From 1349f312f5849411e6d8d5306fa7a13a4c9fc1b2 Mon Sep 17 00:00:00 2001
From: eric <>
Date: Sun, 7 Jun 2009 05:56:25 +0000
Subject: [PATCH] Change the way fds passed over a socket are retreived on the
 receiving side.

Currently the receiver fetches an imsg via imsg_get() and if he expects
an fd, he then calls imsg_get_fd() to fetch the next fd queued on the
imsgbuf from which the imsg came.

This changes hides the fd queueing mechanism to the API user.  When closing
an imsg with an fd, the message is flagged so that the receiving end knows
it must dequeue the fd in imsg_get() and return it with the imsg structure.
This way there is no (less) possible screw up from imsg_get_fd() not being
called directly after imsg_get() by the user. The retreived imsg is
self-contained.

ok pyr@, "I like that" henning@
---
 src/usr.sbin/ntpd/imsg.c | 18 +++++++++++++++---
 src/usr.sbin/ntpd/imsg.h |  6 ++++--
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/usr.sbin/ntpd/imsg.c b/src/usr.sbin/ntpd/imsg.c
index a70cb77d..ff2f21ba 100644
--- a/src/usr.sbin/ntpd/imsg.c
+++ b/src/usr.sbin/ntpd/imsg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: imsg.c,v 1.15 2009/06/07 00:40:46 eric Exp $	*/
+/*	$OpenBSD: imsg.c,v 1.16 2009/06/07 05:56:25 eric Exp $	*/
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -28,6 +28,8 @@
 
 #include "imsg.h"
 
+int	 imsg_get_fd(struct imsgbuf *);
+
 void
 imsg_init(struct imsgbuf *ibuf, int fd)
 {
@@ -113,9 +115,14 @@ imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 	imsg->hdr.pid = ntohl(imsg->hdr.pid);
 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
 	ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
-	if ((imsg->data = malloc(datalen)) == NULL) {
+	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) {
@@ -216,6 +223,11 @@ 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->type = htonl(hdr->type);
 	hdr->len = htons(msg->wpos);
 	hdr->flags = htons(hdr->flags);
diff --git a/src/usr.sbin/ntpd/imsg.h b/src/usr.sbin/ntpd/imsg.h
index f70ddb04..427e3e14 100644
--- a/src/usr.sbin/ntpd/imsg.h
+++ b/src/usr.sbin/ntpd/imsg.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: imsg.h,v 1.2 2009/06/06 22:11:25 eric Exp $	*/
+/*	$OpenBSD: imsg.h,v 1.3 2009/06/07 05:56:25 eric Exp $	*/
 
 /*
  * Copyright (c) 2006, 2007 Pierre-Yves Ritschard <pyr@openbsd.org>
@@ -59,6 +59,8 @@ struct imsgbuf {
 	pid_t			 pid;
 };
 
+#define IMSGF_HASFD	1
+
 struct imsg_hdr {
 	u_int32_t	 type;
 	u_int16_t	 len;
@@ -69,6 +71,7 @@ struct imsg_hdr {
 
 struct imsg {
 	struct imsg_hdr	 hdr;
+	int		 fd;
 	void		*data;
 };
 
@@ -101,6 +104,5 @@ struct buf *imsg_create(struct imsgbuf *, u_int32_t, u_int32_t, pid_t,
 int	 imsg_add(struct buf *, void *, u_int16_t);
 void	 imsg_close(struct imsgbuf *, struct buf *);
 void	 imsg_free(struct imsg *);
-int	 imsg_get_fd(struct imsgbuf *);
 int	 imsg_flush(struct imsgbuf *);
 void	 imsg_clear(struct imsgbuf *);