
+	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
+		(elm2)->field.tqe_next->field.tqe_prev =		\
+		    &(elm2)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm2)->field.tqe_next;		\
+	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
+	*(elm2)->field.tqe_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_CONCAT(head1, head2, field) do {				\
+	if (!TAILQ_EMPTY(head2)) {					\
+		*(head1)->tqh_last = (head2)->tqh_first;		\
+		(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
+		(head1)->tqh_last = (head2)->tqh_last;			\
+		TAILQ_INIT((head2));					\
+	}								\
+} while (0)
+
+#endif	/* !_SYS_QUEUE_H_ */
diff --git a/compat/recallocarray.c b/compat/recallocarray.c
new file mode 100644
index 0000000..74a919a
--- /dev/null
+++ b/compat/recallocarray.c
@@ -0,0 +1,82 @@
+/*	$OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $	*/
+/*
+ * Copyright (c) 2008, 2017 Otto Moerbeek <[email protected]>
+ *
+ * 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 <errno.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "compat.h"
+
+/*
+ * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
+ * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
+ */
+#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
+
+void *
+recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
+{
+	size_t oldsize, newsize;
+	void *newptr;
+
+	if (ptr == NULL)
+		return calloc(newnmemb, size);
+
+	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
+		errno = ENOMEM;
+		return NULL;
+	}
+	newsize = newnmemb * size;
+
+	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
+		errno = EINVAL;
+		return NULL;
+	}
+	oldsize = oldnmemb * size;
+
+	/*
+	 * Don't bother too much if we're shrinking just a bit,
+	 * we do not shrink for series of small steps, oh well.
+	 */
+	if (newsize <= oldsize) {
+		size_t d = oldsize - newsize;
+
+		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
+			memset((char *)ptr + newsize, 0, d);
+			return ptr;
+		}
+	}
+
+	newptr = malloc(newsize);
+	if (newptr == NULL)
+		return NULL;
+
+	if (newsize > oldsize) {
+		memcpy(newptr, ptr, oldsize);
+		memset((char *)newptr + oldsize, 0, newsize - oldsize);
+	} else
+		memcpy(newptr, ptr, newsize);
+
+	explicit_bzero(ptr, oldsize);
+	free(ptr);
+
+	return newptr;
+}
diff --git a/configure.ac b/configure.ac
index 474f750..38393b1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,7 +12,6 @@ AM_SILENT_RULES([yes])
 # system files.
 AM_MAINTAINER_MODE([enable])
 AC_CONFIG_SRCDIR([i3lock.c])
-AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_MACRO_DIR([m4])
 
 dnl Verify macros defined in m4/ such as AX_SANITIZERS are not present in the
@@ -63,10 +62,57 @@ AC_CHECK_TYPES([mode_t, off_t, pid_t, size_t, ssize_t], , [AC_MSG_FAILURE([canno
 
 # Checks for library functions.
 AC_FUNC_FORK
-AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK
-AC_FUNC_STRNLEN
 AC_CHECK_FUNCS([atexit dup2 ftruncate getcwd gettimeofday localtime_r memchr memset mkdir rmdir setlocale socket strcasecmp strchr strdup strerror strncasecmp strndup strrchr strspn strstr strtol strtoul], , [AC_MSG_FAILURE([cannot find the $ac_func function, which i3lock requires])])
 
+# Check for functions with a compatibility implementation.
+AC_CONFIG_LIBOBJ_DIR(compat)
+AC_REPLACE_FUNCS([ \
+	getdtablecount \
+	freezero \
+	recallocarray \
+])
+
+# Look for imsg_init in libutil.
+AC_SEARCH_LIBS(imsg_init, util, found_imsg_init=yes, found_imsg_init=no)
+if test "x$found_imsg_init" = xyes; then
+	AC_DEFINE([HAVE_IMSG], [], [imsg in libutil])
+else
+	AC_LIBOBJ(imsg)
+	AC_LIBOBJ(imsg-buffer)
+fi
+
+# Look for a suitable queue.h.
+AC_CHECK_DECL(
+	TAILQ_CONCAT,
+	found_queue_h=yes,
+	found_queue_h=no,
+	[#include <sys/queue.h>]
+)
+AC_CHECK_DECL(
+	TAILQ_PREV,
+	found_queue_h=yes,
+	found_queue_h=no,
+	[#include <sys/queue.h>]
+)
+AC_CHECK_DECL(
+	TAILQ_REPLACE,
+	,
+	found_queue_h=no,
+	[#include <sys/queue.h>]
+)
+if test "x$found_queue_h" = xyes; then
+	AC_DEFINE([HAVE_QUEUE_H], [], [OpenBSD queue.h])
+fi
+
+# Look for /proc/$$.
+AC_MSG_CHECKING(for /proc/\$\$)
+if test -d /proc/$$; then
+	AC_DEFINE([HAVE_PROC_PID], [], [/proc])
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+fi
+
 # Checks for libraries.
 
 AC_SEARCH_LIBS([floor], [m], , [AC_MSG_FAILURE([cannot find the required floor() function despite trying to link with -lm])])
@@ -100,6 +146,7 @@ PKG_CHECK_MODULES([CAIRO], [cairo])
 # Checks for programs.
 AC_PROG_AWK
 AC_PROG_CPP
+AC_PROG_EGREP
 AC_PROG_INSTALL
 AC_PROG_MAKE_SET
 AC_PROG_RANLIB
@@ -112,7 +159,11 @@ AX_CHECK_COMPILE_FLAG([-Wunused-value], [AX_APPEND_FLAG([-Wunused-value], [AM_CF
 AC_SUBST(AM_CFLAGS)
 
 # Checks for header files.
-AC_CHECK_HEADERS([fcntl.h float.h inttypes.h limits.h locale.h netinet/in.h paths.h stddef.h stdint.h stdlib.h string.h sys/param.h sys/socket.h sys/time.h unistd.h], , [AC_MSG_FAILURE([cannot find the $ac_header header, which i3lock requires])])
+AC_CHECK_HEADERS([fcntl.h float.h inttypes.h limits.h locale.h netinet/in.h paths.h stddef.h stdint.h stdlib.h string.h sys/param.h sys/socket.h sys/time.h sys/types.h sys/uio.h unistd.h], , [AC_MSG_FAILURE([cannot find the $ac_header header, which i3lock requires])])
+# Check for various headers. Alternatives included from compat.h.
+AC_CHECK_HEADERS([ \
+	libutil.h \
+])
 
 AC_CONFIG_FILES([Makefile])
 
diff --git a/i3lock.c b/i3lock.c
index 134fdda..429214b 100644
--- a/i3lock.c
+++ b/i3lock.c
@@ -6,8 +6,6 @@
  * See LICENSE for licensing information
  *
  */
-#include <config.h>
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <pwd.h>
@@ -47,6 +45,7 @@
 #include "unlock_indicator.h"
 #include "randr.h"
 #include "dpi.h"
+#include "compat.h"
 
 #define TSTAMP_N_SECS(n) (n * 1.0)
 #define TSTAMP_N_MINS(n) (60 * TSTAMP_N_SECS(n))