constify data parameter in imsg_add() and imsg_compose()

ok deraadt@

src/lib/libutil/imsg.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: imsg.c,v 1.4 2013/02/01 15:22:18 gilles Exp $	*/
+/*	$OpenBSD: imsg.c,v 1.5 2013/12/26 17:32:33 eric Exp $	*/
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -164,7 +164,7 @@ imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 
 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)
+    pid_t pid, int fd, const void *data, u_int16_t datalen)
 {
 	struct ibuf	*wbuf;
 
@@ -234,7 +234,7 @@ imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
 }
 
 int
-imsg_add(struct ibuf *msg, void *data, u_int16_t datalen)
+imsg_add(struct ibuf *msg, const void *data, u_int16_t datalen)
 {
 	if (datalen)
 		if (ibuf_add(msg, data, datalen) == -1) {

src/lib/libutil/imsg.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: imsg.h,v 1.2 2010/06/23 07:53:55 nicm Exp $	*/
+/*	$OpenBSD: imsg.h,v 1.3 2013/12/26 17:32:33 eric Exp $	*/
 
 /*
  * Copyright (c) 2006, 2007 Pierre-Yves Ritschard <pyr@openbsd.org>
@@ -98,12 +98,12 @@ 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 *, u_int32_t, u_int32_t, pid_t,
-	    int, void *, u_int16_t);
+	    int, const void *, u_int16_t);
 int	 imsg_composev(struct imsgbuf *, u_int32_t, u_int32_t,  pid_t,
 	    int, const struct iovec *, int);
 struct ibuf *imsg_create(struct imsgbuf *, u_int32_t, u_int32_t, pid_t,
 	    u_int16_t);
-int	 imsg_add(struct ibuf *, void *, u_int16_t);
+int	 imsg_add(struct ibuf *, const void *, u_int16_t);
 void	 imsg_close(struct imsgbuf *, struct ibuf *);
 void	 imsg_free(struct imsg *);
 int	 imsg_flush(struct imsgbuf *);

src/lib/libutil/imsg_init.3

@@ -1,4 +1,4 @@
-.\" $OpenBSD: imsg_init.3,v 1.10 2013/11/13 21:04:46 benno Exp $
+.\" $OpenBSD: imsg_init.3,v 1.11 2013/12/26 17:32:33 eric Exp $
 .\"
 .\" Copyright (c) 2010 Nicholas Marriott <nicm@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 .\" OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: November 13 2013 $
+.Dd $Mdocdate: December 26 2013 $
 .Dt IMSG_INIT 3
 .Os
 .Sh NAME
@@ -57,7 +57,7 @@
 .Fn imsg_get "struct imsgbuf *ibuf" "struct imsg *imsg"
 .Ft int
 .Fn imsg_compose "struct imsgbuf *ibuf" "u_int32_t type" "uint32_t peerid" \
-    "pid_t pid" "int fd" "void *data" "u_int16_t datalen"
+    "pid_t pid" "int fd" "const void *data" "u_int16_t datalen"
 .Ft int
 .Fn imsg_composev "struct imsgbuf *ibuf" "u_int32_t type" "u_int32_t peerid" \
     "pid_t pid" "int fd" "const struct iovec *iov" "int iovcnt"
@@ -65,7 +65,7 @@
 .Fn imsg_create "struct imsgbuf *ibuf" "u_int32_t type" "u_int32_t peerid" \
     "pid_t pid" "u_int16_t datalen"
 .Ft int
-.Fn imsg_add "struct ibuf *buf" "void *data" "u_int16_t datalen"
+.Fn imsg_add "struct ibuf *buf" "const void *data" "u_int16_t datalen"
 .Ft void
 .Fn imsg_close "struct imsgbuf *ibuf" "struct ibuf *msg"
 .Ft void